Evaluation of cultivated land quality in Xizang and Qinghai

Cultivated land quality in terms of soil properties and technical conditions in Xizang and Qinghai were evaluated, to identify dominant limiting factors and explore macroscopic influences, aiming to provide support to enhance productivity of cultivated land and ensure food security in plateau regions． The evaluation indicator weights are determined based on the combination of subjective and objective weightings, a random forest method is introduced to explore the influence of regional macronatural-economic-social factors． Cultivated land in Xizang and Qinghai is mainly medium land, accounting for 44.6% of the total area． Medium land is mostly sloping land in the Huangshui Valley area of Qinghai． The high slope of field surface restricts utilization as arable land． Elevation and distances to city centers have important effects on the cultivated land quality globally. In most areas, elevation and arable land quality show a negative correlation． The influence of distance to city on the cultivated land quality varies spatially． In the central and southern Xizang and frontier belt areas, high quality cultivated land is often laid out around cities due to improvement of technical conditions． In contrast, in the valley areas of the northeastern plateau, soil quality of arable land adjacent to urban periphery is lower and degradation is more likely to occur．