| Abstract | Population dynamics is a field rich in theory and poor in long-term observational data. Finding sources of long-term data is critical as ecosystems around the globe continue to change in ways that current theories and models have failed to predict. Here we show how long-term ecological data can improve our understanding about palaeo-population change in response to external environmental factors, antecedent conditions and community diversity. We examined a radiometrically dated sediment core from the Didachara Mire in the mountains of south-western Georgia (Caucasus) and analysed multiple biological proxies (pollen, fern spores, non-pollen palynomorphs, charcoal, diatoms, chrysophyte cysts, midges, mites and testate amoebae). Numerical techniques, including multivariate ordination, rarefaction, independent splitting and trait analysis, were used to assess the major drivers of changes in community diversity and population stability. Integrated multi-proxy analyses are very rare in the Caucasus, making this a unique record of long-term ecological change in a global biodiversity hotspot. Synthesis. Population changes in the terrestrial community coincided primarily with external environmental changes, while populations within the peatland community were affected by both internal and external drivers at different times. In general, our observations accord with theoretical predictions that population increases lead to greater stability and declines lead to instability. Random variation and interspecific competition explain population dynamics that diverged from predictions. Population change and diversity trends were positively correlated in all taxonomic groups, suggesting that population-level instability is greater in more diverse communities, even though diverse communities are themselves more stable. There is a continuing need to confront population theory with long-term data to test the predictive success of theoretical frameworks, thereby improving their ability to predict future change. |
| Text | 382278 2018 10.1111/1365 2745.12865 Scopus 2 s2.0 85031100563 ISI Web of Science WOS 000417839700028 chironomids diatoms diversity Georgia palaeoecology and land use history pollen population dynamics testate amoebae Long term population dynamics Theory and reality in a peatland ecosystem Connor S.E.; Colombaroli D.; Confortini F.; Gobet E.; Ilyashuk B.P.; Ilyashuk E.A.; van Leeuwen J.F.N.; Lamentowicz M.; van der Knaap W.O.; Malysheva E.; Marchetto A.; Margalitadze N.; Mazei Y.; Mitchell E.A.D.; Payne R.J.; Ammann B. School of Geography, University of Melbourne, Melbourne, VIC, , Australia; CIMA FCT, University of the Algarve, Faro, , , , Portugal; CIMA FCT, University of the Algarve, Faro, , , , Portugal; CIMA FCT, University of the Algarve, Faro, , , , Portugal; Institute of Plant Sciences Oeschger Centre for Climate Change Research, University of Bern, Bern, , Switzerland; Museo Civico di Scienze Naturali, Bergamo, , Italy; Institute of Ecology, University of Innsbruck, Innsbruck, , Austria; Institute for Alpine Environment, European Academy Bozen/Bolzano, Bozen/Bolzano, , Italy; Laboratory of Wetland Ecology and Monitoring, Department of Biogeography and Paleoecology, Faculty of Geographical and Geological Sciences, Adam Mickiewicz University, Pozna , , Poland; Department of Zoology and Ecology, Penza State University, Penza, , Russian Federation; Institute for Ecosystem Study, National Research Council, Verbania Pallanza, , Italy; Botanical Institute, Ilia State University, Tbilisi, GA, , United States; M.V. Lomonosov Moscow State University, Moscow, , Russian Federation; Laboratory of Soil Biodiversity, University of Neuchatel, Neuchatel, , Switzerland; Jardin Botanique de Neuchatel, Neuchatel, , Switzerland; Environment Department, University of York, York, , United Kingdom Population dynamics is a field rich in theory and poor in long term observational data. Finding sources of long term data is critical as ecosystems around the globe continue to change in ways that current theories and models have failed to predict. Here we show how long term ecological data can improve our understanding about palaeo population change in response to external environmental factors, antecedent conditions and community diversity. We examined a radiometrically dated sediment core from the Didachara Mire in the mountains of south western Georgia Caucasus and analysed multiple biological proxies pollen, fern spores, non pollen palynomorphs, charcoal, diatoms, chrysophyte cysts, midges, mites and testate amoebae . Numerical techniques, including multivariate ordination, rarefaction, independent splitting and trait analysis, were used to assess the major drivers of changes in community diversity and population stability. Integrated multi proxy analyses are very rare in the Caucasus, making this a unique record of long term ecological change in a global biodiversity hotspot. Synthesis. Population changes in the terrestrial community coincided primarily with external environmental changes, while populations within the peatland community were affected by both internal and external drivers at different times. In general, our observations accord with theoretical predictions that population increases lead to greater stability and declines lead to instability. Random variation and interspecific competition explain population dynamics that diverged from predictions. Population change and diversity trends were positively correlated in all taxonomic groups, suggesting that population level instability is greater in more diverse communities, even though diverse communities are themselves more stable. There is a continuing need to confront population theory with long term data to test the predictive success of theoretical frameworks, thereby improving their ability to predict future change. 106 Published version http //www.scopus.com/inward/record.url eid=2 s2.0 85031100563 partnerID=q2rCbXpz Articolo 2018_Journal_of_Ecology106_333_346.pdf Articolo in rivista Blackwell Science. 1365 2745 Journal of ecology Online Journal of ecology Online J. ecol. Online aldo.marchetto MARCHETTO ALDO |
