Exploring patterns and impacts of farmland and construction land upslope in China: based on an integrated slope spectrum and sensitivity model

As demand for land resources is rapidly growing nowadays, developing on slope lands has become a way to relieve pressure on flat lands. Although some studies use the concept of slope spectrum to explore the trend of land use upslope, relying solely on the slope spectrum is too broad and prevents deeper research. Therefore, using China's land use and DEM data from 2000 to 2020, our study integrated the slope spectrum and the slope sensitivity coefficient (SSC) calculated by the land use transfer matrix as a new approach and method for understanding the underlying formations and impacts of upslope in farmland and construction land, supporting regional management strategies. The results show that: 1) Farmlands were upslope in the South and developed horizontally in the North, and construction lands were upslope nationwide. 2) Using the land use transfer matrix and SSC, we classified farmland upslope as passive and active patterns, and construction land upslope as saturation and avoidance patterns based on their land use transfer mechanisms in slope space. Provinces with passive and saturation patterns are mainly located near the east coast. 3) Different patterns of upslope have distinct impacts on sustainable development. The passive pattern harms food security while the active pattern can relieve pressure on food security but increases ecological risks. Saturation pattern damages food security, ecological protection, and city livability, but avoidance pattern can promote food security and ecological protection. The findings will serve as an essential reference for developing land use strategies aimed at sustainable development.