Contrasting policy shifts influence the pattern of vegetation production and C sequestration over pasture systems: A regional-scale comparison in Temperate Eurasian Steppe

Abstract Socio-economical conditions profoundly influence terrestrial ecosystems, especially the agroecosystems. However, the effects of large-scale “top-down” socio-economical changes on patterns of vegetation production and C sequestration in pastures remain largely unclear. The contrasting institutional and policy shifts in 1990s over the two sub-region of Temperate Eurasian Steppe (TES), i.e., the Kazakh Steppe (KS) and the Mongol Steppe (MS), provide a unique opportunity to illustrate the human and natural interactions. Combining multiple information from remote sensing, land model, climate and inventory data, this study investigated how the regional trend and inter-annual variability (IAV) of leaf area index (LAI), net primary productivity (NPP), net ecosystem productivity (NEP) were associated with different institutional and policy shifts. From 1997 to 2016, climate is the primary control factor to the IAV of the ecosystem indexes (EIs, i.e., LAI, NPP, NEP) at a regional view. Highly contrasting impacts of human appropriation indexes (HAIs, i.e., livestock number and agricultural GDP) to the EIs were found for the two sub-region. The effect of HAIs on EIs was weak in the MS, but significant negative correlations between HAIs and EIs were found in the KS. Further decomposition into administrative divisions showed that the swift rise of human appropriation in China was accompanied with increases in grassland NPP and NEP, owing to the policy shift to sustainable management. But the institutional shift to market-driven economy and increasing human appropriation generally acted as a negative factor to EIs in various countries over the KS, especially in Uzbekistan and Turkmenistan. Regional evidences revealed the importance of large-scale socio-economic shifts in shaping the pattern of important ecosystem properties of grasslands and emphasized the importance of sustainability development in managing pasture systems.