Unveiling the drivers of nematode community structure and function across rice agroecosystems

Abstract

Rice agroecosystems has drawn global attention due to its unique transition of flooding to wetland to a terrestrial ecosystem with high biodiversity throughout its growing period. While biodiversity of the aboveground organisms in the rice ecosystem is well studied, understanding the diversity and functions of soil biota, particularly the nematofauna, are often neglected. In the present study, variations in soil nematode community composition in response to edaphic and climatic variables were assessed (n = 501 samples) across three agro-ecological zones of Jharkhand, India. Functional diversity measures were used to estimate the biological soil health of different rice growing areas across the agroecological zones. Relative contribution of edaphic, climatic and spatial structure in shaping nematode community composition was measured using variation partitioning. Among the identified nematode genera (n = 58), Meloidogyne spp. was the most abundant and dominant taxon. Taxonomic diversity measures varied significantly across agro-ecological zones, with highest diversity reported in the central and north-eastern plateau, followed by the south-eastern plateau and western plateau. Average annual temperature, annual precipitation, available nitrogen and organic carbon had significant relationships with taxonomic diversity measures. The spatial variation map of the nematode community composition depicted spatial heterogeneity across agro-ecological zones. Climatic predictors also strongly influenced both the community composition and richness of nematodes, while edaphic factors showed a strong influence on beta diversity, but not on variation partitioning. A moderate level of spatial structure pattern suggested limited dispersal of nematodes. Functional diversity measures based on nematode community composition depicted better soil biological health in the central and north-eastern plateau than rest two zones. This study demonstrates how climatic predictors have a greater influence on nematode community composition than edaphic parameters, presumably as a result of intensively managed rice agroecosystems.