Soil seed banks represent a critical but hidden stock for potential future plant diversity on Earth. Here we compiled and analyzed a global dataset consisting of 15,698 records of species diversity ...and density for soil seed banks in natural plant communities worldwide to quantify their environmental determinants and global patterns. Random forest models showed that absolute latitude was an important predictor for diversity of soil seed banks. Further, climate and soil were the major determinants of seed bank diversity, while net primary productivity and soil characteristics were the main predictors of seed bank density. Moreover, global mapping revealed clear spatial patterns for soil seed banks worldwide; for instance, low densities may render currently species-rich low latitude biomes (such as tropical rain-forests) less resilient to major disturbances. Our assessment provides quantitative evidence of how environmental conditions shape the distribution of soil seed banks, which enables a more accurate prediction of the resilience and vulnerabilities of plant communities and biomes under global changes.
Earth system models demonstrate large uncertainty in projected changes in terrestrial carbon budgets. The lack of inclusion of adaptive responses of vegetation communities to the environment has been ...suggested to hamper the ability of modeled vegetation to adequately respond to environmental change. In this study, variation in functional responses of vegetation has been added to an earth system model (ESM) based on ecological principles. The restriction of viable mean trait values of vegetation communities by the environment, called ‘habitat filtering’, is an important ecological assembly rule and allows for determination of global scale trait–environment relationships. These relationships were applied to model trait variation for different plant functional types (PFTs). For three leaf traits (specific leaf area, maximum carboxylation rate at 25 °C, and maximum electron transport rate at 25 °C), relationships with multiple environmental drivers, such as precipitation, temperature, radiation, and CO₂, were determined for the PFTs within the Max Planck Institute ESM. With these relationships, spatiotemporal variation in these formerly fixed traits in PFTs was modeled in global change projections (IPCC RCP8.5 scenario). Inclusion of this environment‐driven trait variation resulted in a strong reduction of the global carbon sink by at least 33% (2.1 Pg C yr⁻¹) from the 2nd quarter of the 21st century onward compared to the default model with fixed traits. In addition, the mid‐ and high latitudes became a stronger carbon sink and the tropics a stronger carbon source, caused by trait‐induced differences in productivity and relative respirational costs. These results point toward a reduction of the global carbon sink when including a more realistic representation of functional vegetation responses, implying more carbon will stay airborne, which could fuel further climate change.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Predicting ecosystem responses to global change is a major challenge in ecology. A critical step in that challenge is to understand how changing environmental conditions influence processes across ...levels of ecological organization. While direct scaling from individual to ecosystem dynamics can lead to robust and mechanistic predictions, new approaches are needed to appropriately translate questions through the community level. Species invasion, loss, and turnover all necessitate this scaling through community processes, but predicting how such changes may influence ecosystem function is notoriously difficult. We suggest that community-level dynamics can be incorporated into scaling predictions using a trait-based response-effect framework that differentiates the community response to environmental change (predicted by response traits) and the effect of that change on ecosystem processes (predicted by effect traits). We develop a response-and-effect functional framework, concentrating on how the relationships among species' response, effect, and abundance can lead to general predictions concerning the magnitude and direction of the influence of environmental change on function. We then detail several key research directions needed to better scale the effects of environmental change through the community level. These include (1) effect and response trait characterization, (2) linkages between response-and-effect traits, (3) the importance of species interactions on trait expression, and (4) incorporation of feedbacks across multiple temporal scales. Increasing rates of extinction and invasion that are modifying communities worldwide make such a research agenda imperative.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
BACKGROUND: Recent decades have seen a major surge in the study of interspecific variation in functional traits in comparative plant ecology, as a tool to understanding and predicting ecosystem ...functions and their responses to environmental change. However, this research has been biased almost exclusively towards vascular plants. Very little is known about the role and applicability of functional traits of non-vascular cryptogams, particularly bryophytes and lichens, with respect to biogeochemical cycling. Yet these organisms are paramount determinants of biogeochemistry in several biomes, particularly cold biomes and tropical rainforests, where they: (1) contribute substantially to above-ground biomass (lichens, bryophytes); (2) host nitrogen-fixing bacteria, providing major soil N input (lichens, bryophytes); (3) control soil chemistry and nutrition through the accumulation of recalcitrant polyphenols (bryophytes) and through their control over soil and vegetation hydrology and temperatures; (4) both promote erosion (rock weathering by lichens) and prevent it (biological crusts in deserts); (5) provide a staple food to mammals such as reindeer (lichens) and arthropodes, with important feedbacks to soils and biota; and (6) both facilitate and compete with vascular plants. APPROACH: Here we review current knowledge about interspecific variation in cryptogam traits with respect to biogeochemical cycling and discuss to what extent traits and measuring protocols needed for bryophytes and lichens correspond with those applied to vascular plants. We also propose and discuss several new or recently introduced traits that may help us understand and predict the control of cryptogams over several aspects of the biogeochemistry of ecosystems. CONCLUSIONS: Whilst many methodological challenges lie ahead, comparative cryptogam ecology has the potential to meet some of the important challenges of understanding and predicting the biogeochemical and climate consequences of large-scale environmental changes driving shifts in the cryptogam components of vegetation composition.
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BFBNIB, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Variation in plant functional traits is the product of evolutionary and environmental drivers operating at different scales. Little is known about whether, or how, this variation is coordinated ...between aboveground and belowground organs across and within spatial scales. We address these questions using a hierarchically designed dataset of pairwise leaf and root traits related to carbon and nutrient economy of 64 species belonging to 14 plant communities in northern Chinese semi-arid and arid regions. While both root and leaf traits showed most of their variance among (individuals and) species within communities, leaf trait variance tended to be relatively higher at coarser spatial scales than root trait variance. While leaf nitrogen (N) per area to root N per length ratio increased and specific leaf area to specific root length and leaf N to root N ratios decreased from semi-arid to arid environments owing to climatic/edaphic shifts, the matching pairs showed a strong pattern of positive correlation that was upheld across spatial scales and geographic areas. Thus, trade-offs in plant resource investment across organs within individual vascular plants are constrained within a rather narrow range of variation. A new challenge will be to test whether and how such trait coordination is also seen within and across other biomes of the world.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
1. While the importance of wood decay for the global carbon balance is widely recognized, surprisingly little is known about its long-term dynamics and its abiotic and biotic drivers. Progress in ...this field is hindered by the long time-scales inherent to the low decay rates of wood and the lack of short-term methods to assess long-term decomposition dynamics in standardized field conditions. 2. Here, we present such a method, which relies on the sampling and short-term incubation of wood from several decay stages covering the entire decay process. Together these short-term decay steps are used to model and discriminate between three potential decay dynamics (linear, exponential and sigmoid) using an iterative optimization procedure. We applied this method to analyse long-term wood decay of six subarctic tree species (six stems and two roots) and test the hypotheses that (i) different wood species follow distinct decay dynamics and (ii) interspecific variation in wood traits controls variation in wood decay rates in a standardized environment. 3. We found interspecific variation in long-term wood decay dynamics: decay of Alnus and Salix stems was best described by exponential models, whereas decay of Sorbus stems and Betula and Pinus roots was best fitted by linear models and Betula, Pinus and Populus stems each displayed a sigmoid decay dynamics (up to 5-year initial lag phase). A six-fold variation was observed between the decomposition half-lives of all eight wood types, from 6.8 years (6.1-7.5, 95% C.I.) for Alnus stems to 41.3 years (34.5-51.8) for Pinus roots. Initial wood traits such as pH (R² = 0.92), dry matter content (R² = 0.79) and lignin (R² = 0.73) were good predictors of long-term wood decay rates. 4. Synthesis. Our findings suggest changing decay dynamics across wood species and types that are likely to arise from changing underlying wood decay processes (i. e. varying wood functional traits/decomposer community interactions). Our new method, which combines advantages of direct observations and the chronosequence approach, allows reliable comparisons of species contributions to long-term wood decay rates and provides future opportunities to experimentally disentangle intrinsic and external abiotic and biotic drivers of long-term wood decay processes.
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BFBNIB, FZAB, GIS, IJS, INZLJ, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZRSKP
Global environmental change, related to climate change and the deposition of airborne N-containing contaminants, has already resulted in shifts in plant community composition among plant functional ...types in Arctic and temperate alpine regions. In this paper, we review how key ecosystem processes will be altered by these transformations, the complex biological cascades and feedbacks that might result, and some of the potential broader consequences for the earth system. Firstly, we consider how patterns of growth and allocation, and nutrient uptake, will be altered by the shifts in plant dominance. The ways in which these changes may disproportionately affect the consumer communities, and rates of decomposition, are then discussed. We show that the occurrence of a broad spectrum of plant growth forms in these regions (from cryptogams to deciduous and evergreen dwarf shrubs, graminoids and forbs), together with hypothesized low functional redundancy, will mean that shifts in plant dominance result in a complex series of biotic cascades, couplings and feedbacks which are supplemental to the direct responses of ecosystem components to the primary global change drivers. The nature of these complex interactions is highlighted using the example of the climate-driven increase in shrub cover in low-Arctic tundra, and the contrasting transformations in plant functional composition in mid-latitude alpine systems. Finally, the potential effects of the transformations on ecosystem properties and processes that link with the earth system are reviewed. We conclude that the effects of global change on these ecosystems, and potential climate-change feedbacks, cannot be predicted from simple empirical relationships between processes and driving variables. Rather, the effects of changes in species distributions and dominances on key ecosystem processes and properties must also be considered, based upon best estimates of the trajectories of key transformations, their magnitude and rates of change.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
1. A fundamental trade-off among vascular plants between traits inferring rapid resource acquisition and those leading to conservation of resources has now been accepted broadly, but is based on ...empirical data with a strong bias towards leaf traits. Here, we test whether interspecific variation in traits of different plant organs obeys this same trade-off and whether within-plant trade-offs are consistent between organs. 2. Thereto, we measured suites of the same chemical and structural traits from the main vegetative organs for a species set representing aquatic, riparian and terrestrial environments including the main vascular higher taxa and growth forms of a subarctic flora. The traits were chosen to have consistent relevance for plant defence and growth across organs and environments: carbon, nitrogen, phosphorus, lignin, dry matter content, pH. 3. Our analysis shows several new trait correlations across leaves, stems and roots and a striking pattern of whole-plant integrative resource economy, leading to tight correspondence between the local leaf economics spectrum and the root (r = 0.64), stem (r = 0.78) and whole-plant (r = 0.93) economics spectra. 4. Synthesis. Our findings strongly suggest that plant resource economics is consistent across species' organs in a subarctic flora. We provide thus the first evidence for a 'plant economics spectrum' closely related to the local subarctic 'leaf economics spectrum'. Extending that concept to other biomes is, however, necessary before any generalization might be made. In a world facing rapid vegetation change, these results nevertheless bear considerable prospects of predicting below-ground plant functions from the above-ground components alone.
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BFBNIB, FZAB, GIS, IJS, INZLJ, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZRSKP
Understanding what drives soil fauna species composition through space and time is crucial because we should preserve soil fauna biodiversity and its key role in ecosystem functioning in this era of ...fast environmental change. As plant leaf litter provides both food and habitat for soil fauna, a focus on litter traits that relate to these two functions will help in understanding soil invertebrate community structure and dynamics comprehensively. To advance this agenda, we propose a conceptual framework to explicitly link the invertebrate community composition to the temporal dynamics of the litter trait space defined by two axes: a food-quality axis related to plant resource economics and chemistry and a habitat-quality axis related to litter particle size and shape.
Disentangling of what drives the composition and dynamics of belowground diversity is needed to predict ecosystem-level consequences of environmental change.Incorporating the notion that soil fauna live in ‘a house made of food’ could bridge the gap between soil fauna diversity and plant community solely based on litter traits as a food source.To assess the dynamic habitat for soil fauna, partly through their own feeding activities, we add temporal aspects into the trait space defined by food- and habitat-related trait axes.Integration of temporal dynamics in trait-based ecology is critical to assess almost all ecological processes accompanied by temporal change in traits of targeted organisms.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
AIM: Recent meta‐analyses have revealed that plant traits and their phylogenetic history influence decay rates of dead wood and leaf litter, but it remains unknown if decay rates of wood and litter ...covary over a wide range of tree species and across ecosystems. We evaluated the relationships between species‐specific wood and leaf litter decomposability, as well as between wood and leaf traits that control their respective decomposability. LOCATION: Global. METHODS: We compiled data on rates of wood and leaf litter decomposition for 324 and 635 tree species, respectively, and data on six functional traits for both organs. We used hierarchical Bayesian meta‐analysis to estimate, for the first time, species‐specific values for wood and leaf litter decomposability standardized to reference conditions (k*wₒₒd and k*ₗₑₐf) across the globe. With these data, we evaluated the relationships: (1) between wood and leaf traits, (2) between each k* and the selected traits within and across organs, and (3) between wood and leaf k*. RESULTS: Across all species k*wₒₒd and k*ₗₑₐf were positively correlated, phylogenetically clustered and correlated with plant functional traits within and across organs. k* of both organs was usually better described as a function of within‐ and cross‐organ traits, than of within‐organ traits alone. When analysed for angiosperms and gymnosperms separately, wood and leaf k* were no longer significantly correlated, but each k* was still significantly correlated to the functional traits. MAIN CONCLUSIONS: We demonstrate important relationships among wood and leaf litter decomposability as after‐life effects of traits from the living plants. These functional traits influence the decomposability of senesced tissue which could potentially lead to alterations in the rates of biogeochemical cycling, depending on the phylogenetic structure of the species pool. These results provide crucial information for a better representation of decomposition rates in dynamic global vegetation models.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
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