A monetary valuation of the spatial flow of nature’s contributions to people in the middle reaches of the Yellow River

Gross ecosystem product (GEP) assessment can convert physical quantities of nature’s contribution into monetary units, so that measure regulating nature's contribution to people (NCP) with a unified standard to support decision-making. The nature's contributions and people's needs are often spatial mismatch, while most of assessments lacked the integration of NCP and GEP in a spatial flow view, which is not conducive to the cross-regional policy making of "who benefits, who pays". Taking six typical cities of the Loess Plateau as a case, we valued the GEP of four material NCPs and three regulating NCPs from 2000 to 2020. We established spatial flow allocation methods for water supply, soil retention, sandstorm prevention to decompose the GEP contributions of the three regulating NCPs to the neighboring and downstream cities, so as to combine the nature's contributions located in the middle reaches and the neighboring and downstream people's needs in the form of monetary value. The results show that the GEP of the six cities in the Loess Plateau grew from 20.22 billion Yuan in 2000 to 36.98 billion Yuan in 2020, with the material NCP growing from 10.54 billion Yuan to 26.95 billion Yuan, and the regulating NCP growing from 9.67 billion Yuan to 10.03 billion Yuan. In the extraterritorial flow of regulating NCPs, GEP for water supply NCP and soil retention NCP flowed to downstream of the Yellow River, GEP for sandstorm prevention NCP flowed to neighboring cities to the east and south of the study area. The flow of NCPs exhibited spatial heterogeneity, with the city benefiting from the greatest variety of NCP types differing from the city benefiting from the highest flow value of NCPs. The assessment demonstrates the feasibility of integrating the NCP and GEP indicator systems to spatially guide cross-regional payment for ecosystem services policy.