Maintenance Mechanism And Ecological Restoration Of Castanopsis Sclerophylla Populations On Islands In Qiandao Lake Region

Dominant species usually play an important role in communities. One of the major goals of ecological restoration is to restore ability of long-term self-maintenance of dominant species. Studying maintenance mechanism of remnant populations in fragmented habitats helps us to predict their fates, while revealing the factor that may affect restoration is an important approach to realize eco-restoration.Qiandao Lake lies in east China and was formed in 1959 when the Xin'anjiang Hydroelectric Plant was built. There are 1078 islands with the area larger than 2500 m~2 and many smaller islands, when the water level is 108.0m. Potential natural vegetation is evergreen broadleaved forests dominated by Castanopsis sclerophylla and Cyclobalabopsis glauca. Now the vegetation on islands was dominated by the pioneer species Pinus massoniana, which is apt to disease, such as pine wood nematodes, and therefore there is a need to restore potential vegetation.Previous surveys indicated that, on some islands, there are some evergreen broadleaved species remaining, and Castanopsis sclerophylla is the most common one. Our study site is located at southeaster region of Qiandao Lake. A total of 31 islands and 2 peninsulas had been investigated, and the DBH, the rate of seed-setting and contribution of reproduction of C. sclerophylla populations were surveyed. Genetic structure of populations, totally 467 individuals sampled, was studied by nuclear and chloroplast microsatellite markers. We also introduced seeds and seedlings of C. sclerophylla to islands, and wanted to reveal the factors limiting the restoration of C. sclerophylla on islands. The major findings are as follow:1. C. sclerophylla can be found on islands with the area larger than 0.63 hm~2 and altitude higher than 105.4m, indicating that adult tree can endure temporary water flooding. Number of individuals on islands, with a range from 4 to more than 4000, was significantly related with the area or altitude of islands.2. Population structure indicated that, at genet level, C. sclerophylla on large (>100hm~2) and most medium (10-100hm~2) islands could be self-sustainable, while on small (<10hm~2) and some...