Vertical differentiation and root cause of land use and ecosystem service intensity at dune-interdune in the agro-pastoral ecotone in northern China

Desertification is showing a trend of overall reversal and partial expansion in the agro-pastoral ecotone in northern China (APENC). Dune-interdune is the typical micro-topography in APENC and is the expansion area of desertification. Research on anti-desertification strategy at dune-interdune is of great significance to further anti-desertification. This paper studies the vertical differentiation of land use and ecosystem service intensities at dune-interdune in APENC. The fundamental reason of the vertical differentiation of land use and ecosystem service intensities is explored with monitoring data of soil moisture at different locations of dune-interdune. Cultivated land is mainly distributed in areas with an elevation < 241 m. Grain provisioning ecosystem service intensity (GPESI) and maize leaf provisioning ecosystem service intensity (MLPESI) show a downward trend with the increase in elevation at dune-interdune. GPESI has a tipping point at the elevation of 241 m. Forage provisioning ecosystem service intensity and sand fixation regulating ecosystem service intensity are high in areas with low or high elevations while low in the central area. Groundwater depth is the root cause for vertical differentiation of land use and ecosystem service intensities at dune-interdune. According to vertical changes of land use and ecosystem service intensities, and groundwater level, cultivated land with an elevation greater than 241 m should be stopped for cultivation to anti-desertification. The area of dune-interdune within 6 m of groundwater depth can be used as cultivated land. The conclusion has an important reference for other similar regions in the world.