Importance of nutrient loading and irrigation in gross primary productivity trends in India

Abstract

Investigating the effects of various environmental factors on gross primary productivity (GPP) is crucial for quantifying the carbon exchange between the atmosphere and the terrestrial vegetation for managing climate change. Although it is well known that various natural and anthropogenic factors (e.g., climate change, agricultural activities, and atmospheric CO2 concentration change) can alter GPP, their relative influences are not clearly understood in every region. In this study, we consider several factors and investigate their roles in increasing the GPP in large parts of India. We considered about three decades (1980s to late 2000s) of GPP data and use a regression based systematic approach to find out the most likely cause explaining the trends in India. This study suggests that the common suspects like CO2 and climate may have limited influence on the GPP trends in India when compared to anthropogenic influences. Our results instead support the notion that GPP trends in India are mainly shaped by agricultural activities through nutrient loading (R2=0.68) and irrigation (R2=0.1). Overall, our study reveals the potential of agricultural activities in altering the carbon budget of a region.