Climate, degradation, and biodiversity interactions drive herb biomass in the Hindukush mountain ecosystem

Abstract Understanding the drivers of herbaceous productivity is crucial for managing vulnerable mountain ecosystems under changing climate and land use pressures. This study investigates the direct and indirect drivers governing herb biomass in the Hindukush Himalaya (HKH) using field measurements from 225 sample plots from multiple sites. We employed bivariate correlation analysis and structural equation modeling (SEM) to quantify the effects of available soil nitrogen, precipitation, temperature, degradation, elevation, and biodiversity. The results indicated that herb biomass was positively and directly associated with soil available nitrogen ( β  = 0.7***), precipitation ( β  = 0.17***), and species richness ( β  = 0.101*). However, elevation had a significant negative direct effect on herb biomass ( β  = − 0.151**). Indirectly, degradation was positively associated with both soil available nitrogen ( β  = 0.255***) and species richness ( β  = 0.477***), consistent with a model pathway in which these variables mediate degradation’s association with herb biomass. Precipitation was also indirectly associated with herb biomass through its positive association with soil-available nitrogen ( β  = 0.333***). These findings highlight the importance of considering both direct and indirect (interactive) pathways among environmental variables when interpreting productivity patterns in Himalayan pastoral systems.