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Soil microbes drive ecosystem function and play a critical role in how ecosystems respond to global change. Research surrounding soil microbial communities has rapidly increased in recent decades, and substantial data relating to phospholipid fatty acids (PLFAs) and potential enzyme activity have been collected and analysed. However, studies have mostly been restricted to local and regional scales, and their accuracy and usefulness are limited by the extent of accessible data. Here we aim to improve data availability by collating a global database of soil PLFA and potential enzyme activity measurements from 12,258 georeferenced samples located across all continents, 5.1% of which have not previously been published. The database contains data relating to 113 PLFAs and 26 enzyme activities, and includes metadata such as sampling date, sample depth, and soil pH, total carbon, and total nitrogen. This database will help researchers in conducting both global- and local-scale studies to better understand soil microbial biomass and function.

Leaching – the release of elements from organic matter through dissolution in water – plays an important role in biogeochemical cycling and ecosystem processes. However, our limited understanding of the patterns and underlying drivers of element solubility in leaves hinders accurate predictions of leaching over space and time in terrestrial ecosystems. In this study, we quantify the solubility of carbon (C), nitrogen (N) and phosphorus (P) from leaves of Betula pubescens – a widespread boreal tree species – across a post-fire retrogressive chronosequence. We then relate solubility to variation in leaf-level traits and ecosystem properties (e.g. soil chemistry, tree density and productivity) across the chronosequence to quantify micro- and macro-scale determinants of leaching. We find that P is much more soluble than C and N and is released in solution mainly in readily accessible mineral form. Solubility patterns are strongly related to foliar chemical and structural traits, particularly for green leaves. Metrics related to ecosystem properties exert a stronger influence over solubility from senesced leaf litter. Overall, our results indicate that leaching could constitute an important flux of nutrients to the soil, particularly for P. The rate and spatio-temporal pattern of this leaching flux may be predicted from foliar traits and ecosystem properties. Further application of the method should allow for rapid integration of leaching-related foliar traits into broader plant trait frameworks and models of ecosystem biogeochemical cycling.

There has been much recent interest in understanding how abiotic factors such as light, nutrients, and soil moisture affect the composition and biomass of lichen communities. Meanwhile, whether and how ground layer vegetation such as bryophytes and shrubs also influence lichen communities have received much less attention, particularly regarding how these effects vary across environmental gradients. In this study, we used a long-term (19-year) biodiversity manipulation experiment to assess the importance of feather moss and ericaceous dwarf shrub removals on the composition and diversity (assessed via metabarcoding) and biomass (assessed via PLFA markers) of terricolous lichen communities along a 5000-year boreal forest post-fire chronosequence in northern Sweden. Overall, our results showed that shrub removals had a greater impact than moss removals on the biomass and composition of lichen communities. Shrub removals increased lichen alpha-diversity while decreasing lichen beta-diversity. This is mainly because, although the number of lichen species increased in the absence of shrubs, lichen communities were strongly dominated by Cladonia spp. However, the effects of shrub removals were context-dependent, with greater effects observed in older ecosystems. Our results highlight that shrubs had a greater impact than moss in shaping terricolous lichen communities in boreal forests, with increasing effects from young ecosystems to older ones. We conclude that the foreseen expansion of vascular plants such as ericaceous shrubs into high latitude regions will probably have negative consequences on lichen cover, but that these effects will be dependent on the environmental context.

Tropical peatlands are important global carbon sinks, and the ways they differ from adjacent forest ecosystems in environmental functions have not been well characterized. Our study investigated family-level floristic and soil differences between adjacent paired patches of intact waterlogged peat forests and kerangas (free-draining heath) forests in Brunei Darussalam. For each patch, we examined total and labile nutrient concentrations in soils, tree stand diversity and structural characteristics, functional traits of live leaves and leaf litter, and nutrient resorption during leaf senescence. We found that total nutrients were more abundant in peat and kerangas humus than in kerangas sand, while available nutrients were highest in kerangas humus, suggesting that anoxic conditions in peat soils impair mineralization of nutrients to available forms but do not lead to losses of nutrient capital. We also found significant compositional differences among those families that occur frequently in both peat and kerangas plots. Despite this, family-level measures of tree diversity and structural characteristics, including tree abundance and stand basal area, did not differ between forest types. Similarly, leaf and litter functional traits and nutrient resorption were invariant across forest types, indicating low plasticity of leaf characteristics associated with plant nutrition. This suggests that belowground carbon accumulation in peatlands is disconnected from aboveground plant community characteristics and is likely driven by belowground processes.

Climate change is expected to increase the frequency of severe droughts, but it remains unclear whether soil biotic conditioning by plant communities with varying species richness or functional group diversity moderate plant–soil feedback (PSF)—an important ecosystem process driving plant community dynamics—under altered rainfall regimes. We conducted a two-phase PSF experiment to test how plant diversity affects biotic PSF under different rainfall regimes. In Phase 1, we set up mesocosms with 15 plant assemblages composed of two grasses, two forbs and two nitrogen-fixing legumes [one, two, three, or six species from one, two, or three functional group(s)] common to the semi-arid eastern Eurasian Steppe. Mesocosms were subjected to two rainfall amounts (ambient, 50% reduction) crossed with two frequencies (ambient, 50% reduction) for a growing season (~3 months). Conditioned soil from each mesocosm was then used in Phase 2 to inoculate (7% v/v) sterilised mesocosms planted with the same species as in Phase 1 and grown for 8 weeks. Simultaneously, the same plant assemblages were grown in sterilised soil to calculate PSF based on plant biomass measured at the end of Phase 2. Feedback effects differed amongst plant assemblages, but were not significantly altered by reduced rainfall treatments within any plant assemblage. This suggests that the examined interactions between plant and soil microbial communities were resistant to simulated rainfall reductions and that increasing plant diversity did not moderate PSF under altered rainfall regimes. Moreover, increasing plant species richness or functional group diversity did not lessen the magnitude of PSF differences between ambient and reduced rainfall treatments. Collectively, these findings advance our understanding of plant diversity's potential to mitigate climate change effects on PSF, showing that in semi-arid grasslands, higher plant diversity may not moderate PSF responses to altered rainfall regimes and highlighting the importance of considering species-specific traits and interaction stability.

Human land use intensification is increasing biodiversity loss worldwide through fragmenting contiguous natural habitats into spatially isolated patches of varying sizes. However, it is poorly known as to how the area and isolation of patches operate to jointly alter biological community composition for contrasting land use types, particularly for belowground organisms. Oceanic islands that vary in human activities provide an ideal model system for examining how patch area and isolation affects community dissimilarity resulting from land use change. We conducted a paired sampling design that included both natural woodland (i.e. land covered with woody plants, including trees and shrubs) and degraded grassland for each of 20 islands differing in area and remoteness in the largest archipelago of Eastern China. We used this design to investigate how island area and remoteness shape the community dissimilarity of soil fauna between woodland and grassland directly and indirectly through changing climatic and habitat properties. The dissimilarity of soil fauna communities for each island was estimated by measuring total beta (β) diversity and its turnover and nestedness components between woodland and grassland. We found that land use change did not decrease taxa richness but did alter community composition overall. There was no relationship of island area with community dissimilarity when it was estimated by total β-diversity, due to contrasting responses of its turnover and nestedness components to island area. Soil faunal compositional dissimilarity between woodland and grassland along the area gradient was mainly related to the gain and loss of unique taxa in grassland. On small islands, nestedness was the primary contributor to total β-diversity, due to a loss of soil fauna taxa as habitats shifted from woodland to grassland, and suggests that natural habitats serve as refuges for soil organisms. Meanwhile on larger islands, turnover was the main contributor to total β-diversity, suggesting that diverse land uses can increase biodiversity across habitats. Additionally, high habitat differences combined with favorable climatic conditions (such as low wind speed) on larger islands facilitated species turnover but diminished nestedness. Meanwhile island remoteness did not affect total β-diversity or its components, but it did significantly enhance the negative impact of land-use conversion on the abundance of larger-bodied taxa. These findings suggest that island area, and therefore landscape patch area, play a crucial role in shaping the dissimilarity of soil faunal communities that stem from human land use change. Our results highlight that partitioning total β-diversity into its turnover and nestedness components is essential for understanding the impact of land use change on soil faunal community composition in fragmented habitats.

Phosphorus (P) is one of the most important elements for soil biology and biogeochemistry worldwide. Yet, despite decades of research, important uncertainties persist about the drivers and changes in soil P forms during long-term soil formation. Here, we analyzed topsoils from nine globally distributed retrogressive soil chronosequences aiming to evaluate the relative contribution of key environmental factors (that is, soil age, substrate origin, climate, soil attributes, and vegetation) in explaining the long-term dynamics of primary, occluded, non-occluded, organic, and total P across different terrestrial ecosystems. We found that, rather than soil age, substrate origin was the main driver controlling the fate of different P fractions across contrasting environmental conditions. Moreover, our findings suggest that temporal patterns governing the long-term dynamics of different P forms as soils develop are not consistent among soil chronosequences, which is a result of contrasting environmental conditions, especially substrate origin. We further showed that topsoil total P was the greatest at intermediate soil development stage across the globe. Lastly, our results showed that P fractions were highly correlated with multiple surrogates of ecosystem services, such as carbon sequestration, plant productivity, and biodiversity. Together, our work provides new insights into the natural history of P availability, and further highlights that substrate origin, rather than soil age, is essential to predict changes in P availability in response to physical perturbation and climate change.

Soil bacterial and fungal communities play fundamental roles in biogeochemical cycles and ecosystem stability. Urbanization alters soil properties and microbial habitats, driving shifts in community composition, yet the divergent responses of bacteria and fungi and their ecological consequences remain inadequately understood. To elucidate these differential responses, we investigated soil bacterial and fungal communities along an urbanization gradient, ranging from undisturbed reference forests to urban parks, across three distinct climatic regions. To capture different disturbance intensities, urban parks were classified by tree age into old parks (>60-year-old trees) and young parks (10–20-year-old trees). Climate had a strong influence on soil microbiota, yet urbanization still significantly altered both bacterial and fungal communities in all regions. Urban disturbances homogenized soil microbial communities: average similarity among bacterial communities increased from ∼79 % in forests to ∼85 % in young urban parks, indicating substantial homogenization, whereas fungal communities showed little homogenization. Urbanization also homogenized microbial functional traits, with a greater reduction in trait dissimilarity for bacteria than for fungi. Bacterial communities exhibited high adjustability to urban conditions, dominated by generalist taxa (∼90 %), whereas fungal communities consisted mostly of specialists (∼83 %). Despite these asynchronous responses—bacteria adjusting and homogenizing more than fungi—overlapping functional traits between bacteria and fungi help maintain functional resilience in urban ecosystems.

Whether and how biodiversity affects ecosystem functioning has long been hotly debated in ecological research and conservation. Important in this debate is how interactions between species in a community lead to non-additive effects (i.e. effects that deviate from predictions based on the effects of each single species) on ecosystem processes. Such non-additivity has been widely reported for individual processes, for example productivity, decomposition, fire, herbivory or pollination.

However, species in a community are simultaneously involved in multiple ecosystem processes. We therefore propose a trait-based conceptual approach to connect non-additive effects based on species interactions across different specific ecosystem processes and illustrate its potential. The approach involves plotting the direction and strength of non-additivity due to species interaction effects for any given ecosystem process against the values of relevant predictive traits for all possible pairs of species considered in a community.

Synthesis: We show how to compare the non-additivity patterns for different ecosystem processes using similar ‘currency’ and how to link these to the main effects of the same species on these ecosystem processes. This way the species' effects on higher-level ecosystem functioning (e.g. carbon cycling), in present and future environmental scenarios, can be better quantified. The conceptual framework requires empirical testing and incorporation of relevant environmental factors.

In Boreal forests, wildfires are common disturbance agents, important for sustaining forest regeneration and ecosystem processes. However, climate warming has intensified fire activity and severity in recent years, and warmer conditions following fire can alter environmental factors affecting tree seedling survival and growth. Management interventions can potentially counterbalance the effects of fire severity and warming. Using a field experiment, we investigated the main and interactive effects of fire severity, experimental warming, understory shrub presence and salvage logging on the growth of different conifer (Picea abies and Pinus sylvestris) provenances, to provide insight about how tree seedlings of various species respond to multiple environmental drivers following fire. Our study shows that low fire severity without salvage logging resulted in poorer seedling above-ground growth, whereas experimental warming and ericaceous shrubs removal increased seedling biomass regardless of fire severity or logging treatment. Our results suggest that enhanced light availability and reduced resource competition from the understory supports the growth of conifer seedlings following fire. Post-fire warming further stimulated the growth of conifer seedlings (particularly in high-severity burn areas) potentially due to increased early colonization by fast-growing deciduous trees. Moreover, in warmer conditions, northern provenances of P. sylvestris planted in southern locations also showed greater height growth compared to local populations, highlighting the potential for assisted migration under climate change. Synthesis and applications. This study demonstrates that artificial regeneration through planting can support forest recovery following wildfire, especially under high fire severity in sites where natural regeneration is poor. Salvage logging can enhance the growth of P. sylvestris seedlings and indirectly benefit P. abies on low-severity sites by facilitation by deciduous species that create favourable microhabitats. However, the broader ecological impacts of salvage logging (such as on biodiversity loss and soil and habitat structure) must be considered in management planning. Post-fire vegetation management, including control of competitive ericaceous shrubs, may further improve seedling establishment. Selecting climate-adapted seedling provenances can boost reforestation success under future warming. These findings support an adaptive management framework that integrates fire severity, logging intensity, understory control and assisted migration to foster resilient forest landscapes in a changing climate.