Does pH matter for ecosystem multifunctionality? An empirical test in a semi‐arid grassland on the Loess Plateau

Multitrophic Diversity of the Biotic Community Drives Ecosystem Multifunctionality in Alpine Grasslands

Biodiversity and ecosystem multifunctionality are currently hot topics in ecological research. However, little is known about the role of multitrophic diversity in regulating various ecosystem functions, which limits our ability to predict the impact of biodiversity loss on human well-being and ecosystem multifunctionality. In this study, multitrophic diversity was divided into three categories: plant, animal, and microbial communities (i.e., plant diversity, rodent diversity, and bacterial and fungal diversity). Also, 15 ecosystem functions were divided into four categories-water conservation, soil fertility, nutrient cycling and transformation, and community production-to evaluate the significance of biotic and abiotic variables in maintaining ecosystem multifunctionality. Results indicated that species diversity at multiple trophic levels had a greater positive impact on ecosystem multifunctionality than species diversity at a single trophic level. Notably, the specific nature of this relationship depended on the niche breadths of plants, indicating that plants played a key role in linking above and belowground trophic levels. Abiotic factors such as altitude and pH directly acted on ecosystem multifunctionality and could explain changes in ecosystem functions. Overall, our study offers valuable insights into the critical role of multitrophic species diversity in preserving ecosystem multifunctionality within alpine grassland communities, as well as strong support for the importance of biodiversity protection.

Effects of volcanic environment on Setaria viridis rhizospheric soil microbial keystone taxa and ecosystem multifunctionality

Keystone taxa are significant within ecosystem multifunctionality, as certain species fulfil essential functions such as recycling soil nutrients, promoting plant growth, influencing biogeochemical processes, and contributing to human health maintenance. However, there are still gaps regarding the relationship between microbial communities in volcanic rhizospheric soil and ecosystem multifunctionality. As a result, in this research, we employed Illumina MiSeq high-throughput sequencing to analyse the microbial community composition of rhizospheric soil from volcanic S. viridis. Compared with non-volcanic areas, volcanic soils have higher fungal alpha diversity and the absolute abundance of bacteria (16S gene copies) showed significant variation between the two successions (P < 0.0001). The network analysis further demonstrated that the microbial diversity in non-volcanic regions surpassed that of the volcanic area. The volcanic fungi network has more nodes and edges, is more complex than non-volcanic areas (Nodes: 425 vs. 770; Edges: 21844 vs. 74532), and more rhizosphere growth-promoting bacteria are enriched. Regression analysis and correlation networks showed that fungal communities were more closely associated with ecosystem multifunctionality than bacteria. This study lays the groundwork for examining the microbial keystone taxa in the rhizosphere of volcanic plants and offers valuable insights into the multifaceted functions of plant rhizospheric soil ecosystems.

Leguminous green mulching alters the microbial community structure and increases microbial diversity by improving nitrogen availability in subtropical orchard systems in China

Microorganisms, the major decomposers of plant residues, are crucial for soil nutrient cycling. Living grass mulching effectively alters microbial community structure and promotes nutrient cycling. However, its consistency with mulching ages and growth periods remains unclear. Therefore, this study aims to clarify the dynamic characteristics of microbial communities and enzyme activities across different mulching ages. In this study, high-throughput sequencing technology was used to investigate bacterial and fungal community evolution in three mulching treatments with Vicia villosa for 8 years (VV_8), 4 years (VV_4), and clean tillage in a citrus orchard. This study covered three growth periods (citrus-grass: spring sprouting to budding period [SSBP], fruit swelling to withering period [FSWP], and fruit maturity to seeding period [FMSP]). The results showed that VV_4 and VV_8 treatments increased bacterial and fungal alpha diversity as well as the activities of nitrogen (N), carbon (C), and phosphorus cycling enzymes. C-cycling enzyme activity was the primary key factor driving changes in microbial diversity across growth periods. Under leguminous green mulching, bacteria alpha diversity increased the most during FSWP, while fungi increased the most during FMSP. Additionally, the relative abundance of Ascomycota and Basidiomycota significantly increased during the FSWP and FMSP, reaching 63.65-73.80 % and 79.73-84.51 %, respectively. With increasing mulching ages, the structural stability and synergistic effects of microorganisms were correspondingly enhanced. Furthermore, available nutrients determined microbial community evolution, with N availability being a key factor influencing microbial diversity, especially fungal diversity. In conclusion, as mulching ages increase, improved nutrient availability gradually enhances microbial diversity, synergistic interactions, and nutrient cycling functions, with copiotrophic taxa occupying a key position in the microbial network. FSWP is a critical turning point for enhancing microbial activity and C-cycling function. This study offers theoretical support for developing microbial regulation strategies to improve soil quality in orchard management practices.

Testing the ectomycorrhizal-dominance hypothesis for ecosystem multifunctionality in a subtropical mountain forest

Mycorrhizal associations are key mutualisms that shape the structure of forest communities and multiple ecosystem functions. However, we lack a framework for predicting the varying dominance of distinct mycorrhizal associations in an integrated proxy of multifunctionality across ecosystems. Here, we used the datasets containing diversity of mycorrhizal associations and 18 ecosystem processes related to supporting, provisioning, and regulating services to examine how the dominance of ectomycorrhiza (EcM) associations affects ecosystem multifunctionality in subtropical mountain forests in Southwest China. Meanwhile, we synthesized the prevalence of EcM-dominant effects on ecosystem functioning in forest biomes. Our results demonstrated that elevation significantly modified the distributions of EcM trees and fungal dominance, which in turn influenced multiple functions simultaneously. Multifunctionality increased with increasing proportion of EcM associations, supporting the ectomycorrhizal-dominance hypothesis. Meanwhile, we observed that the impacts of EcM dominance on individual ecosystem functions exhibited different relationships among forest biomes. Our findings highlight the importance of ectomycorrhizal dominance in regulating multifunctionality in subtropical forests. However, this ectomycorrhizal feedback in shaping ecosystem functions cannot necessarily be generalized across forests. Therefore, we argue that the predictions for ecosystem multifunctionality in response to the shifts of mycorrhizal composition could vary across space and time.

Biodiversity drives ecosystem multifunctionality in sandy grasslands?

Plant communities and soil microbiomes play a crucial role in regulating ecosystem multifunctionality (EMF). However, whether and how aboveground plant diversity, belowground soil microbial diversity and interactions with environmental factors affect EMF in sandy grasslands under climate change conditions is unclear. Here, we selected 15 typical grassland communities from the Horqin sandy grassland along temperature and precipitation gradients, using the mean annual temperature (AMT), mean annual precipitation (AP), soil temperature (ST), soil water content (SW) and pH as abiotic factors, and plant diversity (PD) and soil microbial diversity (SD) as biodiversity indicators. The effects of biodiversity and abiotic factors on individual ecosystem functions and EMF were studied. We found that PD and its components, plant species richness (SR), species diversity (PR) and genetic diversity (GD), had significant effects on aboveground biomass (AGB) and major factors involved in ecosystem nitrogen cycling (plant leaf nitrogen content (PLN) and soil total nitrogen content (STN)) (P < 0.05). Soil fungal diversity (FR) has a greater impact on ecosystem function than soil bacteria (BR) and archaea (ABR) in sandy grasslands and mainly promotes the accumulation of soil microbial carbon and nitrogen (MBC, MBN) (P < 0.05), STC and STN (P < 0.01). PD and two types of SD (FR and ABR) significantly regulated EMF (P < 0.01). Among the abiotic factors, soil pH and SW regulated EMF (P < 0.05), and SW and ST directly drove EMF (P < 0.05). PD drove EMF significantly and indirectly (positively) through soil pH and ST (P < 0.001), while SD drove EMF weakly and indirectly (negatively) through AP and PD (P > 0.05). PD was a stronger driving force on EMF than SD. These results improve our understanding of the drivers of multifunctionality in sandy grassland ecosystems.

Reproductive height determines the loss of clonal grasses with nitrogen enrichment in a temperate grassland

Tall clonal grasses commonly display competitive advantages with nitrogen (N) enrichment. However, it is currently unknown whether the height is derived from the vegetative or reproductive module. Moreover, it is unclear whether the height of the vegetative or reproductive system regulates the probability of extinction and colonization, and determines species diversity. In this study, the impacts on clonal grasses were studied in a field experiment employing two frequencies (twice a year vs. monthly) crossing with nine N addition rates in a temperate grassland, China. We found that the N addition decreased species frequency and increased extinction probability, but did not change the species colonization probability. A low frequency of N addition decreased species frequency and colonization probability, but increased extinction probability. Moreover, we found that species reproductive height was the best index to predict the extinction probability of clonal grasses in N-enriched conditions. The low frequency of N addition may overestimate the negative effect from N deposition on clonal grass diversity, suggesting that a higher frequency of N addition is more suitable in assessing the ecological effects of N deposition. Overall, this study illustrates that reproductive height was associated with the clonal species extinction probability under N-enriched environment.

Biodiversity of network modules drives ecosystem functioning in biochar-amended paddy soil

Introduction

Soil microbes are central in governing soil multifunctionality and driving ecological processes. Despite biochar application has been reported to enhance soil biodiversity, its impacts on soil multifunctionality and the relationships between soil taxonomic biodiversity and ecosystem functioning remain controversial in paddy soil.

Methods

Herein, we characterized the biodiversity information on soil communities, including bacteria, fungi, protists, and nematodes, and tested their effects on twelve ecosystem metrics (including functions related to enzyme activities, nutrient provisioning, and element cycling) in biochar-amended paddy soil.

Results

The biochar amendment augmented soil multifunctionality by 20.1 and 35.7% in the early stage, while the effects were diminished in the late stage. Moreover, the soil microbial diversity and core modules were significantly correlated with soil multifunctionality.

Discussion

Our analysis revealed that not just soil microbial diversity, but specifically the biodiversity within the identified microbial modules, had a more pronounced impact on ecosystem functions. These modules, comprising diverse microbial taxa, especially protists, played key roles in driving ecosystem functioning in biochar-amended paddy soils. This highlights the importance of understanding the structure and interactions within microbial communities to fully comprehend the impact of biochar on soil ecosystem functioning in the agricultural ecosystem.

Aerobic composting with sauerkraut fermentation waste water: Increasing the stability and complexity of bacterial community and changing bacterial community assembly processes

Aerobic composting renders the sauerkraut fermentation waste water harmless while adding soluble nutrients. Unravelling the bacterial community assembly processes, changes in community robustness and community cohesion and the relationship between them under composting treatment of sauerkraut fermentation waste water is an interesting topic. Sauerkraut fermentation waste water was used for composting, which increased bacterial linkages, community robustness, competitive behaviour during warming periods and cooperative behaviour during cooling periods, and the control of community assembly processes shifts from deterministic processes (variable selection) to stochastic processes (decentralised limitation). At the same time, the influence of community robustness and community cohesion on community assembly processes was increased. Community cohesion and robustness were significantly correlated with community function. These results indicate that community robustness and community cohesion are critical for the biological handling of hazardous substances.

Biodiversity and soil pH regulate the recovery of ecosystem multifunctionality during secondary succession of abandoned croplands in northern China

The 'Grain-for-Green' program in China provides a valuable opportunity to investigate whether spontaneous restoration can reverse the deterioration of grassland ecosystem functions. Previous studies have focused on individual ecosystem functions, but the response of and mechanisms driving variation in ecosystem multifunctionality (EMF) during restoration are poorly understood. Here, we quantified EMF using productivity, nutrient cycling, and water regulation functions along abandoned croplands in a recovery chronosequence (5, 15 and 20 years) and in natural grasslands in the desert steppe and typical steppe. We also analyzed the effects of plant and microbial diversity and an abiotic factor (soil pH) on EMF. Our results showed that EMF increased gradually concomitant with recovery time, shifting toward EMF values comparable to those in natural grasslands in both desert and typical steppe. Similar results were found for the productivity function, the water regulation function, and soil organic carbon. However, even after 20 years of restoration, EMF did not reach the levels observed in natural grasslands. Structural equation modeling showed that the driving mechanisms of EMF differed between the two steppe types. Specifically, in the desert steppe, plant diversity, especially the diversity of perennial graminoids and perennial herbs, had a positive effect on EMF, but in the typical steppe, soil bacterial diversity had a negative effect, while soil pH had a positive effect on EMF. Our results demonstrated that spontaneous grassland restoration effectively enhanced EMF, and emphasized the importance of biodiversity and soil pH in regulating EMF during secondary succession. This work provides important insights for grassland ecosystem management in arid and semi-arid regions.

Soil microbiomes and one health

The concept of one health highlights that human health is not isolated but connected to the health of animals, plants and environments. In this Review, we demonstrate that soils are a cornerstone of one health and serve as a source and reservoir of pathogens, beneficial microorganisms and the overall microbial diversity in a wide range of organisms and ecosystems. We list more than 40 soil microbiome functions that either directly or indirectly contribute to soil, plant, animal and human health. We identify microorganisms that are shared between different one health compartments and show that soil, plant and human microbiomes are perhaps more interconnected than previously thought. Our Review further evaluates soil microbial contributions to one health in the light of dysbiosis and global change and demonstrates that microbial diversity is generally positively associated with one health. Finally, we present future challenges in one health research and formulate recommendations for practice and evaluation.