ObjectiveLong maintenance of soil fertility is an important research content of sustainable forest management in plantation.

MethodThis article aims to explore the soil fertility changes on the treatment stands after Pinus massoniana pure forest transferred into uneven-aged conifer-hardwood mixed forest by thinning and then interplanting with Altingia gralilipes, Schima superba, Phoebe bournei, respectively. The soil physical and chemical properties of four treatments were determined after forest interplanting with broadleaved tree species at the 1st, 5th, 10th and 20th years.

ResultThe soil aggregate composition, soil pore, soil organic matter and soil nutrient content of the four treatments of forest soil all showed increasing trend with time, and this trend increased as time went on. The order of the increased amount of soil characteristics showed as Pinus massoniana × Altingia gralilipes (MPA)> Pinus massoniana × Phoebe bournei (MPP)> Pinus massoniana × Schima superba (MPS)> pure Pinus massoniana (PP). The differences in soil characteristics among the first three mixed stands were small, but the differences between the first three mixed forest and pure Pinus massoniana stands were significant. Compared the soil characteristics of the transformation forest between the first year and the 20th year, it was found that, in 0-2cm soil of MPA, MPP, MPS and PP forest, the water stability aggregates of dry soil diameter >0.25mm increased by 5.21%, 4.67%, 3.78%, 1.24%, the total soil porosity increased by 3.82%, 3.78%, 3.01%, and 0.49%, soil organic matter increased by 9.67, 8.39, 7.26, 2.84g/kg, soil total nitrogen (N) content increased by 0.22, 0.13, 0.14, 0.05g/kg, and soil total phosphorus(P) increased by 0.10, 0.06, 0.05, 0.04g/kg, respectively.

ConclusionThe transformation forest of Pinus massoniana intercropping with broadleaved tree species has good function in fertilizing soil, and is conducive to the maintenance and sustainable management of the public welfare forest.