Greenspaces are important for sustaining healthy urban environments and their human populations. ... more Greenspaces are important for sustaining healthy urban environments and their human populations. Yet their capacity to support multiple ecosystem services simultaneously (multiservices) compared with nearby natural ecosystems remains virtually unknown. We conducted a global field survey in 56 urban areas to investigate the influence of urban greenspaces on 23 soil and plant attributes and compared them with nearby natural environments. We show that, in general, urban greenspaces and nearby natural areas support similar levels of soil multiservices, with only six of 23 attributes (available phosphorus, water holding capacity, water respiration, plant cover, arbuscular mycorrhizal fungi (AMF), and arachnid richness) significantly greater in greenspaces, and one (available ammonium) greater in natural areas. Further analyses showed that, although natural areas and urban greenspaces delivered a similar number of services at low (>25% threshold) and moderate (>50%) levels of functioning, natural systems supported significantly more functions at high (>75%) levels of functioning. Management practices (mowing) played an important role in explaining urban ecosystem services, but there were no effects of fertilisation or irrigation. Some services declined with increasing site size, for both greenspaces and natural areas. Our work highlights the fact that urban greenspaces are more similar to natural environments than previously reported and underscores the importance of managing urban greenspaces not only for their social and recreational values, but for supporting multiple ecosystem services on which soils and human well-being depends. Marked changes have occurred in urban areas over the past century due to the increasing concentration of people in large cities. Currently, more than half of the world's population lives in cities, placing increasing stress on urban environments, their residents and infrastructure 1. This urban population is expected to increase to about 68% by 2050 2 , increasing the need to protect and improve the quality and accessibility of urban greenspaces, which include city parks, residential gardens and roadside verges. The health and social benefits of urban greenspaces are increasingly important for promoting social and physical wellbeing, and for alleviating the negative stresses associated with living in large urban centres 3-8. Globally, there is increasing recognition by state and city planning bodies of the importance of ecosystem services both in urban and semi-natural environments 9. More recent work aims to improve the extent to which land use decisions affect the provision of ecosystem services and therefore human well-being 10. Greenspace soils support a wide range of ecosystem services such as plant productivity, habitat for soil organisms, nutrient availability for plants and microbes, plant-soil symbiosis, pathogen control, and water regulation. All of these services are
Increases in aridity forecasted by the end of this century will decouple the cycles of soil carbo... more Increases in aridity forecasted by the end of this century will decouple the cycles of soil carbon (C), nitrogen (N) and phosphorus (P) in drylands-the largest terrestrial biome on Earth. Little is known, however, about how changes in aridity simultaneously affect the C:N:P stoichiometry of organisms across multiple trophic levels. It is imperative that we understand how aridity affects ecological stoichiometry so that we can develop strategies to mitigate any effects of changing climates. We characterized the C, N, P concentration and stoichiometry of soils, autotrophs (trees, N-fixing shrubs, grasses and mosses) and heterotrophs (microbes and ants) across a wide aridity gradient in Australia. Our results suggest that increases in aridity by the end of this century may alter the C:N:P stoichiometry of heterotrophs (ants and microbes), non-woody plants and in soil, but will not affect that one from woody-plants. In particular, increases in aridity were
Drylands comprise one-third of Earth's terrestrial surface area and support over two billion peop... more Drylands comprise one-third of Earth's terrestrial surface area and support over two billion people. Most drylands are projected to experience altered rainfall regimes, including changes in total amounts and fewer but larger rainfall events interspersed by longer periods without rain. This transition will have ecosystem-wide impacts but the long-term effects on microbial communities remain poorly quanti ed. We assessed belowground effects of altered rainfall regimes (+ 65% and − 65% relative to ambient) at six sites in arid and semi-arid Australia over a period of three years (2016-2019) coinciding with a signi cant natural drought event (2017-2019). Microbial communities differed signi cantly among semiarid and arid sites and across years associated with variation in abiotic factors, such as pH and carbon content, along with rainfall. Rainfall treatments induced shifts in microbial community composition only at a subset of the sites (Milparinka and Quilpie). However, differential abundance analyses revealed that several taxa, including Acidobacteria, TM7, Gemmatimonadates and Chytridiomycota, were more abundant in the wettest year (2016) and that their relative abundance decreased in drier years. By contrast, the relative abundance of oligotrophic taxa such as Actinobacteria, Alpha-proteobacteria, Planctomycetes, and Ascomycota and Basidiomycota, increased during the prolonged drought. Interestingly, fungi were shown to be more sensitive with increasing drought intensity and to rainfall treatment than bacteria with Basidiomycota mostly dominant in the reduced rainfall treatment. Moreover, correlation network analyses showed more positive associations among stress-tolerant dominant taxa following the drought (i.e., 2019 v 2016). Our result indicates that such stress-tolerant taxa play an important role in how whole communities respond to changes in aridity. Such knowledge provides a better understanding of microbial responses to predicted increases in rainfall variability and the impact on the functioning of semi-arid and arid ecosystems.
Statement of authorship: M.D-B. designed this study. M.D-B. and D.J.E. were involved in the colle... more Statement of authorship: M.D-B. designed this study. M.D-B. and D.J.E. were involved in the collection of the soils used in this study. M.D-B. conducted statistical modeling. The manuscript was written by M.D-B, and edited by D.J.E.
Aim: Cyanobacteria have shaped the history of life on Earth, and continue to play important roles... more Aim: Cyanobacteria have shaped the history of life on Earth, and continue to play important roles as carbon and nitrogen fixers in terrestrial ecosystems. However, their global distribution and ecological preferences remain poorly understood, particularly for two recently discovered non-photosynthetic cyanobacterial classes (Sericytochromatia and Melainabacteria). Location: 237 locations across six continents encompassing multiple climates (arid, temperate, tropical, continental and polar) and vegetation types (forests, grasslands and shrublands). Time period: Sampling was carried out between 2003 and 2015. Major taxa studied: Photosynthetic and non-photosynthetic cyanobacterial taxa Methods: We conducted a field survey and used co-occurrence network analysis and structural equation modelling to evaluate the distribution and environmental preferences of soil cyanobacteria across the globe. These ecological preferences were used to create a global atlas (predictive distribution maps) of soil cyanobacteria. Results: Network analyses identified three major groups of cyanobacteria taxa, which resembled the three main cyanobacterial classes: the photosynthetic Oxyphotobacteriadominated cluster, which were prevalent in arid and semiarid areas, and the nonphotosynthetic Sericytochromatiaand Melainabacteria-dominated clusters, which preferred hyperarid oligotrophic and acidic/ humid environments, respectively. Main conclusions: This study provides novel insights into the environmental preferences of non-photosynthetic cyanobacteria in soils globally. Our findings highlight the contrasting environmental preferences among the three clusters of cyanobacteria and suggest that alterations in environmental conditions linked to climate change may result in important changes in the ecology and biogeography of these functionally important microorganisms.
1. Grazing by domestic livestock is sometimes promoted as a management tool to benefit biodiversi... more 1. Grazing by domestic livestock is sometimes promoted as a management tool to benefit biodiversity. In many situations, however, it can produce negative outcomes. 2. Here, we examine the impacts of recent and historic livestock grazing on bird communities in the semi-arid woodlands in eastern Australia, testing the notion that grazing removes the suppressive effect of structurally complex vegetation on miners, thereby reducing the richness and abundance of small birds. 3. We used time-and area-limited searches of 108 sites varying in livestock grazing history and intensity, to explore the direct and indirect effects of grazing, habitat complexity and the abundance of aggressive, large-bodied birds on smaller-bodied birds using two-way analysis of variance and structural equation modelling. 4. Small birds were less abundant and had lower richness in the presence of miners. Our structural equation models indicated that recent grazing had direct suppressive effects on the abundance of miners, and both richness and abundance of all but the largest-bodied bird groups. However, higher levels of historic livestock grazing reinforced the competitive exclusion of the six small-bodied bird groups (insectivores, nectarivores, declining woodland birds, small ground-foraging birds, all small birds and all non-miners) by aggressive miners via reductions in habitat complexity. Moreover, the strength of any suppressive effects on small birds or positive effects on large birds by miners increased with increasing miner abundance. 5. Synthesis and applications. Our results highlight the importance of vegetation structural complexity, not only for providing habitat for woodland birds, but also as barriers to the invasion and competitive dominance of miners. Our findings suggest that management actions aimed at reducing tree and shrub density to promote open woodlands are likely to have significant negative consequences for the conservation of small woodland birds.
Little is known about the role of ant colonies in regulating the distribution and diversity of so... more Little is known about the role of ant colonies in regulating the distribution and diversity of soil microbial communities across large spatial scales. Here, we conducted a survey across >1000 km in eastern Australia and found that, compared with surrounding bare soils, ant colonies promoted the richness (number of phylotypes) and relative abundance of rare taxa of fungi and bacteria. Ant nests were also an important reservoir for plant pathogens. Our study also provides a portfolio of microbial phylotypes only found in ant nests, and which are associated with high nutrient availability. Together, our work highlights the fact that ant nests are an important refugia for microbial diversity.
The species-area relationship is one of the most widely reported ecological theories accounting f... more The species-area relationship is one of the most widely reported ecological theories accounting for biodiversity of plants and animals. However, we lack solid experimental data demonstrating whether this key ecological theorem also applies in the microbial world. Here, we conducted a microcosm study to evaluate the role of habitat area in driving the diversity, abundance, composition and functioning (i.e., four enzyme activities linked to organic matter decomposition) of soil bacterial communities. Thus, we aim to evaluate whether the principle of species-area relationship is potentially applicable to soil microbes. We established a fully factorial experimental design of three island sizes (~9, 50 and 150 cm 2) by two sterile soils (low, high resources). After six months of glasshouse incubation, habitat-area was positively related to bacterial richness, relative abundance of Chloroflexi, Verrucomicrobia and δproteobacteria, and soil functions in both soils. Soil with higher resources always had the greatest bacterial richness and functions. Our findings provide a proof of concept by demonstrating the potential importance of both habitat-area and resource availability in driving soil bacterial biodiversity and functioning.
We have little information on how and why soil microbial community assembly will respond to predi... more We have little information on how and why soil microbial community assembly will respond to predicted increases in aridity by the end of this century. Here, we used correlation networks and structural equation modeling to assess the changes in the abundance of the ecological clusters including potential winner and loser microbial taxa associated with predicted increases in aridity. To do this, we conducted a field survey in an environmental gradient from eastern Australia, and obtained information on bacterial and fungal community composition for 120 soil samples, and multiple abiotic and biotic factors. Overall our structural equation model explained 83% of the variance in the two mesic modules. Increases in aridity led to marked shifts in the abundance of the two major microbial modules found in our network, which accounted for >99% of all phylotypes. In particular, the relative abundance of one of these modules, the Mesic-Module-#1, which was positively related to multiple soil properties and plant productivity, declined strongly with aridity. Conversely, the relative abundance of a second dominant module (Xeric-Module-#2) was positively correlated with increases in aridity. Our study provides evidence that network analysis is a useful tool to identify microbial taxa that are either winners or losers under increasing aridity and therefore potentially under changing climates. Our work further suggests that climate change, and associated land degradation, could potentially lead to extensive microbial phylotypes exchange and local extinctions, as demonstrated by the reductions of up to 97% in the relative abundance of microbial taxa within Mesic-Module-#1.
Soil contamination is one of the main threats to ecosystem health and sustainability. Yet little ... more Soil contamination is one of the main threats to ecosystem health and sustainability. Yet little is known about the extent to which soil contaminants differ between urban greenspaces and natural ecosystems. Here we show that urban greenspaces and adjacent natural areas (i.e., natural/semi-natural ecosystems) shared similar levels of multiple soil contaminants (metal(loid)s, pesticides, microplastics, and antibiotic resistance genes) across the globe. We reveal that human influence explained many forms of soil contamination worldwide. Socioeconomic factors were integral to explaining the occurrence of soil contaminants worldwide. We further show that increased levels of multiple soil contaminants were linked with changes in microbial traits including genes associated with environmental stress resistance, nutrient cycling, and pathogenesis. Taken together, our work demonstrates that human-driven soil contamination in nearby natural areas mirrors that in urban greenspaces globally, and highlights that soil contaminants have the potential to cause dire consequences for ecosystem sustainability and human wellbeing. Soil contamination challenges many of the United Nations Sustainable Development Goals such as good health and wellbeing, sustainable ecosystems and cities, and climate change regulation 1,2. Environmental stress associated with soil contamination, either from natural or anthropogenic origins, can directly affect biodiversity and ecosystem functions 3 , and further compromise the resistance and resilience of ecosystems to climate change and natural disasters 1. Moreover, soil contamination in urban areas can negatively influence the health of city residents through cross-media migration-induced risk (e.g., toxic metal(loid)s affecting drinking water quality and vapor intrusion of
This is an open access article under the terms of the Creative Commons Attribution License, which... more This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
The relationship between biodiversity and biomass has been a long standing debate in ecology. Soi... more The relationship between biodiversity and biomass has been a long standing debate in ecology. Soil biodiversity and biomass are essential drivers of ecosystem functions. However, unlike plant communities, little is known about how the diversity and biomass of soil microbial communities are interlinked across globally distributed biomes, and how variations in this relationship influence ecosystem function. To fill this knowledge gap, we conducted a field survey across global biomes, with contrasting vegetation and climate types. We show that soil carbon (C) content is associated to the microbial diversity-biomass relationship and ratio in soils across global biomes. This ratio provides an integrative index to identify those locations on Earth wherein diversity is much higher compared with biomass and vice versa. The soil microbial diversity-to-biomass ratio peaks in arid environments with low C content, and is very low in C-rich cold environments. Our study further advances that the reductions in soil C content associated with land use intensification and climate change could cause dramatic shifts in the microbial diversity-biomass ratio, with potential consequences for broad soil processes.
Background and aims Livestock grazing and climate change are two of the most important global cha... more Background and aims Livestock grazing and climate change are two of the most important global change drivers affecting ecosystem functioning in drylands. Grazing and climate are known to influence the cover and composition of biocrusts, which are substantial components of dryland soils globally. Much less is known, however, about how these global change drivers affect the functional diversity of biocrust communities in these ecosystems. Methods Here, we evaluate the role of increasing aridity and grazing intensity in driving the functional diversity of biocrusts. We collected data on multiple biocrust functional traits and community composition, recent and historic grazing intensity, and vascular plants at 151 sites from drylands in eastern Australia. We then used structural equation modelling and a fourth corner analysis to examine the combined effects of aridity and grazing on biocrust functional diversity and individual functional traits. Results Aridity had a significant direct suppressive effect on biocrust functional diversity. Effects of grazing by livestock, kangaroos and rabbits on functional diversity were predominantly indirect and suppressive, mediated by a reduction in biocrust cover. Grazing did, however, promote functional diversity via an increase in vascular plant richness, with a concomitant increase in biocrust richness. The overall effect of grazing on biocrust functional diversity however was negative. Fourth corner analyses revealed that livestock grazing had a significant negative effect on the ability of biocrusts to stabilise the soil. Aridity had strong negative effects on biocrust height and their ability to absorb water and capture sediment. Few significant relationships were detected between enzyme-related traits and environmental variables. Conclusions Our findings provide novel evidence that the combination of increasing aridity and intensified livestock grazing will reduce the functional diversity and capabilities of biocrust communities, with resultant declines in ecosystem functioning.
Despite having key functions in terrestrial ecosystems, information on the dominant soil fungi an... more Despite having key functions in terrestrial ecosystems, information on the dominant soil fungi and their ecological preferences at the global scale is lacking. To fill this knowledge gap, we surveyed 235 soils from across the globe. Our findings indicate that 83 phylotypes (<0.1% of the retrieved fungi), mostly belonging to wind dispersed, generalist Ascomycota, dominate soils globally. We identify patterns and ecological drivers of dominant soil fungal taxa occurrence, and present a map of their distribution in soils worldwide. Whole-genome comparisons with less dominant, generalist fungi point at a significantly higher number of genes related to stress-tolerance and resource uptake in the dominant fungi, suggesting that they might be better in colonising a wide range of environments. Our findings constitute a major advance in our understanding of the ecology of fungi, and have implications for the development of strategies to preserve them and the ecosystem functions they provide.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Australia’s distinctive biogeography means that it is sometimes considered an ecologically unique... more Australia’s distinctive biogeography means that it is sometimes considered an ecologically unique continent with biological and abiotic features that are not comparable to those observed in the rest of the world. This leaves some researchers unclear as to whether findings from Australia apply to systems elsewhere (or vice-versa), which has consequences for the development of ecological theory and the application of ecological management principles. We analyzed 594,612 observations spanning 85 variables describing global climate, soil, geochemistry, plants, animals, and ecosystem function to test if Australia is broadly different to the other continents and compare how different each continent is from the global mean. We found significant differences between Australian and global means for none of 15 climate variables, only seven of 25 geochemistry variables, three of 16 soil variables, five of 12 plant trait variables, four of 11 animal variables, and one of five ecosystem function ...
SummaryEcological theory posits that temporal stability patterns in plant populations are associa... more SummaryEcological theory posits that temporal stability patterns in plant populations are associated with differences in species’ ecological strategies. However, empirical evidence is lacking about which traits, or trade-offs, underlie species stability, specially across different ecosystems.To address this, we compiled a global collection of long-term permanent vegetation records (>7000 plots from 78 datasets) from a wide range of habitats and combined this with existing trait databases. We tested whether the observed inter-annual variability in species abundance (coefficient of variation) was related to multiple individual traits and multivariate axes of trait variations (PCoA axes).We found that species with greater leaf dry matter content and seed mass were consistently more stable over time (lower variability in species abundance) although other leaf traits played a significant role as well, albeit weaker. Using multivariate axes did not improve predictions by specific trait...
ABSTRACTStudies of biological soil crusts (biocrusts) have proliferated over the last few decades... more ABSTRACTStudies of biological soil crusts (biocrusts) have proliferated over the last few decades. The biocrust literature has broadened, with more studies assessing and describing the function of a variety of biocrust communities in a broad range of biomes and habitats and across a large spectrum of disciplines, and also by the incorporation of biocrusts into global perspectives and biogeochemical models. As the number of biocrust researchers increases, along with the scope of soil communities defined as ‘biocrust’, it is worth asking whether we all share a clear, universal, and fully articulated definition of what constitutes a biocrust. In this review, we synthesize the literature with the views of new and experienced biocrust researchers, to provide a refined and fully elaborated definition of biocrusts. In doing so, we illustrate the ecological relevance and ecosystem services provided by them. We demonstrate that biocrusts are defined by four distinct elements: physical struct...
Proceedings of the National Academy of Sciences, 2020
Significance The stability of ecological communities under ongoing climate and land-use change is... more Significance The stability of ecological communities under ongoing climate and land-use change is fundamental to the sustainable management of natural resources through its effect on critical ecosystem services. Biodiversity is hypothesized to enhance stability through compensatory effects (decreased synchrony between species). However, the relative importance and interplay between different biotic and abiotic drivers of stability remain controversial. By analyzing long-term data from natural and seminatural ecosystems across the globe, we found that the degree of synchrony among dominant species was the main driver of stability, rather than species richness per se. These biotic effects overrode environmental drivers, which influenced the stability of communities by modulating the effects of richness and synchrony.
Greenspaces are important for sustaining healthy urban environments and their human populations. ... more Greenspaces are important for sustaining healthy urban environments and their human populations. Yet their capacity to support multiple ecosystem services simultaneously (multiservices) compared with nearby natural ecosystems remains virtually unknown. We conducted a global field survey in 56 urban areas to investigate the influence of urban greenspaces on 23 soil and plant attributes and compared them with nearby natural environments. We show that, in general, urban greenspaces and nearby natural areas support similar levels of soil multiservices, with only six of 23 attributes (available phosphorus, water holding capacity, water respiration, plant cover, arbuscular mycorrhizal fungi (AMF), and arachnid richness) significantly greater in greenspaces, and one (available ammonium) greater in natural areas. Further analyses showed that, although natural areas and urban greenspaces delivered a similar number of services at low (>25% threshold) and moderate (>50%) levels of functioning, natural systems supported significantly more functions at high (>75%) levels of functioning. Management practices (mowing) played an important role in explaining urban ecosystem services, but there were no effects of fertilisation or irrigation. Some services declined with increasing site size, for both greenspaces and natural areas. Our work highlights the fact that urban greenspaces are more similar to natural environments than previously reported and underscores the importance of managing urban greenspaces not only for their social and recreational values, but for supporting multiple ecosystem services on which soils and human well-being depends. Marked changes have occurred in urban areas over the past century due to the increasing concentration of people in large cities. Currently, more than half of the world's population lives in cities, placing increasing stress on urban environments, their residents and infrastructure 1. This urban population is expected to increase to about 68% by 2050 2 , increasing the need to protect and improve the quality and accessibility of urban greenspaces, which include city parks, residential gardens and roadside verges. The health and social benefits of urban greenspaces are increasingly important for promoting social and physical wellbeing, and for alleviating the negative stresses associated with living in large urban centres 3-8. Globally, there is increasing recognition by state and city planning bodies of the importance of ecosystem services both in urban and semi-natural environments 9. More recent work aims to improve the extent to which land use decisions affect the provision of ecosystem services and therefore human well-being 10. Greenspace soils support a wide range of ecosystem services such as plant productivity, habitat for soil organisms, nutrient availability for plants and microbes, plant-soil symbiosis, pathogen control, and water regulation. All of these services are
Increases in aridity forecasted by the end of this century will decouple the cycles of soil carbo... more Increases in aridity forecasted by the end of this century will decouple the cycles of soil carbon (C), nitrogen (N) and phosphorus (P) in drylands-the largest terrestrial biome on Earth. Little is known, however, about how changes in aridity simultaneously affect the C:N:P stoichiometry of organisms across multiple trophic levels. It is imperative that we understand how aridity affects ecological stoichiometry so that we can develop strategies to mitigate any effects of changing climates. We characterized the C, N, P concentration and stoichiometry of soils, autotrophs (trees, N-fixing shrubs, grasses and mosses) and heterotrophs (microbes and ants) across a wide aridity gradient in Australia. Our results suggest that increases in aridity by the end of this century may alter the C:N:P stoichiometry of heterotrophs (ants and microbes), non-woody plants and in soil, but will not affect that one from woody-plants. In particular, increases in aridity were
Drylands comprise one-third of Earth's terrestrial surface area and support over two billion peop... more Drylands comprise one-third of Earth's terrestrial surface area and support over two billion people. Most drylands are projected to experience altered rainfall regimes, including changes in total amounts and fewer but larger rainfall events interspersed by longer periods without rain. This transition will have ecosystem-wide impacts but the long-term effects on microbial communities remain poorly quanti ed. We assessed belowground effects of altered rainfall regimes (+ 65% and − 65% relative to ambient) at six sites in arid and semi-arid Australia over a period of three years (2016-2019) coinciding with a signi cant natural drought event (2017-2019). Microbial communities differed signi cantly among semiarid and arid sites and across years associated with variation in abiotic factors, such as pH and carbon content, along with rainfall. Rainfall treatments induced shifts in microbial community composition only at a subset of the sites (Milparinka and Quilpie). However, differential abundance analyses revealed that several taxa, including Acidobacteria, TM7, Gemmatimonadates and Chytridiomycota, were more abundant in the wettest year (2016) and that their relative abundance decreased in drier years. By contrast, the relative abundance of oligotrophic taxa such as Actinobacteria, Alpha-proteobacteria, Planctomycetes, and Ascomycota and Basidiomycota, increased during the prolonged drought. Interestingly, fungi were shown to be more sensitive with increasing drought intensity and to rainfall treatment than bacteria with Basidiomycota mostly dominant in the reduced rainfall treatment. Moreover, correlation network analyses showed more positive associations among stress-tolerant dominant taxa following the drought (i.e., 2019 v 2016). Our result indicates that such stress-tolerant taxa play an important role in how whole communities respond to changes in aridity. Such knowledge provides a better understanding of microbial responses to predicted increases in rainfall variability and the impact on the functioning of semi-arid and arid ecosystems.
Statement of authorship: M.D-B. designed this study. M.D-B. and D.J.E. were involved in the colle... more Statement of authorship: M.D-B. designed this study. M.D-B. and D.J.E. were involved in the collection of the soils used in this study. M.D-B. conducted statistical modeling. The manuscript was written by M.D-B, and edited by D.J.E.
Aim: Cyanobacteria have shaped the history of life on Earth, and continue to play important roles... more Aim: Cyanobacteria have shaped the history of life on Earth, and continue to play important roles as carbon and nitrogen fixers in terrestrial ecosystems. However, their global distribution and ecological preferences remain poorly understood, particularly for two recently discovered non-photosynthetic cyanobacterial classes (Sericytochromatia and Melainabacteria). Location: 237 locations across six continents encompassing multiple climates (arid, temperate, tropical, continental and polar) and vegetation types (forests, grasslands and shrublands). Time period: Sampling was carried out between 2003 and 2015. Major taxa studied: Photosynthetic and non-photosynthetic cyanobacterial taxa Methods: We conducted a field survey and used co-occurrence network analysis and structural equation modelling to evaluate the distribution and environmental preferences of soil cyanobacteria across the globe. These ecological preferences were used to create a global atlas (predictive distribution maps) of soil cyanobacteria. Results: Network analyses identified three major groups of cyanobacteria taxa, which resembled the three main cyanobacterial classes: the photosynthetic Oxyphotobacteriadominated cluster, which were prevalent in arid and semiarid areas, and the nonphotosynthetic Sericytochromatiaand Melainabacteria-dominated clusters, which preferred hyperarid oligotrophic and acidic/ humid environments, respectively. Main conclusions: This study provides novel insights into the environmental preferences of non-photosynthetic cyanobacteria in soils globally. Our findings highlight the contrasting environmental preferences among the three clusters of cyanobacteria and suggest that alterations in environmental conditions linked to climate change may result in important changes in the ecology and biogeography of these functionally important microorganisms.
1. Grazing by domestic livestock is sometimes promoted as a management tool to benefit biodiversi... more 1. Grazing by domestic livestock is sometimes promoted as a management tool to benefit biodiversity. In many situations, however, it can produce negative outcomes. 2. Here, we examine the impacts of recent and historic livestock grazing on bird communities in the semi-arid woodlands in eastern Australia, testing the notion that grazing removes the suppressive effect of structurally complex vegetation on miners, thereby reducing the richness and abundance of small birds. 3. We used time-and area-limited searches of 108 sites varying in livestock grazing history and intensity, to explore the direct and indirect effects of grazing, habitat complexity and the abundance of aggressive, large-bodied birds on smaller-bodied birds using two-way analysis of variance and structural equation modelling. 4. Small birds were less abundant and had lower richness in the presence of miners. Our structural equation models indicated that recent grazing had direct suppressive effects on the abundance of miners, and both richness and abundance of all but the largest-bodied bird groups. However, higher levels of historic livestock grazing reinforced the competitive exclusion of the six small-bodied bird groups (insectivores, nectarivores, declining woodland birds, small ground-foraging birds, all small birds and all non-miners) by aggressive miners via reductions in habitat complexity. Moreover, the strength of any suppressive effects on small birds or positive effects on large birds by miners increased with increasing miner abundance. 5. Synthesis and applications. Our results highlight the importance of vegetation structural complexity, not only for providing habitat for woodland birds, but also as barriers to the invasion and competitive dominance of miners. Our findings suggest that management actions aimed at reducing tree and shrub density to promote open woodlands are likely to have significant negative consequences for the conservation of small woodland birds.
Little is known about the role of ant colonies in regulating the distribution and diversity of so... more Little is known about the role of ant colonies in regulating the distribution and diversity of soil microbial communities across large spatial scales. Here, we conducted a survey across >1000 km in eastern Australia and found that, compared with surrounding bare soils, ant colonies promoted the richness (number of phylotypes) and relative abundance of rare taxa of fungi and bacteria. Ant nests were also an important reservoir for plant pathogens. Our study also provides a portfolio of microbial phylotypes only found in ant nests, and which are associated with high nutrient availability. Together, our work highlights the fact that ant nests are an important refugia for microbial diversity.
The species-area relationship is one of the most widely reported ecological theories accounting f... more The species-area relationship is one of the most widely reported ecological theories accounting for biodiversity of plants and animals. However, we lack solid experimental data demonstrating whether this key ecological theorem also applies in the microbial world. Here, we conducted a microcosm study to evaluate the role of habitat area in driving the diversity, abundance, composition and functioning (i.e., four enzyme activities linked to organic matter decomposition) of soil bacterial communities. Thus, we aim to evaluate whether the principle of species-area relationship is potentially applicable to soil microbes. We established a fully factorial experimental design of three island sizes (~9, 50 and 150 cm 2) by two sterile soils (low, high resources). After six months of glasshouse incubation, habitat-area was positively related to bacterial richness, relative abundance of Chloroflexi, Verrucomicrobia and δproteobacteria, and soil functions in both soils. Soil with higher resources always had the greatest bacterial richness and functions. Our findings provide a proof of concept by demonstrating the potential importance of both habitat-area and resource availability in driving soil bacterial biodiversity and functioning.
We have little information on how and why soil microbial community assembly will respond to predi... more We have little information on how and why soil microbial community assembly will respond to predicted increases in aridity by the end of this century. Here, we used correlation networks and structural equation modeling to assess the changes in the abundance of the ecological clusters including potential winner and loser microbial taxa associated with predicted increases in aridity. To do this, we conducted a field survey in an environmental gradient from eastern Australia, and obtained information on bacterial and fungal community composition for 120 soil samples, and multiple abiotic and biotic factors. Overall our structural equation model explained 83% of the variance in the two mesic modules. Increases in aridity led to marked shifts in the abundance of the two major microbial modules found in our network, which accounted for >99% of all phylotypes. In particular, the relative abundance of one of these modules, the Mesic-Module-#1, which was positively related to multiple soil properties and plant productivity, declined strongly with aridity. Conversely, the relative abundance of a second dominant module (Xeric-Module-#2) was positively correlated with increases in aridity. Our study provides evidence that network analysis is a useful tool to identify microbial taxa that are either winners or losers under increasing aridity and therefore potentially under changing climates. Our work further suggests that climate change, and associated land degradation, could potentially lead to extensive microbial phylotypes exchange and local extinctions, as demonstrated by the reductions of up to 97% in the relative abundance of microbial taxa within Mesic-Module-#1.
Soil contamination is one of the main threats to ecosystem health and sustainability. Yet little ... more Soil contamination is one of the main threats to ecosystem health and sustainability. Yet little is known about the extent to which soil contaminants differ between urban greenspaces and natural ecosystems. Here we show that urban greenspaces and adjacent natural areas (i.e., natural/semi-natural ecosystems) shared similar levels of multiple soil contaminants (metal(loid)s, pesticides, microplastics, and antibiotic resistance genes) across the globe. We reveal that human influence explained many forms of soil contamination worldwide. Socioeconomic factors were integral to explaining the occurrence of soil contaminants worldwide. We further show that increased levels of multiple soil contaminants were linked with changes in microbial traits including genes associated with environmental stress resistance, nutrient cycling, and pathogenesis. Taken together, our work demonstrates that human-driven soil contamination in nearby natural areas mirrors that in urban greenspaces globally, and highlights that soil contaminants have the potential to cause dire consequences for ecosystem sustainability and human wellbeing. Soil contamination challenges many of the United Nations Sustainable Development Goals such as good health and wellbeing, sustainable ecosystems and cities, and climate change regulation 1,2. Environmental stress associated with soil contamination, either from natural or anthropogenic origins, can directly affect biodiversity and ecosystem functions 3 , and further compromise the resistance and resilience of ecosystems to climate change and natural disasters 1. Moreover, soil contamination in urban areas can negatively influence the health of city residents through cross-media migration-induced risk (e.g., toxic metal(loid)s affecting drinking water quality and vapor intrusion of
This is an open access article under the terms of the Creative Commons Attribution License, which... more This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
The relationship between biodiversity and biomass has been a long standing debate in ecology. Soi... more The relationship between biodiversity and biomass has been a long standing debate in ecology. Soil biodiversity and biomass are essential drivers of ecosystem functions. However, unlike plant communities, little is known about how the diversity and biomass of soil microbial communities are interlinked across globally distributed biomes, and how variations in this relationship influence ecosystem function. To fill this knowledge gap, we conducted a field survey across global biomes, with contrasting vegetation and climate types. We show that soil carbon (C) content is associated to the microbial diversity-biomass relationship and ratio in soils across global biomes. This ratio provides an integrative index to identify those locations on Earth wherein diversity is much higher compared with biomass and vice versa. The soil microbial diversity-to-biomass ratio peaks in arid environments with low C content, and is very low in C-rich cold environments. Our study further advances that the reductions in soil C content associated with land use intensification and climate change could cause dramatic shifts in the microbial diversity-biomass ratio, with potential consequences for broad soil processes.
Background and aims Livestock grazing and climate change are two of the most important global cha... more Background and aims Livestock grazing and climate change are two of the most important global change drivers affecting ecosystem functioning in drylands. Grazing and climate are known to influence the cover and composition of biocrusts, which are substantial components of dryland soils globally. Much less is known, however, about how these global change drivers affect the functional diversity of biocrust communities in these ecosystems. Methods Here, we evaluate the role of increasing aridity and grazing intensity in driving the functional diversity of biocrusts. We collected data on multiple biocrust functional traits and community composition, recent and historic grazing intensity, and vascular plants at 151 sites from drylands in eastern Australia. We then used structural equation modelling and a fourth corner analysis to examine the combined effects of aridity and grazing on biocrust functional diversity and individual functional traits. Results Aridity had a significant direct suppressive effect on biocrust functional diversity. Effects of grazing by livestock, kangaroos and rabbits on functional diversity were predominantly indirect and suppressive, mediated by a reduction in biocrust cover. Grazing did, however, promote functional diversity via an increase in vascular plant richness, with a concomitant increase in biocrust richness. The overall effect of grazing on biocrust functional diversity however was negative. Fourth corner analyses revealed that livestock grazing had a significant negative effect on the ability of biocrusts to stabilise the soil. Aridity had strong negative effects on biocrust height and their ability to absorb water and capture sediment. Few significant relationships were detected between enzyme-related traits and environmental variables. Conclusions Our findings provide novel evidence that the combination of increasing aridity and intensified livestock grazing will reduce the functional diversity and capabilities of biocrust communities, with resultant declines in ecosystem functioning.
Despite having key functions in terrestrial ecosystems, information on the dominant soil fungi an... more Despite having key functions in terrestrial ecosystems, information on the dominant soil fungi and their ecological preferences at the global scale is lacking. To fill this knowledge gap, we surveyed 235 soils from across the globe. Our findings indicate that 83 phylotypes (<0.1% of the retrieved fungi), mostly belonging to wind dispersed, generalist Ascomycota, dominate soils globally. We identify patterns and ecological drivers of dominant soil fungal taxa occurrence, and present a map of their distribution in soils worldwide. Whole-genome comparisons with less dominant, generalist fungi point at a significantly higher number of genes related to stress-tolerance and resource uptake in the dominant fungi, suggesting that they might be better in colonising a wide range of environments. Our findings constitute a major advance in our understanding of the ecology of fungi, and have implications for the development of strategies to preserve them and the ecosystem functions they provide.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Australia’s distinctive biogeography means that it is sometimes considered an ecologically unique... more Australia’s distinctive biogeography means that it is sometimes considered an ecologically unique continent with biological and abiotic features that are not comparable to those observed in the rest of the world. This leaves some researchers unclear as to whether findings from Australia apply to systems elsewhere (or vice-versa), which has consequences for the development of ecological theory and the application of ecological management principles. We analyzed 594,612 observations spanning 85 variables describing global climate, soil, geochemistry, plants, animals, and ecosystem function to test if Australia is broadly different to the other continents and compare how different each continent is from the global mean. We found significant differences between Australian and global means for none of 15 climate variables, only seven of 25 geochemistry variables, three of 16 soil variables, five of 12 plant trait variables, four of 11 animal variables, and one of five ecosystem function ...
SummaryEcological theory posits that temporal stability patterns in plant populations are associa... more SummaryEcological theory posits that temporal stability patterns in plant populations are associated with differences in species’ ecological strategies. However, empirical evidence is lacking about which traits, or trade-offs, underlie species stability, specially across different ecosystems.To address this, we compiled a global collection of long-term permanent vegetation records (>7000 plots from 78 datasets) from a wide range of habitats and combined this with existing trait databases. We tested whether the observed inter-annual variability in species abundance (coefficient of variation) was related to multiple individual traits and multivariate axes of trait variations (PCoA axes).We found that species with greater leaf dry matter content and seed mass were consistently more stable over time (lower variability in species abundance) although other leaf traits played a significant role as well, albeit weaker. Using multivariate axes did not improve predictions by specific trait...
ABSTRACTStudies of biological soil crusts (biocrusts) have proliferated over the last few decades... more ABSTRACTStudies of biological soil crusts (biocrusts) have proliferated over the last few decades. The biocrust literature has broadened, with more studies assessing and describing the function of a variety of biocrust communities in a broad range of biomes and habitats and across a large spectrum of disciplines, and also by the incorporation of biocrusts into global perspectives and biogeochemical models. As the number of biocrust researchers increases, along with the scope of soil communities defined as ‘biocrust’, it is worth asking whether we all share a clear, universal, and fully articulated definition of what constitutes a biocrust. In this review, we synthesize the literature with the views of new and experienced biocrust researchers, to provide a refined and fully elaborated definition of biocrusts. In doing so, we illustrate the ecological relevance and ecosystem services provided by them. We demonstrate that biocrusts are defined by four distinct elements: physical struct...
Proceedings of the National Academy of Sciences, 2020
Significance The stability of ecological communities under ongoing climate and land-use change is... more Significance The stability of ecological communities under ongoing climate and land-use change is fundamental to the sustainable management of natural resources through its effect on critical ecosystem services. Biodiversity is hypothesized to enhance stability through compensatory effects (decreased synchrony between species). However, the relative importance and interplay between different biotic and abiotic drivers of stability remain controversial. By analyzing long-term data from natural and seminatural ecosystems across the globe, we found that the degree of synchrony among dominant species was the main driver of stability, rather than species richness per se. These biotic effects overrode environmental drivers, which influenced the stability of communities by modulating the effects of richness and synchrony.
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