Abstract: Broadleaved transformation is one of the key directions for sustainable management of Pinus massoniana forests, but little is known about the changes of soil stoichiometric characteristics. Here, we investigated soil stoichiometric characteristics across pure Pinus massoniana forest (CK, 40-year-old), Pinus massoniana (40-year-old) and Cinnamomum camphora (10-year-old) mixed forest (X1, transformed from pure Pinus massoniana forest), Pinus massoniana (40-year-old) and Cinnamomum camphora (20-year-old) mixed forest (X2, transformed from pure Pinus massoniana forest), and 30-year-old Cinnamomum camphora forest (X3). We examined the vertical characteristics of soil organic carbon (C), total nitrogen (N), total phosphorus (P) and their stoichiometric ratios at soil depths of 0-20, 20-40, 40-60 cm. The results showed that: (1) Soil C, N, P contents and their stoichiometric ratios decreased with increasing soil depth. (2) Soil C, N contents and C∶N significantly increased with increasing transformation time, while soil P content remained relatively stable. Soil C∶P and N∶P in CK were significantly lower than those in other stands (P<0.05), showing a trend of mixed forest (X1 and X2) > broadleaved forest (X3) > coniferous forest (CK). (3) Forest type significantly affected soil C, N, P contents and their ecological stoichiometric ratios (P<0.05). Soil depth had significant effect on soil C and N contents (P<0.05). However, forest type and soil depth showed no interaction in affecting soil N and P contents. (4) There were significant positive correlations among soil C, N and P contents. Soil C and N∶P, soil N and C∶P, and soil P and C∶N showed significant positive correlations. Overall, the broadleaved transformation of Pinus massoniana forest increased soil C and N contents and the ratios of soil C∶N, C∶P, and N∶P.

Key words: Pinus massoniana, broadleaved-oriented transformed forest, ecological stoichiometry, forest type, soil layer