Search

β-carotene (BCR) is the most abundant carotenoid, a colorant, antioxidant, and provitamin A. The extreme hydrophobicity of this hydrocarbon requires special mechanisms for distribution in aqueous media, including water-soluble carotenoproteins. However, all known carotenoproteins prefer oxygenated carotenoids and bind BCR inefficiently. Here, we present the crystal structure of the BCR-binding protein (BBP) from gregarious male locusts, which is responsible for their vivid yellow body coloration, in complex with its natural ligand, BCR. BBP forms an antiparallel tubular homodimer with α/β-wrap folded monomers, each forming a hydrophobic 47 Å long, coaxial tunnel that opens outward and is occupied by one s-cisC6-C7, all-trans BCR molecule. In the BCR absence, BBP accepts a range of xanthophylls, with reduced efficiency depending on the position and number of oxygen atoms, but rejects lycopene. The structure captures a pigment complex with a Takeout 1 protein and inspires potential applications of BBP as a BCR solubilizer. [Display omitted] • Crystal structure of a soluble protein in complex with β-carotene (BBP) determined • Extended BBP dimer has tubular subunits each binding a single β-carotene molecule • BBP is selective for β-carotene, rejects lycopene, and tolerates some xanthophylls • BBP apoform shows efficient ligand-assisted refolding when dissolved in 8 M urea Among soluble carotenoproteins, those binding carotenes are rare. Egorkin et al. determined the crystal structure of genuine β-carotene-binding protein (BBP) from gregarious locusts responsible for their yellow body coloration. Reconstitution studies revealed a selectivity for β-carotene, inability to bind lycopene, and unusual blue spectral shifts for carotenoids upon binding to BBP. [ABSTRACT FROM AUTHOR]

Computational Fluid Dynamics (CFD) modeling was used to study solid-liquid extraction applied to Robinia pseudoacacia. Experimental and simulation studies on maceration and continuous flow extractions were performed at various solid-solvent ratios and flow rates. To validate the CFD modeling results, parameters such as diffusivity or diffusion coefficient and kinetic parameter of the extracts were estimated from experimental kinetic data. A good agreement was found between the CFD model and the experimental data. The mass diffusivity of the extracts in the liquid phase was 1.7 x 10-7 m²/s (R² = 0.985) and 1.8 x 10-7 m²/s (R² = 0.992) for dihydrorobinetin (DHR) and robinetin (Rob). Moreover, the phase change coefficient was 1.2 x 10-4 and 1.6 x 10-41/s for DHR and Rob, respectively. In addition, static maceration was combined with continuous flow extraction. The optimal condition was 213 min of static maceration followed by a flow of 1 mL/min for 465 min to obtain yields of 45.18 and 6.64 mg/g DHR and Rob, respectively. [ABSTRACT FROM AUTHOR]

The formation of gaps serves as a pivotal force in shaping forest dynamics, especially in highly disturbed environments like coastal shelterbelt forests, but few studies have delved into evaluating the gap features in these forests and their impact on seedling regeneration. We investigated the gap features, microhabitat heterogeneity, and seedling regeneration of the woody species within canopy gaps of different sizes (small, medium, and large) in a mixed coastal forest of eastern China. We also evaluated the effects of gap features and microhabitat factors on seedling performance. The coastal forests under investigation had predominantly small gaps (56 %), with the large gaps only accounting for 16 %. Irrespective of gap size, the gap center was associated with higher light intensity, wind speed, and herb coverage but lower air humidity, litter thickness, and soil salinity than the gap edge positions. However, large gaps stood out with higher light intensity and wind speed but lower air humidity, litter thickness, herb coverage, and soil total nitrogen than small or medium gaps. Gap size also exerted a significant impact on the seedling regeneration pattern of woody species, for example, in small gaps, Robinia pseudoacacia seedlings had the highest species importance value, while in medium and large gaps, Ligustrum compactum showed the highest importance value. Upon the monitoring of seedling growth, we observed significant interspecific variations in the survival and growth rates of the seedlings, with R. pseudoacacia and L. compactum had the most potential to serve as the gap fillers. Gap size, within-gap position, and their interactions all significantly affected the seedling regeneration, but within-gap position was the primary feature affecting regeneration. A path analysis provided further clarification on the direct and indirect impacts of microhabitat factors on crucial metrics pertaining to the seedlings, in which light intensity and soil total nitrogen exhibited significant positive effects enhancing seedling regeneration. By contrast, wind speed and soil salinity exerted inhibitory influences that hindered the regeneration process. These findings bridge the knowledge gap in understanding the regeneration dynamic of woody species and the critical factors that shape seedling regeneration in natural gaps of coastal shelterbelt forests, which would facilitate the gap-based silviculture in the future to restore the degenerated shelterbelt forests of eastern China. [Display omitted] • The size of canopy gaps in coastal forests were relatively small. • The effects of within-gap positions on seedling regeneration should be considered. • Light intensity and soil total nitrogen greatly advanced the seedling regeneration. • Wind speed and soil salinity suppressed the regeneration. • Robinia pseudoacacia and Ligustrum compactum are most suitable species for gap filling. [ABSTRACT FROM AUTHOR]

Both sulfur (S) supply and legume-rhizobium symbiosis can significantly contribute to enhancing the efficiency of phytoremediation of heavy metals (HMs). However, the regulatory mechanism determining the performance of legumes at lead (Pb) exposure have not been elucidated. Here, we cultivated black locust (Robinia pseudoacacia L.), a leguminous woody pioneer species at three S supply levels (i.e., deficient, moderate, and high S) with rhizobia inoculation and investigated the interaction of these treatments upon Pb exposure. Our results revealed that the root system of Robinia has a strong Pb accumulation and anti-oxidative capacity that protect the leaves from Pb toxicity. Compared with moderate S supply, high S supply significantly increased Pb accumulation in roots by promoting the synthesis of reduced S compounds (i.e., thiols, phytochelatin), and also strengthened the antioxidant system in leaves. Weakened defense at deficient S supply was indicated by enhanced oxidative damage. Rhizobia inoculation alleviated the oxidative damage of its Robinia host by immobilizing Pb to reduce its absorption by root cells. Together with enhanced Pb chelation in leaves, these mechanisms strengthen Pb detoxification in the Robinia -rhizobia symbiosis. Our results indicate that appropriate S supply can improve the defense of legume-rhizobia symbiosis against HM toxicity. [Display omitted] • High S supply significantly increased Pb accumulation in roots by promoting the synthesis of reduced S compounds. • High S strengthened the antioxidant system in leaves of Robinia under Pb. • Weakened defense at deficient S supply indicated by enhanced oxidative damage. • Root of Robinia has a strong Pb accumulation and anti-oxidative capacity that protect the leaves from Pb toxicity. • Rhizobia inoculation alleviated the oxidative damage of its Robinia host by immobilizing Pb to reduce its absorption in roots. [ABSTRACT FROM AUTHOR]

• Seedling responses to drought were assessed by cultivation experiments. • R. pseudoacacia had higher drought resilience than P. tabuliformis. • The daily ET was highly promoted by R n when rainfall > 300 mm. • P. tabuliformis had higher water use efficiency than R. pseudoacacia. Seedling survival is vital for ecological restoration and carbon neutrality on the Loess Plateau, yet large-scale afforestation in North China has reduced soil water availability in arid and semi-arid areas, complicating efforts to sustain young trees. The water consumption strategies of commonly planted trees and their eco-hydrological responses to varying water conditions remain unclear. Two common tree seedlings, Robinia pseudoacacia and Pinus tabuliformis , were cultivated using soil column experiments to simulate the initial stage of afforestation. Six irrigation treatments (in 100, 200, 300, 400, 500 and 600 mm) were applied to investigate the effect of rainfall recharge on tree physiological traits and water consumptions from June to August in 2021–2022. Results indicated that the both species experienced reduced leaf gas exchange under drought (<200 mm) and flood (>500 mm), and it was decreased when the vapour pressure deficit >2 kPa. R. pseudoacacia exhibited lower stomatal conductance and transpiration but higher leaf water use efficiency than P. tabuliformis under drought, indicating better drought resilience. The daily evapotranspiration (ET) of the two species was both limited by soil moisture when irrigation <300 mm, while it was promoted by solar radiation when irrigation > 300 mm. A precipitation threshold of 300 mm was identified as critical for seedling growth. Moreover, the mean ET of R. pseudoacacia and P. tabuliformis was 190.43–648.40 and 196.30–620.40 mm, respectively, in the 100–600 mm irrigation treatments during June to August in 2021–2022, and the mean water use efficiency of P. tabuliformis was 55.1 % higher than that of R. pseudoacacia at the plant level. This study will provide critical insights into water consumption strategies to water stress on early afforestation, offering guidance for species selection and ecological restoration on the Loess Plateau. [ABSTRACT FROM AUTHOR]

The escalating environmental repercussions of pesticide use in pest and disease management underscore the urgency for alternative strategies. One promising avenue involves harnessing natural antifungal properties present in plant extracts. This study aimed to assess the antifungal efficacy of aqueous and ethanolic extracts from five medicinal plants, viz., C. sativa L., S. moorcraftiana L., S. nigrum L., F. vesca L., and R. pseudoacacia, which were screened for their antifungal activity against various soil-borne fungi, viz., A. niger , A. flavus , A. terreus , R. stolonifer, M. mucedo, F. oxysporum, A. alternata, P. notatum, C. cladosporioides, and C. lunata. Phytochemical analysis exhibited the presence of phenols, alkaloids, tannins, flavonoids, quinines, and terpenoids. Results revealed potent antifungal activity across all tested fungi, significantly inhibiting mycelial growth compared to control. S. nigrum and C. sativa extracts exhibited the highest efficacy against multiple fungal pathogens. The inhibition in mycelial growth in ethanolic and aqueous plant extracts of C. sativa against A. niger varies between 3.00 mm to 6.00 mm and 4.00 mm–6.33 mm, against A. flavus 3.33 mm–11.66 mm and 4 mm–12.66 mm, A. terreus (3.00 mm–6.00 mm and 3.66 mm–7.00 mm), R. stolonifer (3.00 mm–5.33 and 3.66 mm–6.33 mm), M. mucedo (8.33 mm–17.66 mm and 9.66 mm–18.66 mm), F. oxysporum (6.66 mm–12.33 mm and 7.33 mm–13.33 mm), A. alternata (4.66 mm–11.33 mm and 5.33 mm–14.00 mm), P. notatum (9.33 mm–23.00 mm and 9.66 mm–24.33 mm), C. cladosporioides (4.33 mm–8.66 mm and 5.33 mm–9.66 mm), and C. lunata (14.00 mm–20.33 mm and 17.00 mm–21.33 mm) in different concentrations of plant extracts respectively. Likewise, the inhibition in mycelial growth in ethanolic and aqueous plant extracts of S. nigrum against A. niger at different concentrations varies between 8.00 mm to 17.66 mm and 9.00 mm–18.66 mm, A. flavus (8.33 mm–12.66 mm and 9 mm–14 mm), A. terreus (2.33 mm–5.66mm and 3 mm–7 mm), R. stolonifer (13.33 mm–20.33 mm and 17.66 mm–24.66 mm), M. mucedo (10.66 mm–12.00 mm and 11.66 mm–13.00 mm), F. oxysporum (15.66 mm–22.33 and 18.00 mm–24.00 mm), A. alternata (10.66 mm–13.00 mm and 11.66 mm–14.00 mm), P. notatum (5.33 mm–13.33 mm and 6.33 mm–18.66 mm, C. cladosporioides (3.33 mm–7.66 mm and 4.00 mm–8.00 mm), and C. lunata (3.66 mm–6.33 mm and 4.66 mm–6.66 mm), respectively. These findings suggest that these plant extracts have the potential to be natural fungicides, providing promising alternatives for disease management in agriculture. • Escalating environmental consequences of pesticide usage prompt search for alternatives. • Study investigates antifungal properties of extracts from five medicinal plants viz, Cannabis sativa, Salvia moorcraftiana, Solanum nigrum, Fragaria vesca , Robinia pseudoacacia. • Target fungi: Aspergillus niger, Aspergillus flavus, Aspergillus terreus, Rhizopus stolonifer, Mucor mucedo, Fusarium oxysporum, Alternaria alternata, Penicillium notatum, Cladosporium cladosporioides, and Curvularia lunata. • Solanum nigrum and Cannabis sativa extracts most effective; Robinia pseudoacacia least effective. • Potential for these plant extracts as natural fungicides, offering alternative disease management methods. [ABSTRACT FROM AUTHOR]

As soil structural units, soil aggregates are crucial in soil total nitrogen and organic carbon sequestration, which has been gradually discovered by scholars. However, how aggregates affect the storage of soil organic carbon and soil total nitrogen pools through aggregate proportion and their carbon and nitrogen content, remain unclear. Here, we examined soil aggregate composition, and the characteristics of aggregate-associated organic carbon and total nitrogen under different recovery years (15, 30, and 45 years) to explore the contribution in different sizes aggregates to soil carbon and nitrogen accumulation and its driving factors across different vegetation types of Natural grasslands (NG), Caragana korshinskii plantations (CK), and Robinia pseudoacacia plantations (RP) on the loess hilly areas. The results indicate that microaggregates dominated all soils, with the average proportions of 44.91 % in NG, 44.47 % in CK, and 42.19 % in RP. Yet, with the increase of recovery years, the proportion of microaggregates reduced and the proportion of macroaggregates rised. After vegetation restoration, the contents of carbon and nitrogen in soil and aggregates were increased. In addition, macroaggregate contributed more than 71.5 %, 67.0 %, and 67.9 % to organic carbon and total nitrogen stocks in NG, CK, and RP, respectively. The result that highlights the fact that macroaggregate is critical drivers of soil organic carbon and total nitrogen accumulation in different vegetation types. The growing percentage of macroaggregates was a key factor in the accumulation of soil organic carbon and total nitrogen stocks in NG, while the increasing percentage of macroaggregates and their associated carbon and nitrogen contents jointly led to an explicit increase in soil organic carbon and total nitrogen stocks in CK and RP. Overall, our findings revealed the soil organic carbon and total nitrogen accumulation process mediated by macroaggregates during vegetation recovery period on the Loess Plateau, providing a scientific basis for a deeper understanding of the potential of soil organic carbon and total nitrogen sequestration during the vegetation restoration in fragile habitats. [Display omitted] • Revegetation decreased microaggregate and increased macroaggregate proportions. • C and N contents in bulk soil and aggregates were promoted after restoration. • Macroaggregates plays a key role in C and N accumulation in all vegetation types. • Increased macroaggregate proportion promoted C and N accumulation in NG. • Increased C and N contents and proportion of macroaggregate promoted C and N accumulation in CK and RP. [ABSTRACT FROM AUTHOR]

Vegetation restoration can increase soil organic carbon (SOC) sequestration through the physical protection of soil aggregates. However, the soil aggregate stability and C flow pathway associated with long-term plantation restoration have not yet been fully characterized. Here, we conducted a study on Robinia pseudoacacia plantations at different recovery stages, studied the distribution and stability of aggregates, analysed the aggregate-associated organic carbon (OC) content and δ13C value, and quantified the aggregate C flow pathway. The results revealed that vegetation restoration increased the proportion of large macroaggregates (LMAs) and decreased the proportion of small macroaggregates (SMAs), with no changes observed in the proportion of microaggregates (MIAs) or silt + clay (SC) at 0–20 cm. The indices of aggregate stability, namely, the mean weight diameter (MWD), geometric mean diameter (GMD) and structural stability index (SSI), increased under vegetation restoration at 0–20 cm, with maximum values of 3.83 mm, 2.88 mm, and 2.00 %, respectively, at 35 years of age (35Y). The OC content of the LMAs increased from 10.96 to 21.64 g kg−1 and from 7.27 to 10.05 g kg−1 in the 0–20 cm and 20–40 cm layers, respectively. LMAs and SMAs had the greatest contributions to SOC accumulation in the 0–20 cm and 20–40 cm layers, respectively. The δ13C value increased with decreasing aggregate size. The C flow pathway was from macroaggregates to MIAs or SC. Compared with abandoned farmland, vegetation restoration decreased the aggregate C flow intensity in the 0–20 cm layer. The soil aggregate stability and aggregate-associated OC content decreased with increasing soil depth, but the soil δ13C value exhibited the opposite trend. Vegetation restoration regulated soil aggregate stability by influencing the fine root biomass (FRB) and SOC content. In summary, our analysis offers a valuable reference for the controlling effect of aggregation on C stability influenced by vegetation restoration. • Vegetation restoration increased soil aggregate stability. • Vegetation restoration favours SOC stability by decreasing the soil δ13C value. • C flow and stabilization were from macroaggregate to microaggregate or silt + clay. • Plantation decreased the C flow intensity compared to that in farmland (0–20 cm). [ABSTRACT FROM AUTHOR]

Although the microbial fixation of CO 2 is a key process in regulating soil carbon cycling, the effects of vegetation type on microbial carbon-fixing pathways and their driving factors in soils have yet to be sufficiently established. In this study, based on macro-genome sequencing and other analytical methods, we sought to determine the soil physicochemical properties, soil organic carbon contents, carbon-fixing microorganisms, and carbon-fixing genes in areas of farmland (FL), grassland (GL). Robinia pseudoacacia (RP), Caragana korshinskii (CAK), and Prunus sibirica (PS) in the Wuliwan watershed of the Loess Plateau region of China. Our findings revealed that the organic carbon contents of the assessed soils increased in the following order: FL < GL∼PS < CAK < RP (P < 0.05). Re-vegetation-based restoration was found to enhance soil organic carbon pool stability. Compared with farmland soil, the proportions of recalcitrant organic carbon had increased by 6 % and 9 % in the soil at sites that had undergone restoration with C. korshinskii and R. pseudoacacia respectively. Among the identified carbon fixation pathways, the DC/4-HB cycle had the highest relative abundance of 25.10–25.52 %. The dominant groups of carbon-fixing microorganisms were identified as Actinobacteria and Proteobacteria , accounting for over 60 % of the total abundance. Furthermore, analysis based on a partial least squares path model revealed labile organic carbon and soil nitrate nitrogen as the primary drivers of carbon fixation pathways. Collectively, our findings in this study provide evidence to indicate that restoration of vegetation on the Loess Plateau can contribute to increases in soil organic carbon content and stability and the abundance of carbon-fixing microorganisms, with R. pseudoacacia and C. korshinskii having the most significant effects in this regard. These findings have important implications for restorative vegetation carbon pool management and provide additional perspectives for understanding global carbon cycling. • Afforestation increases soil carbon content and proportion of recalcitrant organic carbon. • The DC/4-HB cycle had the highest relative abundance. • Actinobacteria and Proteobacteria are the main phyla of CO 2 fixing. • Soil labile organic carbon and nitrate nitrogen are the key factors driving microbial CO 2 fixation. [ABSTRACT FROM AUTHOR]

To foster sustainable forest development amid global warming, it is imperative to enhance the quality of existing forest stands while avoiding excessive depletion of soil moisture. This study established 24 Robinia pseudoacacia L. standard plots (40 × 40 m2) in the Caijiachuan watershed, located in the gully region of the Loess Plateau, Shanxi Province, China, to monitor soil moisture content from 2007 to 2021. Additionally, the study examined the influence of 19 ecological factors, including climate, topography, and stand characteristics, on soil moisture. The findings indicated a sustained decline in soil moisture storage across the 0–200 cm soil profile, with significant depletion at 0–140 cm. The soil moisture content at depths of 80–200 cm was critically low, resulting in a "dry soil layer" during years with low precipitation. Climatic factors (average annual temperature and annual precipitation) and stand factors (uniform angle index, stand density, litter thickness, and Simpson diversity index of the shrubs) emerged as dominant factors impacting soil moisture variations. An increase in average annual temperature due to global warming, compounded by suboptimal stand density, primarily drove soil moisture depletion. Using a multivariate optimization equation to model the relationship between dominant factors and soil moisture storage, this study recommends a dynamic stand management strategy. This strategy involves selective thinning or replanting of Robinia pseudoacacia L. trees, targeting a gradual reduction in optimal stand density from 1500 to 1000 plants·ha−1 over the next two decades. Additionally, transitioning stand spatial arrangements from uniform or clustered to random distributions, maintaining ideal litter thickness (2.43–2.47 cm), and enhancing shrub diversity are advisable. Such measures can alleviate soil moisture deficits in Robinia pseudoacacia L. stands attributable to global warming, thereby promoting the Loess Plateau's sustainable forestry advancement. [Display omitted] • Deteriorating soil moisture conditions in the plantations of the Loess Plateau. • Global warming and inappropriate stand densities are causes of soil moisture loss. • Recommendations for dynamic, decreasing density regulation to optimize stands. • Contribution to sustainable forest development amid global warming. [ABSTRACT FROM AUTHOR]

[Display omitted] • Initial litter quality played a significant role in regulating litter decomposition. • Litter decomposition in pure and mixed plantations lacked home-field advantage. • Similar microbial composition in arid environments contributed to the lack of HFA. • The mixing effect of litter decomposition interfered with the home-field advantage. • This study supports the context-dependency of the home-field advantage hypothesis. Litter decomposition plays a critical role in the nutrient cycling of terrestrial ecosystems. According to the home-field advantage (HFA) hypothesis, litter decomposes more rapidly in its home habitat (where it originates) compared to other habitats (referred to as away). Although this hypothesis has been widely tested in natural forests, it remains controversial and lacks support for plantations, especially in dry ecosystems where microbial activities are limited. To clarify it, the present study investigated litter mass loss, nutrient dynamics, and decomposer communities in a 549-day reciprocal transplant experiment of litter decomposition in Robinia pseudoacacia (RP) and Hippophae rhamnoides (HR) pure plantations and their mixed plantations (5:5 and 8:2 ratios) on the Loess Plateau, China. The rate of mass, carbon (C), nitrogen (N) and phosphorus (P) loss in litter differed depending on litter type of species component and plantation type they were placed in. HR litter lost mass and released C, N, and P fastest, irrespective of plantation type. The overall mass loss of the four litter types were the fastest under 5:5 mixed plantations. However, litter did not decompose more rapidly in its home soil compared to the away soil. The structural equation modeling revealed that initial litter quality played a significant role in regulating the loss of C and N across decomposition stages, while the climate variations and microbial chemistry also contributed to the process. The similarity in soil microbial communities across plantation types, along with the limited interaction between litter and microbes in arid environments, could help elucidate the lack of HFA, with other factors such as the litter type exerting a minor influence. In summary, this study does not substantiate the hypothesis of home-field advantage but supports its context-dependency. Thus, regional heterogeneity should be taken into account when predicting the carbon cycle of forest ecosystems in future studies. [ABSTRACT FROM AUTHOR]

The natural durability of wood against basidiomycetes is an important reference value for the use of wood species as construction timber. However, only three test fungi must be used for durability testing according to European standards, although a much larger number of wood-destroying basidiomycetes are known. Here, we used a modified test protocol of the EN 113-2 standard to examine the abilities of two strains of Perenniporia meridionalis , one of them freshly isolated and the other being in culture for 23 years, to degrade wood of beech (Fagus sylavatica), English oak (Quercus robur) and black locust (Robinia pseudoacacia) by measuring the mass loss after 16 weeks of incubation at 22 °C, 26 °C and 30 °C, and 70 % relative humidity. The obligatory test fungus Trametes versicolor was used as a reference. We found that the degradation abilities of all fungal isolates increased with higher temperatures. Furthermore, the freshly isolated strain of P. meridionalis caused higher mass loss than the long-term cultured strain. For beech and black locust wood the highest mass loss was caused by Trametes versicolor , while for English oak it was the fresh isolate of Perenniporia meridionalis. In conclusion, our study demonstrates that Perenniporia meridionalis is a potent wood decaying fungus, which exhibited a higher degradation ability for English oak than the obligatory used white rot test fungus Trametes versicolor , and thus could become a useful indicator in the future when evaluating durability of this type of wood. • P. meridionalis is a potent decay agent of English oak and European beech. • Black locust wood is more resistant against P. meridionalis. • Fungal wood degradation activity increased with incubation temperature. [ABSTRACT FROM AUTHOR]

• Rainfall exclusion reduced both replenishment and consumption of forest soil water. • Sustained reduction in rainfall input caused formation of a dried soil layer. • Rainfall exclusion caused fine root distribution more concentrating to shallow layer. • Dried soil layer hindered root development and water consumption in deeper soil. Soil drying is frequently observed in mature forests in water-limited regions, and poses a threat to sustainable development of the ecosystems. Herein, we assessed the effects of rainfall reduction on the water-use characteristics of a black locust (Robinia pseudoacacia) plantation in a sub-humid region of the Loess Plateau, China. Paired plots were established in the plantation, including a treatment with 30 % throughfall exclusion and a control. We comparatively investigated the dynamics of soil water content (SWC) throughout the profile in the two plots after four years of the treatment and determined the contribution of soil water storage (SWS) in each soil layer to water consumption according to the SWS budget. While SWC across the profile in the control plot showed general responses to replenishment and consumption under rainy and dry weather conditions, respectively, the treatment plot had smaller replenishment and consumption in deep layers, causing an aggravated deficiency in SWS and the formation of a temporary dried soil layer (DSL) at a depth of 55–100 cm. The cumulative decrement in SWS during each dry event (consecutive rainless days of ≥ 5-day duration) in the control plot was significantly correlated with SWC at 100–160 cm, suggesting a substantial contribution of water consumption from this layer. However, the treatment plot showed a major contribution to water consumption from the 0–100 cm soil layer during dry events. The vertical distribution of the root system supports these findings, which differed from our hypothesis that deep soil water would be used in response to reduced rainfall input. The distribution of fine root density in the treatment plot was relatively shallower (0–22 and 0–73.1 cm accounting for 50 % and 90 % of fine roots, respectively) than in the control plot (0–31.2 and 0–103.5 cm for corresponding values). These findings indicate that soil water deficiency resulted in the formation of DSL, which hindered water consumption and root development deeper in the soil profile. The severity and recovery of the DSL may be jointly determined by the vertical distribution of SWS and transpiration demand of the plantation. These findings provide insights for water resource management and sustainable development of the plantations in this region. [ABSTRACT FROM AUTHOR]

• Clarified the synergy between stand regeneration and forest ecological function. • Identified the primary factors influencing natural regeneration in RP stands. • Formulated an optimization model to enhance stand regeneration capacity. • Proposed measures for advancing high-quality forestry on the Loess Plateau. Contemporary forestry research prioritizes the advancement of high-quality forestry, especially in ecologically vulnerable areas. To this end, enhancing the ecological function and natural regeneration capacity of planted forest stands is crucial. This study investigated synergistic or trade-off relationships between stand regeneration capacity and the ecological functions (including water conservation, soil conservation, carbon sequestration, and understory plant diversity) of Robinia pseudoacacia L. (RP) plantations in the Caijiachuan watershed of the Loess Plateau using Root Mean Square Deviation. The results indicated that stand regeneration capacity exhibited synergistic, moderate trade-off, and high trade-off relationships with soil and water conservation, stand carbon sequestration, and understory plant diversity, respectively. Notably, stand regeneration capacity had a synergistic relationship with the overall forest ecological function (sum of the above functions), suggesting that the overall forest ecological function can be simultaneously improved by enhancing stand regeneration capacity. Redundancy analyses revealed that the regeneration capacity was primarily influenced by soil moisture content (SMC), stand density (SD), total transmitted light, herbaceous species richness, litter accumulation, and soil available phosphorus (AP). According to the stand optimization model, the highest regeneration capacity of RP was observed under the following conditions: 1742 trees·hm−2 for SD, 15.29 % for SMC (higher than the mean value of 33.53 % for the existing RP), 41.69 mg·kg−1 for AP (higher than the mean value of 15.84 %), and 1.84 for LAI (lower than the mean value of 20.0 %). Therefore, to achieve the simultaneous enhancement of the regeneration capacity and overall ecological function of RP stands, foresters should prioritize adjusting SD to an appropriate range through thinning or replanting. Additionally, regular pruning of specific branches of individual trees is essential to mitigate the adverse effects of high LAI on stand regeneration. Where feasible, soil moisture and nutrients can also be increased, but excessive levels of AP should be avoided. [ABSTRACT FROM AUTHOR]

[Display omitted] • Vegetation restoration on the Loess Plateau increased the extend and depth of infiltration. • Vegetation restoration on the Loess Plateau has altered the pattern of uniform water infiltration, resulting in a distinct preferential flow in the infiltration processes. • Mixed-mode afforestation is better than single-dominant-species afforestation to promote precipitation infiltration. • The preferential flow phenomenon was more pronounced in the natural secondary forest than that in plantation forests. In order to improve the fragile ecological environment, the Loess Plateau region of China has implemented a large number of long-term forest vegetation restoration projects. Infiltration, as an important part of the hydrological cycle, is also changing with vegetation restoration, and a comprehensive study of these changes is an essential aspect of evaluating the effectiveness of vegetation restoration. In the study, three typical forest vegetation types in the Loess Plateau were selected to investigate and analyse infiltration characteristics and infiltration patterns by staining tracer experiments. The results showed that (1) vegetation restoration increased the extend and depth of infiltration. (2) The extent of infiltration in mixed plantation forest of Pinus tabulaeformis and Robinia pseudoacacia was better than that in pure Pinus tabulaeformis plantation forest. (3) Vegetation restoration resulted in more pronounced preferential flow phenomenon in the infiltration processes. (4) The preferential flow phenomenon was more pronounced in the natural secondary forest than in plantation forests, especially if the amount of infiltrated water was low. (5) The extent of infiltration was mainly influenced by the infiltration water volume, soil water content, and total soil porosity; and the degree of preferential flow development was mainly influenced by the infiltration water volume, soil organic matter, and root distribution. At present, vegetation restoration on the Loess Plateau can play a role in promoting precipitation infiltration, and mixed-mode afforestation is better than single-dominant-species afforestation to fulfil this function of forests. [ABSTRACT FROM AUTHOR]

[Display omitted] • SCN and SSA increase while E decreases with Robinia pseudoacacia restoration. • Change in soil charge properties mostly due to clay, silt, and organic matter. • Vegetation restoration increases ion-soil particle electrostatic adsorption energy. • Revegetation and ion concentration determine ion diffusion activation energy. Vegetation restoration is an effective strategy for restoring soil function and improving soil quality in ecologically fragile areas; both soil nutrient conservation and interfacial transport are profoundly affected by it. However, reports elucidating the impacts of this on ion adsorption at the soil-water interface from an electrochemical perspective are scarce. This study selected soils from artificial Robinia pseudoacacia forests of different ages in the loess hilly region, with cropland serving as the control, to investigate changes in soil basic physicochemical properties, surface electrochemical properties, and the adsorption processes of cations (Na+, Ca2+, and Mg2+) at the soil-water interface, as well as the intrinsic relationships among these factors. Results show that soil surface charge number (SCN) and specific surface area (SSA) increase with the planting years of vegetation, while the electric field strength (E) decreases. Clay, silt, and organic matter are the major contributing factors to the changes in soil surface electrochemical properties during vegetation restoration, which in turn drive the response of base-cation interface adsorption kinetics. For a given cation type, the adsorption rate constants and equilibrium adsorption amounts increase with increasing SCN and SSA. The electrostatic adsorption energy between ions and soil surfaces increases with the years of vegetation restoration, with the greatest increase in energy proportion for Na+ (3.037 %), Ca2+ (1.805 %), and Mg2+ (1.670 %). Correspondingly, the diffusion activation energy involved in ion interface adsorption reaction kinetics decreases with the increase in vegetation restoration years, leading to more thorough ion exchange adsorption reactions and larger equilibrium adsorption amounts. The diffusion activation energy sequence for ions is Na+ > Mg2+ > Ca2+, while the observed sequence for cation equilibrium adsorption amounts is Ca2+ > Mg2+ > Na+. This study provides model predictions and scientific references for nutrient conservation and interfacial transport during the vegetation restoration process. [ABSTRACT FROM AUTHOR]

Forests are exposed to human-induced and natural disturbances generating opportunities for new species to establish, including non-native woody species. Understanding how disturbance characteristics interact with the site context and invasive species traits to drive invasion processes is crucial for designing sustainable forest management. Here, we use the case study of the deciduous broadleaved forest belt of Canton Ticino (Switzerland) to identify the main factors determining the presence of non-native invasive woody species in recently disturbed forests. We identified and selected 851 forest gaps caused by natural, silvicultural or other anthropogenic disturbances between 2008 and 2015. For each gap, the presence of non-native invasive woody species as well as the characteristics of the corresponding landscape, site, and the gap itself were determined. For the six most frequent non-native invasive woody species, we identified the parameters that influenced their presence by means of modelling approach. The resulting variable coefficients were then used to create maps of colonisation risk. Among the six target species (i.e., Ailanthus altissima, Buddleja davidii, Robinia pseudoacacia, Paulownia tomentosa, Prunus laurocerasus, and Trachycarpus fortunei), the factors influencing their presence were either shared (e.g., distance to the next colonisation hotspot), partially shared (e.g., distance to buildings, altitude, aspect), or completely species-dependent (e.g., topography, slope, distance to powerlines). Like in other mountainous areas, non-native invasive woody species concentrate at low altitudes and near densely populated areas where hotspots of seed-bearing individuals can be found. Moreover, different life-history groups (i.e., wind-dispersed pioneer species vs. animals-dispersed evergreens) shared specific invasion patterns characteristics. In addition to general management strategies, we argue that more species-specific strategies should be adopted to prevent the colonisation by non-native invasive woody species. In this context, the consideration of seed-bearing individual hotspots should be given highest priority, followed by the type and the characteristics of the disturbance. [Display omitted] • Disturbances and landscape feature modulate invasive woody species colonisation. • Colonisation patterns are either shared or species-specific. • Invasive woody species concentrate at low altitudes near seed-bearing individuals. • Removing seed-bearing individuals before a silvicultural intervention is crucial. • Colonization risk maps are provided to plan accompanying measures after a disturbance. [ABSTRACT FROM AUTHOR]

[Display omitted] • The replenishment showed an increase–decrease trend with increased thinning intensity. • A 35 % thinning intensity improved the replenishment of soil water by rainfall. • The leaf area index and initial soil water content controlled the replenishment. • Reasonable thinning intensity is determined by replenishment and retention. Soil water plays a key role in vegetation growth and recovery, mainly replenished by rainfall in the water-limited areas. Thinning is an important practice for forest reconstruction and soil water regulation. However, the effects of different thinning intensities on the dynamics of soil water and its replenishment by rainfall have been inadequately quantified, which could provide a guide for reasonable thinning intensity determination for in high-density forests from a hydrological perspective. In this study, one nonthinning plot and 5 plots with different thinning intensities, i.e., 35 % (light), 45 % (medium), 55 % (moderate), 65 % (heavy) and 80 % (extremely heavy) in Robinia pseudoacacia plantations, which are widely planted on the Loess Plateau, were set up. The volumetric soil water content (SWC) at 0–200 cm depths and rainfall were observed simultaneously and continuously for up to two years. The soil properties and vegetation structure in each plot were also measured regularly. The results showed that (1) the SWC in all the thinning plots was significantly greater than that in the nonthining plot (P < 0.05). (2) The replenishment increased with increasing thinning intensity, and then decreased after reaching a maximum at T 35 % under most rainfall events except for light events. (3) The variations in the soil water response characteristics among the plots with different thinning intensities were mainly significantly correlated with the initial soil water content (ISWC), leaf area index (LAI) and understorey vegetation characteristics (P < 0.05). (4) Based on the relationship between soil water replenishment and retention with thinning intensity and stand density, quantitative equations were fitted to determine the reasonable thinning intensity (22–28 %) and retained stand density (1019–1091 trees/ha), respectively. Our study concluded that thinning could effectively improve soil water, especially light thinning, which could obviously enhance the replenishment of soil water by rainfall in Robinia pseudoacacia plantations. This study can provide a reference for determining forest thinning intensity or stand retention density, which is beneficial for water and reforestation management in water-limited regions. [ABSTRACT FROM AUTHOR]

Rhizobia can be used to enhance the phytoremediation of cadmium-contaminated soils by legumes, and a symbiotic nitrogen-fixing system has been shown to reshape the structure of rhizosphere microbiota in a mining area. However, little is known about the temporal dynamics and possible roles of rhizosphere microbiota in rhizobia-enhanced phytoremediation. A rhizobox experiment was conducted using Robinia pseudoacacia alone or inoculated with Mesorhizobium loti HZ76 under greenhouse conditions. Rhizosphere bacterial communities were characterized over a 90-day period at three levels of cadmium (determined by the distance from the mining area; uncontaminated: 0.08 mg kg−1, contaminated: 0.39 and 1.72 mg kg−1). Rhizobial inoculation considerably improved the phytoremediation efficiency, such as increasing plant biomass and cadmium accumulation by approximately two times at 90 days after planting. The bacterial community structure shifted remarkably with increasing duration of remediation. Bacterial diversity exhibited a decreasing trend in the first 60 days and then recovered at 90 days. Despite having no discernible impact on the bacterial community structure in the rhizosphere, rhizobial inoculation enabled the enrichment of potentially beneficial taxa (e.g., Microvirga , Mesorhizobium , Diaphorobacter , Steroidobacter , Brevundimonas) with resistance to heavy metals and involvement in nutrient cycling. The bacterial co-occurrence networks of low and high cadmium-contaminated soils showed the highest average degree and clustering coefficient at 60 and 30 days, respectively. Some bacterial taxa involved in nitrogen fixation (e.g., Rhizobacter , Mesorhizobium), denitrification (e.g., Niastella , Nitrospira), and carbon turnover (e.g., Solirubrobacter , Brevundimonas) were found to be potential keystone taxa. The collective findings clarify possible mechanisms by which rhizosphere bacteria participate in phytoremediation of cadmium-contaminated mining soils using the R. pseudoacacia–M. loti symbiotic system. • Mesorhizobium loti was used to enhance phytoremediation by Robinia pseudoacacia. • The best effect of rhizobial inoculation was observed in low Cd-contaminated soil. • The responses of rhizosphere bacteria to rhizobial inoculation were time-dependent. • Rhizosphere bacterial communities showed temporal variability during remediation. • Potential keystone taxa played distinct roles at different remediation stages. [ABSTRACT FROM AUTHOR]

• Significant variation was found in the seasonal and annual litterfall biomass of the three types of forest stands. • The seasonal dynamics of litterfall biomass of twigs, leaf and fruits exhibited a 'unimodal pattern' with a peak in October. • Temperature played a key role in the climatic factors affecting forest litterfall processes. Litterfall is a link in the energy flow and material cycling of ecosystems, which maintain the primary productivity of forests. However, there is no consensus regarding the factors driving for the litterfall biomass dynamics because of the high spatial–temporal heterogeneity. Herein, we investigated and compared the stand litter biomass, litterfall biomass, including its components in the pure Robinia pseudoacacia forest (RL), pure Platycladus orientalis forest (PL), and mixed forest of Robinia pseudoacacia and Platycladus orientalis (ML) from 2020 to 2022 in the gully erosion area of the Loess Plateau. Correlation and multiple regression analyses were used to study the relationships among the amount of stand litter, litterfall biomass, and seasonal temperature and precipitation. Significant variation was found in the seasonal and annual litterfall biomass of the three types of forest stands. Annual stand litter biomass was in the order PL > RL > ML, whereas the annual litterfall biomass was in the order RL > ML > PL. The seasonal dynamics of litterfall biomass of twigs, leaf and fruits exhibited a 'unimodal pattern' with a peak in October. Annual leaf litterfall biomass formed, the main body of litter in all the components, accounting for 57.14–67.05 % of the total litterfall biomass. The correlation and regression analysis results showed that the stand litter biomass was primarily affected by the average temperature. Total litterfall biomass and twigs, leaf, and fruits were significantly affected by the precipitation and the maximum temperature, however, flower litterfall biomass was mainly affected by the average temperature. Overall, our results indicated that temperature plays a key role in the climatic factors affecting forest litterfall processes, while different climatic conditions and biological characteristics probably caused the differences in litterfall biomass. In the long term, temperature will potentially play a leading role in altering carbon storage and nutrient cycling as the climate warms. [ABSTRACT FROM AUTHOR]

• Water use strategy was assessed by plant water uptake and physiological responses. • R. pseudoacacia use an opportunistic water use strategy in 11- and 25-yr plantations. • R. pseudoacacia use a conservative water use strategy in 33- and 43-yr plantations. • R. pseudoacacia exhibited similar stem embolism resistant ability in four plantations. Understanding water use strategy is essential to evaluate plant adaptability in water-limited regions, but whether this strategy changes with plant growth needs further investigation. Robinia pseudoacacia is an exotic pioneer plantation species widely planted in the semiarid Loess Plateau of China to restore degraded ecosystems. Plant water uptake proportion from different soil layers and the water uptake pattern calculated through soil water uptake niche breadth (B index) were determined for R. pseudoacacia in 11-, 25-, 33–, and 43-yr plantations. Leaf physiological parameters and carbon stable isotopic composition (δ13C) were measured concurrently to calculate short-term and long-time integrated water use efficiency (WUE). Then, the water use strategy for R. pseudoacacia at different plantation ages was assessed through water uptake patterns, stomatal conductance (g s), and WUE variation under varied soil water conditions. Results showed that R. pseudoacacia maintained high g s and low short-term WUE and δ13C through a relative equal water uptake pattern and absorbed water within 0 − 400 cm soil depths in 11- and 25-yr plantations. However, this species exhibited an exclusive water uptake pattern and absorbed water mainly from 50 − 400 cm soil depth, adopted low g s and high short-term WUE and δ13C in 33– and 43-yr plantations. Therefore, R. pseudoacacia transited from an opportunistic to a conservative water use strategy with plant growth. The short-term WUE and δ13C were mainly and significantly influenced by g s and specific leaf area, respectively. Furthermore, the significant influence of B index on g s , δ18O Δ , short-term WUE , and δ13C indicated that R. pseudoacacia coordinated both water uptake pattern and water use behavior to contend with varied soil water conditions. This study suggested that changes in age-related water use strategy were essential for the adaptability of R. pseudoacacia in water-limited conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Trees showed differential responses in water-use strategies to tunnel excavation. • Tunnel excavation resulted in evergreen trees extraction more groundwater. • Tunnel excavation resulted in lesser reduction of transpiration for evergreen trees. • While tunnel excavation resulted in a higher increase of WUE i for deciduous trees. • Varying root and stomatal structures may lead to diverse tree water-use patterns. Tunnel(s) excavation could decrease groundwater levels and soil water storage and consequently change trees growth conditions in karst areas. However, the adaptation mechanisms of different tree species to altered hydrological conditions caused by tunnel(s) construction in karst areas remain unknown. Here, we investigated the water-use strategies of two different tree species (the evergreen Ligustrum lucidum and deciduous Robinia pseudoacacia) in response to tunnel excavation in a typical subtropical karst trough valley by using the sap flow density, stable isotopes (δ13C, δ2H, and δ18O) and MixSIAR models. Tunnel excavation resulted in a 3.7–6.3 % reduction in soil moisture content (SMC) in Zhongliang Mountain Karst Trough (ZMKT) Valley. Both tree species demonstrated reduced transpiration in tunnel-affected valley (TAV) compared to tunnel-unaffected valley (TUAV) (transpiration in TAV was only 77.6 % of TUAV), with evergreen trees exhibiting a smaller decline in transpiration compared to deciduous trees. Furthermore, the proportions of karst groundwater utilized by evergreen and deciduous tree species in TAV were 8.3 % and 5.0 % higher than in TUAV, respectively, with evergreen tree species exhibiting greater absorption of karst groundwater than deciduous tree species. Meanwhile, the average leaf δ13C values and WUE i (intrinsic water-use efficiency) of both tree species in TAV were 0.9 ‰ and 15.7 μmol/mol higher than those in TUAV, respectively, with evergreen trees exhibiting a smaller increase in WUE i compared to deciduous trees. These results indicate that tunneling-induced water stress events may prompt trees to adopt more conservative water-use strategies. Evergreen tree species rely on more karst groundwater absorption to sustain relatively higher transpiration rates, and deciduous trees adapt to severe water stress by increasing their WUE i or shedding leaves to minimize transpiration. Our finding contributes to the evaluation of eco-hydrological processes in karst areas affected by tunnel(s) excavation. [ABSTRACT FROM AUTHOR]

• Artificial locust forest restoration process promotes preferential flow. • 2–5 mm, 30–40 mm and > 50 mm roots promote preferential flow. • 5–15 mm roots have inhibitory effect on preferential flow fraction. • <2 mm, 10–30 mm, and 40–50 mm roots show no significant effect on preferential flow. • Decayed root diameter, length and volume all improved preferential flow. Preferential flow significantly influences regional water cycles, and affecting surface and subsurface runoff processes. By comparing soil infiltration characteristics across various forest ages, it can be evaluated how artificial black locust forests on the Loess Plateau contribute to the resilience of soil and water conservation. In this study, we analyzed the spatial distribution characteristics of roots of black locust plants using field investigations and statistical analyses and determined the effects of the root characteristics on the preferential flow in the semi-arid of the Loess Plateau, China. The results showed that the root biomass, root length density, and root volume ratio of young forests were significantly lower than those of middle-aged and mature forests (P < 0.05), and root characteristic parameters varied significantly among different root diameters and soil layers.. The average volume of decayed root channels in mature forests, accounting for approximately 0.16 % in a unit volume of soil, was 3.1 times that of young forests and 4.9 times that of middle-aged forests. Preferential flow increased with forest age in artificial black locust forests. 2–5 mm, 30–40 mm and > 50 mm roots promoted preferential flow to varying degrees, while roots of 5–15 mm inhibited the preferential flow. < 2 mm, 10–30 mm and 40–50 mm roots has no effect on preferential flow (P > 0.05). The size and density of decayed root channels significantly improve soil preferential flow, and the differences among forest ages are linked to the network created by rotten roots. These findings indicate that living roots of different diameters and decayed roots contribute to soil preferential flow to varying extents. The results provided a conceptual basis for understanding the potential impact of vegetation roots on surface runoff during the vegetation restoration ecosystems process in the Loess Plateau. [ABSTRACT FROM AUTHOR]

Water use efficiency (WUE) as an indicator reflecting plant drought resistance, is crucial for plant survival adaptation and forestland sustainability especially in water scarce areas during revegetation. The understanding of WUE characteristics of major tree species at different ages and the key factors influencing WUE in the loess hilly region is currently lacking. The study selected Caragana korshinskii (CK) and Robinia pseudoacacia (RP) plantations, two species widely planted in different plantation ages (16, 30, and 47 years), in the loess hilly region. The instantaneous water use efficiency (WUEt) and short-term water use efficiency (WUEs) of these plantations were calculated to investigate the factors influencing both WUEt and WUEs. The results showed that the WUEt and WUEs of CK plantations showed an increasing trend with increasing plantation age, while the RP plantations was lowest at 30 years. The soil water content (SWC) in CK and RP plantations demonstrated an upward trend as the age of the plantations increased, while the pH showed a decreasing trend. Older CK plantations had high porosity of soil (Ps) and saturated hydraulic conductivity (Ks), coupled with a low bulk density (BD). Unlike CK plantations, the maximum value of Ps in RP plantations was observed at 30 years. The soil organic carbon (SOC), dissolved organic carbon (DOC), total nitrogen (TN), and dissolved organic nitrogen (DON) contents of RP and CK plantations increased with the increase of restoration years. Except for net photosynthetic rate (An), the 16-year RP and CK showed strong photosynthesis. During the revegetation process, soil and leaf factors explained 85.31% and 90.52% of the differences in WUEt and WUEs under plantations at different stand ages. Among them, DON and intercellular CO 2 concentration (Ci) were the most sensitive factors to WUE in soil physicochemical and leaf physiological properties, respectively. The interaction between soil physicochemical and leaf physiological properties significantly influences variations in WUEt and WUEs. These variations were primarily constrained by the synergistic effects of DON, SWC and, Ci. In conclusion, our study underscores the importance of soil and leaf factors in affecting WUE, contributing to improved understanding of water utilization capacity and stand growth strategies during vegetation restoration. [Display omitted] • Study on WUE of vegetation restoration process in the Loess Plateau. • WUE of CK increased with increasing stand age and RP was lowest at 30 years. • The synergistic effect of soil and leaf properties on WUE is crucial. • The changes in WUE are constrained by the synergistic effects of DON, SWC, and Ci. [ABSTRACT FROM AUTHOR]

Quantifying the evapotranspiration (ET) water consumption characteristics of typical vegetation [ Robinia pseudoacacia (single vegetation), mixed plantations of Robinia pseudoacacia and Platycladus orientalis (double-mixed vegetation), and natural grassland (multiple-mixed vegetation)] in the Chinese Loess Plateau has both theoretical and practical significance. However, the proportionality and inverse hypotheses of ET , namely, the FAO-56 method and generalized complementary relationship (GCR), have limitations when used individually to estimate ET , evaporation (E), and transpiration (T). This study explores the feasibility of scaling water stress coefficient (K s) using calibration-free or parameterized GCR for different vegetation types and quantities. The single crop coefficient (K c) curves and basal crop coefficient adjustment (K cb-a / K cb-p) curves of typical vegetation were defined and validated to partition ET without soil moisture usage. The results revealed that both curves exhibited polynomial functional response relationships to the week ordinal (WO) of the growing season within a complete hydrological cycle (with 0.60 < R2 < 0.78 at the 0.01 significance level). By expressing the soil evaporation coefficient (K e) as a function of K s , K c , and K cb , the calibration-free combined method (combining the GCR and the FAO-56 method – GCR/FAO-56) demonstrated superior simulation performance for E , T , and ET across different vegetation types with an average Nash–Sutcliff Efficiency of 0.71 during the validation period compared to that of the parameterized method, with the highest sensitivity in E simulation. The simulated E , T , and ET values closely matched the actual values and maintained the order of Robinia pseudoacacia > mixed plantation > natural grassland during the growing season. The average biases for E , T , and ET during the validation period were 18.5, 7.0, and 25.5 mm, respectively, in Robinia pseudoacacia ; 10.8, 11.1, and 19.7 mm in mixed plantation; and 2.7, 7.0, and 19.6 mm in natural grassland. The overall T / ET ratios for both plantations exceeded 51.07%, with mixed plantation being higher, surpassing 70% in dry years and exhibiting minimal variation in T (44.4 mm) across hydrological years. However, T / ET ratios in natural grassland were < 0.5, indicating that E was the primary form of water consumption. Average relative biases of the simulated and actual T / ET values were only 1.76%, 2.53%, and 1.87% for Robinia pseudoacacia , mixed plantation, and natural grassland, respectively. Furthermore, the accuracy of the calibration-free combined method increased with the number of vegetation species during the validation period. This study extended and discussed the feasibility in typical vegetation of combining the positive and negative correlation principles of evapotranspiration and further provided a possibility for how to partition ET with a fewer dataset [ R n , u , T avg , RH or T d , P , LAI ] without soil moisture, and also provided scientific suggestions for future vegetation restoration as well as water resources management. • Evapotranspiration can be partitioned without using soil moisture. • This method combined the FAO-56 model and the generalized complementary relationship. • The water stress coefficient can be quantified by meteorological data. • Single crop and basal crop coefficients can be predicted by the week ordinal. • The soil evaporation coefficient can be predicted without using soil moisture. [ABSTRACT FROM AUTHOR]

• The priming effect initially increased and decreased thereafter with stand age. • Nitrogen addition induced attenuation in priming effect. • Phosphorus addition induced enhancements in priming effect. • Mineral protection and nutrient limitation co-explained the effect of nutrient addition. Changes in plant carbon (C) inputs to soil due to afforestation can affect the decomposition rate of the old soil C, with this so-called priming effect being dependent on the soil nitrogen (N) and phosphorus (P) availability following the establishment of the new forest. However, the patterns and drivers of the priming effect in afforested soils as well as its responses to nutrient (i.e., N and P) addition remain unclear. In this study, soil samples were collected from various sites along a 45-year Robinia pseudoacacia afforestation chronosequence on the Loess Plateau in China, and incubation experiment with the addition of 13C-labeled glucose and nutrients (N or P) was conducted. The results showed that, regardless of N or P addition, the pattern of temporal changes in the soil priming effect was the same along the chronosequence: initially increasing and then decreasing, with a peak at the 20-year site. The lower C accessibility (indicated by a high mineral associated organic C (MOC) content determined the priming effect patterns after afforestation. Moreover, the soil priming effect after afforestation differed depending on the type of nutrient added; that is, it decreased with N addition but increased with P supplied. This suggests that the decomposition of old soil C at the late stage was inhibited by N addition but stimulated after P addition. Aside from soil and microbial properties, aggravated microbial nutrient limitation was a primary reason for the decreased priming effect response induced by N addition, whereas the increased response caused by P addition was due to the alleviation of microbial P limitation. Collectively, our findings shed light on the contrasting impacts of nutrient addition on the priming effect in afforested ecosystems and highlight the importance of mineral protection and microbial nutrient limitation in regulating this phenomenon under changing nutrient availability conditions. [ABSTRACT FROM AUTHOR]

Nitrogen (N 2)-fixing legumes can be used for phytoremediation of toxic heavy metal Mercury (Hg) contaminated soil, but N 2 -fixation highly relies on phosphorus (P) availability for nodule formation and functioning. Here, we characterized the significance of P deficiency for Hg accumulation and toxicity in woody legume plants. Consequences for foliar and root traits of rhizobia inoculation, Hg exposure (+Hg) and low P (-P) supply, individually and in combination were characterized at both the metabolite and transcriptome levels in seedlings of two Robinia pseudoacacia L. provenances originating from contrasting climate and soil backgrounds, i.e., GS in northwest and the DB in northeast China. Our results reveal that depleted P mitigates the toxicity of Hg at the transcriptional level. In leaves of Robinia depleted P reduced oxidative stress and improved the utilization strategy of C, N and P nutrition; in roots depleted P regulated the expression of genes scavenging oxidative stress and promoting cell membrane synthesis. Rhizobia inoculation significantly improved the performance of both Robinia provenances under individual and combined +Hg and -P by promoting photosynthesis, increasing foliar N and P content and reducing H 2 O 2 and MDA accumulation despite enhanced Hg uptake. DB plants developed more nodules, had higher biomass and accumulated higher Hg amounts than GS plants and thus are suggested as the high potential Robinia provenance for future phytoremediation of Hg contaminated soils with P deficiency. Soil pollution and nutrient depletion constitute serious threats for human and environmental health. However, information on the responses of plants to combined Hg pollution and P depletion has so far not been reported, at both, the metabolite and transcriptome levels. In the present study, we characterized the interaction of Hg exposure with P depletion in Robinia -rhizobia associations of two Robinia provenances originating from different environments at the metabolic and transcriptional levels. Provenance-specific differences in Robinia performance upon rhizobia inoculation at Hg and low P exposure were identified. From these results we recommend one of the two Robinia provenances for future remediation of Hg contaminated soils with low P content. [Display omitted] • P depletion showed antagonistic effects when combined with Hg exposure on Robinia-rhizobia symbiosis. • Rhizobia inoculation improved plant performance under combined Hg and depleted P. • Provenance-specific responses of Robinia plants. • Mechanisms in physiological and transcriptional levels were reported. • The DB provenance is feasible than GS for phytoremediation of Hg exposure in P-depleted soil. [ABSTRACT FROM AUTHOR]

Perennial industrial crop (PIC) biomass is produced in a cyclic manner, which necessitates its storage to ensure a continuous supply for bioenergy industry. The biomass composition and properties change during storage. These are the reasons for designing over two-year experiment which covers PIC species popular in Europe (willow, poplar, black locust, miscanthus), whose biomass was stored in bales during this period in five systems (uncovered; under foil, T120, T200; and in a shed). The following was performed during the storage period: samples were collected, proximate and ultimate analysis was conducted, higher and lower heating value was calculated, and the lignocellulose and extractives content was determined. The results showed the dependence of the stored biomass properties on the species, storage system and storage time, as well as on their combination. PIC bales storage in a shed, T120 and T200, were found to preserve acceptable thermophysical properties and the chemical composition of the biomass for a period of up to two years. The analyzed changes of each attribute or a group of attributes should be individually referred to for each potential method of use (thermal conversion installations, installations for biomass conversion to bioproducts, including biofuels, etc.). [ABSTRACT FROM AUTHOR]

A significant characteristic of the strata in the Yimeng Mountain area is the dual earth-rock structure. Soil thickness directly affects the habitat conditions and is closely related to the survival rate of vegetation. This study aims to reveal the spatial distribution characteristics and influencing factors of the soil thickness in a typical watershed in the Yimeng mountain area. In April 2019, 1816 soil thickness measurements were collected in the Yimeng Mountain area. The differences in the soil thickness, spatial distribution characteristics, and influencing factors of the different land use types were analysed using multivariate statistics and geostatistics. The results revealed the following conclusions. (1) There are significant differences in the soil thicknesses of the different land use types, i.e., farmland (42.63 cm) > forest land (39.26 cm) > grassland (20.35 cm). (2) The optimal semi-variogram model of soil thickness is an exponential model (R2 = 0.914). The ST in the study area has a medium spatial correlation. The high value areas of Populous simonii Carr. and slope farmland and the low value areas of Robinia pseudoacacia L. and grasslands exhibit spatial clustering. (3) The soil thickness varies significantly with land preparation measures, slope direction, and slope position. The high soil thickness values are mainly concentrated on the terrace preparation measures, the half shady slope, and the lower slope. These results provide a scientific basis for improving the survival rate of near-natural vegetation restoration in the Yimeng Mountain area in the earth-rocky mountainous areas of northern China. [ABSTRACT FROM AUTHOR]

Biogenic volatile organic compounds (BVOCs) have significant effects on atmospheric chemistry, ozone formation and secondary organic aerosol formation. Considering few investigations about BOVCs emissions in north China where is facing serious air pollution in recent years, emissions of various BVOCs from 24 dominant forest species in Beijing were measured from June to September in 2018, using a dynamic headspace sampling method. More than one hundred BVOCs in the collected samples were identified by using an automatic thermal desorption-gas chromatography/mass spectrometry, and their emission rates based on leaf biomass were calculated. Isoprene and monoterpenes were verified to be the dominant BVOCs emitted from the tree species, accounting for more than 50% of the total BVOCs. Generally, broad-leaved species displayed high isoprene emission rates, especially the Platanus occidentalis (21.36 µg/(g⋅hr)), Robinia pseudoacacia (11.55 µg/(g⋅hr)), and Lonicera maackii (9.17 µg/(g⋅hr)), while coniferous species emitted high rates of monoterpenes, such as Platycladus orientalis (27.18 µg/(g⋅hr)), Pinus griffithii (23.11 µg/(g⋅hr)), and Pinus armandii (7.42 µg/(g⋅hr)). High emission rates of monoterpenes from the broad-leaved species of Buxus megistophylla (13.07 µg/(g⋅hr)) and Ligustrum vicaryi (5.74 µg/(g⋅hr)), and high isoprene emission rate from the coniferous tree of Taxus cuspidata (5.86 µg/(g⋅hr)) were also observed. The emission rates of sesquiterpenes from each tree were usually 10–100 times smaller than those of isoprene and monoterpenes. Additionally, relatively high emission rates of oxygenated volatile organic compounds and other alkenes than isoprene and monoterpenes were also found for several tree species. BVOCs emission rates from 24 dominant tree species in Beijing. Image, graphical abstract [ABSTRACT FROM AUTHOR]

and carbon-related measurements can help elucidate drought-induced plant mortality. To study drought mortality mechanisms, seedlings of two woody species, including the anisohydric Robinia pseudoacacia and isohydric Quercus acutissima , were cultivated in a greenhouse and subjected to intense drought by withholding water and mild drought by adding half of the amount of daily water lost. Patterns of leaf and root gas exchange, leaf surface areas, growth, leaf and stem hydraulics, and carbohydrate dynamics were determined in drought-stressed and control seedlings. We detected a complete loss of hydraulic conductivity and partial depletion of total nonstructural carbohydrates contents (TNC) in the dead seedlings. We also found that intense drought triggered a more rapid decrease in plant water potential and a faster drop in net photosynthesis below zero, and a greater TNC loss in dead seedlings than mild drought. Additionally, anisohydric R. pseudoacacia suffered a rapider death than the isohydric Q. acutissima. Based on these findings, we propose that hydraulic conductivity loss and carbon limitation jointly contributed to drought-induced death, while the relative contributions could be altered by drought intensity. We thus believe that it is important to illustrate the mechanistic relationships between stress intensity and carbon-hydraulics coupling in the context of isohydric vs. anisohydric hydraulic strategies. • There were complete conductivity loss and partial C depletion in dead plants. • Intense drought also resulted in a smaller C loss and in a rapid conductivity loss when compared with mild drought. • Anisohydric R. pseudoacacia suffered higher risk of hydraulic failure, and a rapid mortality than isohydric Q. acutissima. [ABSTRACT FROM AUTHOR]

• Vegetation restoration has significantly promoted soil and water conservation; • Afforestation leads to strong evapotranspiration than abandoned farmland; • Afforestation may lead to water depletion in the late restoration stage; • Abandoned farmland is more conducive to sustainability of vegetation restoration; Vegetation restoration has been widely implemented to restore degraded land. However, vegetation expansion may result in the overconsumption of soil moisture and soil desiccation, which in turn exacerbates land degradation. To ensure the sustainability of ecological restoration, it is necessary to optimise restoration patterns. Two restoration patterns (afforestation with Robinia pseudoacacia L. (RP) and abandoned farmland (AL)) along a revegetation chronosequence (0, 9, 17, 27, and 42 years) were selected to analyse variations in soil and hydrological characteristics on the Loess Plateau, China. The results showed that for the two revegetation types, the soil quality index (SQI) increased markedly (p < 0.05) and the soil loss (SL) and surface runoff (R) decreased significantly (p < 0.05) over time, indicating that vegetation restoration improves soil quality and prevents soil and water erosion. The annual increments of soil moisture storage (Ws) within a 200 cm depth notably decreased during the late restoration stage (>27 years) for the artificial forest. Moreover, forest also showed increasing actual evapotranspiration (ET) trends and decreasing Ws trends. These results suggest that afforestation might lead to overconsumption of water and soil water depletion during the late restoration stage. Although RP sites had higher SQI (22.2–36.7 %) values and lower SL (47.0–81.4 %) and R (86.5–196.8 %) values when compared with AL sites, the change rates of the SQI, R, and SL at RP sites were stable or decreased over a period of restoration, while these rates showed increasing tendencies under AL sites. These suggests that natural grasslands may be more beneficial than artificial forests during the late restoration stage. Therefore, naturally restored grasslands are highly recommended for sustainable ecological restoration in the semiarid and arid areas of the Loess Plateau or in similar areas elsewhere. [ABSTRACT FROM AUTHOR]

• Soil physical properties were strongly related to land use, slope aspect, slope position and their interactions. • 19 year old locust was the most effective at improving the BD and Ks. • Better soil physical properties were obtained on the north slope and down slope. • Soil physical properties displayed different changes with locust restoration year. • Key factor affecting forest growth and soil quality improvement varied with forest ages. Soil particle size distribution (PSD), bulk density (BD), saturated hydraulic conductivity (Ks), soil water content (SWC) and generalized soil structure index (GSSI) are key physical properties for vegetation growth and are easily affected by natural and anthropogenic factors. However, how these soil physical properties respond to land use, slope aspect, slope position, and their interactions are less clearly understood. Here, an experiment with three land uses (cropland, grassland, and black locust [ Robinia pseudoacacia L.] forests after 4, 9, 15, and 19 years of restoration), two slope aspects (south and north slope) and two slope positions (up and down slope) were conducted in the hilly loess region of China. The results showed the following: (1) The variation in different physical properties were driven by different factors of land use, slope aspect, slope position and their interactions. (2) The 9, 15 and 19 year old locust forests significantly decreased the BD by 6.75 %–19.32 % and increased the Ks by 69.96 %–195.97 % compared with grassland, while the cropland had higher SWC and GSSI values than the grassland and locust forests. (3) Soil physical properties were higher on the north slope than on the south slope and were larger on the down slope than on the up slope. (4) The BD, Ks, SWC, and GSSI of locust forests displayed different changes with the restoration year. (5) The key factor affecting forest growth and soil quality improvement varied with forest ages. Overall, 19 year old locust was the most effective at improving the BD and Ks. Furthermore, slope aspect, slope position and restoration time should be considered when evaluating the response of physical properties to land uses. [ABSTRACT FROM AUTHOR]

The role of rhizobia in alleviating cadmium (Cd) stress in woody legumes is still unclear. Therefore, two types of black locust (Robinia pseudoacacia L.) with high and low Cd accumulation abilities were selected from 11 genotypes in China, and the effects of rhizobium (Mesorhizobium huakuii GP1T11) inoculation on the growth, CO 2 and H 2 O gas exchange parameters, Cd accumulation, and the absorption of mineral elements of the high (SX) and low Cd-accumulator (HB) were compared. The results showed that rhizobium-inoculation significantly increased biomass, shoot Cd contents, Cd accumulation, root-to-shoot translocation factor (TF) and the absorption and accumulation of mineral elements in both SX and HB. Rhizobium-inoculation increased chlorophyll a and carotenoid contents, and the intercellular carbon dioxide concentrations in HB plants. Under Cd exposure, the high-accumulator SX exhibited a significant decrease in photosynthetic CO 2 fixation (Pn) and an enhanced accumulation of Cd in leaves, but coped with Cd exposure by increasing chlorophyll synthesis, regulating stomatal aperture (Gs), controlling transpiration (Tr), and increasing the absorption and accumulation of mineral elements. In contrast, the low-accumulator HB was more sensitive to Cd exposure despite preferential accumulation of Cd in roots, with decreased chlorophyll and carotenoid contents, but significantly increased root biomass. Compared to the low-accumulator HB, non-inoculated Cd-exposed SX plants had higher chlorophyll contents, and rhizobium-inoculated Cd-exposed SX plants had higher Pn , Tr , and Gs as well as higher levels of P, K, Fe, Ca, Zn, and Cu. In conclusion, the high- and low-Cd-accumulator exhibited different physiological responses to Cd exposure. Overall, rhizobium-inoculation of black locust promoted the growth and heavy metal absorption, providing an effective strategy for the phytoremediation of heavy metal-contaminated soils by this woody legume. [Display omitted] • The presence of rhizobia significantly enhanced Cd accumulation. • Rhizobium inoculation increased Cd root-to-shoot TF. • Rhizobium inoculation promoted mineral element absorption. • Rhizobium inoculation enhanced the tolerance of low-Cd accumulator to Cd. • Black locust can be a potential woody plant in phytoremediation. [ABSTRACT FROM AUTHOR]

Urban vegetation plays an important role in filtering atmospheric pollution. Understanding the functional traits of the plants that have strong capacity to retain fine particulate matter (PM 2.5) is important to design configuration schemes for urban green spaces. In this study, phenological observations, direct sampling, and electron microscope analysis of leaf surfaces were conducted to analyze and compare the 65 plant species commonly grown in green spaces in Beijing in terms of their ability to retain particulates from the air. Analyses of the size distribution of particles revealed that >94% of the particles retained on leaf surfaces were smaller than 10 μm (PM 10), and the majority of these (>87%) were smaller than 2.5 μm (PM 2.5). Coarse particles accounted for <6% of all retained particles. The average volume percentage of PM 10 was 93.8%, that of PM 2.5 was 35.8%, and that of coarse particulates (D p > 10 μm) was 17.8%. The PM 2.5 retention amount per unit leaf area differed greatly among tree and shrub species. This number was 38.8 times higher for Acer truncatum (0.659 g·m−2) than for Salix matsudana (0.017 g·m−2), and 33.4 times higher for Buxus sinica (1.168 g·m−2) than for Sabina vulgaris (0.035 g·m−2). The trees with the strongest capacity to retain PM 2.5 on a whole-plant basis were ranked as A. truncatum (115.639 g·week−1) , Robinia pseudoacacia (48.876 g·week−1), Platanus acerifolia (43.413 g·week−1), Celtis bungeana (37.383 g·week−1), Sophora japonica (31.998 g·week−1), Diospyros kaki (29.945 g·week−1), and Ginkgo biloba (27.613 g·week−1), while the tree species with the strongest PM 2.5 retention capability per year were A. truncatum (3245.170 g·year−1), R. pseudoacacia (1744.198 g·year−1), C. bungeana (1199.707 g·year−1), S. japonica (1108.382 g·year−1), Sabina chinensis (895.712 g·year−1) and G. biloba (865.733 g·year−1). The shrubs with the strongest ability to retain PM 2.5 on a whole-plant basis were ranked as Prunus cistena (3.921 g·week−1), Syringa oblata Lindl. var. alba Rehder (3.767 g·week−1), Lespedeza bicolor (2.642 g·week−1), Hibiscus syriacus (2.255 g·week−1), Paeonia suffruticosa (1.969 g·week−1), and Amygdalus triloba (1.831 g·week−1), while the shrub species with the strongest ability PM 2.5 retention capability per year were P. cistena (113.933 g·year−1) , S. oblata Lindl. var. alba Rehder (98.736 g·year−1), L. bicolor (70.457 g·year−1), and H. syriacus (60.645 g·year−1). The results of this study will be useful for designing planting schemes for green spaces in urban areas to optimize the retention of particulates from the air. [Display omitted] • An approach was developed to study the ability of 65 plants to retain air particles. • A comparison on the PM 2.5 annual retention ability per plant for 65 urban plant species were conducted. • Functional traits of plants and environmental factors jointly affected the air particles retained by the plants. • Scheme on plant community planning towards improving air quality was suggested. [ABSTRACT FROM AUTHOR]

• Soil moisture content varied with soil depth, upslope distance, vegetation type, and time. • Soil organic carbon and moisture were lowest in Robinia pseudoacacia plantations. • Grassland showed lower soil moisture loss and greater organic carbon sequestration. • On the Loess Plateau, afforestation within grassland may enhance ecosystem services. Large-scale afforestation is considered controversial as an ecosystem renewal strategy for the Loess Plateau of China, since it may increase soil organic carbon (SOC) but may also exacerbate water shortages. In our study, we aimed to clarify how afforestation and slope affect soil moisture content (SMC) and SOC and their interaction particularly for deep hillslope profiles on long hillslopes, in terms of the trade-off between soil moisture and organic carbon. This study investigated SMC and SOC density (SOCD) from 0 to 400 cm hillslope depth profiles at 20 m intervals uphill to 100 m in the May and October (the beginning and end of the growing period, respectively) from 2015 to 2017. The three sampling sites were located in Robinia pseudoacacia plantation, natural forest, and natural grassland as the control. Soil moisture deficit and SOC sequestration of plantation were compared to those of grassland, and the trade-off between SMC and SOCD was evaluated. The results showed that SMC and SOCD were the lowest in the Robinia pseudoacacia plantation, indicating that the plantation exhibited a greater soil moisture deficit and SOC loss than the grassland. In the plantation and natural forestland, the subsoil (100–400 cm) exhibited greater soil moisture deficit and SOC loss than the soil (0–100 cm). SOCD increased while SMC decreased with upslope distance for all hillslope layers in both plantation and natural forestland. The downslope sites exhibited more severe soil moisture deficit, and greater SOC loss than the upslope sites. Natural grassland exhibited low water depletion and high SOC sequestration. Further, the downslope plantation sites exhibited the lowest root mean square deviation for the relationship between SMC and SOCD. Based on these findings, a vegetation restoration strategy involving afforestation of downslope patches within a contiguous grassland matrix may achieve high-level maintenance of ecosystem services. These findings provide a theoretical basis for vegetation restoration on the Loess Plateau. [ABSTRACT FROM AUTHOR]

Robinia pseudoacacia plantations play an important role in improving the ecological environment of the Chinese Loess Plateau (CLP). However, drought stress is emerging as the major threat of sustainable growth in R. pseudoacacia plantations under the background of global warming and increasing water scarcity. Investigating the responses of plant water use to drought and the associated regulating mechanism in R. pseudoacacia is helpful for improving understanding of plant survival strategies and developing sustainable forest management practices under climate change. In this study, we monitored the canopy transpiration (T r) dynamics with synchronous observations of soil water content and leaf water potentials in R. pseudoacacia plantations during two different hydrological years (2021 and 2022) at two sites featuring semihumid (Changwu) and semiarid (Mizhi) climate conditions. Results showed that normalized T r exhibited stronger relationships with meteorological variables at the Changwu site than Mizhi site, as well as under non-drought condition compared to drought condition. The canopy stomatal conductance (G c) decreased significantly with increasing vapor pressure deficit (VPD) and soil drought at both sites. The sensitivity of G c to VPD revealed more strict stomatal regulation of transpiration in response to drought at the Changwu site, and less strict stomatal regulation at the Mizhi site. Relationship between midday and predawn water potentials indicated a partial isohydric strategy in response to drought, and reflected stomatal closure tends to occur more rapidly than hydraulic conductivity loss in R. pseudoacacia. These results suggest that the T r and G c values of R. pseudoacacia and their sensitivity to climate weakened as soil drought progresses and varied with different climatic conditions, and R. pseudoacacia exhibited flexible stomatal regulation of transpiration and water use strategies in response to drought. • Canopy transpiration (T r) and stomatal conductance (G c) vary with climate and soil moisture conditions. • Sensitivities of T r and G c to environmental factors are weakened with soil drought progresses. • R. pseudoacacia shows flexible stomatal regulation and water use strategies in response to drought. • T r is strongly controlled by leaf stomata and positively responds to leaf water potential and hydraulic conductance. [ABSTRACT FROM AUTHOR]

Analysis of landslide events by studying anomalies in tree-ring series of disturbed trees provides unique data on past landslide behaviour. However, a comprehensive spatio-temporal model of landslide evolution using dendrogeomorphic data has not yet been constructed. In terms of determining landslide hazard, one of the key issues, besides the frequency of movements, is their magnitude. Thus, this study is aimed at constructing a model of landslide area development including quantification of landslide displacements. Moreover, not only standard macroscopic growth disturbance but also quantitative anatomical parameters of tree rings were used as a basis for these objectives. The research was carried out on a landslide of the Váh river bank (Slovakia) using data from 32 disturbed black locust (Robinia pseudoacacia L.) individuals. Anatomical analysis revealed a reduction in the vessel lumen area in response to landslide movements. The response was associated with tension wood formation or damage to the tree root system. The reconstructed chronology of landslide movements revealed the main phase of landslide in 2017 and its subsequent evolution. Based on the chronological information and the morphology of the landslide body, a spatio-temporal model of the landslide evolution from the initial slope failure to the present was constructed. The model showed the interrelationships between vertical displacement of the main block, compression and tension deformations within the landslide body, and lateral erosion of the landslide toe by the river. Quantification of the magnitude of landslide displacements was realized from exposed roots in tension cracks but also from the ruptured tree trunk. The limitations and advantages of both approaches are discussed. [Display omitted] • Data from 32 trees and seven roots were used to date landslide movements. • Dating was based on anatomical growth responses of disturbed trees. • The magnitude of landslide movements was quantified using tree-ring based data. • A spatio-temporal model of landslide development was built. [ABSTRACT FROM AUTHOR]

The Yellow River Delta (YRD) is the second largest petrochemical base in China and the impact of human activities has been continuously increasing in recent decades, however, the contamination status of seldom monitored trace elements (SMTEs) in YRD has rarely been reported. This study evaluated the levels, vertical distributions, contamination status and sources of SMTEs in soil samples of three different land use types in YRD. The results indicated that the vertical distributions of SMTEs contents showed a gradually upward increasing trend for the soil profiles of black locust forest, while the SMTEs contents displayed a gradually upward decreasing trend for the soil profiles of cotton field. However, the SMTEs contents in the oil field area showed no significant difference among different depths. The vertical distributions of SMTEs were very likely related to the anthropogenic disturbance in the later stage. The environmental pollution status assessment of SMTEs showed obvious enrichment of Cs, Sn, and U in the soils of YRD. Moreover, the potential source analysis based on multivariate statistical methods indicated that Ga, Rb, Cs, Sc, Sn, Tl, Be, Bi, Ca and Mo were clustered together and positively correlated with Al, Fe, Mg and K, and may be mainly associated with geochemical weathering process, while the Ce, La, Th, U, Nb, Ta, and Hf may be impacted by both natural process and human activities. Though the SMTEs pollution status was not very serious, our results highlighted the non-negligible influence of anthropogenic activities on vertical distributions of SMTEs in three different land use types from YRD. Our results provide valuable information for understanding the vertical distribution and pollution status of SMTEs in YRD. • Non-negligible influence of anthropogenic activities on vertical distributions of SMTEs in YRD • SMTEs displayed an upward decreasing trend for the soil profiles of cotton field. • Obvious enrichment of Sn, Cs and U was observed in YRD soils. • Sources of most SMTEs are mainly related to the geochemical weathering process. [ABSTRACT FROM AUTHOR]

Interaction of different environmental constrains pose severe threats to plants that cannot be predicted from individual stress exposure. In this context, mercury (Hg), as a typical toxic and hazardous heavy metal, has recently attracted particular attention. Nitrogen (N 2)-fixing legumes can be used for phytoremediation of Hg accumulation, whereas N availability could greatly affect its N 2 -fixation efficiency. However, information on the physiological responses to combined Hg exposure and excess N supply of woody legume species is still lacking. Here, we investigated the interactive effects of rhizobia inoculation, Hg exposure (+Hg), and high N (+N) supply, individually and in combination (+N*Hg), on photosynthesis and biochemical traits in Robinia pseudoacacia L. seedlings of two provenances, one from Northeast (DB) and one from Northwest (GS) China. Our results showed antagonistic effects of combined + N*Hg exposure compared to the individual treatments that were provenance-specific. Compared to individual Hg exposure, combined + N*Hg stress significantly increased foliar photosynthesis (+50.6%) of inoculated DB seedlings and resulted in more negative (−137.4%) δ 15N abundance in the roots. Furthermore, combined + N*Hg stress showed 47.7% increase in amino acid N content, 39.4% increase in NR activity, and 14.8% decrease in MDA content in roots of inoculated GS seedlings. Inoculation with rhizobia significantly promoted Hg uptake in both provenances, reduced MDA contents of leaves and roots, enhanced photosynthesis and maintained the nutrient balance of Robinia. Among the two Robinia provenances investigated, DB seedlings formed more nodules, had higher biomass and Hg accumulation than GS seedlings. For example, total Hg concentrations in leaves and roots and total biomass of inoculated DB seedlings were 1.3,1.9 and 3.4 times higher than in inoculated GS seedlings under combined + N*Hg stress, respectively. Therefore, the DB provenance is considered to possess a higher potential for phytoremediation of Hg contamination compared to the GS provenance in environments subjected to N deposition. [Display omitted] • Combined exposure to Hg and N deposition poses potential threats to environmental health. • N2-fixing woody legumes of Robinia pseudoacacia L. can be used for future phytoremediation. • Antagonistic effect of combined Hg exposure and high N supply on Robinia -rhizobia association. • Inoculation with Rhizobium promoted Robinia plant Hg uptake. • Provenance-specific responses of Robinia showed great potential for phytoremediation approaches. [ABSTRACT FROM AUTHOR]

• Computational fluid dynamics (CFD) modeling applied to solid-liquid extractions. • Pressurized hot water extraction (PHWE) showed a high extraction affinity for phenolic and sugar compounds. • PHWE presented higher flavonoids (DHR and Rob) yields than other techniques. • The degradation of DHR and rob occurred at temperatures above 120 °C. • PHWE is an efficient and green method to extract and concentrate flavonoids compounds from Robinia Pseudoacacia wood. Computational Fluid Dynamics (CFD) simulation was used to study the solid-liquid extraction of Robinia Pseudoacacia wood by pressurized hot water extraction (PHWE). The proposed model couples momentum and mass transfer, including the extraction kinetics. The model is based on transport species and flow in a porous medium. The results show that the extraction of the two main flavonoids, Dihydrorobinetin (DHR) and Robinetin (Rob), increased with increasing temperature up to 120 °C, with values of 46.85±1.44 and 6.84±0.42 mg/gdB, respectively. However, at higher temperatures, these flavonoids degraded. Additionally, the exhaustive extraction cycle, ranging from 80 to 160 °C, was found to be less effective when compared to extraction at 120 °C.The kinetic parameters were included in the CFD simulation. As a result, a good agreement between the results of CFD simulation and experimental data was found with R2 > 0.97. The model predicts the temperature distribution inside the reactor during the pre-heating period, the evolution of the DHR and Rob concentrations at the reactor outlet, and the effect of degradation at high extraction temperatures. [Display omitted] [ABSTRACT FROM AUTHOR]

Urea is the most frequently used nitrogen (N) fertilizer worldwide. However, the mechanisms in plants to cope with excess urea are largely unknown, especially for woody legumes that can meet their N demand by their own N 2 -fixation capacity. Here, we studied the immediate consequences of different amounts of urea application and exposure duration on photosynthesis, N metabolism, and the activity of antioxidative enzymes of Robinia pseudoacacia seedlings. For this purpose, seedlings were grown for 3 months under normal N availability with rhizobia inoculation and, subsequently, 50 mg N kg−1 was applied to the soil twice with urea as additional N source. Our results show that excess urea application significantly promoted photosynthesis, which increased by 80.3% and 84.7% compared with CK after the 1st and 2nd urea applications, respectively. The increase in photosynthesis translated into an increase in root and nodule biomass of 88.7% and 82.0%, respectively, while leaf biomass decreased by 4.8% after the first application of urea. The N content in leaves was 92.6% higher than in roots, but excess urea application increased the N content of protein and free amino acids in roots by 25.0%, and 43.3%, respectively. Apparently, enhanced root growth and N storage in the roots constitute mechanisms to prevent the negative consequences of excess N in the shoot upon urea application. Nitrate reductase (NR) activity of leaves and roots increased by 74.4% and 26.3%, respectively. Glutathione reductase (GR) activity in leaves and roots was enhanced by 337% and 34.0%, respectively, but then decreased rapidly to the initial level before fertilization. This result shows that not only N metabolism, but also antioxidative capacity was transiently promoted by excess urea application. Apparently, excess urea application initially poses oxidative stress to the plants that is immediately counteracted by enhanced scavenging of reactive oxygen species via enhanced GR activity. [Display omitted] • Applied excess urea significantly promoted photosynthesis. • Different biomass accumulation among plant organs by excess urea application. • Both N metabolism and anti-oxidative capacity were promoted by excess applied urea. • Enhanced scavenging of ROS via enhanced GR activity by Robinia to excess urea. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal (AM) fungi, influencing many important ecosystem processes, widely occur in saline soils, and thus understanding their biogeographic patterns is of primary interest in saline ecosystem restoration. Fine roots and rhizosphere soils were sampled in black locust (Robinia pseudoacacia) plantations in four saline sites in northern China to detect soil properties and AM fungal attributes including their colonization level, spore density, hyphal density and community composition. Arbuscular mycorrhizal fungal attributes varied with sampling sites, and this variation was mostly attributed to changes in habitat characteristics and geographic distance. Habitat characteristics shape the root- and soil-inhabiting AM fungal communities to the same extent, whereas geographic distance seems to contribute more to root-inhabiting AM fungal assemblages. The level of root colonization by vesicles, arbuscules and hyphae and the density of AM fungal spores and hyphae in soils were found to be related to the relative abundance of AM fungal species such as root-inhabiting Rhizophagus intraradices and soil-inhabiting Sclerocystis sinuosa. All the results suggest that changes in habitat characteristics and geographic distance may induce biogeographic patterns of AM fungi, and these patterns are closely related to AM symbiosis in roots and the development of AM fungi in soils. • Arbuscular mycorrhizal fungal community held large heterogeneity in saline soil. • Habitat shaped root- and soil-inhabiting AM fungi to the same extent. • Geographic distance contributed more to root-inhabiting AM fungi. • Changes in habitat and geographic distance determined AM fungal biogeography. • The AM symbiosis and development were related with their biogeographic patterns. [ABSTRACT FROM AUTHOR]

Lignin streams produced in biorefineries are commonly used to obtain energy. In order to increase the competitiveness of this industry, new lignin valorization routes are necessary, for which a depth characterization of this biological macromolecule is essential. In this context, this study analyzed lignin streams of Robinia pseudoacacia L. generated during organosolv and acid hydrolysis pre-treatments and during the subsequent enzymatic hydrolysis. These lignins included dissolved lignins from pre-treatment liquors and saccharification lignins from pre-treated materials. Chemical composition and structural features were analyzed by analytical standard methods and Fourier Transform Infrared spectroscopy (FTIR), size exclusion chromatography (SEC), 13C solid state nuclear magnetic resonance (13C NMR) and 1H–13C two-dimensional nuclear magnetic resonance (2D NMR); while thermal characterization included thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). In general, all studied lignins contained a predominance of β - O -4′ aryl ether linkages, followed by resinol (β - β ′) and phenylcoumaran (β -5′), with a predominance of syringyl over guaiacyl and hydroxyphenyl units. Nevertheless, the dissolved lignins revealed a removal of linkages, especially β - O -4′, leading to an enrichment of phenolic groups. Moreover, high thermal stability and good thermoplasticity were characteristics of these lignins. Contrary, the saccharification lignins exhibited a more intact structure, but with an important remaining carbohydrates content. • Lignin streams from R. pseudoacacia L. generated in different transformation processes are studied • Lignin streams included dissolved lignins from pre-treatment liquors and saccharification lignins. • The dissolved lignins appeared more degraded, with a high phenolic content, high thermal stability and good thermoplasticity. • The saccharification lignins exhibited a more intact structure, but with an important residual carbohydrates. • The different characteristics of evaluated lignins define the way to valorize them. [ABSTRACT FROM AUTHOR]

• Bark of six typical species of the mixed Atlantic forest of the Basque Country were characterised. • Sweet chestnut and Common ash have the highest extractive content with 31.89 and 29.44% of the total, respectively. • Black locust has the highest suberin content, 16.37%. • Phenolic content and three different antioxidant activities (DPPH, ABTS and, FRAP) were measured. • Potential use of barks as source for different biomolecules was assessed. Bark is one of the most available by-product derived from the wood-base industry because of the total volume of the tree that comprised. This study aimed at evaluating the chemical composition of barks of six typical species of the mixed Atlantic forest of the Basque Country and the potential of their extractives. The used species were Northern red oak (Quercus rubra), Common oak (Quercus robur), Common ash (Fraxinus excelsior), Iberian White birch (Betula celtiberica), Sweet chestnut (Castanea sativa) and Black locust (Robinia pseudoacacia). Differences between chemical compositions of all the barks were noted. Extractive content was very high for all the barks remarking Sweet chestnut and Common ash with the highest content with 31.89 and 29.44% respectively. The suberin content was higher than 3% with a maximum value for Black locust of 16.37%. Variation of EtOH/H 2 O was high depending on studied species with a range of extraction yield of 3.08to15.77%. Total phenolic content of the bark extracts ranged from 178.11 to 635.08 mg GAE/g of dry bark extract and total flavonoid content from 439.19 to 1021.78 mg CE/g of dry bark extract. The antioxidant capacity of the bark extracts was measured by DPPH, ABTS and FRAP and the obtained values were ranged from 167.23 and 1912.38 mg TE/g dried bark extract, 561.92 to 1556.57 mg TE/g dried bark extract 146.11 to 640.30 mg TE/g dried bark extract, respectively. The structural differences were confirmed by GPC and FT-IR, where it was observed an average molecular weight differences and different spectra. The obtained results confirm the high interest in barks source as biomolecules for specific uses such as cosmetics or pharmaceuticals among others. [ABSTRACT FROM AUTHOR]

Robinia pseudoacacia (black locust) is a medium-sized deciduous tree, native to the Southeastern United States. Due to a number of beneficial attributes, it has been widely planted and become naturalised in several countries. It has one of the largest distributions in Europe of any introduced plant and has increased its distribution into a number of Southern Hemisphere countries. In its introduced range, the species exhibits a number of invasive tendencies, which result in negative environmental and economic impacts. This review presents information on aspects of the plant's biology and ecology with emphasis on its status in the Southern Hemisphere. Topics covered include taxonomy, morphological attributes, distributions, habitats, relationships with other species, growth and development, reproduction, hybridisation, population dynamics, uses, toxicity and the invasive status of the plant in Southern Hemisphere countries This manuscript also provides insights into management options including biological control, which has never been intentionally implemented against this species. • Black locust is spreading in the Southern Hemisphere. • It now has a broad distribution in South Africa. • Current management options are not always appropriate. • Biological control may be a potential management option. [ABSTRACT FROM AUTHOR]

Highlights • Chemical alterations in honey ripened in beeswax adulterated with paraffin (PF-H). • Beeswax adulteration affects the composition and quality. • Higher water %, lower glucose/water ratio in PF-H (susceptibility to fermentation). • Higher acetic and citric acid content in PF-H; indication of incipient fermentation. • PF ripening media moderately changes the HS-VOCs chemical profile of PF-H. Abstract Analytical parameters were determined for the first time in honey produced in the honeycomb constructed on comb foundations adulterated with 90% of paraffin (PF-H) and compared to honey ripened in genuine beeswax (BWF-H) using physico-chemical and spectroscopic techniques (1H NMR, FTIR-ATR, HS-SPME/GC–MS). Water content was significantly higher (SH) and glucose/water ratio significantly lower in PF-H samples. The contents of acetic and citric acid were marginally significantly higher (MSH) in PF-H samples. These findings suggest that adulterated beeswax affects composition of honey as the set of altered parameters indicate chemical changes leaning towards fermentative processes. Moderately changed headspace chemical profile of PF-H honey was determined depending on the floral source (pentanal, α-pinene and benzaldehyde were SH in BWF-H sunflower honey; butanal was MSH, and 2-phenylethanol was more abundant in BWF-H black locust honey). Higher percentage of nonanal, octane and β-damascenone were found in PF-H samples that could indicate more intensive oxidation. [ABSTRACT FROM AUTHOR]

Highlights • A PLS2-DA build on 1H NMR data of organic extracts revealed variations among production zones of EU acacia honeys. • NMR geographical assessment of EU acacia honeys based on floral secondary markers. • A PLS2 model defines the fractions of Italian and East European acacia honeys in blends. Abstract A geographical discrimination of honey is an important prerequisite for quality and authenticity control. Here, we present a method based on an NMR-metabolomic analysis of organic extracts for a geographical discrimination of commercial European acacia honeys found on the Italian market. All 234 analysed samples show the characteristic 1H NMR profile of acacia (Robinia pseudoacacia) honey. However, a PLS2-DA model revealed variations among production zones allowing the successful geographical differentiation with a 100% of overall correct classification rate. Moreover, a PLS2 model is able to predict the proportions in binary blends of Italian and Eastern European acacia honeys. The geographical distinction and the possibility to characterize the content of blends derive from different markers content originating from minor nectar contributions of the acacia-accompanying flora. [ABSTRACT FROM AUTHOR]

Abstract The effects of vegetation restoration on plant characteristics and soil physicochemical properties have been widely documented; however, knowledge of the variation in soil ecoenzymatic activity and stoichiometry remains limited, particularly with respect to their relationship with plant and soil variables in restored ecosystems. Here, the vegetation and soil from one farmland and two restored land-use types (Robinia pseudoacacia plantations: RP and abandoned lands: AL) of four age classes (10, 18, 28, and 43-years) were investigated and sampled on the Loess Plateau, China. The activity of C, N, and P-acquiring enzymes (β-1,4-glucosidase, BG; β-1,4-N-acetylglucosaminidase, NAG; leucine aminopeptidase, LAP; and alkaline phosphatase, AP) and other major influencing factors (soil physical properties, soil nutrient contents, and microbial biomass) were determined. It was found that both restoration time and vegetation types significantly affect plant characteristics, soil physical properties, soil nutrient content, and microbial biomass. Soil BG, NAG + LAP, and AP enzyme activities were higher in RP and AL than in farmland, and increased with restoration time in AL. For RP, the activity of these enzymes increased from year 10 to year 28, then decreased from year 28 to year 43. Soil ecoenzymatic C:P and N:P activity ratios were ordered: farmland > AL > RP, and decreased with restoration time in AL and RP; thus, P limitation was stronger in RP than in AL and increased with restoration time in both AL and RP. Soil ecoenzymatic C:N:P acquisition ratios of farmland, AL, and RP deviated from the 1:1:1 ratio and depended on the availability of environmental nutrients and demand for microbial nutrients. The vegetation characteristics and soil physical properties were closely related to the nutrient acquisitions of microbes and, ultimately, contributed towards shaping soil ecoenzymatic activity and stoichiometry (particularly vegetation coverage, belowground biomass, soil water content, soil bulk density, and pH). Furthermore, variation in soil ecoenzymatic activity and stoichiometry was better accounted by dissolved nutrients in the soil (particularly C and N) and microbial biomass (particularly N and P) than by plant characteristics and soil properties. Overall, this study demonstrates that the C:N:P stoichiometry of soil microbes and ecoenzymatic activity is nutrient dependent, rather homeostatic, with the potential to influence nutrient cycling on the Loess Plateau. Graphical abstract Image 1 Highlights • Soil ecoenzymatic C:N:P acquisition ratios deviated from the 1:1:1. • Soil ecoenzymatic activity ratio was not in homeostasis but resource dependent. • P limitation of microbial metabolisms increased with restoration time. • Soil ecoenzymatic stoichiometry were influenced by both plant and soil properties. • Soil dissolved nutrients and microbial biomass have stronger effect on soil ecoenzymatic stoichiometry than plant and soil properties. [ABSTRACT FROM AUTHOR]