Effects Of Forest Fragmentation And Succession On Rodent Diversity And Seed Fate Of Oil Tea (Camellia Oleifera)

Forest fragmentation is often defined as a process during which a large expanse of forest is transformed into a number of smaller patches of smaller total area, isolated from each other by a matrix of habitats unlike the origin owing to human disturbance or nature disaster. It is considered to be a major driver of biodiversity loss due to the patch size, edge effect and isolation, and further changes the internal environmental conditions and community structure of forest. Forest succession is the natural replacement of plant or animal species, or species associations, in an area over time. The community composition of animal and plant and species distribution are affected directly or indirectly by forest succession, which can also lead to forest community biodiversity loss. Therefore, It consequently exhibit important theoretical and practical significance on studying the change of biodiversity under the condition of forest fragmentation and succession and its effects on the dynamics of the forest regeneration.In a fragmented subtropical forest in the Dujiangyan Region, Southwest China, in order to explore the impacts of forest succession on the community structure and diversity of wild animals, we investigated rodent communities using live traps in the 21 plots with 5 different types of forest succession(i.e. 0-5 year, 6-10 year, 11-20 year, 21-30 year and 100-year old primary-secondary forest as control) during 2012 to 2013. We also studied the effects of forest fragmentation(patch size) and succession on storage and dispersal of oil-tea seeds and animal feeding effectiveness, we investigated rodent communities using recapture methods and then released and tracked tag oil-tea seeds in the 11 plots with different patch sizes(small patch: 0.5-1.5 ha and large patch: 9-30 ha) and succession stages(early phase 10-20 a and medium phase 20-40 a)(in this study, each type there are two repeated samples, the rest of the three plots namely Banruosi temple old primary-secondary forest, succession stages for 100 a, as the control group) in the fall of 2013. It can provide basic data and theoretical basis for the forest natural regeneration and artificial forestation.The results showed that:(1)It was found that Niviventer fulvescens, Apodemus draco, N. confucianus, A. chevrieri, A. latronum and Leopoldamys edwardsi were the main rodent species in research area. Species richness and diversity parameters of rodents were similar among 5 different types of forest succession, but trapped rodent individuals were higher in primary-secondary forest than in any other recently succession forest. The species and relative density of rodents were affected by patch sizes and succession stages of habitat types. The numbers of rodents species in control patch were more than in large patch with early to medium phase and small patch with early phase, and were least in small patch with medium phase. The relative density of rodents in the early phase were the largest, followed by in small patch with medium phase, and in large patch with medium phase to primary forest were least.(2)The rates of predation and dispersal of oil tea seeds were significantly affected by patch sizes and succession stages. The dispersal rate was lower in the control patch than small patch, and also, in small patch than in large patch. Between different succession stages, the dispersal rate was lower in habitats of succession for 100 year than succession for 20 to 40 years, and also, in habitat of succession for 20 to 40 years than succession for 10 to 20 years. The seed fate of oil tea was also influenced by patch sizes and succession stages. The feeding fate was higher in large patch than in small patch or in control patch, and in habitats of succession for 10 to 20 years than succession for 20 to 40 years or succession for 100 year. The rodents preferred hoarding seeds in small patch and in early succession stage. The second dispersal rate was higher in habitats of small patch and in early succession stage with larger rodents density, and most of the size of the storage point only had a single seed.(3)The transportation distance of oil tea seeds was influenced by patch sizes and succession stages. The rodents in large patch and early succession stage tend to feed or bury oil tea seeds in further distance. Seed germination is not only need to escape the predation of rodents and fungal infections, but also need to an adaptive environmental conditions. Though the proportion of seed germination was higher in control group than that in other habitats, but in general the numbers of seed germination were fairly few, this may be the main reasons lead to poor natural regeneration.