Warming inhibits Increases in Vegetation Net Primary Productivity despite Greening in India

TL;DR

Despite significant greening in India indicated by increased Leaf Area Index, warming has constrained carbon uptake, leading to a decline in Net Primary Productivity in key forest regions, highlighting the need for climate-resilient forest management.

Contribution

This study reveals that warming inhibits NPP growth in Indian forests despite greening, providing new insights into climate impacts on forest carbon dynamics.

Findings

LAI increased by 18.51% from 2001-2019

NPP decreased by 6.19% over the same period

Warming hotspots identified in Northeast India, Peninsular India, and Western Ghats

Abstract

India is the second-highest contributor to the post-2000 global greening. With satellite data, here we show that this 18.51% increase in Leaf Area Index (LAI) during 2001-2019 fails to translate into increased carbon uptake due to warming constraints. Our analysis further shows 6.19% decrease in Net Primary Productivity (NPP) during 2001-2019 over the temporally consistent forests in India despite 6.75% increase in LAI. We identify hotspots of statistically significant decreasing trends in NPP over the key forested regions of Northeast India, Peninsular India, and the Western Ghats. Together, these areas contribute to 31% of the NPP of India (1274.8 TgC.year -1). These regions are the warming hotspots in India. Decreasing photosynthesis and stable respiration, above a threshold temperature, are the key reasons behind the declining NPP. Warming has already started affecting carbon uptake in Indian forests and calls for improved climate resilient forest management practices in a warming world.