Abstract
Abstract
Land surface phenology (LSP) can reveal important connections between vegetation dynamics and climate but remains poorly understood in evergreen winter-rainfall shrublands globally. Field-based studies have indicated diverse plant functional strategies in shrublands, but further work is required to link LSP to vegetation functional composition in these regions. We analysed time-series of the normalised difference vegetation index (NDVI) in fynbos shrublands of South Africa using multi-spectral imagery from satellites and unmanned aerial vehicles (UAVs). We investigated the climate drivers of seasonal vegetative phenology and long-term NDVI trends at multiple spatial scales ranging from the landscape to individual species. At coarse spatial resolutions, NDVI time-series indicated rainfall-driven vegetation dynamics in fynbos, both at inter and intra-annual time scales. However, high-resolution time-series from UAVs exposed an underlying divergence in vegetative phenology and long-term NDVI trends between shallow and deep-rooted growth forms. Phenophases and NDVI trends of isolated, deep-rooted, overstory shrubs were decoupled from rainfall relative to dense overstory patches and shallow-rooted understory growth forms. Variations in growth form phenology were not detected at coarse spatial scales due to scaling and competitive effects based on the functional composition of the vegetation.
Funder
Smuts Memorial Botanical Fellowship
South African Agency for Science and Technology Advancement
Reference52 articles.
1. Impacts of climate change in the Greater Cape Floristic Region;Altwegg,2014
2. A review of vegetation indices;Bannari;Remote Sens. Rev.,1995
3. Photosynthetic response and adaptation to temperature in higher plants;Berry;Annu. Rev. Plant Physiol.,1980
4. Landscapes, rock types, and climate of the Greater Cape Floristic Region;Bradshaw,2014
5. The Cape Town “Day Zero” drought and Hadley cell expansion;Burls;npj Clim. Atmos. Sci.,2019