Effects Of Island Characteristics On Arthropods Species Diversity And Conservation In The Thousand-island Lake Region

Thousand-Island Lake is an artificial lake formed with intensively anthropogenic interference, the original landscape fragmented and had been divided into a large number of islands with varying size and shape by water. Biodiversity change caused by landscape fragmentation is the current hotspot in ecology. The typical fragmentation area in Thousand-Island Lake region located in Xiaojinshan forest farm was selected for study, and the grid method was used to investigate the quantity and species number of arthropods on 50 islands. We focused on how island characteristics influenced on arthropod diversity. The major results summarized as follows:1. The islands were ordered in decreasing size, and the corresponding species including species with high-dispersal ability, species with low-dispersal ability, herbivorous species, predatory and parasitic species were tabulated. A total of 329 species were founded in the research area, 104 species with low-dispersal ability, 225 species with high-dispersal ability, 208 herbivorous species, a total of 101 predatory and parasitic species and 20. other species included. Our results showed the species appearing on the island more than 5 times according to the sensitivity of the area is divided into four categories: 17 herbivorous species were sensitive to island area while 11 species were not, and 15 species were between sensitive and insensitive; 10 predatory species were area-sensitive while 9 species were not, and 4 species were between area-sensitive and insensitive; There is no law for the other species, which could be found less than 5 times, however, most of them were found only in the larger islands may be extremely area-sensitive. Whether all of the arthropods, or predatory species and herbivorous species, all of the groups showed a non-random distribution, as there exist more species on the small islands than the large islands with the same cumulative area.2. The analysis of the relationship between the arthropod species richness on 50 islands and island area had been done and the best fitting model were selected, results show that: the total arthropod species richness, species richness of arthropods with high-dispersal ability, species richness of arthropods with low-dispersal ability, herbivorous species richness and predator species richness all increased with island area, and the relationship between number of species and island area in line with the classic model of island biogeography.3. The inter-correlation of the five parameters to measure island geographical features (the island area, elevation, shape, the minimum distance between the islands and the minimum distance between the island and the mainland) and the correlation between the five parameters and species number were analyzed, with the stepwise regression analysis the combined effects of the five factors affected on the species number of arthropods were investigated, and the results show as follows: the island area and shape index, elevation, as well as the minimum distance between islands and the mainland was significantly correlated; the shape index was also significantly correlated with elevation and the minimum distance between islands and the mainland; The species number of arthropods were affected by island area, elevation, shape and distance synthetically; The minimum distance between the islands neither significantly affected the species number of the arthropods, nor significantly correlated with species number of each arthropods group; the minimum distance between island and the mainland and island shape index were both predictors for species with high-dispersal ability and species with low-dispersal ability, elevation is predictor for the the former species while the latter was affected by the island size; predatory species and herbivorous species, is governed by integrated effect of island area, elevation and shape, but the model yield by the stepwise regression showed that the minimum distance between island and the mainland is also a predictor for the former. The species number of plant significantly correlated with the species number of arthropods, the species number of arthropods increased with species number of plants, however, the growth trend of the species number of herbivores and the species number of predator is more in line.4. Compared the cumulative numbers and average diversity and evenness of herbivorous species, predatory species and all species in different scenarios of aggregating individual islands by small, medium, large and mixed categories, respectively, we are able to examine how species number changed with theincreasing total area of habitat and which island combination gave rise to thehighest species number and highest diversity index. Our results showed that, for agiven total area of island habitat, mixing islands of different sizes and a number ofsmall islands gave rise to the highest species number of arthropods in terms ofherbivorous species, predatory species and total species number, but both thediversity and evenness of small islands were lower than the mixing islands, so wewould be prefer mixing islands for the conservation of arthropods.