1. State Key Laboratory of Subtropical Mountain Ecology (Funded by Ministry of Science and Technology and Fujian Province),Fujian Normal University, 350007, Fuzhou, China;
2. College of Geographical Science, Fujian Normal University, 350007, Fuzhou, China;
3. Institute of Geography, Fujian Normal University, 350007, Fuzhou, China
[Background] Large areas of degraded lands have been restored in red soil regions of south China since 1980s, which provides tremendous ecological and economic services such as soil and water conservation, carbon sequestration and environment protection. Some problems such as soil degradation,soil and water loss and tree disease decline, however, also appeared after several decades of ecological restoration due to lack of knowledge about soil characteristics, which seriously threatens the stability and sustainability of plantation. The contents of carbon, nitrogen, and phosphorous are important indexes of forest management, which respond positively to the environmental conditions. In recent years, the ecological stoichiometry has received considerable attentions. However, few studies have been reported about the patterns of soil stoichiometry across ecological restoration. [ Methods ] We took Pinus. massoniana woodlands as research objects, and determined the content variations of total organic carbon (C), total nitrogen (N), and total phosphorous (P) in soil, as well as ecological stoichiometric ratios across different ecological restoration years at 6 sites. Six P. massoniana woodlands were the ones restored by 0 year (CK1), 2 years, 13 years, 30 years, 33 years, and secondary forest (CK2), respectively. Those study sites were expected to be distinguished at the level of ecological restoration years along the typical eroded red soil region in Hetian town, Changting County, Fujian Province. [Results] 1) The contents of C and N in soil increased in the restoring process of degraded red soil. However, the P content was not considerable changed. The soil C, N and P contents in the forest of restored 2-33 years were still significantly lower than those in CK2. 2) The ratios of C:N, C:P and N:P tended to increase with the restored years increasing, especially soil C:N ratio of restored 2-33 years was approaching to those in CK2. 3) C content and C:N, C content and C:P, N and N:P all were in positive correlation, but P content had no significant correlation with N:P. [Conclusions] Soil C, N and P contents were out of balance in the non-restored eroded red soil (CK1). Despite some areas have been restored for 30 or 33 years, the nutrient contents still were lower than those in secondary forest (CK2). In other words, the typical eroded red soil restoration is a long-term process. Moreover, soil stoichiometry ratios were mainly restricted by soil C and N contents in the restoring process of degraded red soil. It suggests that a vegetation recovery is more sensitive to N than to P at this typical eroded red soil region. Thus, this study will help to reveal the nutrient cycling of P. massoniana woodlands by combing with stoichiometric characteristics of soil C, N, and P comprehensively and systematically. Therefore, it is very important to guide the ecological restoration of eroded red soil,and further improving the productivity of forest system should be carried out.