Effect of syndynamic on soil saturated hydraulic conductivity

Saturated hydraulic conductivity (Ks) is a critical parameter affecting soil infiltration capacity and water flow, and Ks is sensitive to different land use patterns. To study the effect of vegetation secondary succession on Ks, the experiment was conducted in the evergreen broad-leaved forests with the succession chronosequences of 155 years in Tiantong National Forest Park, Zhejiang Province, Eastern China. Ks was measured by the constant-hydraulic head method along 60 cm soil profiles under the different vegetation succession stages. The results showed that values of Ks reduced quickly with soil depth under different succession stages. There were significant differences of Ks among all the succession stages in the 0-20 cm soil depth. The average Ks in the 60 cm soil profile significantly increased from the bare land, Lithocarpus glaba + Laroptahon chenese shrub, Pinus massonian forest, Schima superba + Pinus massoniana forest, Schima superba forest to Castanopsis fargesii forest. In the shrub stage, the average Ks had showed significant difference to bare land. In the Schima superba forest, the average Ks had increased significantly. When the succession went into the climax stage, the average Ks reached maximum value (3.28 mm/min). Soil bulk density, non-capillary porosity, and silt content were the key factors which affected Ks. Soil organic matter (SOM) was also increased with vegetation succession and positively correlated to Ks. This study suggested that Ks was significantly improved with the forest succession process in Tiantong National Forest Park. High values of Ks could explain that why the overland flow was rarely occurred in this region.