Objective Soil and water conservation is an important pathway to enhance terrestrial carbon sink capacity. Conducting assessments of soil and water conservation carbon sink capacity is of significant importance for quantitatively evaluating the contribution of regional soil and water conservation to carbon neutrality.

Methods This study quantitatively assessed the soil and water conservation carbon sink capacity of the Lijiang River Basin in 2024 by establishing a localized assessment indicator system and employing a distributed calculation method that combined remote sensing inversion and field monitoring.

Results The analysis indicated that: 1) compared with the scenario without watershed management, the carbon sequestration increment amounts (in terms of CO₂ equivalent, the same below) from soil and water conservation in the Lijiang River Basin were 36.612 9 million tons, of which vegetation contributed 60.18%, soil contributed 39.77%, and water retention contributed only 0.05%. 2) The soil conservation and carbon sequestration amounts from soil and water conservation measures in the Lijiang River Basin were 4.112 million tons, with vegetation measures and tillage measures accounting for 91.25% and 8.54%, respectively, while engineering measures contributed only 0.21%. 3) Erosion reduction and emission reduction amounts from soil and water conservation measures in the Lijiang River Basin were 0.822 4 million tons, with arbor forest land and shrub forest land together accounting for over 85% of the total. 4) The carbon sequestration increment amounts per hectare of soil and water conservation vegetation measures were 45.40 tons, which was 6.26 and 9.45 times that of slope soil and water conservation engineering measures and soil and water conservation tillage measures, respectively. The soil conservation and carbon sequestration amounts per hectare of vegetation measures were 4.76 tons, while engineering measures achieved 4.46 tons and tillage measures 2.16 tons.

Conclusions The study demonstrates that the carbon sequestration increment amounts from soil and water conservation measures in the Lijiang River Basin are equivalent to offsetting emissions from 14.08 million tons of standard coal, highlighting the significant carbon neutrality potential of ecological management in karst regions.