Declining net carbon sequestration of west-central Indian ecosystem in response to frequently occurring drought: Inference from satellite measurements and modeling

Extreme weather events significantly impact vegetation dynamics, with droughts becoming increasingly frequent and adversely affecting plant growth and carbon sequestration. Understanding vegetation responses to such events is essential for effective climate change mitigation, as it directly influences the capacity of ecosystems to absorb Carbon Dioxide (CO₂). This study investigates the impact of the 2016 drought in west-central India on vegetation productivity and ecosystem carbon exchange. We utilize satellite-based reflectance products, including Vegetation Indices (VIs) and Solar-Induced chlorophyll Fluorescence (SIF), alongside carbon flux estimates from vegetation models such as a subset of the TRENDY ensemble, Vegetation Photosynthesis and Respiration Model (VPRM), and FLUXNET-X. VIs and SIF were analyzed to identify the vegetation responses to drought and to assess model performance in the absence of extensive ground-based observations. Our findings indicate that the region’s carbon uptake capacity declined by 30 Tg C season⁻¹ due to the 2016 drought. The region persisted as a net carbon source annually, with 75% of the source contribution from the drought period. However, ecosystem respiration remained largely unaffected. The drought significantly suppressed vegetation growth, with deciduous vegetation experiencing the most severe impact. When croplands recovered more quickly, shrublands showed a slower recovery, and deciduous vegetation exhibited the longest delay in post-drought recovery. The vegetation models employed generated varied ecosystem carbon fluxes, but most of them showed similar levels of responses to the drought. The uncertainties in these models emphasize the need for better representation of ecological processes and high-density observations in this region. The outcome of this study can help in making important policy decisions at the national level, especially for managing ecosystems and maintaining carbon storage during extreme weather events.