Abstract:

Aims: The impacts of habitat fragmentation on biodiversity are a critical research area in ecology and conservation biology. However, there is still insufficient understanding of how habitat fragmentation affects species diversity and activity rhythm. The purpose of this study is to investigate the diversity of birds and animals in fragmented forests and to explore the effects of patch size and stand age on the diversity of mammals and birds, as well as the daily activity rhythm of dominant species.

Methods: From July 2018 to July 2021, researchers used infrared cameras to survey mammal and bird species in 21 fragmented forest patches located in the Dujiangyan region of Sichuan Province. The “vegan” package in R was used to generate the species accumulation curve; the linear mixed model of the “lme4” package in R was used to analyze the relationship between species richness and relative abundance index, and factors such as patch sizes, stand ages, and seasonal variations; the “overlap” package and “activity” package in R were used to analyze the daily activity rhythm and niche overlap of two dominant species and anthropogenic activities, through kernel density estimation and coefficient of overlap analyses.

Results: This study documented a total of 63 species of wild animals, which belonged to 10 orders and 25 families. These species included 52 species of birds and 11 species of mammals. Notably, 12 of the recorded species are Class-II national protected animals, such as Macaca thibetana, Prionailurus bengalensis, Chrysolophus pictus, and Tragopan temminckii; 7 species are endemic to China, including M. thibetana, Muntiacus reevesi, and Bambusicola thoracicus; 1 species (Arctonyx collaris) is red listed by the IUCN as Vulnerable (VU), and two species (M. thibetana and Elaphodus cephalophus) are listed as Near Threatened (NT). The research found that the species richness and relative abundance index of mammals increased as patch sizes increased. However, there was no significant correlation between bird species richness and relative abundance index, and patch sizes. Stand ages did not have significant correlations with the relative abundance index of mammals and birds. Furthermore, the study showed that the bird species richness and relative abundance index were significantly higher in the dry season than in the wet season. In contrast, the relative abundance index of mammals was significantly lower in the dry season than in the wet season, while mammal species richness did not significantly differ between the dry and wet season. The daily activity rhythm curves of the two dominant species (i.e., C. pictus and B. thoracicus) were highly overlapping and showed no significant niche differentiation; the overlap of daily activity rhythm increased as patch size but decreased with stand ages. In addition, the diurnal activity of the two dominant bird species showed a noticeable avoidance of anthropogenic activities during certain times.

Conclusion: Our findings indicate that forest fragmentation mainly affects mammal diversity and the daily activity rhythm of dominant birds. Therefore, it is crucial to enhance the use of new technologies such as infrared cameras to monitor, study and protect the diversity of wildlife in areas outside protected zones and national parks. Our results provide valuable insights for further studies on the impact of habitat fragmentation on biodiversity and species coexistence.

Key words: biodiversity, camera trapping, habitat fragmentation, forest succession, daily activity rhythm, niche differentiation