Upland buzzard (Buteo hemilasius), Saker falcon (Falco cherrug), and Himalayan vulture (Gyps himalayensis) are three common large raptors in the Sanjiangyuan National Park (SNP), China's first national park. Among them, Upland buzzard and Saker falcon play a significant role in controlling plateau rodent populations and reducing the transmission of pathogens carried by rodents. The Himalayan vulture can provide services for the redistribution and recycling of nutrients in the ecosystem, and play an irreplaceable role in the celestial burial culture of Tibetans in China. Exploring their habitat suitability is important for the protection of the three raptors. Our research was based on the current distribution of Upland buzzard, Saker falcon, and Himalayan vulture that we had extensively surveyed in the Sanjiangyuan National Park from 2016 to 2017. Combined with the correlation analysis of environmental variables, we utilized maximum entropy model (MaxEnt) to evaluate and compare the habitat suitability of the three species in the Sanjiangyuan National Park. Elevation, climate, and human disturbance factors, which had direct or indirect effects on species survival and reproduction, were all included in the model. Among them, elevation was the most important environmental variables affecting the suitability of habitats of three species. Temperature‐related factor was another important predictor. The high (>60%) suitable habitat areas for Upland buzzard, Saker falcon, and Himalayan vulture were 73,017.63, 40,732.78, and 61,654.33 km2, respectively, accounted for 59.32%, 33.09%, and 50.08% of the Sanjiangyuan National Park and their total suitable area (i.e., the sum area of high and moderate habitats) reached 96.07%, 60.59%, and 93.70%, respectively. Besides, the three species have overlapping areas for the suitable habitats, which means that overlapping areas should be highly valued and protected. Therefore, understanding the distribution of suitable habitats of the three raptors can provide useful information and reasonable reference for us to put forward suggestions for their protection and regional management.
1. Recent plant-soil feedback experiments suggest that arbuscular mycorrhizal (AM) tree species experience stronger conspecific negative density dependence (CNDD) than ectomycorrhizal (EM) tree species. Yet, how these findings inform our understanding of natural systems is limited because the roles of local soil conditions, light availability and tree species abundances in influencing CNDD for AM and EM species are not clear. 2. Here we examined seedling and sapling survival in two temperate old-growth forests (broad-leaved pine and spruce-fir forests) in Northeast China, to evaluate the effects of both conspecific and heterospecific neighbour density, as well as the soil and light environments, on the survival of AM-and EM-dependent trees at early life stages. 3. While light availability increased the survival of EM seedlings, soil organic resources increased EM sapling survival in the spruce-fir plot. AM tree species suffered stronger CNDD than did EM tree species in both plots. In the spruce-fir plot, soil factors and light availability mediated species CNDD but their effects differed between AM and EM species, and also between seedlings and saplings. For seedlings in both plots, we found that AM species exhibited a positive relationship between species abundance and CNDD strength, whereas this relationship was negative for EM species. 4. Synthesis. Our results provide one of the few tests of how fungal symbioses determine species responses to intraspecific and interspecific interactions and the direct effects of local environmental conditions on seedling and sapling survival. We show that mycorrhizal type mediates the strength of CNDD and its relationship with species abundance. These results suggest that tree mycorrhizal association can determine the strength of CNDD effect on both rare and common species, and these CNDD differences are likely to influence the community composition of temperate forests.
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