Climatic controls on ecosystem resilience: combining hierarchical modelling with space borne monitoring of past fire plant biomass accumulation

Presented at the Fynbos Forum (August 6, 2014) in Knysna, South Africa

Abstract

Conserving biodiversity on our changing planet requires understanding how our climate affects ecosystem resilience. This is especially important in disturbance-prone ecosystems such as the Cape Floristic Region (CFR) of South Africa. Fire risk in the CFR is sensitive to climatic variability and a warmer and drier future will likely lead to more frequent fires. However, the sensitivity of post-fire recovery and biomass accumulation to climate is not well understood despite its importance in the fire regime. In this study, I apply a novel hierarchical approach to model post-fire biomass recovery using over a decade of satellite-derived vegetation observations (MODIS NDVI). Recovery rate was positively associated with minimum winter temperature and maximum summer precipitation and negatively associated with precipitation seasonality and maximum summer temperature. By incorporating millions of satellite observations over the last decade, it is now possible to quantify broad scale patterns in ecosystem recovery and identify climatic associations of these ‘recovery gradients’ in post-fire ecosystem dynamics. Despite being ecologically coarse in its reliance on NDVI, this modeling framework allows exploration and development of more specific hypotheses that can be tested in the field with detailed on-the-ground surveys to validate and explain ecosystem recovery predictions. Furthermore, this approach could be combined with ongoing floristic inventories to monitor ecosystem resilience and identify areas with anomalous post-fire recovery trajectories in near-real time.