Abstract: Understanding the spatial variations of ecosystem service value across the altitude gradient is of great significance for sustainable ecosystem management. Based on land use/cover data of 2000 and 2015 in the hill and mountain belt in southern China, we quantitatively analyzed the spatiotemporal variation in ESV and characteristics of altitude gradients in the hill and mountain belt. Compared with that in 2000, the area of broad-leaved forest, artificial surface and bare land areas increased in 2015, while the area of coniferous forest, dry land, paddy field, and shrub areas decreased. Broad-leaved forest and coniferous forest were concentrated between the T₂ gradient (500-800 m). From 2000 to 2015, the ESV increased by 6.483 billion yuan in hilly areas of the hill and mountain belt, with broad-leaved forest and coniferous forest contributing to 33.41% and 28.41% of the total ESV, respectively. Among the single ESVs, the contribution of hydrological regulation was the largest, with a value of 26.20%. Grain production decreased the most, by 369 million yuan. Spatially, ESV was greater in the east-west and less in the central of this region. On the altitude gradient, the ESV per unit area showed a trend of increasing and then decreasing. T₂ altitude was the turning point, with ecosystem service value accounting for 22.51% of the total. The ESV of each altitude gradient showed an increasing trend from 2000 to 2015, with the T₁ altitude (<500 m) increasing the most by 4.072 billion yuan. The geographical detector showed that the percentage of broad-leaved forest, population density, and NDVI were the main factors affecting ESV. After interactive detection, the explanatory power of those influencing factors was significantly enhanced. The results can provide a scientific basis for the ecosystem optimization and management in the hill and mountain belt in southern China.

Key words: land use/cover, ecosystem service value, altitude gradient, southern hill and mountain belt.