Understanding spatiotemporal changes of crop species diversity for India

Agrobiodiversity – a key principle of agroecology – integrates crop diversification as a key component for building resilient agricultural systems. Crop diversification focuses on transitioning from monoculture practices to multiple crop systems, thereby enhancing soil health, biodiversity, promoting dietary and nutritional diversity, and providing economic benefits to farmers. The study aims to quantify and evaluate changes in crop species diversity for India at the subnational scale (district level) and regional scale (Agro-Ecological Zones, AEZs) using the Shannon Index for Crop Species Diversity (CSD), Pielou's Index for Crop Species Evenness (CSE), and Margalef Index for Crop Species Richness (CSR). We analyzed the trends of the harvested area for 56 crops in 711 districts from 1997 to 2019, using a non-parametric method. The results report that regions with high diversity are located in the Southern Peninsular region. In the districts within high diversity regions, apart from rice and wheat, crops like sorghum, safflower, cotton, groundnut, sunflower, and sugarcane showcasing high crop richness with balanced abundance. In contrast, the northwestern and southeastern region shows lower CSD values, as 86 % of the crop composition is dominated by rice, indicating towards a predominance of monocultural practices. The trend analysis reveals that 18 % of the total districts show a significantly increasing trend in CSD and are classified as diversity hotspots, whereas 15 % of the total districts fall in the low diversity region as they show a significant decreasing trend. Based on these results, we argue that there is a need to address the declining crop species diversity, as the homogenization of crop species will have ecological, economic, and nutritional implications. The outcome of the study can help to identify target locations (with low and declining diversity) for designing climate-resilient agricultural practices. • Diversity, richness, & evenness were calculated using Shannon, Margalef, & Pielou's indices. • Southern Peninsula and Central regions show the highest mean crop diversity • Diversity hotspots (increasing trend) – Southern peninsula and Central districts • Southeast, Northeast, & Northern show the lowest mean crop diversity • Low diversity (decreasing trend) - Northwestern & Southeastern districts