Emma J. Sayer

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Verified

Emma verified their affiliation via an institutional email.

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• PhD
• Professor (Full) at Ulm University

Public engagement is widely recognized as a key priority for achieving societal support for research. We spotlight creativity in public engagement as a way of reaching wider audiences and incentivising researcher involvement, demonstrating some of the possibilities with a recent initiative to engage the public with ecology at music festivals.

Predicting future impacts of anthropogenic change on tropical forests requires a clear understanding of nutrient constraints on productivity. We compared experimental fertilization and litter manipulation treatments in an old-growth lowland tropical forest to distinguish between the effects of inorganic nutrient amendments and changes in nutrient c...

Tropical forests are a critical component of the global carbon cycle and their response to environmental change will play a key role in determining future concentrations of atmospheric carbon dioxide (CO2). Increasing primary productivity in tropical forests over recent decades has been attributed to CO2 fertilization, and greater biomass in tropic...

1. The cycling of nutrients in litterfall is considered a key mechanism in the maintenance of tropical forest fertility but its importance has rarely been quantified experimentally. 2. We carried out a long‐term (5 years), large‐scale litter manipulation experiment in lowland semi‐evergreen tropical forest to determine how changes in litterfall aff...

Long-term litter removal increased soil bulk density, overland flow, erosion, and temperature fluctuations and upset the soil water balance, causing lower soil water content during dry periods. Soil pH increased or decreased in response to manipulation treatments depending on forest type and initial soil pH, but it is unclear why there was no unifo...

Forests store substantial amounts of soil organic carbon (SOC), but SOC stocks differ strongly between forest ecosystems dominated by arbuscular mycorrhizal (AM) or ectomycorrhizal (EcM) fungi. In temperate forests, nearly all tree species associate with either AM or EcM fungi, but it is unclear if variation in SOC stocks is linked to the dominance...

Litter decomposition by arthropods, microbes, and fungi is a key ecosystem process in tropical forests, yet its response to forest disturbance and recovery remains poorly understood. To investigate decomposition dynamics across forest succession, we conducted an experiment in the Ecuadorian lowland Chocó (Esmeraldas) using a chronosequence approach...

Globally, urbanization is associated with increased risk for physical and mental diseases. Among other factors, urban stressors (e.g. air pollution) are linked to these increased health risks (e.g. chronic respiratory diseases, depression). Emerging evidence indicates substantial health benefits of exposure to greenspaces in urban populations. Howe...

Tropical forests are generally characterized by high species diversity and low soil phosphorus (P) availability. Although tropical plants have evolved adaptations to low soil P availability, we know relatively little about the strategies of different groups of species to efficiently use P, or how these strategies might shape their distributions. We...

Soil fungi play an essential role in the fungal colonization of deadwood, with consequences for multiple ecosystem functions such as wood decomposition. Nutrient deposition can substantially affect fungal activity, but it is unclear how external nutrient inputs and host plant nutrient content interact to influence soil fungal colonization of deadwo...

p dir="ltr">The Gigante Litter Manipulation exPeriment (GLiMP) was established in 2000 to investigate the contribution to productivity made by nutrients in litterfall. Soil nitrate and nitrogen (N) concentrations in roots and leaves decreased quickly and significantly with litter removal (LR) and increased quickly and significantly with litter addi...

Methane is an important greenhouse gas¹, but the role of trees in the methane budget remains uncertain². Although it has been shown that wetland and some upland trees can emit soil-derived methane at the stem base3,4, it has also been suggested that upland trees can serve as a net sink for atmospheric methane5,6. Here we examine in situ woody surfa...

The Atlantic Forest and Cerrado (Brazilian Savannah) contain a large number of endemic species and high species diversity, particularly for medium and large-bodied mammals. However, there is no large-scale assessment of these animals and their spatial distribution. Our study synthesises the literature on medium and large-bodied mammal surveys in th...

Tropical forest productivity represents an important global carbon sink, but many tropical forests grow on infertile soils. Efficient nutrient cycling by litterfall has long been assumed to maintain tropical tree growth, but there is no direct evidence that the nutrients cycled in litterfall are essential for tropical forest productivity. To test w...

Springtails (Collembola) inhabit soils from the Arctic to the Antarctic and comprise an estimated ~32% of all terrestrial arthropods on Earth. Here, we present a global, spatially-explicit database on springtail communities that includes 249,912 occurrences from 44,999 samples and 2,990 sites. These data are mainly raw sample-level records at the s...

Demonstrating how a study advances the field is an essential criterion for publication in Functional Ecology. However, it is not always clear what constitutes a ‘significant advance’ and many manuscripts are rejected because authors have not demonstrated how their study will advance the field. In this editorial, we explain what the editors of Funct...

The impacts of precipitation change on forest carbon (C) storage will have global consequences, as forests play a major role in sequestering anthropogenic CO2. Although forest soils are one of the largest terrestrial C pools, there is great uncertainty around the response of forest soil organic carbon (SOC) to precipitation change, which limits our...

Secondary tropical forests are increasingly important for their role in the global carbon (C) balance as they can rapidly accumulate aboveground biomass C during regrowth. Substantial amounts of plant-derived carbon are also incorporated into the soil through decomposition processes, but our understanding of soil C dynamics during forest regrowth i...

High-quality and low-quality root litter had contrasting patterns of mass loss. Greater litter-derived C was incorporated into soils under high-quality root litter. Root litter decay rate or litter-derived C were related to soil microbial diversity. Root litter quality had little effect on soil physicochemical properties. High root litter quality w...

Understanding the chemical composition of our planet's crust was one of the biggest questions of the 20th century. More than 100 years later, we are still far from understanding the global patterns in the bioavailability and spatial coupling of elements in topsoils worldwide, despite their importance for the productivity and functioning of terrestr...

Nitrogen (N) deposition is a pervasive anthropogenic change that can alter the dynamics and storage of carbon (C) in tropical soils by altering the transformation of plant litter C to soil organic C (SOC). The response of fungi may be particularly important for explaining how N deposition affects SOC storage in tropical forests because they are the...

Soil life supports the functioning and biodiversity of terrestrial ecosystems. Springtails (Collembola) are among the most abundant soil arthropods regulating soil fertility and flow of energy through above- and belowground food webs. However, the global distribution of springtail diversity and density, and how these relate to energy fluxes remains...

Plant diversity supports multiple ecosystem functions, including carbon sequestration. Recent shifts in plant diversity in rangelands due to increased grazing pressure and climate changes have the potential to impact the sequestration of carbon in arid to semi‐humid regions worldwide. However, plant diversity, grazing intensity and carbon storage a...

Soil respiration in forests contributes to significant carbon dioxide emissions from terrestrial ecosystems but it varies both spatially and seasonally. Both abiotic and biotic factors influence soil respiration but their relative contribution to spatial and seasonal variability remains poorly understood, which leads to uncertainty in models of glo...

Background Two carbon (C) sources are of particular interest for soil organic carbon (SOC) storage under nitrogen (N) deposition: 1) glomalin-related soil protein (GRSP) and 2) microbial residual carbon (MRC) derived from microbial metabolites and residues. Both soil C sources are purported to have long residence times, but their contribution to SO...

Regenerating tropical forests are increasingly important for their role in the global carbon cycle. Carbon stocks in above‐ground biomass can recover to old‐growth forest levels within 60–100 years. However, more than half of all carbon in tropical forests is stored below‐ground, and our understanding of carbon storage in soils during tropical fore...

Grassland is one of the largest terrestrial biomes, providing critical ecosystem services such as food production, biodiversity conservation, and climate change mitigation. Global climate change and land-use intensification have been causing grassland degradation and desertification worldwide. As one of the primary medium for ecosystem energy flow...

Biocrusts are multifaceted communities including mosses, lichens, and cyanobacteria that are crucial for sustaining soil functions in drylands. Most studies on biocrust functions to date have focused on biocrust cover and development, largely in non‐saline soils, and we know very little about the importance of biocrust diversity for maintaining mul...

Human activities pose a major threat to tropical forest biodiversity and ecosystem services. Although the impacts of deforestation are well studied, multiple land-use and land-cover transitions (LULCTs) occur in tropical landscapes, and we do not know how LULCTs differ in their rates or impacts on key ecosystem components. Here, we quantified the i...

Carbon (C) exuded via roots is proposed to increase under drought and facilitate important ecosystem functions. However, it is unknown how exudate quantities relate to the total C budget of a drought‐stressed tree, that is, how much of net‐C assimilation is allocated to exudation at the tree level. We calculated the proportion of daily C assimilati...

File List: BrunnHafner_Ex_Roots_Properties.csv - root characteristics (mass, tips, area) and exudation rates of sampled root branches. BrunnHafner_Soil_Moisture_KROOF.csv - volumetric soil moisture in 2 soil depth increments BrunnHafner_Root_Properties_KROOF.csv - root characteristics (mass, tips, area) and core volume of cores taken for tree leve...

Seasonal precipitation regime plays a vital role in regulating nutrient dynamics in seasonally dry tropical forests. Present evidence suggests that not only wet season precipitation is increasing in the tropics of South China, but also that the wet season is occurring later. However, it is unclear how nutrient dynamics will respond to the projected...

Soil micronutrients limit crop productivity in many regions worldwide, and micronutrient deficiencies affect over two billion people globally. Microbial biofertilizers could combat these issues by inoculating arable soils with microorganisms that mobilize micronutrients, increasing their availability to crop plants in an environmentally sustainable...

Soil life supports the functioning and biodiversity of terrestrial ecosystems. Springtails (Collembola) are among the most abundant soil animals regulating soil fertility and flow of energy through above- and belowground food webs. However, the global distribution of springtail diversity and density, and how these relate to energy fluxes remains un...

Carbon (C) loss due to soil erosion is a major issue in semi‐arid grasslands. The extent of soil erosion is determined by soil properties and vegetation structure, especially during the non‐growing season. In many Inner Mongolian grasslands, intensive land‐use, such as overgrazing and mowing, has severely reduced plant cover and damaged soil struct...

Regional factors, such as historical and contemporary climate conditions, and local factors, such as vegetation structural attributes, can influence current patterns of plant species richness but their relative roles remain unknown, particularly across forest strata. Here, we used a multi-scale survey of temperate forest plots across a large region...

Soil organic matter (SOM) in tropical forests is an important store of carbon (C) and nutrients. Although SOM storage could be affected by global changes via altered plant productivity, we know relatively little about SOM stabilisation and turnover in tropical forests compared to temperate systems. Here, we investigated changes in soil C and N with...

Here we describe and evaluate the success of a multi‐institutional Centre for Doctoral Training (CDT), which was established to address a UK skills shortage in Soil Science. The government‐funded ‘STARS’ (Soils Training And Research Studentships) CDT was established in 2015 across a range of universities and research institutes in the UK. It recrui...

Soils are a fundamental natural resource but intensifying demands and increasing soil degradation necessitate focussed research into the sustainable use of soils. Since soil functioning is critical for the operations and performance of multiple industries, businesses and municipalities, soil scientists need to actively engage with these bodies to o...

Casuarina equisetifolia plantations have been widely established along tropical and subtropical coasts, where they act as a windbreak to shelter coastal areas. These shelter plantations also fulfill important ecosystem service by sequestering large amounts of carbon (C). However, shelter plantations are usually established on nutrient-poor sand dun...

Grazing can alter plant species interactions in natural rangelands, which in turn might influence the productivity of the ecosystem but we do not fully understand how spatial variability in plant diversity-biomass relationships are modulated by grazing intensity. Here, we hypothesized that plant species co-occurrence in rangelands is mainly driven...

Tropical forest biodiversity is being threatened by human activities, and species losses during forest disturbance can compromise important ecosystem functions and services. We assessed how species losses due to tropical forest disturbance affect community functional structure, using Amazonian dung beetles as a model group. We collected empirical d...

The turnover of SOC in soils is strongly influenced by the availability of substrate and nutrients, especially nitrogen (N) and phosphorus (P). Here, we assessed how long-term fertilization modified SOM mineralization in response to added substrate in a tropical forest. We carried out a 90-day incubation study in which we added two structurally sim...

A R T I C L E I N F O Keywords: Soil organic carbon storage Light and heavy density fractions Microaggregates Macroaggregates Forest conversion Land-use history A B S T R A C T The impact of human activities on soil carbon (C) storage in tropical forests has aroused wide concern during the past decades, because these ecosystems play a key role in a...

Interactions between plants and soil microbial communities underpin soil processes and forest ecosystem function, but the links between tree diversity and soil microbial diversity are poorly characterized. Differences in both the taxonomic and functional diversity of trees and microbes can shape soil nutrient status and carbon storage, but the stoi...

Resorption is the active withdrawal of nutrients before leaf abscission. This mechanism represents an important strategy to maintain efficient nutrient cycling; however, resorption is poorly characterized in old-growth tropical forests growing in nutrient-poor soils. We investigated nutrient resorption from leaves in 39 tree species in two tropical...

Drought imposes stress on plants and associated soil microbes, inducing coordinated adaptive responses, which can involve plant–soil signalling via phytohormones. However, we know little about how microbial communities respond to phytohormones, or how these responses are shaped by chronic (long-term) drought. Here, we added three phytohormones (abs...

Aims Aboveground plant litter inputs are important sources of soil carbon (C). We aimed to establish how experimentally altered litter inputs affect soil C to 1-m depth across different ecosystems, and over different timeframes. Methods We performed a meta-analysis of 237 studies across 248 sites worldwide to assess the influence of treatment magn...

Drought is a severe natural risk that increases drying-rewetting frequencies of soils. Yet, it remains largely unknown how forest ecosystems respond to dry-wet cycles, hampering our ability to evaluate the overall sink and source functionality for this large carbon pool. Recent investigations suggest that the release of soluble carbon via root exud...

Grasslands cover an estimated 31%–43% of the Earth’s land surface, possess an intrinsic conservation value, and offer indispensable ecosystem services. However, grasslands have been extensively managed and exploited, face major threats, including land-use change, climate change, woody encroachment, and biological invasion. The primary tools used to...

To predict how species loss will affect ecosystems, it is important to consider how biodiversity influences processes such as decomposition.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The activity of soil microbes is strongly constrained by water availability. However, it is unclear how microbial activity responds to spatial and temporal changes in precipitation, particularly to long-term precipitation changes. To identify the spatiotemporal patterns of microbial responses to precipitation changes of differing durations, we cond...

Global warming has greatly altered winter snowfall patterns, and there is a trend towards increasing winter snow in semi‐arid regions in China. Winter snowfall is an important source of water during early spring in these water‐limited ecosystems, and can also affect nutrient supply. However, we know little about how changes in winter snowfall will...

Land-use change in tropical forests can reduce biodiversity and ecosystem carbon (C) storage, but although changes in aboveground biomass C in human-modified tropical forests are well-documented, patterns in the dynamics and storage of C belowground are less well characterised. To address this, we used a reciprocal litter transplant experiment to a...

Soil organic carbon (SOC) dynamics represent a persisting uncertainty in our understanding of the global carbon cycle. SOC storage is strongly linked to plant inputs via the formation of soil organic matter, but soil geochemistry also plays a critical role. In tropical soils with rapid SOC turnover, the association of organic matter with soil miner...

Tropical reforestation initiatives are widely recognized as a key strategy for mitigating rising atmospheric CO2 concentrations. Although rapid tree growth in young secondary forests and plantations sequesters large amounts of carbon (C) in biomass, the choice of tree species for reforestation projects is crucial, as species identity and diversity...

Nitrogen (N) and phosphorus (P) are essential nutrients for plant metabolism, and their availability often limits primary productivity. Whereas the effects of N availability on photosynthetic capacity are well established, we still know relatively little about the effects of P availability at a foliar level, especially in P‐limited tropical forests...

Functional diversity is commonly used to assess the conservation value of ecosystems, but we have not yetestablished whether functional and taxonomic approaches are interchangeable or complementary to evaluatecommunity dynamics over time and in response to disturbances. We used afive-year dataset of dung beetlesfrom undisturbed forest, primary fore...

Grassland degradation is a worldwide problem that often leads to substantial loss of soil organic matter (SOM). To estimate the potential for carbon (C) accumulation in degraded grassland soils, we first need to understand how SOM content influences the transformation of plant C and its stabilization within the soil matrix. We conducted a greenhous...

Tropical forests on upland soils are assumed to be a methane (CH4) sink and a weak source of nitrous oxide (N2O), but studies of wetland forests have demonstrated that tree stems can be a substantial source of CH4, and recent evidence from temperate woodlands suggests that tree stems can also emit N2O. Here, we measured CH4 and N2O fluxes from the...

Drought is becoming more common globally and has the potential to alter patterns of soil carbon (C) storage in terrestrial ecosystems. After an extended dry period, a pulse of soil CO2 release is commonly observed upon rewetting (the so-called ‘Birch effect’), the magnitude of which depends on soil rewetting frequency. But the source and implicatio...

Improved understanding of the nutritional ecology of arbuscular mycorrhizal (AM) fungi is important in understanding how tropical forests maintain high productivity on low-fertility soils. Relatively little is known about how AM fungi will respond to changes in nutrient inputs in tropical forests, which hampers our ability to assess how forest prod...

Global change is affecting primary productivity in forests worldwide, and this, in turn, will alter long-term carbon (C) sequestration in wooded ecosystems. On one hand, increased primary productivity, for example, in response to elevated atmospheric carbon dioxide (CO2), can result in greater inputs of organic matter to the soil, which could incre...

The majority of above‐ground carbon in tropical forests is stored in wood, which is returned to the atmosphere during decomposition of coarse woody debris. However, the factors controlling wood decomposition have not been experimentally manipulated over time scales comparable to the length of this process. We hypothesized that wood decomposition is...

Heterotrophic soil respiration (SRH) alone can contribute up to 50% of total ecosystem respiration in tropical forests. Whereas the abiotic controls of SRH have been extensively studied, the influence of plant traits is less well characterised. We used field experiments and a modelling approach to test the relative influence of plant traits on SRH...

Appendix S2. ARES design criteria and preliminary tests for validation (contains Figs S2.1 and S2.2).

Appendix S1. ARES assembly and installation protocol (contains Figs S1.1, S1.2 and Table S1.1).

Appendix S3. Protocol and recipe for root exudate solution (contains Table S3.1).

Appendix S4. Supplementary figures (S4.1 and S4.2) and tables (S4.1 and S4.2).

Disturbance can alter tree species and functional diversity in tropical forests, which in turn could affect carbon and nutrient cycling via the decomposition of plant litter. However, the influence of tropical tree diversity on forest floor organisms and the processes they mediate are far from clear. We investigated the influence of different litte...

1. Due to intensifying human disturbance, over half of the world’s tropical forests are reforested or afforested secondary forests or plantations. Understanding the resilience of carbon (C) stocks in these forests, and estimating the extent to which they can provide equivalent carbon (C) sequestration and stabilization to the old growth forest they...

Root exudation is a key component of nutrient and carbon dynamics in terrestrial ecosystems. Exudation rates vary widely by plant species and environmental conditions, but our understanding of how root exudates affect soil functioning is incomplete, in part because there are few viable methods to manipulate root exudates in situ. To address this, w...

Climate change can influence soil microorganisms directly by altering their growth and activity but also indirectly via effects on the vegetation, which modifies the availability of resources. Direct impacts of climate change on soil microorganisms can occur rapidly, whereas indirect effects mediated by shifts in plant community composition are not...

Tropical forest productivity is sustained by the cycling of nutrients through decomposing organic matter. Arbuscular mycorrhizal ( AM ) fungi play a key role in the nutrition of tropical trees, yet there has been little experimental investigation into the role of AM fungi in nutrient cycling via decomposing organic material in tropical forests. We...

The impacts of human activities on tropical forests are widespread and increasing. Hence, a good knowledge base about ecological processes in undisturbed tropical forest is crucial to provide a baseline for evaluating anthropogenic change. Our 5‐year study focused on understanding the background spatial and inter‐annual variation in dung beetle com...

Highly productive tropical forests often occur on nutrient-poor soils . The apparent lack of a relationship between tree growth and site fertility has generated decades of research into which nutrients, if any, limit tropical forest productivity. This chapter looks at the lessons we have learned from several decades of fertilization experiments, wh...