TY - BOOK
T1 - Functional traits drive plant community and ecosystem response to global change across arctic and alpine environments
AU - Chisholm, Chelsea Lee
PY - 2017
Y1 - 2017
N2 - While both abiotic and biotic factors influence community composition and ecosystem properties,the combined effects of both under climate change are still unknown. In this thesis I attempt todisentangle the relative importance of these two factors using information on functional traits inalpine and arctic plant communities and investigate how underlying trait variation contributes tospecies coexistence and ecosystem functioning. My thesis mainly focuses on experimental andobservational research in mountain systems, which are ideal testbeds for questions on the impactsof climate change due to their high biodiversity, natural gradients in climatic factors andprevalence across the globe. Alpine areas, along with the Arctic, are expected to be severelyimpacted by climate change in the future. Understanding the response of these regions tointeracting global change drivers is essential to forecasting shifts in species distributions andecosystem functioning in the future.I first use a globally replicated experiment in mountains to assess the interacting effects ofartificial warming and removal of a dominant species on plant community composition. I foundthat the effect of warming and removal is most pronounced in the averaged trait values of theremaining plant community, but that this effect differed across elevations and regions. Using thissame experimental framework, I used functional trait data to assess the impacts of warmingtreatment and removal on carbon flux in mountain ecosystems. I found large effects of removal onboth ecosystem productivity and respiration and an overall null net effect on ecosystem exchangeof carbon across regions. I also examined how trait variation underlies predictions of individualtree growth across climate space in Norwegian forests, using hierarchical Bayesian modelling.Here I found that competition is generally stronger in warmer climates, and that functional traitsdo not consistently predict growth across climate space. I also demonstrated that the inclusion offunctional trait information as stabilizing niche differences in competition indices is supported inmany of the deciduous trees in these northern temperate and boreal forests. I next assessed theinterplay between ground processes and plant communities on changes in phenology due totemperature-induced permafrost melt in the high Arctic and found that plant phenology is largelydelayed in ice-rich areas. Finally, colleagues and I used an observational approach to assesschanges in nutrient dynamics across replicated treeline transects in temperate regions around theglobe, where we found consistent temperature-mediated changes in both ground-layer plant andsoil nutrients across elevation.In summary, my research stresses the importance of including information on functional identity instudies at scales of the individual, community and ecosystem. I found strong links betweenfunctional trait identity and ecosystem functioning across alpine meadows and treeline ecotones. Acommon thread throughout this thesis is the importance of contingency in ecology, whether this isdriven by differing climatic and edaphic attributes across continents or small differences inpermafrost across 1 m2 areas. In all, these findings demonstrate the necessity for includingunderlying variation in functional traits across environmental gradients in studies of plantcommunity structure, coexistence and ecosystem response to global change drivers.
AB - While both abiotic and biotic factors influence community composition and ecosystem properties,the combined effects of both under climate change are still unknown. In this thesis I attempt todisentangle the relative importance of these two factors using information on functional traits inalpine and arctic plant communities and investigate how underlying trait variation contributes tospecies coexistence and ecosystem functioning. My thesis mainly focuses on experimental andobservational research in mountain systems, which are ideal testbeds for questions on the impactsof climate change due to their high biodiversity, natural gradients in climatic factors andprevalence across the globe. Alpine areas, along with the Arctic, are expected to be severelyimpacted by climate change in the future. Understanding the response of these regions tointeracting global change drivers is essential to forecasting shifts in species distributions andecosystem functioning in the future.I first use a globally replicated experiment in mountains to assess the interacting effects ofartificial warming and removal of a dominant species on plant community composition. I foundthat the effect of warming and removal is most pronounced in the averaged trait values of theremaining plant community, but that this effect differed across elevations and regions. Using thissame experimental framework, I used functional trait data to assess the impacts of warmingtreatment and removal on carbon flux in mountain ecosystems. I found large effects of removal onboth ecosystem productivity and respiration and an overall null net effect on ecosystem exchangeof carbon across regions. I also examined how trait variation underlies predictions of individualtree growth across climate space in Norwegian forests, using hierarchical Bayesian modelling.Here I found that competition is generally stronger in warmer climates, and that functional traitsdo not consistently predict growth across climate space. I also demonstrated that the inclusion offunctional trait information as stabilizing niche differences in competition indices is supported inmany of the deciduous trees in these northern temperate and boreal forests. I next assessed theinterplay between ground processes and plant communities on changes in phenology due totemperature-induced permafrost melt in the high Arctic and found that plant phenology is largelydelayed in ice-rich areas. Finally, colleagues and I used an observational approach to assesschanges in nutrient dynamics across replicated treeline transects in temperate regions around theglobe, where we found consistent temperature-mediated changes in both ground-layer plant andsoil nutrients across elevation.In summary, my research stresses the importance of including information on functional identity instudies at scales of the individual, community and ecosystem. I found strong links betweenfunctional trait identity and ecosystem functioning across alpine meadows and treeline ecotones. Acommon thread throughout this thesis is the importance of contingency in ecology, whether this isdriven by differing climatic and edaphic attributes across continents or small differences inpermafrost across 1 m2 areas. In all, these findings demonstrate the necessity for includingunderlying variation in functional traits across environmental gradients in studies of plantcommunity structure, coexistence and ecosystem response to global change drivers.
UR - https://rex.kb.dk/primo-explore/fulldisplay?docid=KGL01010655135&context=L&vid=NUI&search_scope=KGL&tab=default_tab&lang=da_DK
M3 - Ph.D. thesis
BT - Functional traits drive plant community and ecosystem response to global change across arctic and alpine environments
PB - Natural History Museum of Denmark, Faculty of Science, University of Copenhagen
ER -