Seasonal,interannual and decadal drivers of tree and grass productivity in an Australian tropical savanna |
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| Authors: | Caitlin E Moore Jason Beringer Randall J Donohue Bradley Evans Jean‐François Exbrayat Lindsay B Hutley Nigel J Tapper |
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| Institution: | 1. School of Earth, Atmosphere and Environment, Monash University, Clayton, Vic., Australia;2. Genomic Ecology of Global Change, Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL, USA;3. The UWA school of Agriculture and Environment, University of Western Australia, Crawley, WA, Australia;4. CSIRO Land and Water, Canberra, ACT, Australia;5. Australian Research Council Centre of Excellence for Climate System Science, Sydney, NSW, Australia;6. Department of Environmental Sciences, The University of Sydney, Eveleigh, NSW, Australia;7. Terrestrial Ecosystem Research Network Ecosystem Modelling and Scaling Infrastructure, The University of Sydney, Eveleigh, NSW, Australia;8. School of GeoSciences and National Centre for Earth Observation, University of Edinburgh, Edinburgh, UK;9. School of Environment, Research Institute for the Environment and Livelihoods, Charles Darwin University, Casuarina, NT, Australia |
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| Abstract: | Tree–grass savannas are a widespread biome and are highly valued for their ecosystem services. There is a need to understand the long‐term dynamics and meteorological drivers of both tree and grass productivity separately in order to successfully manage savannas in the future. This study investigated the interannual variability (IAV) of tree and grass gross primary productivity (GPP) by combining a long‐term (15 year) eddy covariance flux record and model estimates of tree and grass GPP inferred from satellite remote sensing. On a seasonal basis, the primary drivers of tree and grass GPP were solar radiation in the wet season and soil moisture in the dry season. On an interannual basis, soil water availability had a positive effect on tree GPP and a negative effect on grass GPP. No linear trend in the tree–grass GPP ratio was observed over the 15‐year study period. However, the tree–grass GPP ratio was correlated with the modes of climate variability, namely the Southern Oscillation Index. This study has provided insight into the long‐term contributions of trees and grasses to savanna productivity, along with their respective meteorological determinants of IAV. |
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| Keywords: | carbon sequestration DIFFUSE model gross primary productivity MODerate resolution Imaging Spectroradiometer random forest Southern Oscillation Index |
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