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In recent decades, alpine meadows have experienced severe degradation owing to external disturbances. Although soil microorganisms are critical for ecosystem services, little is known about their responses to soil degradation and the potential patterns in alpine meadows. To solve this question, we collected and analyzed soil samples from three degraded alpine meadows situated on the Qinghai-Tibet Plateau. We aimed to examine the effects of degradation on soil microbial diversity and identify the ecological predictors for the diversity of bacteria and fungi. Our results showed that alpine meadow degradation significantly changed soil bacterial and fungal diversity and community composition. Specifically, the relationship between bacterial and fungal diversity and degradation intensity was a hump-shaped, with the highest diversity observed at a moderate degradation level. Additionally, alpine meadow degradation-induced changes in microbial diversity were strongly correlated with decreased plant production, with fungal diversity showing a closer link with below-ground biomass (BGB) than with bacterial diversity. Our findings offer empirical evidence that intermediate disturbance (i.e., moderate degradation) may be beneficial for supporting soil biodiversity. This has important implications for informing policy and management strategies meant to conserve soil biodiversity and ecosystem services when facing anthropogenic change.

Ambitious climate change mitigation goals require novel carbon (C) sinks in agricultural systems. Thus, the establishment of new hedgerows is increasingly attracting attention as a C sequestration measure. Despite hedgerows being a traditional agroforestry system, few studies have been conducted on hedgerow C stocks. Data on below‐ground biomass (BGB) in particular are limited. The aim of this study was therefore to quantify both above‐ground biomass (AGB) and BGB C stocks, as well as litter and soil organic C stocks, of established hedgerow systems by destructive sampling at three sites in northern Germany. The total biomass C (TBC) stock of the sampled hedgerows was 105 ± 11 Mg ha−1 on average. An additional 11 ± 2 Mg ha−1 were found in hedgerow litter and dead roots. Coarse roots (34% of TBC), stumps (22%) and harvestable biomass (20%) were the largest biomass C pools of the hedgerows. The BGB:AGB ratio was 0.7 ± 0.1, showing the importance of BGB in old hedgerow systems. Compared with other woody systems, these old hedgerows seem to have a different biomass distribution, with more biomass allocated below‐ground. About 15% of BGB C stock was stored in fine roots, whereas 85% was stored in coarse roots. The topsoil (0–30 cm) contained 85% of coarse root biomass C and 51% of fine root biomass C. Hedgerow C stock exceeded that of average German forests, and thus demonstrated their large potential for C sequestration when newly planted. This study provides detailed empirical data on C stocks in old hedgerow systems, and thus can be used to take hedgerow C sinks into account in C farming frameworks. [ABSTRACT FROM AUTHOR]

Abstract Ambitious climate change mitigation goals require novel carbon (C) sinks in agricultural systems. Thus, the establishment of new hedgerows is increasingly attracting attention as a C sequestration measure. Despite hedgerows being a traditional agroforestry system, few studies have been conducted on hedgerow C stocks. Data on below‐ground biomass (BGB) in particular are limited. The aim of this study was therefore to quantify both above‐ground biomass (AGB) and BGB C stocks, as well as litter and soil organic C stocks, of established hedgerow systems by destructive sampling at three sites in northern Germany. The total biomass C (TBC) stock of the sampled hedgerows was 105 ± 11 Mg ha−1 on average. An additional 11 ± 2 Mg ha−1 were found in hedgerow litter and dead roots. Coarse roots (34% of TBC), stumps (22%) and harvestable biomass (20%) were the largest biomass C pools of the hedgerows. The BGB:AGB ratio was 0.7 ± 0.1, showing the importance of BGB in old hedgerow systems. Compared with other woody systems, these old hedgerows seem to have a different biomass distribution, with more biomass allocated below‐ground. About 15% of BGB C stock was stored in fine roots, whereas 85% was stored in coarse roots. The topsoil (0–30 cm) contained 85% of coarse root biomass C and 51% of fine root biomass C. Hedgerow C stock exceeded that of average German forests, and thus demonstrated their large potential for C sequestration when newly planted. This study provides detailed empirical data on C stocks in old hedgerow systems, and thus can be used to take hedgerow C sinks into account in C farming frameworks.

Selecting cultivars with greater biomass results in higher yields and greater carbon sequestration. Storage of atmospheric carbon in the plant/soil pool contributes not only to food security but also to mitigating climate change and other agroecological benefits. The objective of this study was to determine: (1) grain, residue, and root biomass yields; (2) harvest indexes; (3) residue-to-product ratio; (4) root-to-shoot ratio; (5) biomass carbon and nitrogen contents; and (6) C:N ratios for two new and two old winter wheat cultivars. The greatest yield difference was found between old Srpanjka (the lowest) and new Kraljica (the highest) cultivar where grain, residue, root, and total biomass yield was higher by 38%, 91%, 71%, and 64%, respectively. Total biomass was composed of 40–47% grain, 10–11% roots, 32–36% stems + leaves, 9–11% chaff, and 1–2% spindle. The range of HI was 0.45–0.53, RPR 0.91–1.25, and R:S ratio 0.12–0.13. For all cultivars, positive carbon and negative nitrogen balance within the plant pool was determined. Still, root biomass and rhizodeposition carbon remain open questions for a better understanding of agroecosystems' C dynamics. [ABSTRACT FROM AUTHOR]

Legumes have a wide range of positive effects on soil properties, including nitrogen and carbon storage, soil structure and the phytosanitary condition of crops. From an agronomic point of view, legumes are most valued for their ability to take up atmospheric nitrogen in symbiosis with nitrogen-fixing bacteria. The aim of this research was to determine the effect of legume residues (peas, fodder beans, narrow-leaved lupins) on the N (Ntotal) and organic carbon (Corg) accumulation in soil and N leaching under temperate climate conditions. The experiment was carried out in lysimetric equipment in 2016–2023. The effect of legumes on Corg and Ntotal accumulation in soil and N leaching were studied in a Fabaceae–Cereals sequence. Three species of legumes—peas, fodder beans and narrow-leaved lupines—were tested; spring barley (Hordeum vulgare L.) was grown as a control treatment. The lysimeter surface area was 1.75 m2 and the experimental soil layer was 0.60 m (sand loam Haplic Luvisol). It was found that after harvesting, more residues were incorporated into the soil with lupines (p < 0.05), which, compared to pea and bean residues, increased Ntotal and Corg concentrations in the soil. There was a strong correlation (r = 0.95) between the Ntotal concentration in the soil and the N amount incorporated with residues. Mineral N released during residue decomposition was leached from the humic horizon under conditions of excess moisture in the autumn–winter period and increased the nitrate concentration in the lysimeter water. The increase in concentration was recorded within 5 to 6 months after the application of the residues. As a result, the N leaching losses increased on average by 24.7–33.2% (p < 0.05) during the year of legume cultivation. In the following year, after legume residue incorporation, the effect of residues on nitrate concentration and N leaching decreased and did not differ significantly from that of barley residues. [ABSTRACT FROM AUTHOR]

Stumps and coarse roots form an important C pool and nutrient pool in a Larix olgensis (Larix olgensis Henry) plantation ecosystem, and their decomposition processes would affect nutrient cycling dynamics of the overall Larix olgensis plantation. We studied the decomposition and release of nutrients from stumps and coarse roots that were cleared 0, 6, 16, 26 and 33 years ago in Northeast China. The stumps and coarse roots were divided into stump discs (SD), stump knots (SK), coarse roots (>10 cm in diameter) (CR1), medium-coarse roots (5–10 cm in diameter) (CR2) and fine-coarse roots (2–5 cm in diameter) (CR3). During the entire 33-year study period, SK, CR1, CR2 and CR3 lost 87.37%, 96.24%, 75.76% and 91.98% of their initial mass, respectively. The average annual decomposition rate (k) was 0.068 for SD, 0.052 for SK, 0.092 for CR1, 0.068 for CR2 and 0.066 for CR3. After 33 years of decomposition, CR3 lost 5% of its initial C, CR2 lost 2%, and SK accumulated 1%, indicating slow C release. The N residues in SK, CR1, CR2 and CR3 were 186%, 109%, 158% and 170%, respectively. Coarse roots released P significantly faster than SD and SK, with 13% of the initial P released in CR1. SD and SK release cellulose, hemicellulose and lignin faster than coarse roots. The results show that Larix olgensis stumps and coarse roots could contribute to soil fertility recovery and serve as a long-term nutrient reservoir for forest vegetation. [ABSTRACT FROM AUTHOR]

AbstractThis study was conducted to investigate the effect of changes in soil moisture content under climate change conditions on the growth response of Quercus dentata, a representative species of the genus Quercus on the Korean peninsula. The results showed that Q. dentata germination increased by 9.4 days under climate change conditions (RCP 4.5 scenario), whereas the below-ground biomass and plant biomass increased by 1.3 and 1.2 times, respectively. However, the soil moisture treatment condition solely affected the leaf area, below-ground biomass, and plant biomass but not the germination percentage, germination speed, above-ground length, and above-ground biomass. The variance across the measured growth variables was considerably higher in the control group than in the climate change treatment group, whereas the variance was lower for lower soil moisture content. The findings suggested that under climate change conditions, Q. dentata germinated rapidly and exhibited broader leaf area and increased development below ground, which may be advantageous for the early establishment of seedlings. However, the plants may face difficulties in conditions with low soil moisture content. In conclusion, with continuous climate changes, Q. dentata seedlings are predicted to efficiently adapt to the altered soil moisture content to exhibit even more reliable growth than with the current condition. However, the growth of Q. dentata seedlings would be more difficult with severely low soil moisture content than with abundant soil moisture content, which is predicted to be detrimental to population maintenance in the long term.

Selecting cultivars with greater biomass results in higher yields and greater carbon sequestration. Storage of atmospheric carbon in the plant/soil pool contributes not only to food security but also to mitigating climate change and other agroecological benefits. The objective of this study was to determine: (1) grain, residue, and root biomass yields; (2) harvest indexes; (3) residue-to-product ratio; (4) root-to-shoot ratio; (5) biomass carbon and nitrogen contents; and (6) C:N ratios for two new and two old winter wheat cultivars. The greatest yield difference was found between old Srpanjka (the lowest) and new Kraljica (the highest) cultivar where grain, residue, root, and total biomass yield was higher by 38%, 91%, 71%, and 64%, respectively. Total biomass was composed of 40–47% grain, 10–11% roots, 32–36% stems + leaves, 9–11% chaff, and 1–2% spindle. The range of HI was 0.45–0.53, RPR 0.91–1.25, and R:S ratio 0.12–0.13. For all cultivars, positive carbon and negative nitrogen balance within the plant pool was determined. Still, root biomass and rhizodeposition carbon remain open questions for a better understanding of agroecosystems’ C dynamics.

Legumes have a wide range of positive effects on soil properties, including nitrogen and carbon storage, soil structure and the phytosanitary condition of crops. From an agronomic point of view, legumes are most valued for their ability to take up atmospheric nitrogen in symbiosis with nitrogen-fixing bacteria. The aim of this research was to determine the effect of legume residues (peas, fodder beans, narrow-leaved lupins) on the N (Ntotal) and organic carbon (Corg) accumulation in soil and N leaching under temperate climate conditions. The experiment was carried out in lysimetric equipment in 2016–2023. The effect of legumes on Corg and Ntotal accumulation in soil and N leaching were studied in a Fabaceae–Cereals sequence. Three species of legumes—peas, fodder beans and narrow-leaved lupines—were tested; spring barley (Hordeum vulgare L.) was grown as a control treatment. The lysimeter surface area was 1.75 m2 and the experimental soil layer was 0.60 m (sand loam Haplic Luvisol). It was found that after harvesting, more residues were incorporated into the soil with lupines (p < 0.05), which, compared to pea and bean residues, increased Ntotal and Corg concentrations in the soil. There was a strong correlation (r = 0.95) between the Ntotal concentration in the soil and the N amount incorporated with residues. Mineral N released during residue decomposition was leached from the humic horizon under conditions of excess moisture in the autumn–winter period and increased the nitrate concentration in the lysimeter water. The increase in concentration was recorded within 5 to 6 months after the application of the residues. As a result, the N leaching losses increased on average by 24.7–33.2% (p < 0.05) during the year of legume cultivation. In the following year, after legume residue incorporation, the effect of residues on nitrate concentration and N leaching decreased and did not differ significantly from that of barley residues.

The geographical location, climate, topography and most important human interference has contributed to the characteristic flora of the old campus of University of Jammu. A total of 24 tree species having 153 individuals belonging to 14 families have been recorded. Out of 24, 23 species belong to Angiosperms (22 dicots and 1 monocot) whereas, only 1 species belong to Gymnosperms. Overall, Moraceae was found to be the dominant family. The total growing stock, total biomass, total carbon content within university campus has been assessed to be 215663.99cm3, 107.83kg, 50.68kg respectively. The total CO2 sequestered by trees and net oxygen produced have been estimated to be 185.84kg and 495.65kg, respectively. Thus, the old campus of University of Jammu with lot of built-up area, roads, lawns, parking places, garden, etc. has sequestered considerably good amount of carbon and also produced considerable amount of oxygen as compared to its size, and its potential for sequestration can be enhanced with the help of management practices and plantation of more trees/shrubs within the permissible areas.

The geographical location, climate, topography and most important human interference has contributed to the characteristic flora of the old campus of University of Jammu. A total of 24 tree species having 153 individuals belonging to 14 families have been recorded. Out of 24, 23 species belong to Angiosperms (22 dicots and 1 monocot) whereas, only 1 species belong to Gymnosperms. Overall, Moraceae was found to be the dominant family. The total growing stock, total biomass, total carbon content within university campus has been assessed to be 215663.99cm3, 107.83kg, 50.68kg respectively. The total CO2 sequestered by trees and net oxygen produced have been estimated to be 185.84kg and 495.65kg, respectively. Thus, the old campus of University of Jammu with lot of built-up area, roads, lawns, parking places, garden, etc. has sequestered considerably good amount of carbon and also produced considerable amount of oxygen as compared to its size, and its potential for sequestration can be enhanced with the help of management practices and plantation of more trees/shrubs within the permissible areas. [ABSTRACT FROM AUTHOR]

Fire is a fundamental ecological factor in savannas because it affects vegetation dynamics and ecosystem functioning. However, the effects of fire on below‐ground compartments, including biomass and root traits, and their regeneration remain poorly understood. In this study, we assess the variation of above‐ and below‐ground plant components along fire‐history gradients in Brazilian open savannas and investigate whether changes in vegetation and soil properties are associated with the responses of below‐ground biomass and root traits.The study was conducted in eight sampling areas of open savanna (campo sujo, i.e. vegetation having low woody cover) within the Cerrado (Brazilian savannas), located along a gradient of time since the last fire (1–34 years); the number of fires that occurred within the past 34 years (0–9 fires) varied by sampling area. In each sampling area, we measured above‐ and below‐ground biomass, root depth distribution, root functional parameters and nutrient levels in the upper soil layers (0–10 cm).Rapid recovery of above‐ground live biomass after a fire was primarily due to resprouting of graminoids. This recovery was associated with an increase in absorptive root biomass in the upper soil layer in the most recently burnt sites, whereas root biomass was unaffected in deeper layers. Root parameters remained constant regardless of fire history but responded to variations in vegetation structure and soil properties. Specific root length (SRL) decreased with K, Mg2+, Al3+, N and C and increased with P concentration. In contrast, root tissue density (RTD) and absorptive root proportion were negatively correlated with soil P. RTD was strongly associated with the above‐ground biomass of graminoids. Soil texture impacted the root system: the proportion of absorptive roots increased with fine sand content in the soil, inversely to transport root biomass. The relationship between fire and soil properties was insignificant.Synthesis. In savannas, fire stimulates absorptive root biomass in response to the higher demand for below‐ground resources. This response is correlated with shoot regrowth after a fire. Variations in morphological root parameters are not directly associated with fire history; instead, they reflect differences in soil chemistry, especially soil P and graminoid biomass changes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Alpine meadow degradation significantly changed soil microbial community composite. • Soil microbial diversity showed hump-shaped patterns with increasing degradation. • The changes in soil microbial diversity were greatly correlated with plant production. In recent decades, alpine meadows have experienced severe degradation owing to external disturbances. Although soil microorganisms are critical for ecosystem services, little is known about their responses to soil degradation and the potential patterns in alpine meadows. To solve this question, we collected and analyzed soil samples from three degraded alpine meadows situated on the Qinghai-Tibet Plateau. We aimed to examine the effects of degradation on soil microbial diversity and identify the ecological predictors for the diversity of bacteria and fungi. Our results showed that alpine meadow degradation significantly changed soil bacterial and fungal diversity and community composition. Specifically, the relationship between bacterial and fungal diversity and degradation intensity was a hump-shaped, with the highest diversity observed at a moderate degradation level. Additionally, alpine meadow degradation-induced changes in microbial diversity were strongly correlated with decreased plant production, with fungal diversity showing a closer link with below-ground biomass (BGB) than with bacterial diversity. Our findings offer empirical evidence that intermediate disturbance (i.e., moderate degradation) may be beneficial for supporting soil biodiversity. This has important implications for informing policy and management strategies meant to conserve soil biodiversity and ecosystem services when facing anthropogenic change. [ABSTRACT FROM AUTHOR]

Background and aims Sand dunes reduce the impact of storms on shorelines and human infrastructure. The ability of these ecosystems to provide sustained coastal protection under persistent wave attack depends on their resistance to erosion. Although flume experiments show that roots of perennial plants contribute to foredune stabilization, the role of other plant organs, and of annual species, remains poorly studied. Furthermore, it remains unknown if restored foredunes provide the same level of erosion resistance as natural foredunes. We investigated the capacity of three widespread pioneer foredune species (the perennial Ammophila arenaria and the annuals Cakile maritima and Salsola kali) to resist dune erosion, and compared the erosion resistance of Ammophila at natural and restored sites. Methods Cores collected in the field were tested in a flume that simulated a wave swash. A multi-model inference approach was used to disentangle the contributions of different below-ground compartments (i.e. roots, rhizomes, buried shoots) to erosion resistance. Key Results All three species reduced erosion, with Ammophila having the strongest effect (36 % erosion reduction versus unvegetated cores). Total below-ground biomass (roots, rhizomes and shoots), rather than any single compartment, most parsimoniously explained erosion resistance. Further analysis revealed that buried shoots had the clearest individual contribution. Despite similar levels of total below-ground biomass, coarser sediment reduced erosion resistance of Ammophila cores from the restored site relative to the natural site. Conclusions The total below-ground biomass of both annual and perennial plants, including roots, rhizomes and buried shoots, reduced dune erosion under a swash regime. Notably, we show that (1) annual pioneer species offer erosion protection, (2) buried shoots are an important plant component in driving sediment stabilization, and (3) management must consider both biological (plants and their traits) and physical (grain size) factors when integrating dunes into schemes for coastal protection. [ABSTRACT FROM AUTHOR]

Efforts to understand why some species become successful invaders and why some habitats are more at risk from invasive species is an important research focus in invasion ecology. With current global climate change, evaluation of the effects of shade and drought on cohabiting native and invasive species from extreme ecosystems is especially important. Acacia tortilis subsp. raddiana is a tree taxon native to arid African deserts. Prosopis glandulosa, native to the southwestern United States and Mexico, is invading African arid and semiarid regions that are habitat for A. t. subsp. raddiana. The aim of this study was to evaluate and compare the tolerance and responses of the seedlings of these two tree species to shade, water stress and their interactions. We measured and recorded growth rates and morphological, biochemical and physiological plant traits under two radiation and two water treatments in greenhouse conditions. Radiation intensity was a stronger driver of the performance of both species than water availability. Beyond the independent effects of shade and drought, the interactions of these factors yielded synergistic effects on seedlings of both tree species, affecting key plant traits. The seedlings of A. t. subsp. raddiana were able to implement important shifts in key functional traits in response to altering abiotic stress conditions, behaving as a stress-tolerant species that is well-adapted to the habitat it occupies in hot arid African deserts. In contrast, the fast-growing seedlings of P. glandulosa were stress-avoiding. The alien P. glandulosa seedlings were highly sensitive to water and shade stress. Moreover, they were particularly sensitive to drought in shade conditions. However, although alien P. glandulosa seedlings were exposed to high stress levels, they were able to avoid permanent damage to their photosynthetic apparatus by mechanisms such as increasing energy dissipation by heat emission and by adjusting the relative allocation of resources to above- and below-ground structures. Our results are useful for conservation planning and restoration of invaded hyperarid ecosystems. • Radiation intensity was a stronger driver of plant responses than water availability. • The interactions between shade and drought yielded synergistic effects. • The seedlings of Acacia tortilis subsp. raddiana behaved as stress-tolerant. • The seedlings of Prosopis glandulosa behaved as stress-avoiding and fast-growing. • Prosopis glandulosa avoided permanent damage to its photosynthetic apparatus under high stress conditions. [ABSTRACT FROM AUTHOR]

Under global warming, fire and the season in which the fire occurs both have important impacts on grassland plant biomass. Still, the effect of fire on below-ground biomass (BB) along a natural aridity gradient and the main impact factors remain unclear. Here, we conducted a fire manipulation experiment (including un-fired, autumn fire and spring fire treatments) to investigate the effects of prescribed fire on BB and its critical determinants along a transect of grassland in northern China. BB had different response strategies in different aridity regions and fire seasons, despite above-ground biomass (AB) and root-shoot ratio were not significantly affected by fire. General linear regression models revealed that the fire changed the trend of increasing BB to decreasing along increasing aridity (p ＜ 0.05). Random forest model (RFM) and partial correlations revealed that the BB was primarily influenced by aridity, followed by the nitrogen (N) and phosphorus (P) concentration ratio of AB under un-fired disturbance. For autumn fire, the BB was primarily influenced by below-ground biomass carbon concentration (BB c), followed by the C and N concentration ratio of BB. For spring fire, the BB was primarily influenced by soil temperature (ST), followed by aridity and soil total phosphorus concentration (Soil p). Furthermore, partial least squares path model (PLS-PM) revealed that autumn fires weakened the effects of environmental factors on BB, while spring fires enhanced the effects of soil nutrients on BB. These suggested that fire disrupted the original stable nutrient dynamics of BB. Our results suggested that fire promoted the growth of BB in relatively humid areas (aridity = 0.51–0.53) while inhibited the growth of BB in relatively arid areas (aridity = 0.68–0.74). BB c and ST may be key drivers of BB after prescribed fire in autumn and spring. • The prescribed fire changed the trend of increasing belowground biomass to decreasing along with increasing aridity. • The belowground biomass of plants was mainly regulated by belowground biomass C after prescribed fire in autumn. • The belowground biomass of plants was mainly regulated by soil temperature after prescribed fire in spring. • The prescribed fire disrupted belowground biomass's original stable nutrient dynamics. [ABSTRACT FROM AUTHOR]

The rising temperature, altering precipitation, and increasing extreme events under climate warming affect the stability and sustainability of grassland ecosystems. The dynamics of above-ground biomass (AGB), below-ground biomass (BGB), and biomass partitioning (BGB:AGB ratio) of grasslands are of fundamental importance to understand their feedback to climate change. In this study, we used grassland productivity data extracted from the Oak Ridge National Laboratory Distributed Active Archive Center, Tennessee, USA, in which the AGB was collected within a 1.0 m × 0.25 m quadrat and the BGB was sampled within the center of the quadrat. Using multiple pairwise tests and Pearson’s correlation analysis, we assessed the variations of grassland productivity and examined the response of single-harvest and annual biomass partitioning of C _3 - and C _4 -dominated grasslands to the growing-season and annual climatic variability and climate extremes in seven sites belonging to four ecoregions (i.e. cold steppe, humid temperate, humid savanna, and savanna). The results show that the annual and single-harvest BGB:AGB ratio varied significantly across the plant types and ecoregions. Overall, the C _3 -dominated grasslands exhibited a higher BGB:AGB ratio than that of C _4 -dominated grasslands. Growing-season temperatures (GSTs) were found to be the key determinants in explaining the single-harvest BGB:AGB ratio rather than growing-season precipitation. For instance, the single-harvest BGB:AGB ratio of C _4 -dominated grasslands increased, while that of C _3 -dominated grasslands decreased with elevated GSTs. The growing-season extreme dry climates significantly increased the single-harvest BGB:AGB ratio of C _4 plants by a large reduction of AGB, potentially affecting the ecosystem functioning and stability. The C _3 -dominated grasslands in the cold steppe ecoregion are at great threat of drought-induced stress, as we observed that growing-season extreme dry climates reduced, albeit insignificantly, both the single-harvest AGB and BGB. This study provides key insights into factors influencing the biomass partitioning of C _3 - and C _4 -dominated grasslands and has important implications for assessing the grassland functioning and stability under increasing climate extremes.

Aims: A plant has a limited amount of resources at any time and it allocates them to different structures. In spite of the large number of previous studies on allocation patterns within single species, knowledge of general patterns in species allocation is still very limited. This is because each study was done in different conditions using different methodology, making generalization difficult. We investigate intraspecific above- versus below-ground biomass allocation among individuals across a spectrum of drygrassland plant species at two different developmental stages and ask whether allocation is age- and species specific, and whether differences among species can be explained by their life-history traits and phylogeny. Methods: We collected data on above- and below-ground biomass of seedlings and adult plants of 20 species from a common garden experiment. We analysed data on shoot–root biomass allocation allometrically and studied the relationship between the allometric exponents (slopes on log–log scale), species life-history traits and phylogenetic distances. Important Findings: We found isometric as well as allometric patterns of biomass allocation in the studied species. Seedlings and adult individuals of more than half of the species differed in their above- versus below-ground biomass allometric exponents. Seedlings and adult individuals of the remaining species differed in their allometric coefficients (intercepts). Annual species generally allocated proportionally more to above- than below-ground biomass as seedlings than as adults, whereas perennial species showed the opposite pattern. Plant lifehistory traits, such as plant life span, age of first flowering, month in which the species begin flowering and specific leaf area were much more important in explaining differences in shoot–root allometry among species than were phylogenetic relationships. This suggests that allocation patterns vary greatly among closely related species but can be predicted based on species life-history traits. [ABSTRACT FROM AUTHOR]

Aim of the study: To analyse the decline in aged holm oak coppice forests as regards above-ground and below-ground fractions and physiological features. Area of study: Centre of the Iberian Peninsula (Guadalajara province). Material and methods: 26 pairs of holm oak stools with different vigour but with similar site and structural characteristics within each pair were selected. Morphological (basal area, number of stools, maximum height) and physiological traits (leaf water potential, stomatal conductance) of the standing stools were assessed. Their aerial and underground parts were extracted and different size fractions of both their above and below-ground biomass were quantified. Linear mixed models were built to test the effect of ’Stool vigour’ on the mean behaviour of the measured variables. Additionally, for the aerial part, linear regressions between the weights of the different size fractions and the basal area at breast height were performed using ‘Stool vigour’ as a fixed factor. Main results: For the same site, root depth, and number and diameter of shoots than good vigour stools, poor vigour stools displayed: lower predawn water potential, greater leaf mass per unit of area; lower total leaf area; lower above-ground biomass (in total as well as per fractions); lower fine roots biomass; lower proportion of leaf biomass and a greater proportion of biomass of both all roots and those with diameter 2-7 cm. Research highlights: The above-ground physiological and morphological characteristics of declined stools are interpreted as poorer adaptation to site conditions. Root system architecture was found to be relevant to explain this behaviour.

A study was conducted to investigate the influence of sodicity induced changes in soil physical properties on paddy root growth in the normal agriculture, semi-reclaimed and sodic soils. The root growth (length, length density, biomass and distribution pattern) were unfavourably affected by the soil physical properties (bulk density, soil aggregate stability, available water content, hydraulic conductivity and soil water retention potential) in the case of sodic soil. The microbial biomass carbon, bacterial, fungal population and dehydrogenase activity showed the lower values in the case of sodosol compared to the normal soil. These soil biological properties tend to sustain paddy root growth in normal and semi-reclaimed soils. Principal component analysis revealed that soil physical properties accounted for 98.2% of total variance in root growth. The study revealed that salt stress induces changes in soil physical properties limiting paddy root growth in the salt affected soils. It is important to reclaim sodosols to alleviate salt induced physical stress for optimum paddy root growth.

The ability to predict the spatial distribution of tree root system variables (e.g., the Root system Area (RA), the maximum root diameter, the number of roots in diameter classes, the density of fine roots, etc.) under different environmental conditions is relevant to several scientific disciplines and to engineering practice. In this work, three well known analytical models from the literature are assembled into a unique framework called the Root Distribution Model (RDM). RDM models the expected vertical and horizontal distribution of coarse and fine root system variables for mature plants growing in different environmental conditions ranging from moderately humid to arid climates. All soil and moisture dynamic parameters are physically based, which make the model straightforward to calibrate via a single tuning parameter. At this investigative stage, it is shown that the model has the flexibility to represent a broad range of situations where soil moisture may result from precipitation inputs or from water level fluctuations due to either the presence of a water coarse or of deep aquifers or both. Accordingly, the distribution of the sectional RA may be either positively or negatively skewed, as well as show a peculiar bi-modal structure. The model can be used to study the impact of changing scenarios affecting precipitation, aquifer and channel hydrology. [Display omitted] • Three models from the literature are joined into a unique mathematical framework (Root Distribution Model). • The model has an analytical form that depends on soil and moisture physically based parameters. • The model reproduces the spatial distribution of tree root system variables over a broad range of environmental conditions. [ABSTRACT FROM AUTHOR]

1. Anthropogenically enhanced nutrient availability is often cited among the most important drivers of altered ecosystem function and loss of services world-wide. Although the above-ground consequences of nutrient enrichment on plant growth patterns are numerous and well documented, belowground impacts are less clear but nonetheless critical from a global change perspective. In coastal wetlands, for example, plant-soil-nutrient dynamics directly affect the capacity to sequester carbon as soil organic matter, keep pace with sea level rise and resist storm-induced erosion. 2. Here, we investigate the effects of excess nutrient loading on below-ground plant growth in an oligohaline marsh fertilized for 7 years with a factorial combination of nitrogen (N) and phosphorus (P). We used two common assessment procedures, the ingrowth and standing crop methods, to simultaneously quantify distinct aspects of below-ground plant growth, which are (i) below-ground biomass accumulation into unexploited open resource space and (ii) in situ, or maintenance, belowground biomass of plants in equilibrium with their environment, respectively. Our objective was to determine if plant growth responses to nutrient enrichment differed depending on process and/or biomass component measured. 3. We show that excess N concurrently increased live root biomass accumulation in ingrowth cores and reduced in situ live root standing crop. Similar, albeit non-significant, response trajectories were apparent for other below-ground biomass pools using both methods, excepting dead biomass and total standing crop. A review of previously published research supports our results and suggests that nutrient enrichment consistently has contrasting effects on below-ground plant growth depending on whether biomass accumulation or standing crop is measured, and that living biomass components are most responsive to enhanced nutrient availability. 4. Synthesis. We conclude that eutrophic conditions can be both beneficial and detrimental to ecosystem function by either stimulating below-ground biomass accumulation in unexploited soil or reducing the below-ground standing crop required to sustain the nutritional needs of established plants in mature communities. Thus, nutrient enrichment may, in the short-term, contribute to soil organic matter (i.e. carbon) accumulation by increasing below-ground growth as plants exploit new resource space. Over the long-term, however, nutrient enrichment has the potential to negatively impact soil organic matter content as plants equilibrate to excess nutrient availability by down-regulating below-ground standing crop. [ABSTRACT FROM AUTHOR]

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Background and Aims Empirical studies and allometric partitioning (AP) theory indicate that plant above-ground biomass (MA) scales, on average, one-to-one (isometrically) with below-ground biomass (MR) at the level of individual trees and at the level of entire forest communities. However, the ability of the AP theory to predict the biomass allocation patterns of understorey plants has not been established because most previous empirical tests have focused on canopy tree species or very large shrubs. Methods In order to test the AP theory further, 1586 understorey sub-tropical forest plants from 30 sites in southeast China were harvested and examined. The numerical values of the scaling exponents and normalization constants (i.e. slopes and y-intercepts, respectively) of log–log linear MA vs. MR relationships were determined for all individual plants, for each site, across the entire data set, and for data sorted into a total of 19 sub-sets of forest types and successional stages. Similar comparisons of MA/MR were also made. Key Results The data revealed that the mean MA/MR of understorey plants was 2.44 and 1.57 across all 1586 plants and for all communities, respectively, and MA scaled nearly isometrically with respect to MR, with scaling exponents of 1.01 for all individual plants and 0.99 for all communities. The scaling exponents did not differ significantly among different forest types or successional stages, but the normalization constants did, and were positively correlated with MA/MR and negatively correlated with scaling exponents across all 1586 plants. Conclusions The results support the AP theory’s prediction that MA scales nearly one-to-one with MR (i.e. MA α MR ≈1.0) and that plant biomass partitioning for individual plants and at the community level share a strikingly similar pattern, at least for the understorey plants examined in this study. Furthermore, variation in environmental conditions appears to affect the numerical values of normalization constants, but not the scaling exponents of the MA vs. MR relationship. This feature of the results suggests that plant size is the primary driver of the MA vs. MR biomass allocation pattern for understorey plants in sub-tropical forests. [ABSTRACT FROM AUTHOR]

Aims: Radiata pine ( Pinus radiata D. Don) plantations are widely used to control erosion in New Zealand. However, other species with similar growth but longer rotation lengths and ability to coppice may offer future alternatives to radiata pine. Comparing performance of alternative species to radiata thus becomes important if policy is to be developed to promote them. Methods: The below-ground characteristics (roots) of young redwood ( Sequoia sempervirens (D. Don) Endl.) trees from two established plantations in New Zealand were examined and compared with those of radiata pine, and selected poplar and New Zealand native species. Results: Roots with diameters less than 10 mm comprised over 99 % of total root length in 3-yr-old trees and 98 % of total root length in 4-yr-old trees. For roots greater than 2 mm in diameter, total root length of young redwood trees was greater than that of young radiata pine, poplar and the best performing New Zealand native plant. Total root length at a given root collar diameter for young (1-4 year old) redwood trees was significantly greater than for radiata pine trees. Roots of redwoods were finer and more numerous than for radiata but the below-ground biomass for a given root collar diameter showed no statistical difference between the two species. Conclusions: Redwood, because of its comparable growth rate and the production of many fine lateral roots, has the potential to become a keystone erosion-control species in New Zealand, especially on steep lands where there is an increased risk of post-harvest landsliding associated with moderate to severe rainstorm events. [ABSTRACT FROM AUTHOR]

Grassland covers approximately one-third of the area of China and plays an important role in the global terrestrial carbon (C) cycle. However, little is known about biomass C stocks and dynamics in these grasslands. During 2001-2005, we conducted five consecutive field sampling campaigns to investigate above-and below-ground biomass for northern China's grasslands. Using measurements obtained from 341 sampling sites, together with a NDVI (normalized difference vegetation index) time series dataset over 1982-2006, we examined changes in biomass C stock during the past 25 years. Our results showed that biomass C stock in northern China's grasslands was estimated at 557.5 Tg C (1 Tg=10 g), with a mean density of 39.5 g C m for above-ground biomass and 244.6 g C m for below-ground biomass. An increasing rate of 0.2 Tg C yr has been observed over the past 25 years, but grassland biomass has not experienced a significant change since the late 1980s. Seasonal rainfall (January-July) was the dominant factor driving temporal dynamics in biomass C stock; however, the responses of grassland biomass to climate variables differed among various grassland types. Biomass in arid grasslands (i.e., desert steppe and typical steppe) was significantly associated with precipitation, while biomass in humid grasslands (i.e., alpine meadow) was positively correlated with mean January-July temperatures. These results suggest that different grassland ecosystems in China may show diverse responses to future climate changes. [ABSTRACT FROM AUTHOR]

Aim To investigate large-scale patterns of above-ground and below-ground biomass partitioning in grassland ecosystems and to test the isometric theory at the community level. Location Northern China, in diverse grassland types spanning temperate grasslands in arid and semi-arid regions to alpine grasslands on the Tibetan Plateau. Methods We investigated above-ground and below-ground biomass in China's grasslands by conducting five consecutive sampling campaigns across the northern part of the country during 2001–05. We then documented the root : shoot ratio (R/S) and its relationship with climatic factors for China's grasslands. We further explored relationships between above-ground and below-ground biomass across different grassland types. Results Our results indicated that the overall R/S of China's grasslands was larger than the global average (6.3 vs. 3.7). The R/S for China's grasslands did not show any significant trend with either mean annual temperature or mean annual precipitation. Above-ground biomass was nearly proportional to below-ground biomass with a scaling exponent (the slope of log–log linear relationship between above-ground and below-ground biomass) of 1.02 across various grassland types. The slope did not differ significantly between temperate and alpine grasslands or between steppe and meadow. Main conclusions Our findings support the isometric theory of above-ground and below-ground biomass partitioning, and suggest that above-ground biomass scales isometrically with below-ground biomass at the community level. [ABSTRACT FROM AUTHOR]

Data on the distribution of root biomass are critical to understanding the ecophysiology of vegetation communities. This is particularly true when models are applied to describe ecohydrology and vegetation function. However, there is a paucity of such information across continental Australia. We quantified vertical and horizontal root biomass distribution in a woodland dominated by Angophora bakeri and Eucalyptus sclerophylla on the Cumberland Plains near Richmond, New South Wales. The site was characterised by a duplex (texture contrast) soil with the A horizon (to 70 cm) consisting of loamy sand and the B horizon (to > 10 m) consisting of sandy clay. The topsoil had a smaller bulk density, a smaller water holding capacity but a larger organic component and a larger hydraulic conductivity in comparison to the subsoil. Root biomass was sampled to 1.5 m depth and declined through the soil profile. Whilst total biomass in the B horizon was relatively small, its contribution to the function of the trees was highly significant. Coarse roots accounted for approximately 82% of the root mass recovered. Lateral distribution of fine roots was generally even but coarse roots were more likely to occur closer to tree stems. Variation in tree diameter explained 75% of the variation in total below-ground biomass. The trench method suggested the belowground biomass was 6.03 ± 1.21 kg m−2 but this method created bias towards sampling close to tree stems. We found that approximately 68% of root material was within a 2 m radius of tree stems and this made up 54% of the total number of samples but in reality, only approximately 5 to 10% of the site is within a 2 m radius of tree stems. Based on these proportions, our recalculated belowground biomass was 2.93 ± 0.59 kg m−2. These measurements provide valuable data for modeling of ecosystem water use and productivity. [ABSTRACT FROM AUTHOR]

The aim of this controlled environment experiment was to quantify the distribution of leaf-fed-15N and canopy fed-13C within nodulating, non-nodulating or N fertilized non-nodulating Cicer arietinum L. and in their surrounding rhizosphere soil, excluding soil + root respiration. Nodulating chickpea partitioned 32% of its total N and 27% of its total recoverable C below-ground, of which only 50% of N and 36% of C were in the clean root fraction. Non-nodulating chickpea allocated equal recoverable C but slightly less N (28%) below-ground but lost less C from plant induced below-ground respiration. The importance of this below-ground partitioning for crop systems C and N balances is highlighted by their large (45% and 33%, for N and C, respectively) contribution to the total plant derived residue (recyclable) fraction. Recovered 15N and 13C were greater ( P < 0.05) in the outer-rhizosphere (459 µg 15N and 3.2 mg 13C core−1) than in the inner-rhizosphere soil (detached from roots during freeze-drying; 18 µg 15N and 67 µg 13C core−1) in relation with the relative size of these compartments. This highlights the significance of the outer-rhizosphere soil when estimating C and N budgets and quantifying rhizodeposition, and the benefit of a double (15N, 13C) isotope approach to determine this flow against large background soil C and N pools. [ABSTRACT FROM AUTHOR]

Abstract: Afforestation is one of the most popular after-use options of cut-away peatlands in Scandinavia since it has both economic and aesthetic values and therefore the interest concerning the carbon stock often focuses on tree stands. Consequently, ground vegetation is readily disregarded in the present calculations of the climatic impact of afforestation. However, at the early stages of afforestation vigorous ground vegetation may have a major role in carbon sequestration. The biomass and C stock of ground vegetation and young tree seedlings were examined on an ash-fertilized and afforested cut-away peatland. Six treatments of different mixtures and quantities of wood-ash, peat-ash, biotite or Forest PK-fertilizer were replicated in three plots. Betula pubescens Ehrh. seeds were sown on randomized halves of split plots while the other halves were left unsown. The plant biomass was harvested four growing seasons after the treatments. The live above-ground biomass of ground vegetation on a cut-away peatland was up to two times that of tree seedlings. Furthermore, the below-ground biomass of ground vegetation and tree seedlings was equal to the above-ground biomass, or even greater. In particular, the biomass of mosses multiplied on ash-based fertilized areas compared to the Forest PK-fertilized areas. Our study proved that at the early stages of afforestation ground vegetation was even more important in biomass production and C stock than tree seedlings. Consequently, our results suggest that ground vegetation biomass should also be considered when the climatic impact of afforestation of cut-away peatlands is being calculated. [Copyright &y& Elsevier]

Question: Pollution and eutrophication of surface water is increasingly a problem in agricultural landscapes. Do intact (relatively undisturbed) and degraded forests differ in seasonal nutrient storage and therefore potential to ameliorate nutrient pollution? Location: United States, Midwestern region. Methods: We used three sets of paired plots, where intact plots were located close to disturbed woodlands. Herbaceous perennials located in eight 0.25 m² quadrats in the plots were harvested (in spring and mid-summer), dried, separated into above- and below-ground plant parts, and weighed to determine biomass. Nitrogen, phosphorus and potassium content of the plant tissues were then determined, and these data combined with biomass to estimate nutrient storage. Results: In spring, intact sites had 62% greater above-ground biomass than disturbed sites and 75% greater below-ground biomass. In summer, below-ground biomass of intact plots was still much greater than that of disturbed plots (73 percent), but above-ground biomass was similar. Nutrient tissue concentration generally did not differ, nor did soil nutrient levels. The disturbed sites were largely missing one group of species, the spring ephemerals, and this accounted for the difference in biomass and nutrient storage between sites. Conclusions: Relatively undisturbed woodlands in our study had a much greater capacity to store nutrients, and therefore ameliorate nutrient pollution, in early spring. This is significant because spring is also the time of highest potential leaching of nutrients into surface water. [ABSTRACT FROM AUTHOR]

A new Sim-CYCLE grazing model has been obtained by combining a grazing model (Seligman et al. 1992, Ecol. Model. 60: 45–61) with the Sim-CYCLE model (Ito and Oikawa 2002, Ecol. Model. 151: 143–176). The new model has been validated against a set of field data obtained at Kherlen Bayaan-Ulaan (KBU) grassland. On the basis of the model, the root responses to grazing of KBU grassland have been studied under different conditions of stocking rates and precipitation. Model results indicate that both below-ground biomass (BB) and below-ground net primary production (BNPP) generally decrease with increasing stocking rate. However, if stocking rate is not higher than 0.7 sheep ha−1, a sustainable state of the grassland ecosystem can be achieved after about 100 years, which suggests that the maximum sustainable stocking rate at KBU should be 0.7 sheep ha−1. At the sustainable state, the maximum BB in a year is about 11 Mg DM ha−1 under non-grazing condition, 5 Mg DM ha−1 under 0.4 sheep ha−1 stocking rate, and 4 Mg DM ha−1 under 0.7 sheep ha−1 stocking rate; the BNPP is 1.3 Mg DM ha−1 year−1 under non-grazing condition, and 0.6 Mg DM ha−1 year−1 under 0.4 sheep ha−1 stocking rate, and 0.4 Mg DM ha−1 year−1 under 0.7 sheep ha−1 stocking rate. Ratio of non-assimilation organ to assimilation organ (C/F) increases with increasing stocking rate. The C/F ratio is 10.99 under non-grazing conditions, and 12.11 under 0.7 sheep ha−1 stocking rate. Root turnover rate decreases with increasing stocking rate. The rate is 12% each year under non-grazing conditions, and 11% each year under 0.7 sheep ha−1 stocking rate. In addition, the effect of grazing on the grassland ecosystem under different scenarios of precipitation is also analyzed. Both BB and BNPP increase with increased precipitation, and vice versa. When precipitation is set to be 10% higher than the averaged from 1993 to 2002, the maximum sustainable stocking rate is 0.8 sheep ha−1, and when the precipitation is set to be 15% lower than the averaged, the maximum sustainable stocking rate is 0.6 sheep ha−1. [ABSTRACT FROM AUTHOR]

A chronosequence of Gmelina arborea Roxb. stands ranging from 1 to 6 years old was measured to document changes in growth, biomass and nutrient (N, P and K) contents for three red lateritic sites in Chhattisgarh, India. The stand''s density, survival and growth parameters (DBH, total height, crown diameter and number of branches) varied significantly with age and site. The number of stems was highest (789 trees/ha) in a 1-year-old plantation at site 3 (Kusumi) and lowest (724 trees/ha) in a 6-year-old stand at site 2 (Anandgoan). Allometric equations for stem wood, branches, leaves and roots to tree diameter at breast height were developed to estimate above ground and below ground tree biomass. The total biomass ranged from 3.9 Mg ha−1 in 1-year-old to 53.7 Mg ha−1 in 6-year-old stand. The stem wood contributed from 55.3% (site 3) to 56.3% (site 1), branch wood from 18.3% (site 2) to 19.8% (site 3), roots from 17.9% (site 3) to 18.5% (site 2) and foliage from 6.6% (site 2) to 7.0% (site 3) of the total biomass. The growth and biomass production were poor from establishment to 3 years age and it increased by 1.5–2 times as the plantation aged from 4–6 years. Nutrient accumulation in tree biomass increased with stand age, following the pattern of biomass accumulation. The total nitrogen accumulation in 6-year-old stands at three sites ranged from 212.9 to 279.5 kg ha−1 with a mean annual storage of 238.4 kg ha−1 and total K ranged from 170.8 to 220.5 kg ha−1 with a mean annual storage of 189.9 kg ha−1. Phosphorous storage was lowest which ranged from 15.0 to 19.6 kg ha−1 with a mean storage of 16.8 kg ha−1. The organic matter and nutrients in the soils improved significantly after 6 years of planting. Available N enhanced by 14.9%, 12.0% and 11.3%, K by 10.0%, 9.1% and 10.6%, whereas phosphorous declined by 2.6%, 23.0% and 20.0%, respectively, at soil depths of 0–20, 21–40 and 41–60 cm. The paper discusses the implications of whole tree harvest at 6 years age for fire/pulpwood. [Copyright &y& Elsevier]

Abstract In many temperate and annual grasslands, above-ground net primary productivity (NPP) can be estimated by measuring peak above-ground biomass. Estimates of below-ground net primary productivity and, consequently, total net primary productivity, are more difficult. We addressed one of the three main objectives of the Global Primary Productivity Data Initiative for grassland systems to develop simple models or algorithms to estimate missing components of total system NPP. Any estimate of below-ground NPP (BNPP) requires an accounting of total root biomass, the percentage of living biomass and annual turnover of live roots. We derived a relationship using above-ground peak biomass and mean annual temperature as predictors of below-ground biomass (r 2 = 0.54; P = 0.01). The percentage of live material was 0.6, based on published values. We used three different functions to describe root turnover: constant, a direct function of above-ground biomass, or as a positive exponential relationship with mean annual temperature. We tested the various models against a large database of global grassland NPP and the constant turnover and direct function models were approximately equally descriptive (r 2 = 0.31 and 0.37), while the exponential function had a stronger correlation with the measured values (r 2 = 0.40) and had a better fit than the other two models at the productive end of the BNPP gradient. When applied to extensive data we assembled from two grassland sites with reliable estimates of total NPP, the direct function was most effective, especially at lower productivity sites. We provide some caveats for its use in systems that lie at the extremes of the grassland gradient and stress that there are large uncertainties associated with measured and modelled estimates of BNPP. [ABSTRACT FROM AUTHOR]