Background Hani Terraces were inscribed on the list of the World Cultural Heritage in 2013. The soil water conservation and carbon sequestration functions are evaluated. It is beneficial to the enhancement of the ecosystem function of the Hani Terraces and the sustainable development of the Hani Terraces. It also provides an important basis for the conservation of the Hani Terraces, a World Heritage site.

Methods This paper took the core area of the Hani Terraces in Yuanyang county as the research area. The ecosystem service functions of water soil conservation and carbon storage in Yuanyang county was evaluated based on the InVEST model, combined with land use type, digital elevation model, carbon density data, rainfall, soil data, and vegetation cover. The paper studied characterizing the spatial and temporal distribution of soil and water conservation carbon storage in Yuanyang county from 2000 to 2020.

Results 1) During the 20 years, the land use types in Yuanyang county changed significantly. The land use types in Yuanyang county were dominated by forest land and grassland. The land use types of Yuanyang county showed a trend of four increases and two decreases, with an increase in the areas of cropland, grassland, waters and construction land and a decrease in the areas of forest land and unused land. The areas of forest land decreased by 5676.30 hm², the areas of water and construction land increased by 405.99 hm² and 401.49 hm². 2) From 2000 to 2020, the water conservation capacity of Yuanyang county showed a decreasing trend, and the water conservation capacity decreased by 2.10 × 10⁸ m³, the highest water conservation area was the south and southeast in Yuanyang county, the lowest water conservation area was the north and west in Yuanyang county. Forest land and grassland had both the highest water conservation, while waters was the lowest. 3) From 2000 to 2020, the soil erosion modulus of Yuanyang county was in decreasing trend. It decreased by 6.68 t/(hm²·a). Overall Yuanyang county belonged to the slight erosion and its percentage of 64.43%. In Yuanyang county, minor erosion was distributed in the north and center of the county, and medium and intense erosion was distributed sporadically in the south, southwest, and southeast. The soil and water conservation function of Yuanyang county was in a state of continuous improvement. 4) The carbon sequestration capacity of Yuanyang county was relatively stable from 2000 to 2020. The carbon storage of Yuanyang county increased by 0.13 × 10⁵ t from 2000 to 2010, it decreased by 0.21 × 10⁵ t from 2010 to 2020. The southeastern and southern parts of Yuanyang county had higher carbon storage, showing piecemeal and staggered distribution, mainly due to the fact that it had high forest coverage. The lowest carbon storage was in the central part, showing piecemeal and scattered distribution, mainly construction land and residential settlements.

Conclusions There are higher value of ecosystem services in Yuanyang county. It is necessary to adjust the terrace-to-forest ratio, protect the structural stability of the terraces, enhance hydrological connectivity and rationalize the development of eco-tourism, thus to enhance the value of the composite ecosystem services.