Objective To analyze the influence of soil aggregate structure on the formation of soil priority path for subalpine woodland in central Yunnan for providing scientific basis for the construction of water conservation forest, the restoration and reconstruction of natural forest vegetation in central Yunnan forest area.

Method Based on four subalpine woodland soils of Pinus yunnanensis forest, Pinus armandii forest, Quercus semecarpifolia forest and Keteleeria evelyniana forest in central Yunnan, the soil priority path was extracted by using dye tracing method, combined with Photoshop CS 5, image pro plus 6.0 and surfer 15 image processing software. The structural characteristics of soil aggregates were systematically evaluated, and the effect of soil aggregate structure on priority path was explored by correlation analysis, principal component analysis, grey correlation analysis and coupling degree analysis.

Result Results showed that: (1) the soil of four subalpine forest lands in the study area had good aggregate structure, and the structural stability in the P. armandii forest was the largest, followed by K. evelyniana forest, P. yunnanensis forest, and Q. semecarpifolia forest. The soil aggregate structure was significantly affected by forest land type and soil depth (P < 0.05), and it was correlated with the content of water stable aggregates in different particle sizes. (2) The preferential flow of forest land soil had advantages. The connectivity of priority paths in P. armandii forest was better than that of P. yunnanensis forest, Q. semecarpifolia forest, and K. evelyniana forest. In addition, the number of priority paths gradually decreased with the increase of soil depth. (3) The content of water stable aggregates with particle size > 0.25 mm (WSA), mean weight diameter (MWD), geometric mean diameter (GMD), mean weight soil specific area (MWSSA), percentage of aggregate destruction (PAD) and fractal dimension (D) could better evaluate the structural characteristics of soil aggregates. The correlation with the number of priority paths was more than 0.62, which was important factor affecting the formation of priority paths. (4) The average coupling degree between soil aggregate structure and the number of priority paths for subalpine forest land in central Asia was 0.683, and the system belonged to weak coordination. The coupling coordination degree in P. yunnanensis forest was the largest (0.728), followed by P. armandii forest (0.681), Q. semecarpifolia forest (0.663), and K. evelyniana forest (0.662).

Conclusion Soil aggregate structure is an important factor that affects the formation and occurrence of soil priority path, but it does not play a decisive role in the formation of priority path.