Sensitivity of Vegetation Index and Gross Primary Productivity to Drought and Heat Waves in Europe

Abstract:

Drought and heat waves greatly influenced vegetation growth and photosynthesis. With an increasing frequency, these extreme climate events could alter the carbon cycle at regional and continental scales. To better understand the impacts of drought and heat wave on vegetation and carbon fluxes in temperate terrestrial ecosystems, we first evaluated three vegetation indices (Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), and Land Surface Water Index (LSWI)) during 2000-2013 to determine the sensitivity of these vegetation indices to drought and heat waves in 2003 at 14 CO₂ eddy covariance flux tower sites in Europe. We then ran the satellite-based Vegetation Photosynthesis Model (VPM) at these sites and compared gross primary production (GPP) estimates from the VPM model (GPP_VPM) with estimates from the eddy covariance measurements (GPP_EC). The VPM model is driven by climate data (air temperature and photosynthetically active radiation) and two vegetation indices (EVI and LSWI). The comparison shows that the VPM model has a good capability in predicting vegetation photosynthesis in both normal and drought periods. The results from this research work not only reveals the various sensitivity of NDVI, EVI and LSWI to drought and heat wave in 2003, in Europe, but also shows that the VPM model is a robust tool for modeling GPP in terrestrial ecosystems in Europe.