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Data and code from Mallen-Cooper, M and Cornwell, WK (2020). 'A systematic review of transplant experiments in lichens and bryophytes'. The Bryologist.

Climate change continues to drive a broad range of responses among the world’s biota. For example, there are plants that now flower earlier, animals that have evolved different camouflage, and many species that are shifting their ranges. Range shifting is well-documented for highly mobile taxa such as birds and insects, yet little is known about range shifting in species that form biocrusts—communities of lichens, non-vascular plants, and microbes that live on the soil surface and play important functional roles in nutrient cycling and erosion control. Another key theme of climate change ecology is that some species mediate the responses of other species, for example, by buffering the local microclimate or altering the cycling of nutrients. In line with these two themes, the aim of my thesis is to investigate: 1) what drives range limits in species of biocrust; 2) how biocrust species ranges have responded to recent climate change; 3) how biocrust species ranges are likely to respond to future climate change; and 4) how biocrust species mediate the effects of climate change on soil biota through microclimate buffering. I found that biocrust species are generally carbon limited at their arid range limits (Chapter 2), which suggests that range limits in biocrusts represent the point at which carbon budgets become unsustainable. Chapter 3 describes a field study comparing the modern and historical (25-year-old) distributions of three biocrust species, in which I found no evidence that any species have shifted in space to counteract climate warming. Global species distribution models show that the area of future suitable habitat is likely to be highly variable among biocrust species (Chapter 4), and accessing this habitat will require dispersal over considerable distances (4.6 km yr-1 on average). Finally, I found that tundra lichen mats play a major role in buffering high soil temperatures during summer (Chapter 5). The findings of this thesis are foundational for understanding the spatial aspect of biocrust responses to climate change and can be used to predict and mitigate losses of ecosystem functioning in areas where biocrust species are pushed beyond their niche limits.

Trait and functional trait approaches have revolutionized ecology improving our understanding of community assembly, species coexistence, and biodiversity loss. Focusing on traits promotes comparability across spatial and organizational scales, but terms must be used consistently. While several papers have offered definitions, it remains unclear how ecologists operationalize "trait" and "functional trait" terms. Here, we evaluate how researchers and the published literatures use these terms and explore differences among subdisciplines and study systems (taxa and biome). By conducting both a survey and a literature review, we test the hypothesis that ecologists' working definition of "trait" is adapted or altered when confronting the realities of collecting, analyzing and presenting data. From 486 survey responses and 712 reviewed papers, we identified inconsistencies in the understanding and use of terminology among researchers, but also limited inclusion of definitions within the published literature. Discrepancies were not explained by subdiscipline, system of study, or respondent characteristics, suggesting there could be an inconsistent understanding even among those working in related topics. Consistencies among survey responses included the use of morphological, phonological, and physiological traits. Previous studies have called for unification of terminology; yet, our study shows that proposed definitions are not consistently used or accepted. Sources of disagreement include trait heritability, defining and interpreting function, and dealing with organisms in which individuals are not clearly recognizable. We discuss and offer guidelines for overcoming these disagreements. The diversity of life on Earth means traits can represent different features that can be measured and reported in different ways, and thus, narrow definitions that work for one system will fail in others. We recommend ecologists embrace the breadth of biodiversity using a simplified definition of "trait" more consistent with its common use. Trait-based approaches will be most powerful if we accept that traits are at least as diverse as trait ecologists.

9 páginas.- 5 figuras.- 51 referencias.- Supplementary information The online version contains supplementary material available at https://doi.org/10.1038/s41561-023-01170-x, Soil mosses are among the most widely distributed organisms on land. Experiments and observations suggest that they contribute to terrestrial soil biodiversity and function, yet their ecological contribution to soil has never been assessed globally under natural conditions. Here we conducted the most comprehensive global standardized field study to quantify how soil mosses influence 8 ecosystem services associated with 24 soil biodiversity and functional attributes across wide environmental gradients from all continents. We found that soil mosses are associated with greater carbon sequestration, pool sizes for key nutrients and organic matter decomposition rates but a lower proportion of soil-borne plant pathogens than unvegetated soils. Mosses are especially important for supporting multiple ecosystem services where vascular-plant cover is low. Globally, soil mosses potentially support 6.43 Gt more carbon in the soil layer than do bare soils. The amount of soil carbon associated with mosses is up to six times the annual global carbon emissions from any altered land use globally. The largest positive contribution of mosses to soils occurs under a high cover of mat and turf mosses, in less-productive ecosystems and on sandy and salty soils. Our results highlight the contribution of mosses to soil life and functions and the need to conserve these important organisms to support healthy soils., The study work associated with this paper was funded by a Large Research Grant from the British Ecological Society (no. LRB17\1019; MUSGONET). D.J.E. is supported by the Hermon Slade Foundation. M.D.-B. was supported by a Ramón y Cajal grant from the Spanish Ministry of Science and Innovation (RYC2018-025483-I), a project from the Spanish Ministry of Science and Innovation for the I + D + i (PID2020-115813RA-I00 funded by MCIN/AEI/10.13039/501100011033a) and a project PAIDI 2020 from the Junta de Andalucía (P20_00879). E.G. is supported by the European Research Council grant agreement 647038 (BIODESERT). M.B. is supported by a Ramón y Cajal grant from Spanish Ministry of Science (RYC2021-031797-I). A.d.l.R is supported by the AEI project PID2019-105469RB-C22. L.W. and Jianyong Wang are supported by the Program for Introducing Talents to Universities (B16011) and the Ministry of Education Innovation Team Development Plan (2013-373). The contributions of T.G. and T.U.N. were supported by the Research Program in Forest Biology, Ecology and Technology (P4-0107) and the research projects J4-3098 and J4-4547 of the Slovenian Research Agency. The contribution of P.B.R. was supported by the NSF Biological Integration Institutes grant DBI-2021898. J. Durán and A. Rodríguez acknowledge support from the FCT (2020.03670.CEECIND and SFRH/BDP/108913/2015, respectively), as well as from the MCTES, FSE, UE and the CFE (UIDB/04004/2021) research unit financed by FCT/MCTES through national funds (PIDDAC).