The allocation of biomass reflects a plant’s resource utilization strategy and is significantly influenced by climatic factors. However, it remains unclear how climate factors affect the aboveground and belowground biomass allocation patterns on macro scales. To address this, a study was conducted using aboveground and belowground biomass data for 486 species across 294 sites in China, investigating the effects of climate change on biomass allocation patterns. The results show that the proportion of belowground biomass in the total biomass (BGBP) or root-to-shoot ratio (R/S) in the northwest region of China is significantly higher than that in the southeast region. Significant differences (<i>p</i> < 0.05) were found in BGBP or R/S among different types of plants (trees, shrubs, and herbs plants), with values for herb plants being significantly higher than shrubs and tree species. On macro scales, precipitation and soil nutrient factors (i.e., soil nitrogen and phosphorus content) are positively correlated with BGBP or R/S, while temperature and functional traits are negatively correlated. Climate factors contribute more to driving plant biomass allocation strategies than soil and functional trait factors. Climate factors determine BGBP by changing other functional traits of plants. However, climate factors influence R/S mainly by affecting the availability of soil nutrients. The results quantify the productivity and carbon sequestration capacity of terrestrial ecosystems and provide important theoretical guidance for the management of forests, shrubs, and herbaceous plants.

Determination of the microbial and enzymatic properties in soil is primarily concentrated on the surface layers of the soil profiles; however, it is well known that the transformation of soil organic matter also occurs in the deeper horizons of the soil profile. The aim of this study was to assess any changes in specific sets of enzyme activities and their associated physicochemical properties as affected by two different agricultural land-use systems and soil depth. Changes in the studied properties were determined across four <i>Luvisol</i> profiles in two agricultural land uses (arable land and vineyards). The enzyme activities associated with the transformation of C, N and P were analyzed. Additionally, the activity of some oxidoreductases and the fluorescein diacetate hydrolysis (FDAH) rate were also determined. Moreover, the content of the various forms of soil carbon, nitrogen, phosphorus (including microbial biomass C, N and P) and some other properties (pH, clay and silt content) were assessed. Agricultural land use significantly affected the microbial biomass content and as well as the studied enzyme activities. Most of the studied enzymes exhibited a higher activity in the grapevine (GV) profiles, which was followed by the winter wheat (WW) profiles; however, the largest variability occurred for the urease activity. There was no clear differentiation between the two studied land uses for the activity of nitrate reductase, dehydrogenases, acid phosphatase, or endo- and exo-cellulase. Irrespective of the plant being cultivated, the soil variables decreased significantly with increasing soil depth, wherein the greatest changes were observed between the surface and sub-surface soil horizons (I–II). The activity of some enzymes (e.g., the urease activity in WW profiles) decreased gradually across the soil profiles, while others were located almost solely within the surface layers (e.g., the nitrate reductase activity in the GV profiles as well as invertase in the WW profiles). The α-glucosidase activity did not exhibit any statistically significant changes along the analyzed profiles. The activity of phenol oxidase and peroxidase also revealed different trends along the studied profiles compared to the other enzymes and did not decrease gradually with depth. The microbial biomass of the C, N and P content was generally the highest in the upper horizons and gradually decreased with depth, wherein the largest decrease was observed between the surface and sub-surface horizon. The studied enzyme activities were more dependent on the soil carbon content compared to the other soil properties. And thus, in the C-rich horizons (C > 4 g kg) for the surface and subsurface layers the enzyme activities were highly correlated with TOC, DOC and MBC content as compared to the deeper, C-low horizons (C < 4 g kg). By examining how the microbial and enzymatic properties change across the soil profiles, it is possible to gain valuable insight into the long-term biogeochemical processes that are involved in soil fertility and in the health of agricultural ecosystems.

Although many empirical hypotheses have been proposed and tested to explain the biomass and diversity of aboveground organisms, these hypotheses have not been tested for soil microorganisms across soil depths. Here, we determined the ability of hypotheses concerning physiological tolerance, plant energy, soil energy, and habitat heterogeneity to explain the variance in microbial biomass (as determined by phospholipid fatty acid) and diversity (as determined by high-throughput sequencing) in surface (0–20 cm) and deep (40–60 cm) soil layers on the Mongolian Plateau. We found that aboveground net primary production (ANPP) and plant species richness steeply declined as aridity values increased. Physiological tolerance and habitat heterogeneity explained the spatial variation in ANPP while physiological tolerance and soil energy explained the spatial variation in plant diversity. The relationships between aridity and microbial variables differed between soil layers or microbial groups. Aridity values had hump-shaped relationships with surface-soil bacterial biomass or diversity but had linear and negative relationships with surface-soil fungal biomass or diversity. Aridity values were linearly and negatively related with deep-soil bacterial or fungal biomass but were unrelated with deep-soil bacterial or fungal diversity. We also found the ability of the ecological hypotheses to explain the variances in microbial variables (biomass and diversity) diffed between soil layers or microbial groups on the Mongolia Plateau. The surface-soil bacterial biomass was mainly associated with plant energy and physiological tolerance while surface-soil bacterial diversity was mainly associated with habitat heterogeneity and physiological tolerance; surface-soil fungal biomass and diversity were mainly associated with habitat heterogeneity and physiological tolerance. The deep-soil bacterial biomass and diversity were mainly associated with physiological tolerance and soil energy; deep-soil fungal biomass was mainly associated with plant energy and physiological tolerance while deep-soil fungal diversity was mainly associated with soil energy and habitat heterogeneity. Our results showed that the major ecological hypotheses traditionally applied to plant communities can explain much of the variation in soil microbial biomass and diversity. These findings that identifying ability of ecological hypotheses to explain the variance in both plant and microbial biomass and diversity will be crucial importance to understand biodiversity assembly under ongoing environmental changes.

Different utilization patterns can alter the C, N, P cycles and their ecological stoichiometry characteristics in grassland soils. However, the effects of different utilization patterns on soil microbial biomass, microbial entropy and soil-microorganism stoichiometry imbalance of artificial grassland are not clear. So this study was took different utilization patterns of artificial grassland [i.e., grazing grassland (GG), mowing grassland (MG), enclosed grassland (EG)] as the research object to investigate responses of soil microbial biomass, microbial entropy and soil-microorganism stoichiometry imbalance to different utilization patterns in the karst rocky desertification control area. We found that the contents of microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) were highest in GG, and the content of microbial biomass phosphorus (MBP) was highest in EG. Soil microbial biomass entropy carbon (qMBC) and soil microbial biomass entropy nitrogen (qMBN) of GG and MG were higher than those of EG, but soil microbial biomass entropy phosphorus (qMBP) was opposite. C:N stoichiometry imbalance (C:Nimb) was EG &gt; GG &gt; MG, C:P stoichiometry imbalance (C:Pimb) was EG &gt; MG &gt; GG, N:P stoichiometry imbalance (N:Pimb) was MG &gt; EG &gt; GG. MBN was significantly positive correlated with C:Nimb and C:Pimb, MBC was significantly negative correlated with C:Pimb, MBP was significantly negative correlated with N:Pimb. The redundancy analysis (RDA) results showed that N:Pimb (p = 0.014), C:Nimb (p = 0.014), and C:P in the soil (C:Psoil, p = 0.028) had the most significant effect on microbial entropy. EG had a significant effect on soil microbial biomass and microbial entropy. The results of this study can directly or indirectly reflect the grassland soil quality under different utilization patterns in the karst rocky desertification area, which has a certain reference value for the degraded ecosystem restoration.

Biodiversity loss and drought are substantially altering both above- and below-ground terrestrial ecosystem functioning, but mechanistic understanding of plant diversity effects on the drought resistance of soil microbial biomass remains limited. We designed a mesocosm experiment to examine drought resistance of soil microbial biomass along a plant species richness gradient (five plant species richness levels based on old-field communities). We calculated resistance of microbial biomass to drought and recorded key below-ground properties which may influence microbial resistance to drought (i.e. microbial diversity, microbial community structure, soil carbon stocks and root biomass). Plant species richness had a positive effect on microbial resistance to drought. Variation in microbial resistance to drought was linked to properties of the fungal community in ambient soil (Shannon diversity, arbuscular mycorrhizal fungal richness and abundance) but not soil bacterial diversity. Moreover, microbial resistance to drought increased with increasing root biomass and dissolved organic carbon recorded under ambient conditions. These results highlight the importance of plant diversity for microbial biomass stability in our old-field study system with implications for biogeochemical cycling, and suggest that indirect effects of plant species richness on labile soil carbon and soil fungi may drive resistance of soil microbial biomass to drought. Read the free Plain Language Summary for this article on the Journal blog.

Paddy cultivation in saline soil can rapidly reduce soil salinity, which is an important approach for managing, utilizing, and improving such soils. However, the high salinity of saline soil severely limits the sustainability of paddy production. Adding exogenic organic material to improve soil fertility in saline soil is a key measure for obtaining high-yield, efficient and sustainable cultivation of paddy. This study used a field experiment to explore the influences of different organic materials application on soil desalination and fertility improvement in saline paddy soil. The results showed that the application of dairy manure (DM), sludge vermicompost (SV), and vinegar residue (VR) reduced soil barrier factors, including electrical conductivity (EC) and pH, increased soil fertility, including soil organic carbon (SOC), nitrogen (N), and phosphorus (P), and promoted paddy growth in saline soil. Specifically, soil EC decreased by 29.0%, 32.9% and 49.4% and paddy biomass increased by 27.7%, 63.7% and 107.6% in DM, SV, and VR-treated soils with the highest application rates, respectively, compared to the control. At an equal carbon application rate, VR was more conducive to decreasing soil EC and pH and increasing paddy biomass. Compared to DM and SV, VR addition resulted in an average decrease of 20.7% and 19.1% in soil EC, respectively, and an average increase of 57.3% and 29.5% in paddy biomass. In addition, soil water-stable aggregates (WSA), SOC, N, and P contents in VR-treated soil were lower than those in DM and SV-treated soils. Correlation and path analysis revealed that there was a significant negative correlation between paddy biomass and soil barrier factors. However, EC in VR-treated soil had a direct negative effect on paddy biomass, while EC in DM and SV-treated soils had an indirect negative effect on paddy biomass. Additionally, the direct contribution of soil pH to paddy biomass was higher with VR (−1.49) than that with DM (−0.21) and SV (0.89). In contrast to DM and SV, the effect of soil WSA on paddy biomass in VR-treated soil was mainly an indirect positive effect, and the direct effect was negative. The corresponding results provided new options and ideas for the efficient utilization of saline soils and high-yield cultivation of paddy.

Abstract Background and Aims: Agroecology practices can induce profound changes in soil inevitably influencing soil biological properties and soil functioning. However, we still lack understanding of how soil biodiversity responds to agroecology practices and to what extent such practices, alone or combined, can be beneficial for soil functioning. Understanding soil biological activities under different agroecology practices is important for predicting carbon cycling in agroecosystems. Methods: By taking advantage of a long-term agricultural experimental research station in France, we monitored soil microbes, nematodes and soil respiration over three years in response to agroecology practices that varied in the rate of nitrogen (N) fertilization (low vs high), the tillage type (deep vs reduced), and the crop residue management (retain vs removal). Results: Shifting from conventional to agroecology practices had strong effects on microbial biomass, nematode community and soil respiration. Reduced N and reduced tillage increased microbial biomass carbon, bacterivore and fungivore density. Perennial biomass crop decreased total nematode and herbivore density, but increased microbial biomass. Perennial biomass crop also significantly increased the structure and maturity indices, but decreased the plant parasite indices. Structural equation modelling showed that microbial biomass had a positive correlation with soil respiration in reduced nitrogen, reduced tillage, and residue removal treatments. Bacterivores had a positive correlation with omnivores/predators and soil respiration, while herbivores had a negative correlation with soil respiration in all the treatments. Conclusions: The different agroecological practices tested in this 4-year trial revealed the resilience of nematode communities and associated functions like CO2 respiration according to practices.

Due to the problems of relatively fragile stability, the quality of soil in the drip-irrigated agricultural ecosystem has high spatial heterogeneity and experiences significant degradation. We conducted a two-year field plot study (2021–2022) in a typical region of the arid zone with the “wolfberry” crop as the research object, with three irrigation and three nitrogen application levels, and the local conventional management as the control (CK). Soil quality under experimental conditioning was comprehensively evaluated based on Principal Component Analysis (PCA) and Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS), and regression analyses were carried out between the soil quality evaluation results and wolfberry yield. The results showed that short-term water and nitrogen regulation enhanced the soil nutrient content in the root zone of wolfberry to some extent, but it did not significantly affect soil carbon:soil nitrogen (C_soil:N_soil), soil carbon:soil phosphorus (C_soil:P_soil), and soil nitrogen:soil phosphorus (N_soil:P_soil). When the irrigation quota was increased from I₁ to I₂, the soil microbial biomass carbon, nitrogen, and phosphorus (C_mic, N_mic, and P_mic) tended to increase with the increase in N application, but the microbial biomass carbon:nitrogen (C_mic:N_mic), microbial biomass carbon:phosphorus (C_mic:P_mic), and microbial biomass nitrogen:phosphorus (N_mic:P_mic) did not change significantly. The comprehensive evaluation of the principal components and TOPSIS showed that the combined soil nutrient–microbial biomass and its ecological stoichiometry characteristics were better under the coupled treatments of I₂, I₃, N₂, and N₃, and the overall soil quality under these treatment conditions was significantly better than that under the CK treatment. Under I₁ irrigation, nitrogen application significantly increased the yield of wolfberry, while under I₂ and I₃ irrigation, the wolfberry yield showed a parabolic trend with the increase in nitrogen application. The highest yield was recorded in the I₂N₂ treatment in the first and second years, with yields of 9967 kg hm⁻² and 10,604 kg hm⁻², respectively. The coefficient of determination (explained quantity) of the soil quality based on soil nutrient–microbial biomass and the characteristics of its ecological stoichiometry for wolfberry yield ranged from 0.295 to 0.573. These findings indicated a limited positive effect of these indicators of soil on wolfberry yield. The short-term water and nitrogen regulation partly influenced the soil and soil microbial biomass in agroecosystems, but the effect on elemental balance was not significant. Our findings might provide theoretical support for managing the health of agricultural ecosystems.

This study was conducted in a temperate mixed oak&ndash:pine forest of Central Himalaya, India to (i) evaluate altitudinal and seasonal variations in the microbial biomass carbon (C), nitrogen (N) and phosphorus (P) and (ii) analyse the relationships between soil microbial biomass C, N and P and physico-chemical properties of soil. Three permanent plots were established in natural forest stands along an altitudinal gradient, three replicates were collected seasonally from each site, and microbial biomass (C, N and P) were determined by a fumigation extraction method. Microbial biomass C, N and P decreased significantly (p &lt: 0.01, correlation coefficient 0.985, 0.963, 0.948, respectively) with increasing altitude having maximum values during rainy season and minimum values during winter season. Microbial biomass C, N and P showed positive correlations with silt particles, water holding capacity, bulk density, soil moisture, organic C, total N and P and negative correlations with sand particles, porosity and soil pH. Microbial biomass C was strongly associated with soil microbial N (r = 0.80, p &lt: 0.01) and P (r = 0.89, p &lt: 0.01) content and soil microbial biomass N and P also showed a strong linear relationship (r = 0.92, p &lt: 0.01). Soil microbial biomass exhibited weak seasonality and was highly influenced by altitude and abiotic variables. The significantly high microbial C, N and P during the rainy season (p &lt: 0.01) and low microbial biomass during the winter season may be due to higher immobilization of nutrients from decomposing litter by microbes as the decomposition rate of litter and microbial activity are at their peak during the rainy period. The microbial C:N ratio indicated that soil fertility is influenced by species composition. Our findings suggested that high microbial biomass and low C:N ratios during the rainy season could be considered a nutrient conservation strategy of temperate mixed oak&ndash:pine forest ecosystems.

The relationship between plant productivity, measured according to biomass and species richness, is a fundamental focal point in community ecology, as it provides the basis for understanding plant responses or adaptive strategies. Although studies have been conducted on plant biomass and environmental factors, research concerning mountainous grassland areas is scarce. Therefore, the aim of the present study was to examine the influence of environmental factors on aboveground plant biomass in the mountainous grassland of the Mountain Zebra National Park, South Africa. Biomass distribution was uneven within the park, owing to certain species having relatively higher biomass values. These differences may be attributed to the chemical and physical properties of the soil, including carbon and nitrogen content, soil pH, and soil texture (sand, silt, and coarse fragments). A disc pasture meter was used to collect biomass data. Multiple regression analysis revealed that most environmental factors did not significantly influence plant biomass. The only environmental factor influencing plant biomass was soil pH; the influences of other factors were not statistically significant. The results of this study elucidate the interactions of environmental factors with plant biomass. Future research could investigate how environmental factors influence plant biomass, both below and above the ground in mountainous grassland.