Changes of Water-Related Nature’s Contributions in the Loess Plateau to Downstream People from 2000 to 2020

Abstract

Sustaining or enhancing nature’s contributions to people (NCPs) requires a comprehensive understanding of both nature’s contributions and people’s needs. However, the 2 aspects for water-related NCPs are spatially mismatched. We introduced an assessment framework for water-related NCPs from a spatial flow perspective, considering the local nature’s contributions assessed using the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) model, as well as people’s needs in the downstream assessed via a distance decay method. We assessed 3 water-related NCPs’ spatial distribution and correlation on the Loess Plateau from 2000 to 2020, where a large-scale ecological restoration was implemented that may affect downstream people. The results showed that NCP6 (downstream needs from water yield) showed no increasing trend in the majority watersheds over the past 20 years, in contrast to NCP7 (downstream needs from water purification) and NCP8 (downstream needs from soil conservation). There are spatial synergies among NCP6, NCP7, and NCP8. From 2000 to 2020, the spatial synergy between NCP7 and NCP8 increased while decreased between other NCPs. The temporal dynamics of NCP6 and NCP8 showed a trade-off, while NCP6 and NCP7 showed a synergy. NCP7 and NCP8, in turn, showed a transition from synergy to trade-off. Guided by nature’s contributions and people’s needs, we proposed 3 ecological measures: thinning and intermediate cutting measures, control nonpoint source pollution, and soil and water conservation projects to promote ecological restoration. This assessment can offer multifunctional guidance for planning ecological conservation and restoration in the upstream based on people’s needs in the downstream.