부산대학교 도서관

Field experiments that expose terrestrial ecosystems to climate change factors by manipulations are expensive to maintain, and typically only last a few years. Plant biomassis commonly used to assess responses to climate treatments and to predict climate change impacts. However, response to the treatments might be considerably different between the early years and a decade later. The aim of this data analysis was to develop and apply a method for evaluating changes in plant biomass responses through time, in order to provide a firm basis for discussing how the ‘short-term’response might differ from the ‘long-term’ response. Across 22 sites situated in the northern hemisphere, which covered three continents, and multiple ecosystems (grasslands,shrublands, moorlands, forests, and deserts), we evaluated biomass datasets from long-term experiments with exposure to elevated CO2 (eCO2), warming, or drought. Wedeveloped methods for assessing biomass response patterns to the manipulations using polynomial and linear (piecewise) model analysis and linked the responses to sitespecificvariables such as temperature and rainfall. Polynomial patterns across sites indicated changes in response direction over time under eCO2, warming, and drought. In addition, five distinct pattern types were confirmed within sites: ‘no response’, ‘delayed response’, ‘directional response’, ‘dampening response’, and ‘altered response’ patterns.We found that biomass response direction was as likely to change over time as it was to be consistent, and therefore suggest that climate manipulation experiments should becarried out over timescales covering both short- and long-term responses, in order to realistically assess future impacts of climate change.