Belowground Function Research Articles

Soil function-microbial diversity relationship is impacted by plant functional groups under climate change

Understanding the interactions between plant and soil microbial diversity is crucial for predicting ecosystem responses to environmental changes. While the individual roles of plant and microbial diversity in driving ecosystem functions have been widely investigated, their interplay especially under stress conditions remains largely underexplored. This study investigated how interactions between plant and microbial diversity affect key soil functions during and after drought. We simultaneously manipulated soil microbial diversity and plant species richness, while also considering the influence of plant functional groups (PFGs), to investigate their interactions and effects on key soil functions. Our results revealed independent and interactive effects of plant and microbial diversity in shaping soil functions. Microbial diversity loss significantly altered microbial community structure and impacted microbially-driven soil N and P pools and processes such as N-mineralization. These effects were modulated by plant species richness and varied across different PFGs. The relative influence of plant and microbial diversity on soil functions was context-dependent. Microbial diversity showed stronger effects on specific functions, such as phosphatase activity, and under the drought condition. Plant diversity, particularly through PFGs (e.g. legumes), played an independent role in shaping the microbial-driven soil functions. These findings advance mechanistic insights and highlight the importance of considering both above- and belowground biodiversity, along with their interactions, in shaping soil functions and ecosystem resilience, particularly under environmental stress. Further, it emphasizes the need to explicitly consider PFGs, along with above- and belowground biodiversity, as a strategy for preserving essential belowground functions in the face of ongoing environmental changes.

Trait-Mediated Variation in Seedling Performance in Costa Rican Successional Forests: Comparing Above-Ground, Below-Ground, and Allocation-Based Traits.

The interspecific relationship between functional traits and tree seedling performance can be inconsistent, potentially due to site-to-site or microsite variation in environmental conditions. Studies of seedling traits and performance often focus on above-ground traits, despite the importance of below-ground resource acquisition and biomass allocation to above versus below-ground functions. Here we investigate how varying environmental conditions across sites induce intraspecific variation in organ-level (above-ground, below-ground) and biomass allocation traits, affecting interspecific relationships between these traits and seedling performance. We analyzed trait expression for 12 organ-level and three allocation traits and their relationships with height growth (1716 seedlings) and mortality (15,862 seedlings) for 26 tree species across three sites along a forest successional gradient in Costa Rica. We found significant intraspecific differences across sites in all allocation traits, but only in three of seven above-ground and three of five below-ground organ-level traits. Allocation traits were better predictors of seedling performance than organ-level traits. Relationships between allocation traits and both growth and mortality varied among all sites, but for organ-level traits, only relationships with growth varied among sites. These results underscore that biomass allocation plays a key role in the earliest life stages of trees and that site-specific conditions can influence how functional traits mediate seedling establishment during succession.

Aboveground and belowground biodiversity have complementary effects on ecosystem functions across global grasslands.

Grasslands are integral to maintaining biodiversity and key ecosystem services and are under threat from climate change. Plant and soil microbial diversity, and their interactions, support the provision of multiple ecosystem functions (multifunctionality). However, it remains virtually unknown whether plant and soil microbial diversity explain a unique portion of total variation or shared contributions to supporting multifunctionality across global grasslands. Here, we combine results from a global survey of 101 grasslands with a novel microcosm study, controlling for both plant and soil microbial diversity to identify their individual and interactive contribution to support multifunctionality under aridity and experimental drought. We found that plant and soil microbial diversity independently predict a unique portion of total variation in above- and belowground functioning, suggesting that both types of biodiversity complement each other. Interactions between plant and soil microbial diversity positively impacted multifunctionality including primary production and nutrient storage. Our findings were also climate context dependent, since soil fungal diversity was positively associated with multifunctionality in less arid regions, while plant diversity was strongly and positively linked to multifunctionality in more arid regions. Our results highlight the need to conserve both above- and belowground diversity to sustain grassland multifunctionality in a drier world and indicate climate change may shift the relative contribution of plant and soil biodiversity to multifunctionality across global grasslands.

Grassland woody plant management rapidly changes woody vegetation persistence and abiotic habitat conditions but not herbaceous community composition

Abstract Grasslands are among the most imperilled ecosystems worldwide, and many have experienced degradation due to the loss of historical disturbance regimes and subsequent woody encroachment. Management practitioners often use physical and chemical management interventions in combination with fire to counter encroachment, altering aboveground structure and belowground function, respectively. This may disrupt the feedbacks that perpetuate encroachment and restore the herbaceous community. We use a large‐scale field experiment to assess the initial effects of different management interventions on woody vegetation persistence, abiotic habitat conditions, and herbaceous community composition. We evaluate these effects across seven sites spanning a natural soil moisture gradient to capture one aspect of environmental heterogeneity with which managers regularly contend. We found that chemical intervention, both with and without the addition of physical intervention, was most effective at reducing woody plant cover and abundance, and a second application reduced woody plant abundance by more than one application alone. We also found that any management intervention increased light availability and air temperature and decreased soil moisture, with the combination of physical and chemical interventions having the greatest effects. Finally, none of the management interventions affected herbaceous richness and functional group cover within the study period, indicating delayed or nonexistent effects on herbaceous community composition. Synthesis and application. Our findings suggest that management should focus on chemical intervention for the greatest effects on woody plant persistence and abiotic habitat conditions. Changes to herbaceous community composition may occur in the long term and seem likely since short‐term effects of management were successful in altering processes related to encroachment feedbacks.

Soil cover shapes organic matter pools and microbial communities in soils of maritime Antarctica

Bryophytes and biological soil crusts (biocrusts) are the two major biological soil cover types of maritime Antarctica and play a crucial role for key ecosystem functions in the barely vegetated and little developed soils. Besides their profound impacts on nutrient cycling, they also provide habitats and activity hotspots for unique soil microbial communities. Yet, the effects of biological soil cover on the physical and chemical soil environment and belowground microbial communities have not been comprehensively studied in this fragile ecosystem.We here address the research question how biocrusts and mosses shape the quantity and structure of the soil organic matter pool, and the activity and composition of subjacent microbial communities. Towards this end, we sampled soils under two common, but physiologically distinct moss species, Polytrichastrum alpinum and Sanionia unicinata, and adjacent biological soil crusts at two sites on Deception Island, South Shetland Islands.We found that biocrusts and mosses differentially influenced central soil properties and subjacent soil microbial communities. All major SOM compound groups (carbohydrates, aromatics and phenols, lipids, N-containing polymers) as well as microbial biomass were more abundant in soil under biocrusts. However, microbial mass-specific growth rates were higher in soil under mosses. Our results showed moss-species-specific effects in addition to effects of soil cover type, as P. alpinum affected the activity and structure of soil microbial communities and the composition of soil organic matter stronger than S. unicinata.Our study highlights the interconnectedness between soil cover and soil biogeochemistry, which is crucial for deepening our understanding of belowground functioning in Antarctic soils. This linkage is of particular importance in the context of ongoing rapid climate change on the Antarctic Peninsula, as future shifts in the distribution and abundance of soil cover may substantially impact multiple soil processes in this vulnerable ecosystem.

Toward a coordinated understanding of hydro-biogeochemical root functions in tropical forests for application in vegetation models.

Tropical forest root characteristics and resource acquisition strategies are underrepresented in vegetation and global models, hampering the prediction of forest-climate feedbacks for these carbon-rich ecosystems. Lowland tropical forests often have globally unique combinations of high taxonomic and functional biodiversity, rainfall seasonality, and strongly weathered infertile soils, giving rise to distinct patterns in root traits and functions compared with higher latitude ecosystems. We provide a roadmap for integrating recent advances in our understanding of tropical forest belowground function into vegetation models, focusing on water and nutrient acquisition. We offer comparisons of recent advances in empirical and model understanding of root characteristics that represent important functional processes in tropical forests. We focus on: (1) fine-root strategies for soil resource exploration, (2) coupling and trade-offs in fine-root water vs nutrient acquisition, and (3) aboveground-belowground linkages in plant resource acquisition and use. We suggest avenues for representing these extremely diverse plant communities in computationally manageable and ecologically meaningful groups in models for linked aboveground-belowground hydro-nutrient functions. Tropical forests are undergoing warming, shifting rainfall regimes, and exacerbation of soil nutrient scarcity caused by elevated atmospheric CO2. The accurate model representation of tropical forest functions is crucial for understanding the interactions of this biome with the climate.

Nitrogen availability and plant functional composition modify biodiversity-multifunctionality relationships.

Biodiversity typically increases multiple ecosystem functions simultaneously (multifunctionality) but variation in the strength and direction of biodiversity effects between studies suggests context dependency. To determine how different factors modulate the diversity effect on multifunctionality, we established a large grassland experiment manipulating plant species richness, resource addition, functional composition (exploitative vs. conservative species), functional diversity and enemy abundance. We measured ten above- and belowground functions and calculated ecosystem multifunctionality. Species richness and functional diversity both increased multifunctionality, but their effects were context dependent. Richness increased multifunctionality when communities were assembled with fast-growing species. This was because slow species were more redundant in their functional effects, whereas different fast species promoted different functions. Functional diversity also increased multifunctionality but this effect was dampened by nitrogen enrichment and enemy presence. Our study suggests that a shift towards fast-growing communities will not only alter ecosystem functioning but also the strength of biodiversity-functioning relationships.

Land-use legacies affect the composition and distribution of tree species and their belowground functions in a succession from old-field to mature temperate forest

Forests undergoing ecological succession following abandonment from agricultural use (i.e., old fields) are ubiquitous in temperate regions of the U.S. and Europe. Ecological succession in old fields involves changes in vegetation composition influenced by factors such as land-use history, soil conditions, and dispersal limitations. Species’ behavioral, morphological, physiological and life-history attributes influence the outcomes of environmental and biotic filters on distribution and abundance. However, many studies have focused on aboveground attributes, while less attention has been placed on belowground species characteristics that influence community assembly and function. In this study, we used a trait-based approach to examine how aboveground plant composition and distribution vary with plant root functional traits (e.g., mycorrhizal association) that mediate access for nutrients such as nitrogen (N) and phosphorous (P). We inventoried every tree stem (n ​= ​11,551) in a 10-ha forested area containing old-field and historical forests and matched every species with root functional traits (n ​= ​33) from established databases. We found that land-use history influences community composition and distribution in old-field forests, which also varied with belowground root functional traits. Community composition in old-field forests, which were dominated by Acer saccharum and non-native species, were largely associated with arbuscular mycorrhizae (AM) and higher root nutrient concentrations. On the other hand, community composition in historical forests – largely dominated by Tsuga canadensis – were associated with ectomycorrhiza (EcM) and more variation of root length and depth. These results suggest that changes in aboveground communities have implications for belowground ecosystem services (e.g., nutrient cycling) which are important to forest ecosystem development. Trait-based approaches can elucidate mechanisms of community assembly, and understanding how traits influence species coexistence and interactions can inform management decisions related to biodiversity conservation and restoration efforts in disturbed or altered forests.

Elevated CO2, O3 and their interaction have differential impact on soil microbial diversity and functions in wheat agroecosystems

Elevated carbon dioxide (EC) and elevated ozone (EO) due to changing climate have a significant impact on the plant growth rate, primary productivity, and root turnover. EC and EO could have a differential impact on the structure and functioning of soil microbial communities in terrestrial ecosystems via modifications in the microbial population, soil enzyme activity, decomposition of organic compounds and cycling of nutrients. For the development of sustainable agroecosystems, soil microbial communities are essential due to their major roles in nutrient cycling, crop-microbe interplay and resistance towards biotic/abiotic factors. However, it remains difficult to project how multiple climate change factors would affect below-ground functions. Free-Air CO2 and O3 enrichment facility (FAOCE) was used to explore the effects of EC (550 ± 50 ppm) and EO (65 ± 10 ppb) along with their combined interactive treatment ECO on the structure and abundance of soil microbial community, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and microbes involved in N cycling in wheat crop (Triticum aestivum) under field conditions. The MBC increased by 20% in EC and declined by 5% in EO to ambient control. Treatments EC and ECO stimulated the growth of ammonia and nitrite-oxidizing bacteria. Heterotrophic microbial populations were favoured under EC and inhibited under EO. Treatments indirectly affected the soil microbial community structure by altering N-cycling microbes and modifying MBC and MBN which eventually changed soil fertility and biogeochemistry.

Strong above-ground impacts of a non-native ungulate do not cascade to impact below-ground functioning in a boreal ecosystem.

1. Experimental studies across biomes demonstrate that herbivores can have significant effects on ecosystem functioning. Herbivore effects, however, can be highly variable with studies demonstrating positive, neutral or negative relationships between herbivore presence and different components of ecosystems. Mixed effects are especially likely in the soil, where herbivore effects are largely indirect mediated through effects on plants. 2. We conducted a long-term experiment to disentangle the effects of non-native moose in boreal forests on plant communities, nutrient cycling, soil composition and soil organism communities. 3. To explore the effect of moose on soils, we conduct separate analyses on the soil organic and mineral horizons. Our data come from 11 paired exclosure-control plots in eastern and central Newfoundland, Canada that provide insight into 22-25 years of moose herbivory. We fit piecewise structural equations models (SEM) to data for the organic and mineral soil horizons to test different pathways linking moose to above-ground and below-ground functioning. 4. The SEMs revealed that moose exclusion had direct positive impacts on adult tree count and an indirect negative impact on shrub percent cover mediated by adult tree count. We detected no significant impact of moose on soil microbial C:N ratio or net nitrogen mineralization in the organic or mineral soil horizon. Soil temperature and moisture, however, was more than twice as variable in the presence (i.e. control) than absence (i.e. exclosure) of moose. Overall, we observed clear impacts of moose on above-ground forest components with limited indirect effects below-ground. Even after 22-25 years of exclusion, we did not find any evidence of moose impacts on soil microbial C:N ratio and net nitrogen mineralization. 5. Our long-term study and mechanistic path analysis demonstrates that soils can be resilient to ungulate herbivore effects despite evidence of strong effects above-ground. Long-term studies and analyses such as this one are relatively rare yet critical for reconciling some of the context-dependency observed across studies of ungulates effects on ecosystem functions. Such studies may be particularly valuable in ecosystems with short growing seasons such as the boreal forest.

Land management drives dynamic changes to microbial function through edaphic factors and soil biota

Land management for conservation alters the abiotic and biotic components that underly belowground ecosystem health and function. We know that prescribed burning and grazing influence soil characteristics, nutrients, and biota individually, but rarely have these management effects been explored holistically, affecting an interacting belowground system. Since most belowground functions (e.g., nutrient cycling) arise from feedbacks among many soil factors, a better understanding of system-level responses to distinct management practices, rather than individual component responses, can help us better predict these ecosystem functions. In a late successional tallgrass prairie ecosystem, we contrasted how prescribed fire and mowing altered nutrient cycles through changes to the abiotic soil environment, microbial community structure, and microbial enzyme functions. Individual soil factors responded rapidly to both fire and mowing, and remained different from pre-treatment values. However, as a system, many relationships among soil factors that were present before management and lost directly after management, returned 1 month after management. This shows the system-level resilience to management supported by the long evolutionary history between grasslands, fire, and grazing, and illustrates the importance of understanding management effects from a holistic perspective. Since global disturbance regimes and anthropological influence are predicted to change in the future, understanding how belowground components respond to change as a system can help land managers and ecologists alike conserve endangered ecosystems.

Elevated ozone decreases the multifunctionality of belowground ecosystems.

Elevated tropospheric ozone (O3 ) affects the allocation of biomass aboveground and belowground and influences terrestrial ecosystem functions. However, how belowground functions respond to elevated O3 concentrations ([O3 ]) remains unclear at the global scale. Here, we conducted a detailed synthesis of belowground functioning responses to elevated [O3 ] by performing a meta-analysis of 2395 paired observations from 222 publications. We found that elevated [O3 ] significantly reduced the primary productivity of roots by 19.8%, 16.3%, and 26.9% for crops, trees and grasses, respectively. Elevated [O3 ] strongly decreased the root/shoot ratio by 11.3% for crops and by 4.9% for trees, which indicated that roots were highly sensitive to O3 . Elevated [O3 ] impacted carbon and nitrogen cycling in croplands, as evidenced by decreased dissolved organic carbon, microbial biomass carbon, total soil nitrogen, ammonium nitrogen, microbial biomass nitrogen, and nitrification rates in association with increased nitrate nitrogen and denitrification rates. Elevated [O3 ] significantly decreased fungal phospholipid fatty acids in croplands, which suggested that O3 altered the microbial community and composition. The responses of belowground functions to elevated [O3 ] were modified by experimental methods, root environments, and additional global change factors. Therefore, these factors should be considered to avoid the underestimation or overestimation of the impacts of elevated [O3 ] on belowground functioning. The significant negative relationships between O3 -treated intensity and the multifunctionality index for croplands, forests, and grasslands implied that elevated [O3 ] decreases belowground ecosystem multifunctionality.

Incorporating belowground traits: avenues towards a whole‐tree perspective on performance

Tree performance depends on the coordinated functioning of interdependent leaves, stems and (mycorrhizal) roots. Integrating plant organs and their traits, therefore, provides a more complete understanding of tree performance than studying organs in isolation. Until recently, our limited understanding of root traits impeded such a whole‐tree perspective on performance, but recent developments in root ecology provide new impetuses for integrating the below‐ and aboveground. Here, we identify two key avenues to further develop a whole‐tree perspective on performance and highlight the conceptual and practical challenges and opportunities involved in including the belowground. First, traits of individual roots need to be scaled up to the root system as a whole to determine belowground functioning, e.g. total soil water and nutrient uptake, and hence performance. Second, above‐ and belowground plant organs need to be mechanistically connected to account for how they functionally interact and to investigate their combined impacts on tree performance. We further identify mycorrhizal symbiosis as the next frontier and emphasize several courses of actions to incorporate these symbionts in whole‐tree frameworks. By scaling up and mechanistically integrating (mycorrhizal) roots as argued here, the belowground can be better represented in whole‐tree conceptual and mechanistic models; ultimately, this will improve our estimates of not only the functioning and performance of individual trees, but also the processes and responses to environmental change of the communities and ecosystems they are part of.

Mutual feedback between above- and below-ground controls the restoration of alpine ecosystem multifunctionality in long-term grazing exclusion

Grazing exclusion is widely used to restore the grasslands that degraded by overgrazing. However, it is not clear how the interaction of above- and below-ground functioning affects the restoration of ecosystem multifunctionality in long-term grazing exclusion. Here, long-term grazing exclusion experiments were performed in a desertified alpine grassland of eastern Tibetan Plateau. We measured critical ecosystem functioning indices including species diversity, community biomass, soil water content and soil nutrient concentrations. Our results showed that both above- and below-ground functioning increased over restoration time, with the mean values increased by 187%, 112%, 195%, 92% and 242% from GE2 to GE12 for above-ground biomass, soil water content, soil organic matter, soil total nitrogen and soil total phosphorus, respectively. Species diversity tended to an “inverted U curve” over restoration time. The response of belowground functioning lagged behind that of aboveground functioning during the restoration process. The trade-off values between above- and below-ground ecosystem functioning in the early restoration stage was significantly higher (P < 0.01) than that in the late restoration stage. We also found that the feedback of aboveground functioning on belowground functioning shifted from negative in the early restoration stage to positive in the late stage. The findings of this study suggested that the interaction between above- and below-ground functioning controls the restoration of ecosystem multifunctionality. This study is valuable for improving sustainable grassland policies and optimizing desertified grassland management on the Tibetan Plateau.

Above- and below-ground functional trait coordination in the Neotropical understory genus Costus.

The study of plant functional traits and variation among and within species can help illuminate functional coordination and trade-offs in key processes that allow plants to grow, reproduce and survive. We studied 20 leaf, above-ground stem, below-ground stem and fine-root traits of 17 Costus species from forests in Costa Rica and Panama to answer the following questions: (i) Do congeneric species show above-ground and below-ground trait coordination and trade-offs consistent with theory of resource acquisition and conservation? (ii) Is there correlated evolution among traits? (iii) Given the diversity of habitats over which Costus occurs, what is the relative contribution of site and species to trait variation? We performed a principal components analysis (PCA) to assess for the existence of a spectrum of trait variation and found that the first two PCs accounted for 21.4 % and 17.8 % of the total trait variation, respectively, with the first axis of variation being consistent with a continuum of resource-acquisitive and resource-conservative traits in water acquisition and use, and the second axis of variation being related to the leaf economics spectrum. Stomatal conductance was negatively related to both above-ground stem and rhizome specific density, and these relationships became stronger after accounting for evolutionary relatedness, indicating correlated evolution. Despite elevation and climatic differences among sites, high trait variation was ascribed to individuals rather than to sites. We conclude that Costus species present trait coordination and trade-offs that allow species to be categorized as having a resource-acquisitive or resource-conservative functional strategy, consistent with a whole-plant functional strategy with evident coordination and trade-offs between above-ground and below-ground function. Our results also show that herbaceous species and species with rhizomes tend to agree with trade-offs found in more species-rich comparisons.

Spatiotemporal dynamics of abiotic and biotic properties explain biodiversity–ecosystem‐functioning relationships

AbstractThere is increasing evidence that spatial and temporal dynamics of biodiversity and ecosystem functions play an essential role in biodiversity–ecosystem‐functioning (BEF) relationships. Despite the known importance of soil processes for forest ecosystems, belowground functions in response to tree diversity and spatiotemporal dynamics of ecological processes and conditions remain poorly described. We propose a novel conceptual framework integrating spatiotemporal dynamics in BEF relationships and hypothesized a positive tree species richness effect on soil ecosystem functions through the spatial and temporal stability of biotic and abiotic soil properties based on species complementarity and asynchrony. We tested this framework within a long‐term tree diversity experiment in Central Germany by assessing soil ecosystem functions (soil microbial properties and litter decomposition) and abiotic variables (soil moisture and surface temperature) for two consecutive years in high spatial and temporal resolution. Tree species richness and identity had significant effects on soil properties (e.g., soil microbial biomass). Structural equation modeling revealed that overall soil microbial biomass was partly explained by (1) enhanced temporal stability of soil surface temperature and (2) decreased spatial stability of soil microbial biomass. Overall, spatial stability of soil microbial properties was positively correlated with their temporal stability. These results suggest that spatiotemporal dynamics are indeed crucial determinants in BEF relationships and highlight the importance of vegetation‐induced microclimatic conditions for stable provisioning of soil ecosystem functions and services.

Plant removal across an elevational gradient marginally reduces rates, substantially reduces variation in mineralization.

The loss of aboveground plant diversity alters belowground ecosystem function; yet, the mechanisms underpinning this relationship and the degree to which plant community structure and climate mediate the effects of plant species loss remain unclear. Here, we explored how plant species loss through experimental removal shaped belowground function in ecosystems characterized by different climatic regimes and edaphic properties. We measured plant community composition as well as potential carbon (C) and nitrogen (N) mineralization and microbial extracellular enzyme activity in soils collected from four unique plant removal experiments located along an elevational gradient in Colorado, USA. We found that, regardless of the identity of the removed species or the climate at each site, plant removal decreased the absolute variation in potential N mineralization rates and marginally reduced the magnitude of N mineralization rates. While plant species removal also marginally reduced C mineralization rates, C mineralization, unlike N mineralization, displayed sensitivity to the climatic and edaphic differences among sites, where C mineralization was greatest at the high elevation site that receives the most precipitation annually and contains the largest soil total C pool. Plant removal had little impact on soil enzyme activity. Removal effects were not contingent on the amount of biomass removed annually, and shifts in mineralization rates occurred despite only marginal shifts in plant community structure following plant species removal. Our results present a surprisingly simple and consistent pattern of belowground response to the loss of dominant plant species across an elevational gradient with different climatic and edaphic properties, suggesting a common response of belowground ecosystem function to plant species loss regardless of which plant species are lost or the broader climatic context.

Disturbance alters the forest soil microbiome.

Billions of microorganisms perform critical below-ground functions in all terrestrial ecosystems. While largely invisible to the naked eye, they support all higher lifeforms, form symbiotic relationships with ~90% of terrestrial plant species, stabilize soils, and facilitate biogeochemical cycles. Global increases in the frequency of disturbances are driving major changes in the structure and function of forests. However, despite their functional significance, the disturbance responses of forest microbial communities are poorly understood. Here, we explore the influence of disturbance on the soil microbiome (archaea, fungi and bacteria) of some of the world's tallest and most carbon-dense forests, the Mountain Ash forests of south-eastern Australia. From 80sites, we identified 23,277 and 19,056microbial operational taxonomic units from the 0-10cm and 20-30cm depths of soil respectively. From this extensive data set, we found the diversity and composition of these often cryptic communities has been altered by human and natural disturbance events. For instance, the diversity of ectomycorrhizal fungi declined with clearcut logging, the diversity of archaea declined with salvage logging, and bacterial diversity and overall microbial diversity declined with the number of fires. Moreover, we identified key associations between edaphic (soil properties), environmental (slope, elevation) and spatial variables and the composition of all microbial communities. Specifically, we found that soil pH, manganese, magnesium, phosphorus, iron and nitrate were associated with the composition of all microbial communities. In a period of widespread degradation of global forest ecosystems, our findings provide an important and timely insight into the disturbance responses of soil microbial communities, which may influence key ecological functions.

Evaluation of Bt cotton effects on belowground microbial community structure and function in tropical western India

Evaluation of Bt cotton effects on belowground microbial community structure and function in tropical western India

Responses of soil extracellular enzyme activities and bacterial community composition to seasonal stages of drought in a semiarid grassland

Extreme drought can strongly impact belowground communities and biogeochemical processes, including soil microbial community composition and extracellular enzyme activities (EEAs), which are considered key agents in ecosystem carbon (C) and nutrient cycling. However, our understanding of how seasonal timing of drought during the growing season affects soil microbial communities and their activity remains notably poor. In this study, we investigated the responses of soil physicochemical properties, EEAs, and bacterial community composition to extreme-duration drought imposed in the early-, mid-, or late-stages of the growing season in a semiarid grassland ecosystem in Inner Mongolia, China. Compared with the ambient control, the activities of C-, nitrogen (N)-, and phosphorus (P)-acquisition enzymes were significantly decreased in the mid- and/or late-stages of drought. Bacterial community diversity also significantly decreased in the mid- and late-stage drought treatments. Soil water content was the most important factor explaining changes in soil EEAs and bacterial community composition. At the end of the growing season, the activities of C-, N-, and P-acquisition enzymes had mostly recovered, while the bacterial community diversity in the mid- and late-stage drought treatments was still lower than the ambient control. Overall, our study demonstrates that the effects of extreme drought on soil EEAs and bacterial community composition depend on the timing of drought. Our results highlight that understanding the effects of extreme-duration drought at different stages of the growing season may play a vital role in predicting the responses of belowground function to global changes in grassland ecosystems.