Dynamics and Drivers of Net Primary Production (NPP) in Southern Africa Based on Estimates from Earth Observation and Process-Based Dynamic Vegetation Modelling

Abstract

AbstractTerrestrial net primary production (NPP) is a fundamental Earth system variable that also underpins resource supply for all animals and fungi on Earth. We analysed recent past NPP dynamics and its drivers across southern Africa. Results from the Dynamic Global Vegetation Model (DGVM) LPJ-GUESS correspond well with estimates from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite sensor as they show similar spatial patterns, temporal trends, and inter-annual variability (IAV). This lends confidence to using LPJ-GUESS for future climate impact research in the region. Temporal trends for both datasets between 2002 and 2015 are weak and much smaller than inter-annual variability both for the region as a whole and for individual biomes. An increasing NPP trend due to CO2 fertilisation is seen over the twentieth century in the LPJ-GUESS simulations, confirming atmospheric CO2 as a long-term driver of NPP. Precipitation was identified as the key driver of spatial patterns and inter-annual variability. Understanding and disentangling the effects of these changing drivers on ecosystems in the coming decades will present challenges pertinent to both climate change mitigation and adaptation. Earth observation and process-based models such as DGVMs have an important role to play in meeting these challenges.