Shangri-La locates at the middle of Hengduan Mountains, and is one of the biodiversity hotpots of the world. However, due to commercial logging and expansion of farmland in the last decades, the primary fir forest there has degraded, resulting to numerous primary patches surrounded by secondary forest. Even now the primary fir forest is also subjected to loss and fragmentation. Here we tried to understand how the resident breeding birds responded to the primary forest loss and fragmentation from a landscape approach. The aims of this study were: (1) to determine the respective effects of primary forest loss and fragmentation on forest-dwelling breeding birds; (2) to test the hypothesis that primary forest area correlated negatively with the fragmentation, which stated the effect of fragmentation increased as the primary forest cover decreased. The independent effects of primary forest cover and fragmentation on the distribution of forest Passeriforme breeding birds were studied in 18 landscapes 150ha each, ranging in primary forest cover from 1.64% to 84.92%. For each landscape primary forest cover was measured, and a fragmentation index (independent of forest cover ) was generated using PCA from the measure of average patch area, number of patches and total edge length. Totally 82 Passeriforme birds in eight Families were recorded in the observation. The effects of primary forest cover and fragmentation on species abundance were analyzed using Generalized Linear Models for Multivariate Abundance. Results showed that bird community was sensitive to the primary forest cover generally, but not for the fragmentation index and the interaction between the two factors. Analysis of different functional bird groups also showed similar result. Further analysis with one by one species proved that only four species were sensible to fragmentation index (two positively and two negatively), and only two species sensible to the interaction of the two factors (one positively and one negatively). We conclude that (1) primary forest cover affect the bird community significantly; (2) primary forest fragmentation only affect several bird species; (3) the effect of primary forest cover is greater than that of fragmentation; (4) the effect primary forest fragmentation on species distribution does not increase with decreasing primary forest cover. These results suggest that primary forest cover should be put priority at the conservation of bird diversity, and the traditional practice that to protect bird diversity through reducing the primary forest fragmentation is not enough.
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