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Natural disturbance‐based management (NDBM) is hypothesized to maintain managed forest ecosystem integrity by reducing differences between natural and managed forests. The effectiveness of this approach often entails local comparisons of species composition or diversity for a variety of biota from managed and unmanaged forests. Understory vegetation is regularly the focus of such comparison because of its importance in nutrient cycling, forest regeneration, and for wildlife. However, larger scale comparisons between regions with distinct species assemblages may require a trait‐based approach to better understand understory responses to disturbance. We compared the long‐term effects of retention harvesting on understory vegetation in two large experimental study sites located in eastern and western regions of the Canadian boreal forest. These sites included the Sylviculture en Aménagement Forestier Ecosystémique (SAFE) experiment and the Ecosystem Management Emulating Natural Disturbance (EMEND) experiment, located in the eastern and western regions of Canada, respectively. EMEND and SAFE share common boreal understory species but have distinct tree communities, soils, and climate. Both experiments were designed to evaluate how increasing tree retention after harvest affects biodiversity. Here, we examined taxonomic richness, functional diversity, and functional composition (using community trait mean values) of understory plant communities, and also examine intraspecific trait variability (ITV) for five species common and abundant in both experiments. We observed the limited impacts of retention level on richness, functional diversity, and functional composition of understory plants 20 years postharvest. However, ITV of leaf morphological traits varied between retention levels within each experiment, depending on the species identity. Common species had different functional responses to retention level, showing species‐specific reactions to environmental variation. Our result suggests that understory plant communities in the boreal forest achieve resilience to disturbance both in terms of interspecific and intraspecific functional trait diversity. Such diversity may be key to maintaining understory biodiversity in the face of future disturbances and environmental change. Our results reveal the significance of ITV in plant communities for understanding responses to forest harvesting and the importance of choosing appropriate traits when studying species responses to the environment. [ABSTRACT FROM AUTHOR]

Introduction: The Indian Himalayan forests are remarkable landforms experiencing tremendous climatic variation, constituting complex and diversified ecosystems with prominent vegetation zones. Despite their global significance and substantial research efforts focused on plant diversity in the temperate Himalayan region, only a few studies have explicitly assessed the distribution patterns of understory vegetation in relation to forest compositional types along altitudinal gradients. Methods: To cover a wide range of altitudes and diverse overstory compositions, stands were sampled across four altitudinal ranges from 1500 to 3500 meters above mean sea level with increments of 500 meters in elevation steps. The overstory compositions were classified on the basis of dominant tree species in each stand on the similar sites. Vegetation in the shrub and ground layers was surveyed by visually estimating the percentage coverage within circular plots. Results: A total of 99 understory species including 37 species each in the shrub layer, 62 species in the herb layer vegetation were recorded. The abundance, species diversity and composition of understory vegetation differed significantly along the altitudinal gradient and dominant overstory composition types. Moreover, distinct understory vegetation communities were observed at lower elevations compared to higher elevations, with middle elevations exhibiting intermediate vegetation characteristics. The study also highlighted the importance of dominant overstory composition types in shaping the pattern of understory vegetation abundance, species diversity and composition in the temperate Himalayan region. The higher resource conditions associated with broadleaved stands supported higher understory species abundance at lower elevations, while the heterogeneous conditions induced by the mixedwood stands promoted higher understory species diversity. Conclusion: The hump shaped pattern along the altitudinal gradient appeared to be the most dominant pattern of plant abundance and species diversity and call for more conservation concern towards the middle elevation zones in the temperate Himalayan region. Furthermore, the management interventions should aim at maintaining diverse range of overstory composition types for conserving biodiversity and their ecological functions in the temperate Himalayan region. [ABSTRACT FROM AUTHOR]

Closures in temperate forests have been widely used to evaluate the effects of livestock on conservation and restoration objectives, but their use with management objectives in integrated productive systems in native forests has been poorly studied. Given that the studies are concentrated in the northern hemisphere, it is essential to advance local research to provide management tools to ensure the continuity of the forest component and the functionality of the system. Therefore, we analyzed the response of vegetation to the temporary exclusion of livestock in silvopastoral systems in mixed Austrocedrus chilensis - Nothofagus dombeyi forests of northern Patagonia. We evaluated changes in the structure, composition and functionality of understory vegetation, as well as in the regeneration of dominant canopy species. We selected three medium-sized estates, and in each one established three plots and three paired closures, which were monitored for three years. Closures significantly affected the height growth of N. dombeyi saplings, and marginally the survival of A. chilensis seedlings, while the species richness, composition, cover and functional diversity of the understory showed no changes. The coverage of palatable species was not affected, possibly due to greater limitation by light than herbivory and the short time of exclusion. Under the conditions studied, short-term community closures do not appear to be a suitable tool in farm management to promote forage production or regeneration of the most sensitive forest species. [ABSTRACT FROM AUTHOR]

Background and aims: Increased nitrogen (N) deposition may exacerbate soil phosphorus (P) deficiency, which alters soil greenhouse gas (GHG) emissions by changing soil properties and understory vegetation in subtropical forests. However, the effects of N addition, P addition, and understory vegetation interactions on soil carbon dioxide (CO2) and nitrous oxide (N2O) emissions in forest ecosystems and their underlying mechanisms remain unclear. Methods: We conducted a continuous N and P addition experiment in a subtropical Chinese fir plantation. The effects of N and P addition on soil CO2 and N2O emissions with different understory vegetation were examined using a structural equation model. Results: The addition of N and P did not directly affect soil CO2 emission of the understory, which was affected by understory species (F = 2.86; p = 0.05). N indirectly and positively affects soil CO2 emission through plant elements, and directly affect N2O emission of understory soil. Compared with CK, the addition of N2 promoted the N2O cumulative emission by 74.3%. N has a direct positive effect on soil N2O emissions, while P addition indirectly exerts a negative influence on N2O emissions through its impact on soil properties. Plant elements and soil properties were explained in 26.3% of soil CO2 emissions, of which 17.6% and 16.0% variations were explained by plant elements and soil properties, respectively. Leaf total N was the most important factor for predicting CO2 emissions. Conclusions: Our results suggested that soil CO2 emission was more dependent on plant elements, and soil N2O emission was directly dependent on N addition rather than plant elements. Thus, different patterns of soil GHG emissions and associated controls following N and P addition provided novel insights into predicting the effects of understory vegetation on climate change mitigation outcomes. [ABSTRACT FROM AUTHOR]

In order to explore the management measures to improve the biodiversity of mixed forest of Larix principis-rupprechtii, through investigations and monitoring of understory plant communities in mixed forests of Larix principis-rupprechtii subjected to four different thinning intensities - control group (Ⅰ), light (Ⅱ), moderate (Ⅲ) and heavy (Ⅳ) - within the Beijing Forest Farm, this study analyzed variations in understory vegetation. Results revealed that under the four thinning intensities, the number of understory shrub species were 5, 7, 7, 6 respectively, while herbaceous species were 11, 11, 10, 12, respectively. Shared species encompass species included Rubus crataegifolius, Corylus heterophylla, Spiraea salicifolia, Deutzia scabra, Deyeuxia pyramidalis, Carex tristachya Thunb., and Crepidiastrum lanceolatum. As the forest canopy closure decreased, the number of shrubs and herbaceous plants increased. In the moderate thinning intensity plots (Ⅲ), the number of shrubs was the highest, while in the heavy thinning intensity plots (Ⅳ), the number of herbaceous plants was the highest. Increased thinning intensity prompted a rise in light-loving shrubs such as Zabelia biflora, Sambucus williamsii, and Forsythia suspensa, underscoring the sunlight's impact on vegetation. Significant variations were observed in the ranking of importance values of shrubs and herbs across different thinning intensities. Notably, species like Spiraea salicifolia and Rubus crataegifolius consistently ranked among the top three in all intensities. However, Corylus heterophylla only appeared in the top three at control group (Ⅰ), while Forsythia suspensa was exclusive to heavy thinning (Ⅳ). In the herbaceous layer, Deyeuxia pyramidalis ranked among the top three in light and moderate intensities, with a particularly high value of 37. 16 in the heavy intensity (Ⅳ). Analysis of species diversity, community similarity, and understory diversity suggested that different thinning intensities influence species composition and diversity, increased thinning intensity positively impacted diversity, especially in the herbaceous layer. The results of this study provide an important reference for optimizing the management strategy of mixed larch forest of Larix principis-rupprechtii to improve the conservation effect of biodiversity. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of Botanical Research is the property of Bulletin of Botanical Research Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

IntroductionThe Indian Himalayan forests are remarkable landforms experiencing tremendous climatic variation, constituting complex and diversified ecosystems with prominent vegetation zones. Despite their global significance and substantial research efforts focused on plant diversity in the temperate Himalayan region, only a few studies have explicitly assessed the distribution patterns of understory vegetation in relation to forest compositional types along altitudinal gradients.MethodsTo cover a wide range of altitudes and diverse overstory compositions, stands were sampled across four altitudinal ranges from 1500 to 3500 meters above mean sea level with increments of 500 meters in elevation steps. The overstory compositions were classified on the basis of dominant tree species in each stand on the similar sites. Vegetation in the shrub and ground layers was surveyed by visually estimating the percentage coverage within circular plots.ResultsA total of 99 understory species including 37 species each in the shrub layer, 62 species in the herb layer vegetation were recorded. The abundance, species diversity and composition of understory vegetation differed significantly along the altitudinal gradient and dominant overstory composition types. Moreover, distinct understory vegetation communities were observed at lower elevations compared to higher elevations, with middle elevations exhibiting intermediate vegetation characteristics. The study also highlighted the importance of dominant overstory composition types in shaping the pattern of understory vegetation abundance, species diversity and composition in the temperate Himalayan region. The higher resource conditions associated with broadleaved stands supported higher understory species abundance at lower elevations, while the heterogeneous conditions induced by the mixedwood stands promoted higher understory species diversity.ConclusionThe hump shaped pattern along the altitudinal gradient appeared to be the most dominant pattern of plant abundance and species diversity and call for more conservation concern towards the middle elevation zones in the temperate Himalayan region. Furthermore, the management interventions should aim at maintaining diverse range of overstory composition types for conserving biodiversity and their ecological functions in the temperate Himalayan region.

Abstract [Objective] The study aims to explore the effects of tree species composition and other stand factors on species diversity of plantation communities in different road areas, and provide reference for the construction and management of plantation communities in Chengdu. [Methods] By using the typical plot method, the stand factors and understory vegetation species diversity of 5 different tree species in the plantation community (Ⅰ, poplar pure forest. Ⅱ, camphor and poplar mixed forest. Ⅲ, pure camphor forest. Ⅳ, mixed forest of camphor and eucalyptus. Ⅴ, eucalyptus grandis forest) of Chengdu Ring Expressway were investigated. [Results] (1) A total of 190 species of understory plants belonging to 71 families and 131 genera were recorded in the study area. The number of species of plant families recorded under the forest was more in the herbaceous layer than in the shrub layer, among which the number of understory species recorded in the pure camphor forest was the highest. (2) The important values of Broussonetia papyrifera and Humulus scandens dominated the shrub layer and herb layer of different plantation communities, respectively. (3) The shrub species richness index (D ) of pure camphor forest was significantly higher than that of the other communities (P Ⅳ > Ⅰ > Ⅱ > Ⅴ, of which H of pure camphor forest was significantly higher than that of the other communities, except mixed forest of camphor and eucalyptus (P

Establishment of plantations may be a useful means of vegetation reconstruction in coal mining areas, especially in fragile environments. However, the influence of shrub planting on the relationship between understory vegetation and soil microorganisms remains poorly understood. Here, we describe a field experiment in which the relationships between understory vegetation and soil microorganisms under different planting densities of Amorpha fruticosa L. (A. fruticosa) were investigated. Compared with areas allowed to recover naturally, shrub planting changed the community and increased the biomass of understory vegetation and soil microbes, especially of arbuscular mycorrhizal fungi (AMF). Planting density was also a key factor that influenced understory vegetation and the soil AMF community and biomass. The maximum diversity of understory vegetation and the AMF community occurred at an intermediate density of introduced shrubs, which was considered to be the optimum density of A. fruticosa. The major soil nutrient cycles that influence understory vegetation and the AMF community were also investigated. An optimum density of introduced shrubs was important in the ecological reconstruction of vegetation in the coal mining area. There may also have been an optimum relationship between the understory vegetation and soil microorganisms especially with AMF in the experimental conditions. [ABSTRACT FROM AUTHOR]

Copyright of Acta Prataculturae Sinica is the property of Acta Prataculturae Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The cherry plum (Prunus cerasifera Ehrh.) is considered an invasive plant species in numerous areas of the temperate climate zones around the world. Although this exotic tree can naturalize in a wide spectrum of forest ecosystems, its invasion mechanisms remain totally unknown. This study is the first approach aiming to investigate potential drivers shaping the ecological success of P. cerasifera invasion, with an example of the temperate primeval forest as a model recipient ecosystem. Using generalized linear models, we suggest that the distance to the propagule source may shape considerably this exotic species occurrence in primeval forest's understory, expressed by the presumably high role of birds and small mammals in short-, and large ungulates in long-distance seed dispersion. The probability of this invader occurrence decreased with decreasing functional and phylogenetic diversity of understory vegetation. This suggests the importance of habitat filtering generated in small tree-fall gaps in shaping the P. cerasifera success. Thus, interactions between natural disturbances, characteristics of recipient vegetation, as well as traits of various animal dispersers, may be identified as key drivers promoting the occurrence of P. cerasifera in the primeval forest ecosystem. However, further studies on the patterns of P. cerasifera invasion are needed to identify drivers promoting invasion, as well as the effects of this exotic plant on biodiversity and the functioning of ecosystems. [ABSTRACT FROM AUTHOR]

[Objective] In order to explore the influence of afforestation density of Populus simonii shelterforest in the Naiman Banner Sand area of the southern margin of the Horqin Sandy Land on the vegetation under the forest, the afforestation density suitable for the restoration and stable development of vegetation community diversity was proposed. [Methods] The shelter forest of Populus poplar with similar forest age（867～1 022 plants/hm²,1 444～1 667 plants/hm2, 2 177～2 322 plants/hm²） was taken as the research objects. The survey of each wood ruler, species composition and diversity, vegetation community structure was carried out, and the collected data in the field were statistically analyzed. [Results] Afforestation can significantly improve the rate of vegetation recovery and succession. The size of afforestation density has a significant impact on understory vegetation diversity and community stability. With the decrease of afforestation density, understory herbaceous biomass, species composition richness, species diversity index increase, plant recovery degree and community stability increase. There is a significant negative correlation between afforestation density and vegetation characteristics such as species diversity index, species number, understory vegetation cover, and understory herbaceous biomass（p＜0.01）. [Conclusion] The plantation with density of 867～1 022 plants/hm² has the highest community similarity with the uncultivated grassland site. The vegetation community gradually succeeds towards zonal climax vegetation. [ABSTRACT FROM AUTHOR]

• We quantified the effects of Acacia decurrens (AD) on soil and runoff loss. • AD improved available P and total N and soil organic carbon contents. • Infiltration rate and understory vegetation biomass decrease with age of AD. • Surface runoff increased with the age of AD plantation. • AD plantation significantly reduced soil loss. Acacia decurrens (AD) plantations are increasingly used as an agroforestry practice in the humid Ethiopian highlands, mainly for their economic and ecological benefits. However, their effects on runoff response and soil loss with their growth are poorly understood. The main objective of this study was to examine the responses of runoff and soil loss with AD plantation age in a highland agroecological setting of Ethiopia. A field experiment was conducted during the rainy season in 2019 and 2020 using bounded runoff plots (30 m long × 3 m wide) installed on control and AD plantations of 1 to 4 years. The result showed that soil chemical properties (TN, SOC, and av. P) were improved in AD plots compared to the control. Surface runoff loss increased with the age of the AD plantation. Seasonal runoff was significantly higher (P < 0.01) in year 3 (456 mm) and year 4 (539 mm) AD plots in 2019 and 2020, respectively. This was mainly on account of decreases in understory vegetation biomass and soil infiltration rate and an increase in soil bulk density with AD plantation age. But at all growth stages of AD plantations, sediment concentration and soil loss were significantly reduced compared to the control (P <0.01). Our results imply a need to use suitable soil and water conservation measures such as trenches combined with AD plantations to reduce surface runoff loss and related effects downstream. However, the effects of AD on soil water content need to be revealed by further research. [ABSTRACT FROM AUTHOR]

In northern Alberta, Canada, much of treed boreal peatlands are fragmented by seismic lines—linear disturbances where trees and shrubs are cleared for the exploration of fossil fuel reserves. Seismic lines have been shown to have slow tree regeneration, likely due to the loss of microtopography during the creation of seismic lines. Inverted soil mounding is one of the treatments commonly applied in Alberta to restore seismic lines and mitigate the use of these corridors by wildlife and humans. We assessed the effects of mounding on understory plants and arthropod assemblages three years after treatment application. We sampled five mounded and five untreated seismic lines and their adjacent treed fens (reference fens). Compared to reference fens, mounded seismic lines showed on average lower bryophyte (6.5% vs. 98.1%) and total understory cover (47.2% vs. 149.8%), ground-dwelling spider abundance (226.0 vs. 383 individuals), richness (87.2 vs. 106.4 species) and diversity (19.0 vs. 24.6 species), rove beetle abundance (35.2 vs. 84.8 individuals), and ant richness (9.0 vs. 12.9 species). In contrast, rove beetle and ground beetle richness (39.0 and 14.5 species, respectively) and diversity (16.8 and 7.8 species, respectively) were higher on mounded seismic lines compared to reference fens (richness: 18.0 and 7.5 species, respectively; diversity: 7.0 and 3.8 species, respectively). This is one of the first studies to assess arthropod responses to restoration efforts in the context of oil and gas disturbances in North America, and our results highlight the need to incorporate multiple taxa when examining the impact of such treatments. [ABSTRACT FROM AUTHOR]

AbstractThe use of drones and remote sensing in combination with geospatial analysis is a cost-efficient way to monitor energy distribution networks, especially those in fire-prone areas. This study investigated the use of image and photogrammetric analysis together with segmentation algorithms to assess vegetation height and volume in power line corridors in Southeast Queensland, Australia. Various fuel reduction techniques, including mega-mulching, spot sprays and cool mosaic burns, were implemented, and drone-generated models were employed to evaluate their effectiveness. The fuel hazard reduction and regrowth in terms of vegetation height and volume were recorded and analysed. Importantly, the study demonstrates a robust correlation (R2 = 0.9073; df = 1,16; F = 156; p

The dry temperate forests of Pakistan exhibit rich diversity of understory floral species. These important and endemic plant species play a pivotal role in ecosystem functioning and providing livelihoods to the forest communities. South Waziristan, located in the southwest of Pakistan, is known for its rare pure stands of Pinus gerardiana Wallichex. D. Don forests. The rapidly expanding population and current state of affairs are leading to deforestation and causing disturbance to the understory vegetation of this valuable forest. The current study aims to fill the currently scanty information present in the literature regarding the diversity status of understory vegetation in P. gerardiana forests. Data of understory vegetation diversity were gathered for the northern and southern aspects of the forest. A 50 m2 sampling plot along with the placement of fifty 1x1m2 quadrats on both sites were laid out to determine species dominance, diversity, and evenness using Simpson, Shanon, Marglef, and Buzas–Gibson indices. The study depicted 612 individuals of about 29 species representing 23 families from the study site. The most abundant species in all of the sites was Salvia Glutinosa cccIV = 0.52. The southern aspect depicted the lowest diversity, but had high species dominance. Allium carolinianum DC. in this site was the most important species (IV = 0.74). The most abundant species were medicinal plants (75%), followed by edible plants (25%). Aspect had a significant effect on the understory vegetation and different categories of plants with respect to their diversity, dominance, and evenness as predicted by the various diversity indices. This study provides essential insight in to the florisitic diversity and community structure of the fragile pine nut understory vegetation in South Waziristan, which was hitherto not available. It was concluded that the southern aspect of understudy dry temperate forests depicted lower diversity and density as compared with the northern aspect. But it was observed that the southern aspect more specifically had more density and diversity of medicinal plants. It is therefore the need of the hour that conservation of these species from grazing and unsustainable harvesting must be ensured to sustain the livelihood of the inhabitants.

It is crucial to evaluate the effects of thinning on litterfall production, soil chemical properties, and fine root dynamics when implementing thinning as a silvilcultural technique to enhance tree growth and timber yield in Pinus koraiensis plantations. Thus, we determined the 10-year effects (2007–2017) of different thinning intensities on litterfall production, soil chemical properties, and fine root biomass and necromass within a P. koraiensis plantation in South Korea. The soil chemical parameters and fine root biomass and necromass were also compared across three soil depths (0–10, 10–20, and 20–30 cm). Three thinning treatments were employed: no thinning (CON), light thinning (32% removed, LT), and heavy thinning (64% removed, HT). Results revealed that litterfall was consistent across all thinning treatments, but broadleaf species had considerably higher litterfall production at HT stands than at CON/LT stands. Soil chemical properties, except exchangeable K+, were generally lower at LT stands, particularly at a depth of 20–30 cm soil. After ten years, there was a decrease in fine root biomass and necromass with increasing soil depth. Over 80% of fine roots were found in the upper layer (0–20 cm), while very fine roots (0–1 mm) consisted mainly of 47% pine and 53% other species and were concentrated in the 0–10 cm soil depth in HT. In conclusion, different thinning intensities had diverse effects on the parameters measured within the plantation. Future studies can explore how the effects of thinning intensities on litterfall production, soil chemistry, and fine root dynamics affect species diversity, carbon storage, and understory vegetation in P. koraiensis plantations. [ABSTRACT FROM AUTHOR]

Weed control is considered a critical management operation for the establishment and growth of Eucalyptus globulus and is often performed during the first two years following planting. However, no information has been found related to the effects of weed management on the long-term growth of E. globulus. This study aims to better understand how adjusting the timing of weed control, beyond tree establishment, affects the productivity of eucalypts on two commercial plantations in Central Portugal. Two treatments were considered: weed control when vegetation cover occupied at least 50% of the area with a mean height of at least 50 cm, and no weed control. At the northernmost site, weed control operations were performed during the first 3 years following planting. At the southernmost site, weed control interventions occurred between 1.5 and 8.2 years. Weed control demonstrated to be effective at diminishing vegetation cover density to a maximum of 79% and 94% in the northmost and southmost sites, respectively. Weed control significantly increased E. globulus productivity by the end of the study, demonstrating that the timing of weed management must be adjusted in accordance with the understory competing vegetation cover (weeds) and during the entire rotation, not only during tree establishment. [ABSTRACT FROM AUTHOR]

Copyright of Forest Research is the property of Forest Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To provide theoretical support for nutrient cycling in forest ecosystems, the distribution patterns and stoichiometric characteristics of C, N, and P were investigated, and the effects of forest age and organs on the stoichiometric characteristics of C, N, and P were analyzed in the understory vegetation and litter layers in Pinus massoniana plantation ecosystems in southern Guangxi. The study was performed with 5, 13, 23, 30, 40, and 60-year-old P. massoniana from plantations in the state-owned Paiyang Mountain forestry in Guangxi; the C, N, and P stoichiometric characteristics of the understory vegetation and litter layers of P. massoniana were investigated by collecting samples from different age groups in the field. The C, N, and P contents were 436.13, 6.87, and 0.55 g.kg-1 in the shrub layer; 421.64, 6.09, and 0.59 g.kg-1 in the herbaceous layer; and 406.81, 6.23, and 0.75 g. kg-1 in the litter layer, respectively. The C and N contents of the un-decomposed layer were significantly higher than those of the semi-decomposed layer in all stages of forest age(P<0.05). Overall, the C, N, and P contents of the understory vegetation layer of the P. massoniana plantation in southern Guangxi were low, whereas the litter layer showed low C and N contents, and a high P content. The mean values of N/P of both shrub and herbaceous leaves in the understory vegetation layer were less than 14, indicating that the understory vegetation in this region was N-limited, N fertilizer may be applied as part of the forest husbandry measures, and N-fixing plants may also be introduced to improve soil fertility. [ABSTRACT FROM AUTHOR]

Landslides are a common geodynamic phenomenon that cause substantial life and property damage worldwide. In the present study, we developed models to evaluate landslide susceptibility in forest-covered areas in Lin'an, southeastern China using logistic regression (LR), decision tree (DT), and random forest (RF) techniques. In addition to conventional landslide-related natural and human disturbance factors, factors describing forest cover, including forest type (two plantations (hickory and bamboo) and four natural forests (conifer, hardwood, shrub, and moso bamboo) and understory vegetation conditions, were included as predictors. Model performance was evaluated based on true-positive rate, Kappa value, and area under the ROC curve using a 10-fold cross-validation method. All models exhibited good performance with measures of ≥0.70, although the LR model was relatively inferior. The key predictors were forest type, understory vegetation height (UVH), normalized differential vegetation index (NDVI) in summer, distance to road (DTRD), and maximum daily rainfall (MDR). Hickory plantations yielded the highest landslide probability, while conifer and hardwood forests had the lowest values. Bamboo plantations had probability results comparable to those of natural forests. Using the RF model, areas with a shorter UVH (<1.2 m), a lower NDVI (<0.70), a heavier MDR (>115 mm), or a shorter DTRD (<500 m) were predicted to be landslide-prone. Information on forest cover is essential for predicting landslides in areas with rich forest cover, and conversion from natural forests to plantations could increase landslide risk. Across the study areas, the northwestern part was the most landslide-prone. In terms of landslide prevention, the RF model-based map produced the most accurate predictions for the "very high" category of landslide. These results will help us better understand landslide occurrences in forest-covered areas and provide valuable information for governments in designing disaster mitigation. [ABSTRACT FROM AUTHOR]

Alternative states defined by tree‐canopy dominance result in different ecosystem functioning and shape habitat conditions for the understory vegetation. One example in the boreal forest is the alternation between broadleaf deciduous and coniferous forests. Disturbances related to natural fires and human land uses have produced changes in tree‐canopy dominance in the boreal region where coniferous forests change to broadleaved forests, affecting understory community dynamics and their related ecosystem processes and functions. To analyze the factors driving changes in understory vegetation and the resistance of its vegetation to shifts between alternative states, we compared the effects of changes in the system between two contrasting boreal forest types (black spruce vs. trembling aspen) in adjacent stands with similar topoedaphic conditions. We performed a 5‐year in situ experiment using alternative states as a theoretical framework including two approaches: (1) the ecosystem approach, manipulating environmental conditions of light, litter, and nutrients in each forest type to determine the main mechanisms associated with tree‐canopy dominance that affect the diversity and composition of understory communities; and (2) the community approach, physically exchanging understory communities between alternative states, to determine their resistance under a new tree‐canopy dominance through time, as well as the resilience of the forest understory after a small‐scale disturbance. Results indicate that the understory vegetation of trembling aspen forests were resistant through time both after changes in local conditions in the ecosystem approach and in the new black spruce‐dominated alternative state in the community approach. In contrast, mosses and ericaceous plants that typically dominate the forest floor of black spruce forests were negatively affected by the physical effect of broadleaf litter addition in our ecosystem approach and they were not resistant when transplanted to trembling aspen forests in the community approach, as they decreased in abundance and were invaded by aspen understory community species over time. The understory vegetation is a key forest ecosystem driver that can contribute to maintain the resilience of the boreal system and help to preserve their ecosystem services, which is a key aspect to consider in forest management faced with the effects of climate change. [ABSTRACT FROM AUTHOR]

Understory vegetation contributes considerably to biodiversity and total aboveground biomass of forest ecosystems. Whereas field inventories and LiDAR data are generally used to estimate understory vegetation density, methods for large-scale and spatially continuous estimation of understory vegetation density are still lacking. For an evergreen coniferous forest area in southern China, we developed and tested an effective and practical remote sensing-driven approach for mapping understory vegetation, based on phenological differences between over and understory vegetation. Specifically, we used plant area volume density (PAVD) calculations based on GEDI data to train a support vector regression model and subsequently estimated the understory vegetation density from Sentinel-2 derived metrics. We produced maps of PAVD for the growing and non-growing season respectively, both performing well compared against independent GEDI samples (R2 = 0.89 and 0.93, p

Retention harvesting is advocated as an alternative to intensive timber harvesting, such as clear‐cutting, to better maintain or facilitate recovery of biodiversity and other ecological values in managed forests. However, it is not clear how long the benefits of retention harvests persist.We investigated responses of understory vascular plant cover, richness, diversity (inverse Simpson index) and composition to a gradient in dispersed retention (2% [clear‐ cut], 10%, 20%, 50% and 75% retention; unharvested reference [100% retention]) at 3, 6, 11, and 17 years after harvest, in four boreal mixedwood forest types (deciduous (broadleaf)‐dominated, deciduous‐dominated with conifer understory, mixed, and conifer‐dominated) in western Canada.Understory cover and richness tended to increase in the short‐term (3 years), peaked at 6–11 years with differences following the gradient of harvesting intensity, then plateaued or declined in the second decade (17 years), by which time there were minimal or no differences among harvesting levels, including the reference. Responses for diversity were minimal. In contrast, composition varied along the gradient of harvesting intensity and showed little recovery towards the unharvested condition over the 17‐year period. Generally, for plant community composition, clear‐cut and lower retention treatments (10%, 20%) were similar to one another but differed from the higher retention and unharvested reference treatments.Synthesis and applications: Retention harvests can moderate the negative impacts of harvesting and facilitate the recovery of biodiversity. Our results suggest that for the cover, richness and diversity of understory vascular plants, this moderating influence is weak and short‐lived. However, higher levels of retention can temper changes in understory composition relative to the unharvested forest, but full recovery is likely to be slow and will be complicated by post‐harvest regeneration dynamics. [ABSTRACT FROM AUTHOR]

Artificial pruning is an important silvicultural practice that can produce clear wood in poplar plantations. This study focused on the growth of poplar, understory vegetation diversity and soil properties in response to different pruning intensities in poplar plantations. We implemented three different pruning treatments based on the height-to-crown base (HCB) to tree height (H) ratio in Populus deltoides 'Nanlin 3804′ plantations: CK (no pruning), a 1/3 pruning treatment and a 1/2 pruning treatment. The poplar growth conditions, understory vegetation biodiversity and soil properties were investigated for one year after pruning. Compared with CK, the 1/2 pruning treatment significantly decreased the increment of diameter at breast height (DBHi) and stem volume increment (Vi) by 16.4% and 12.8%, respectively. Meanwhile, pruning significantly promoted understory vegetation biomass and increased the Shannon–Weiner diversity index of understory vegetation, and these variables were positively correlated with pruning intensity. The 1/2 pruning treatment significantly reduced the contents of soil nitrate nitrogen (NO3-N), total inorganic nitrogen (IN) and microbial biomass nitrogen (MBN) by 21.9%, 13.9% and 22.4%, respectively. However, the 1/3 pruning treatment had no significant influence. Pruning mainlyaffectedthe soil enzyme activity in the surface (0–10 cm) layer. The 1/3 and 1/2 pruning treatments significantly decreased soil urease activity by 20.1% and 15.0%, respectively. Furthermore, nonmetric multidimensional scaling analysis showed that the seasonal variation in soil properties was significant, and significant differences among pruning treatments were mainly observed in July and October. Redundancy analysis showed that the growth of aboveground vegetation was significantly correlated with soil properties, particularly soil IN content and urease activity. Therefore, the results highlighted that pruning could promote the growth of understory vegetation and accelerate the transformation of soil nutrients. The 1/2 pruning treatment significantly inhibited the growth of poplar in terms of DBH and V, while the 1/3 pruning treatment promoted the growth of poplar in the short term. Overall, we think that the 1/3 pruning intensity is more suitable for pruning practice. [ABSTRACT FROM AUTHOR]

Introduction: Soil microorganisms are the key factors in elucidating the effects of thinning on tree growth performance, but the effects of vegetation and soil on the species composition and function of soil microorganisms after thinning are still not well elaborated. Methods: The effects of thinning on understory vegetation diversity, soil physicochemical properties and soil microbial community composition were investigated in a thinning trial plantation of Cryptomeria japonica var. sinensis, including four thinning intensities (control: 0%, LIT: 20%, MIT: 30% and HIT: 40%), and the relationships of the microbial community structure with the understory vegetation diversity and soil properties were assessed. Results: The results showed that thinning had a greater effect on the diversity of the shrub layer than the herb layer. The soil bulk density and the contents of soil organic matter, total potassium and nitrogen increased with increasing thinning intensities. The Shannon and Chao indices of soil bacteria and fungi were significantly lower in the LIT, MIT and HIT treatments than in the control. Thinning can significantly increase the abundance of Proteobacteria and Actinobacteria, and higher thinning intensities led to a higher relative abundance of Ascomycota and a lower relative abundance of Basidiomycota, Rozellomycota, and Mortierellomycota. Redundancy analysis indicated that soil physicochemical properties rather than understory vegetation diversity were the main drivers of microbial communities, and fungi were more sensitive to soil properties than bacteria. Functional prediction showed that thinning significantly reduced the potential risk of human diseases and plant pathogens, and the nitrogen fixation capacity of bacteria was the highest in the HIT treatment. Thinning significantly increased the relative abundance of cellulolysis and soil saprotrophs in bacteria and fungi. Conclusion: The findings provide important insights into the effects of thinning on C. japonica var. sinensis plantation ecosystems, which is essential for developing thinning strategies to promote their ecological and economic benefits. [ABSTRACT FROM AUTHOR]

Afforestation is proposed as one of the most effective climate solutions for carbon sequestration. As a majority of threatened species are linked to forests, afforestation can also contribute to mitigate the biodiversity crisis. There is however a caveat: the agricultural legacy (high nutrient availability, altered soil biota structure and function) of new forests constrains the development of forest-adapted species, affects tree growth and stability, and delays environmental benefits from afforestation. We hypothesize that inoculation of former arable land with soil (including microbiome, fauna and seeds/rhizomes of understory vegetation) from old forests along with targeted tree species mixtures will improve productivity and more rapidly restore forest-adapted communities. This will ultimately result in diverse, stable and resilient multifunctional forests. We will test this hypothesis and develop applied inoculation methods by: i) exploring soil biota and benchmarking biodiversity in existing afforestation research Chronosequence platforms (chronosequences and sites with increasing distance to other forests); ii) conducting inoculation experiments in mesocosms to measure seedling performance and, above- and belowground linkages; iii) establishing field-scale inoculation experiments innew and existing afforestations to test short- and long-term inoculation success on forest productivity, biodiversity and soil functioning at the ecosystem scale; iv) incorporating the landscape context into guidelines and tools for spatially explicit prioritization of areas for assisted dispersal. The aims are to resolve barriers for successful restoration and develop landscape-scale afforestation strategies that optimize productivity and biodiversity for the planning and implementation of green infrastructure; and produce basic knowledge on the tree, understory vegetation, soil fauna and microbiome nexus and its effect on forest productivity, biodiversity and soil functions (N-retention, C-sequestration, methane uptake). [ABSTRACT FROM AUTHOR]

Age-related changes in water and nitrogen utilization of crop and understory vegetation in a hinoki cypress plantation forest were investigated from the age of 21 to 46 years in Kochi City, southern Japan. Nitrogen concentration in the leaf litter of hinoki cypress showed a decreasing trend with forest age. The leaf δ15N of hinoki cypress was related to a quadratic function and increased from the age of 21 to 26 years and then decreased to the age of 46 years. These results suggest that older hinoki cypress trees utilize soil nitrogen sources with lower δ15N values, and the competition for soil nitrogen with understory vegetation should be stronger. Carbon isotope discrimination (Δ13C) of hinoki cypress decreased from the age of 21 to 30 years and then increased to the age of 46 years. In contrast, the intrinsic water-use efficiency (iWUE) of hinoki cypress increased from the age of 21 to 36 years and then decreased to the age of 46 years. These findings suggest that hinoki cypress trees in the earlier time increased their iWUE by reducing stomatal opening. In the earlier time, the stomatal opening of understory vegetation increased due to higher soil water availability with decreasing stand density of crop trees. In the later time, the iWUE of hinoki cypress decreased due to lower photosynthetic capacity with nitrogen limitation. These results suggest that the increase in the iWUE of hinoki cypress in response to elevated atmospheric carbon dioxide levels should be smaller in the later time because of stronger competition with understory vegetation for soil nitrogen resources.

The use of drones and remote sensing in combination with geospatial analysis is a cost-efficient way to monitor energy distribution networks, especially those in fire-prone areas. This study investigated the use of image and photogrammetric analysis together with segmentation algorithms to assess vegetation height and volume in power line corridors in Southeast Queensland, Australia. Various fuel reduction techniques, including mega-mulching, spot sprays and cool mosaic burns, were implemented, and drone-generated models were employed to evaluate their effectiveness. The fuel hazard reduction and regrowth in terms of vegetation height and volume were recorded and analysed. Importantly, the study demonstrates a robust correlation (R2 = 0.9073; df = 1,16; F = 156; p <.001) between field observations and drone-derived models, affirming the efficacy of this method in assessing fuel heights. This validation suggests that the approach could represent a viable, cost-efficient option for future monitoring and management of energy distribution networks in fire-prone areas. [ABSTRACT FROM AUTHOR]

As one of the important factors affecting forest soil organic carbon stocks, the effect of understory vegetation types on soil organic carbon and its components was explored to provide a theoretical basis for understory vegetation management and sustainable management in plantation forests. In order to determine the characteristics of soil organic carbon and its components under different understory vegetation types in Subtropical Cunninghamia lanceolata plantation, Indocalamus tessellatus, Diplazium donianum and Oreocnide frutescenssp were taken as research objects. The mass fractions of total organic carbon, recalcitrant organic carbon, readily oxidizable organic carbon, microbial biomass carbon and dissolved organic carbon in each soil layer at 0–10, 10–20, 20–40 and 40–60 cm were measured, and the change characteristics of soil organic carbon components were also studied and compared. The results showed that: (1) The mass fractions of total organic carbon, recalcitrant organic carbon, readily oxidizable organic carbon and microbial biomass carbon in the soils of the three understory vegetation types showed significant decreasing trends along the profile, while the mass fraction of dissolved organic carbon in 0–40 cm soil layer was significantly higher than those in 40–60 cm soil layer. (2) The mass fraction of total organic carbon (5.98–20.66 g·kg−1) had no significant difference among understory vegetation types. The mass fraction and proportion of microbial biomass carbon were higher in the 0–60 cm soil layer under cover of Indocalamus tessellatus, and the mass fractions of recalcitrant organic carbon in the 20–40 cm soil layer under Indocalamus tessellatus cover (8.57 g·kg−1) was significantly higher than that of Oreocnide frutescenssp (5.73 g·kg−1). The soil layer of 0–20 cm under the Diplazium donianum community has a higher mass fraction and proportion of readily oxidizable organic carbon. (3) Correlation analysis showed that soil organic carbon and its components were positively correlated with total nitrogen, dissolved total nitrogen, dissolved organic nitrogen and microbial biomass nitrogen. There is a significant positive correlation among the components of soil organic carbon. (4) Redundancy analysis showed that soil bulk density (41.6%), microbial biomass nitrogen (41.2%), dissolved total nitrogen (43.7%), total nitrogen (9.9%), dissolved organic nitrogen (43.6%) and pH (6.6%) were the most significant environmental factors affecting organic carbon components in four soil layers. Understory vegetation type can influence the distribution characteristics of soil organic carbon components in Cunninghamia lanceolata plantation, and soil active organic carbon components are more susceptible to the influence of understory vegetation type than total organic carbon and recalcitrant organic carbon. [ABSTRACT FROM AUTHOR]

Invasive species affect biodiversity and ecosystem functioning, but their impacts along the abundance gradient has been insufficiently recognized. Here we aimed to assess the impacts of invasive × Sorbaronia fallax nothosubsp. mitschurinii (hereafter × Sorbaronia) spread into temperate Scots pine forests on understory vegetation biodiversity and ecosystem functioning. We hypothesized that × Sorbaronia will affect light transmittance into the forest floor, chemical composition of soil and litter, stand and litter production, and understory vegetation. We assessed the set of experimental plots along the invasion gradient in homogenous soil conditions in Western Poland. Around the initial propagule source (abandoned plantation) we established 66 study plots in a systematic design. Using generalized linear mixed-effects models and redundancy analysis we assessed the response of studied predictors to × Sorbaronia biomass. We showed that the studied taxon decreased light transmittance as well as understory cover and species richness of vascular plants. We also confirmed an increase in soil P and litter P, K, and Ca contents. Therefore × Sorbaronia modified the biogeochemical cycles of temperate Scots pine forests. We did not find an effect of the studied taxon on carbon sequestration, due to no impacts on the litter and soil C pools, or on stand productivity. Revealed impacts are scalable with invasive taxon abundance, expressed as aboveground biomass. The impacts of × Sorbaronia are similar to the impacts of the functionally and phylogenetically close widespread invasive species. The studied taxon has a high potential to negatively affect biodiversity and alter the functioning of temperate Scots pine forests, fulfilling the criteria of 'transformers' as an invasive taxon. Our results provide quantitative evidence for nature conservation and risk assessments related to the spread of the studied taxa. [Display omitted] • Most studies assessed invasive taxa impacts comparing invaded and uninvaded sites. • We assessed impacts of × Sorbaronia along its abundance gradient. • Studied taxon decreased light availability, cover, and understory species richness. • It also increased soil P, and litter P, Ca, and K, affecting biogeochemical cycles. • × Sorbaronia acts as a 'transformer', altering ecosystem functioning. [ABSTRACT FROM AUTHOR]

In northern Alberta, Canada, much of treed boreal peatlands are fragmented by seismic lines—linear disturbances where trees and shrubs are cleared for the exploration of fossil fuel reserves. Seismic lines have been shown to have slow tree regeneration, likely due to the loss of microtopography during the creation of seismic lines. Inverted soil mounding is one of the treatments commonly applied in Alberta to restore seismic lines and mitigate the use of these corridors by wildlife and humans. We assessed the effects of mounding on understory plants and arthropod assemblages three years after treatment application. We sampled five mounded and five untreated seismic lines and their adjacent treed fens (reference fens). Compared to reference fens, mounded seismic lines showed on average lower bryophyte (6.5% vs. 98.1%) and total understory cover (47.2% vs. 149.8%), ground-dwelling spider abundance (226.0 vs. 383 individuals), richness (87.2 vs. 106.4 species) and diversity (19.0 vs. 24.6 species), rove beetle abundance (35.2 vs. 84.8 individuals), and ant richness (9.0 vs. 12.9 species). In contrast, rove beetle and ground beetle richness (39.0 and 14.5 species, respectively) and diversity (16.8 and 7.8 species, respectively) were higher on mounded seismic lines compared to reference fens (richness: 18.0 and 7.5 species, respectively; diversity: 7.0 and 3.8 species, respectively). This is one of the first studies to assess arthropod responses to restoration efforts in the context of oil and gas disturbances in North America, and our results highlight the need to incorporate multiple taxa when examining the impact of such treatments.

It is crucial to evaluate the effects of thinning on litterfall production, soil chemical properties, and fine root dynamics when implementing thinning as a silvilcultural technique to enhance tree growth and timber yield in Pinus koraiensis plantations. Thus, we determined the 10-year effects (2007–2017) of different thinning intensities on litterfall production, soil chemical properties, and fine root biomass and necromass within a P. koraiensis plantation in South Korea. The soil chemical parameters and fine root biomass and necromass were also compared across three soil depths (0–10, 10–20, and 20–30 cm). Three thinning treatments were employed: no thinning (CON), light thinning (32% removed, LT), and heavy thinning (64% removed, HT). Results revealed that litterfall was consistent across all thinning treatments, but broadleaf species had considerably higher litterfall production at HT stands than at CON/LT stands. Soil chemical properties, except exchangeable K+, were generally lower at LT stands, particularly at a depth of 20–30 cm soil. After ten years, there was a decrease in fine root biomass and necromass with increasing soil depth. Over 80% of fine roots were found in the upper layer (0–20 cm), while very fine roots (0–1 mm) consisted mainly of 47% pine and 53% other species and were concentrated in the 0–10 cm soil depth in HT. In conclusion, different thinning intensities had diverse effects on the parameters measured within the plantation. Future studies can explore how the effects of thinning intensities on litterfall production, soil chemistry, and fine root dynamics affect species diversity, carbon storage, and understory vegetation in P. koraiensis plantations.

Weed control is considered a critical management operation for the establishment and growth of Eucalyptus globulus and is often performed during the first two years following planting. However, no information has been found related to the effects of weed management on the long-term growth of E. globulus. This study aims to better understand how adjusting the timing of weed control, beyond tree establishment, affects the productivity of eucalypts on two commercial plantations in Central Portugal. Two treatments were considered: weed control when vegetation cover occupied at least 50% of the area with a mean height of at least 50 cm, and no weed control. At the northernmost site, weed control operations were performed during the first 3 years following planting. At the southernmost site, weed control interventions occurred between 1.5 and 8.2 years. Weed control demonstrated to be effective at diminishing vegetation cover density to a maximum of 79% and 94% in the northmost and southmost sites, respectively. Weed control significantly increased E. globulus productivity by the end of the study, demonstrating that the timing of weed management must be adjusted in accordance with the understory competing vegetation cover (weeds) and during the entire rotation, not only during tree establishment.

Landslides are a common geodynamic phenomenon that cause substantial life and property damage worldwide. In the present study, we developed models to evaluate landslide susceptibility in forest-covered areas in Lin’an, southeastern China using logistic regression (LR), decision tree (DT), and random forest (RF) techniques. In addition to conventional landslide-related natural and human disturbance factors, factors describing forest cover, including forest type (two plantations (hickory and bamboo) and four natural forests (conifer, hardwood, shrub, and moso bamboo) and understory vegetation conditions, were included as predictors. Model performance was evaluated based on true-positive rate, Kappa value, and area under the ROC curve using a 10-fold cross-validation method. All models exhibited good performance with measures of ≥0.70, although the LR model was relatively inferior. The key predictors were forest type, understory vegetation height (UVH), normalized differential vegetation index (NDVI) in summer, distance to road (DTRD), and maximum daily rainfall (MDR). Hickory plantations yielded the highest landslide probability, while conifer and hardwood forests had the lowest values. Bamboo plantations had probability results comparable to those of natural forests. Using the RF model, areas with a shorter UVH (115 mm), or a shorter DTRD (

Dicranopteris is the most representative pioneer species, dominant species and key species in degraded slope land in South China. Dicranopteris could quickly form dense synusia of a single and dominant species. In contrast to the traditional view that Dicranopteris hinders forest regeneration, we found that there are a few species that could settle down in Dicranopteris synusia. We proposed a hypothesis that Dicranopteris synusia could act as an ecological filter. In this study, we transplanted 12 target species seedlings under Dicranopteris synusia with 4 treatments to explore the ecological filtering effect of Dicranopteris synusia, and analyzed the mechanism with soil characteristics. The 4 treatments included the understory removal treatment (UR), the aboveground of Dicranopteris synusia were kept (AF), the root blanket of Dicranopteris synusia were kept (AR) and all of the Dicranopteris were kept (CK). The results showed that: 1) Compared with the red soil under Dicranopteris synusia of Eucalyptus plantation and bare ground, the contents of soil organic matter, total nitrogen, hydrolyzed nitrogen, available phosphorus, available potassium, and exchangeable base ions in the root blanket of Dicranopteris synusia were significantly higher. 2) The majority of the tree species and all of the herbaceous species could not survive with the root blanket of Dicranopteris synusia kept (AR and CK). The species that could survive with the root blanket of Dicranopteris synusia kept were Schima superba, Rhodomyrtus tomentosa, Ilex asprella and Melastoma candidum. The results indicated that Dicranopteris synusia could act as an ecological filter. The key lies in the role of root blanket of Dicranopteris synusia, and not in the improvement of soil nutrients. Theoretically, Dicranopteris synusia, especially the root blanket of Dicranopteris synusia, is closely related to the breakthrough of biological threshold for ecological restoration. In the future, it is necessary to further analyze the structure and function of the root blanket of Dicranopteris synusia. In terms of application, there are a large number of plantation types (such as Eucalyptus plantation) that Dicranopteris occupied as a single dominant understory species in South China. Therefore, we should pay more attention to the ecological filtering effect of Dicranopteris synusia in structural optimization and stand transformation. This study could provide a reference for the restoration and reconstruction of degraded slope land in South China.

To identify the key factors involved in hindering and effectively promoting the natural regeneration of Metasequoia glyptostroboides, five M. glyptostroboides mother trees in the original wild habitat were selected for this study. The sample circle was set with the M. glyptostroboides mother tree as the center. Different understory treatments (community barrier, understory living ground cover barrier, litter barrier, and non-barrier) were used to conduct the zoning experiment to study the effects of vegetation and litter on the natural regeneration of M. glyptostroboides. Different understory treatments were found to have significant effects on M. glyptostroboides seedling regeneration density, survival rate, height, base diameter, root length, leaf number, leaf area, aboveground biomass, and underground biomass (P＜0.01) . All seedling germination growth indicators reached their maximum values in the non-barrier area, followed by the litter barrier area, understory living ground cover barrier area, and community barrier area. The living ground, litter, and community environment all hindered the natural regeneration of M. glyptostroboides. The order of inhibition on its seed germination and seedling growth was community environment＞living ground＞litter. The dynamic changes in seedling height exhibited the S type growth curve (R~2≥0.893), whereas the seedling regeneration density in all four treatments displayed an inverted "V" shape distribution. The non-barrier treatment significantly promoted the natural regeneration of M. glyptostroboides, under which the survival rate, seedling height, base diameter, root length, leaf number, leaf area, growth rate, and biomass were the highest. Thus, for the conservation and management of M. glyptostroboides populations, the living ground cover and litter should be adequately cleared to provide a suitable environment for seed germination and seedling growth, and promote the natural regeneration of M. glyptostroboides populations in the future. [ABSTRACT FROM AUTHOR]

Weeping cypress is an endemic tree species that is widely planted in China, and the simple stand structure and fragile ecosystem of its plantation are common issues. Exploring the effect of different gap sizes on the soil bacterial community structure of weeping cypress plantations can provide a theoretical basis for the near-natural management of forest plantations. We, therefore, constructed three kinds of forest gaps with different sizes in weeping cypress plantations, namely, small (50–100 m²), medium (100–200 m²), and large gaps (400–667 m²), for identifying the key factors that affect soil bacterial communities following the construction of forest gaps. The results suggested that the herb layer was more sensitive than the shrub layer, while the Simpson, Shannon, and richness indices of the herb layer in plots with gaps were significantly higher than those of designated sampling plots without any gaps (CK). The presence of large gaps significantly increased the understory plant diversity and the Shannon and Simpson indices of the soil bacterial alpha diversity. There were obvious changes in the community composition of soil bacteria following the construction of forest gaps. The dominant bacterial phyla, orders, and functions were similar across the plots with different gap sizes. Of the indicator bacterial species, the abundance of the nitrogen-fixing bacteria, Lysobacter_ yangpyeongensis, and Ensifer_meliloti, was significantly different across plots with different gap sizes and accounted for a large proportion of the bacterial population of plots with medium and large gaps. The understory plant diversity was mostly related to the soil bacterial community than to other soil factors. The results of structural equation modeling indicated that the understory plant diversity was the most important environmental factor in driving the composition and diversity of bacterial communities. The construction of forest gaps significantly improved the understory plant diversity, physicochemical properties of the soil, and bacterial diversity in weeping cypress plantations, and the results of the comprehensive evaluation were in the order: large gaps > small gaps > medium gaps > CK. Our results suggested that large gaps are beneficial for the diversity of above-ground plant communities and underground soil bacterial communities. [ABSTRACT FROM AUTHOR]

Despite many studies showing biodiversity responses to warming, the generality of such responses across taxonomic groups remains unclear. Very few studies have tested for evidence of bryophyte community responses to warming, even though bryophytes are major contributors to diversity and functioning in many ecosystems. Here, we report an empirical study comparing long‐term change in bryophyte and vascular plant communities in two sites with contrasting long‐term warming trends, using "legacy" botanical records as a baseline for comparison with contemporary resurveys. We hypothesized that ecological changes would be greater in sites with a stronger warming trend and that vascular plant communities, with narrower climatic niches, would be more sensitive than bryophyte communities to climate warming. For each taxonomic group in each site, we quantified the magnitude of changes in species' distributions along the elevation gradient, species richness, and community composition. We found contrasted temporal changes in bryophyte vs. vascular plant communities, which only partially supported the warming hypothesis. In the area with a stronger warming trend, we found a significant increase in local diversity and dissimilarity (β‐diversity) for vascular plants, but not for bryophytes. Presence–absence data did not provide sufficient power to detect elevational shifts in species distributions. The patterns observed for bryophytes are in accordance with recent literature showing that local diversity can remain unchanged despite strong changes in composition. Regardless of whether one taxon is systematically more or less sensitive to environmental change than another, our results suggest that vascular plants cannot be used as a surrogate for bryophytes in terms of predicting the nature and magnitude of responses to warming. Thus, to assess overall biodiversity responses to global change, abundance data from different taxonomic groups and different community properties need to be synthesized. [ABSTRACT FROM AUTHOR]

The ecological construction in coastal saline-alkali areas urgently needs to be explored in terms of water-salt regulation management and functional irrigation. In this paper, the extremely severe saline soil in the eastern coastal area of the North China Plain was selected for vegetation rehabilitation by drip irrigation. Through two-year field experiments, the spatial and temporal soil salinity-water dynamics of three land use types (LUTS) under two irrigation strategies (IIS) were systematically studied. The results revealed: (1) The soils in the understory grassland and shrub land root zones remained stable for desalination, with the average ECe decreasing to 0.69 dS/m and 0.71 dS/m under autumn irrigation at surface, and 0.66 dS/m and 0.85 dS/m under winter irrigation. And a slight salt accumulation occurred in the bare land in stage IV. (2)The soil surface moisture increased, and the bulk density decreased significantly with drip irrigation. The final moisture of understory grassland and shrub land was 3.85 and 2.97 times that of the bare land layer at 0-10 cm, 2.55 and 1.97 times at 10-20 cm, and 1.61 times and 1.47 times at 20-40 cm, respectively. (3)Due to quick salt rinsing, Salix matsudana and Hibiscus maintained a high survival rate, and the germination of understory vegetation further increased the vegetation coverage. Meanwhile perennial understory herbs gradually became the dominant species, which positively effects on the maintenance of soil low-salt environment. (4)There were significant differences in SWC and ECe between autumn and winter irrigation treatment during stage I and stage II, indicating that irrigation strategies only impact on soil water-salt movement in the early stage. While there was no significant difference between understory grassland and shrub land, indicating that the research about the effects of vegetation cover type on water-salt transport should take a longer time scale., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Afforestation plays an important role in controlling soil erosion and nutrient loss on the Loess Plateau in China. However, previous studies on soil nutrient changes have mainly focused on the effects of tree species, whereas little is known about how changes in shrubs and herbs caused by afforestation drive soil nutrient changes. In this study, we examined the variation characteristics of understory vegetation and soil nutrients for different vegetation types. The results showed that compared to abandoned farmland, plantations significantly increased soil organic carbon and total nitrogen but had no significant effect on total phosphorus. Robinia pseudoacacia L. forests were more effective than Pinus tabuliformis Carr. forests in increasing soil nutrient content. In addition, herbaceous vegetation in the R. pseudoacacia forest better explained the soil nutrient variation, and herb abundance was the best explanatory variable; however, shrub vegetation contributed more to soil nutrient variation in the P. tabuliformis forest, and shrub abundance contributed the most. Accordingly, we determined that understory plant abundance, rather than species richness, may be the most important factor driving soil nutrient changes. Specifically, herb abundance in the R. pseudoacacia forest may drive soil nutrient changes mainly by regulating herb biomass and litter biomass. By contrast, shrub abundance in the P. tabuliformis forest indirectly affected soil organic carbon mainly by altering shrub biomass. Furthermore, although the phylogenetic relationships had less effect on soil nutrients than species composition, they also made important contributions. Therefore, the phylogenetic relationships should also be considered in addition to species composition when assessing the impact of vegetation on soil properties in the future. [ABSTRACT FROM AUTHOR]

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Riparian soil processes and vegetation are sensitive to water availability. Urbanization can alter riparian water availability by modifying stream flows and stream channel morphology. In cities, runoff from impervious surfaces tends to increase stormflow magnitudes, causing stream channels to incise, or downcut. This change in channel morphology has been linked to lowered water tables and drier conditions in temperate urban riparian zones, leading to shifts in riparian nitrogen (N) cycling and vegetation communities. In Mediterranean climates with distinct wet and dry periods, there is an additional dynamic to consider: runoff from urban water use can cause streams to flow when they would otherwise be dry. This dry‐season stream flow could create increased, rather than decreased, water availability in urban riparian zones. However, channel incision may counteract this effect. We asked whether dry‐season stream flow interacted with channel incision to influence riparian soil characteristics and understory vegetation along streams in Sacramento, California, which has a Mediterranean climate with an intense summer dry season. At 40 stream reaches that varied by severity of downcutting and presence of dry‐season flow, we sampled soils and vegetation on top of stream banks and at the margin of the low‐flow channel, an important location for nutrient cycling in dry climates. We measured soil moisture, organic matter, and ∂15N, as well as total and perennial understory vegetation cover. We found that channel characteristics associated with incision limited the influence of dry‐season stream flow on soil moisture, and this interaction appears to have lasting effects on soil organic matter and perennial vegetation on bank tops. At the stream margin, channel downcutting was associated with reduced soil organic matter and vegetation cover, while dry‐season flow was associated with increased vegetation cover. Values of soil ∂15N pointed to limited hydrologic linkage between stream flows and riparian bank soils along incised streams. Our findings suggest that channel incision could limit the ability of urban riparian ecosystems to mitigate low‐flow water quality. However, where streams are not incised in Mediterranean climates, dry‐season flows from urban runoff may actually increase riparian productivity and N cycling above historical levels. [ABSTRACT FROM AUTHOR]

Age-related changes in water and nitrogen utilization of crop and understory vegetation in a hinoki cypress plantation forest were investigated from the age of 21 to 46 years in Kochi City, southern Japan. Nitrogen concentration in the leaf litter of hinoki cypress showed a decreasing trend with forest age. The leaf δ15N of hinoki cypress was related to a quadratic function and increased from the age of 21 to 26 years and then decreased to the age of 46 years. These results suggest that older hinoki cypress trees utilize soil nitrogen sources with lower δ15N values, and the competition for soil nitrogen with understory vegetation should be stronger. Carbon isotope discrimination (Δ13C) of hinoki cypress decreased from the age of 21 to 30 years and then increased to the age of 46 years. In contrast, the intrinsic water-use efficiency (iWUE) of hinoki cypress increased from the age of 21 to 36 years and then decreased to the age of 46 years. These findings suggest that hinoki cypress trees in the earlier time increased their iWUE by reducing stomatal opening. In the earlier time, the stomatal opening of understory vegetation increased due to higher soil water availability with decreasing stand density of crop trees. In the later time, the iWUE of hinoki cypress decreased due to lower photosynthetic capacity with nitrogen limitation. These results suggest that the increase in the iWUE of hinoki cypress in response to elevated atmospheric carbon dioxide levels should be smaller in the later time because of stronger competition with understory vegetation for soil nitrogen resources. [ABSTRACT FROM AUTHOR]

We assessed the understory vegetation types in temperate Kashmir Himalayan coniferous forests, their species composition and what function ecological drivers execute in shaping compositional trends using a multivariate statistical approach. The agglomerative clustering analysis depicted eight discrete plant associations in terms of herb species composition with simple underlying indicator species and ecological drivers. At one extreme, we found alpine and subalpine areas (Tanacetum multicaule Sch.Bip. – Aconitum heterophyllum Wall. ex Royle – Lomatogonium caeruleum (Royle) Harry Sm. ex B.L. Burtt community (TAL)) occupying high elevations (2961.88±205.56 m) with notable species richness (6.04), while lower (2459.36±94.07 m) areas are inhabited by Thalictrum minus L. – Galium aparine L. – Achillea millefolium L. (TGA) community. The Poa pratensis L.– Senecio chrysanthemoides DC. – Clinopodium umbrosum (M.Bieb.) Kuntze (PSC) community was most diverse, supported higher species diversity (Shannon=2.22±0.07; Simpson=0.84±0.01; Fisher's α=4.51±0.30) and also exhibited a maximum number of trails crossing the plot. Canonical Correspondence analysis (CCA) examined the species-ecological interactions and displayed a significant role of most studied environmental variables in the species distribution patterns. The latter in the decreasing significance order comprised precipitation (F = 2.3; p = 0.001), latitude (F = 2.15; p = 0.001), grazing (F = 1.56; p = 0.01), longitude (F = 1.63; p = 0.013), slope (F = 1.33; p = 0.07), elevation (F = 1.32; p = 0.07), aspect (F = 0.1; p = 0.47), trails (F = 0.78; p = 0.85) and mean monthly minimum temperature (F = 1.23; p = 0.172). The variance partitioning used to evaluate the comparative significance of topographic, climatic and disturbance factors on understory vegetation composition depicted that topography (14.26%) strongly partitioned the vegetation distribution subsequently followed by climatic (11.52%) and disturbance (4.49%) factors.

Despite the importance of species mixtures to ecosystem-based forest management, density effect of broadleaf trees in the mixture on understory vegetation and soil properties are poorly understood. In this study, we examine the effects of trembling aspen [aspen] (Populus tremuloides Michx.) -white spruce [ spruce] (Picea glauca (Moench) Vos) mixtures that vary in the proportion of aspen on understory vegetation cover, soil nutrient supply rates, and soil properties. Data were collected from an established study located in Alberta, Canada at age 20 and included the following treatments: 1. Natural regeneration of pure aspen; 2. Retaining only 1600 planted spruce ha−1 by controlling aspen and understory vegetation; 3. Retaining only 1600 planted spruce ha−1 by controlling understory vegetation; 4–7. Retaining only 400 planted spruce ha−1 along with unthinned aspen, 2000, 1200, and 800 aspen ha−1. In mixed stands, competition control around the spruce was done for its establishment, and subsequent thinning was done to control the density of aspen. The findings of our analysis showed that mixed stands had higher total vascular plant cover, potential soil N supply rates, soil pH, and lowered C: N ratio compared to monocultures of spruce or aspen. The treatment (mixed stands) with unthinned aspen along with spruce increased the above-mentioned variables most compared to other mixtures. Moreover, total forb cover was higher in the mixture with the highest density of aspen, but grass cover was higher in the lowest density of aspen. Our findings hint that the effect of mixing tree species on understory vegetation cover may be influenced by the density of broadleaf tree in the mixture. Further studies need to be conducted to reach a concrete conclusion. Regardless, this result might be useful for forest managers to take a decision for ecosystem-based forest management. • Total understory vegetation cover was higher in the mixture than in monoculture. • The mixture increased the potential nitrogen supply rates compared to monoculture. • Soil properties were improved in the mixture compared to monoculture. • The mixture effect was dependent on the density of broadleaf in the treatments. [ABSTRACT FROM AUTHOR]

Large herbivores are considered a natural and important determinant for high biodiversity in woodland habitats and have been increasingly reintroduced to nature areas across Europe with the aim of re-establishing natural processes to promote and protect biodiversity. One of the herbivore species playing an increasing role in ecological restoration initiatives is the European bison – the largest extant terrestrial mammal in Europe. However, despite numerous reintroductions of bison for biodiversity purposes, the empirical evidence for their impact is highly limited. Using permanent plots, we investigated the impact of European bison on ground vegetation in forest habitats over a period of eight years. The bison increased the species richness of vascular plants, though mainly to the benefit of graminoids. The effect varied, however, among forest types, with the strongest effect in oak forests with dense and abundant ground vegetation while beech forests characterized by full canopy cover were unaffected. Bison also benefitted bryophytes, which increased in abundance, indicating a generally altered competitive environment with reduced dominance. These results thus provide some of the first empirical evidence, indicating that European bison can promote plant species diversity in forest habitats, by removal of plant biomass, zoochorous seed dispersal, and creation of microhabitat. We thus suggest that introduction of European bison to mixed light woodlands can be a good strategy, benefitting both biodiversity and the conservation of the threatened herbivore species itself. • European bison increase species richness of vascular plants in forest. • Bison grazing increases abundance of bryophytes. • Effects of bison grazing vary among forest habitat types. • The strongest effect is in habitats with dense and abundant ground vegetation. [ABSTRACT FROM AUTHOR]