Abstract As human activities continue to expand, wildlife persistence faces escalating threats from roads. In Wolong area of Giant Panda National Park, the local giant pandas (Ailuropoda melanoleuca) are divided into two population groups along the National Highway G350 (NHG). Therefore, selecting suitable areas to help those giant pandas communicate across the NHG is necessary. In this research, we evaluated the presence of human activities and simulated their absence to analyze how they affect the giant panda's habitat in Wolong. Subsequently, based on the kernel density estimation (KDE) for giant pandas and the main human distribution locations, we selected suitable areas for the population link between the two road sections on the NHG. We simulated the absence of human activities on the two road sections to compare changes in the habitat suitability index (HSI) and connectivity value (CV) relative to their presence. We aimed to carefully select the area for future giant panda corridor plans and simulate whether eliminating human activities will significantly improve the HSI and CV of the area. Our results show that: (1) Human activities presence has led to subtle changes in the landscape pattern of suitable habitats and a decrease in Wolong by 78.76 km2 compared to their absence. (2) Human activities presence significantly reduced HSI and CV in the 1000 m buffer along the NHG compared to their absence. (3) The HSI and CV of the 1000 m buffer in the simulated absence of human activities for the two road sections were significantly higher than their presence. This research identified the optimal road section for crossing the NHG to link giant panda population groups and habitats in Wolong. These insights are significant for formulating conservation decisions and corridor plans and for promoting wildlife conservation in reserves amid high levels of human activity.

Livestock grazing and the collection of bamboo shoots are the main threats to giant panda (Ailuropoda melanoleuca) habitat in the Liangshan Mountains in China. It is important to clarify the effect of these disturbances to the giant panda to formulate targeted management policies. Based on species distribution models and daily activity models, we investigated the effects of livestock grazing and bamboo shoot collection on giant pandas from May 2021 to July 2022. Our results indicated the giant panda's suitable habitat in the reserve covered 51.83 km2 (15.02% of the reserve area). Grazing and bamboo shoot collection led to losses of 19.08 km2 and 7.68 km2 of suitable habitat, respectively. Together, the 2 activities resulted in a loss of 28.35 km2 of suitable habitat, which was more than half of the area of panda habitat. The areas of suitable habitat for giant pandas significantly overlapped with the areas affected by both disturbances. Giant pandas did not show significant differences in daily activity rhythms under a single disturbance, but the daily activity rhythms of giant pandas differed when we compared the area combining the 2 disturbances with the undisturbed area. Our study reveals that the anthropogenic disturbances in the reserve have varying effects on the suitable habitat range and daily activity rhythm of giant pandas and evidence of a synergistic effect. Therefore, when formulating relevant conservation policies, it is important to fully evaluate the extent and characteristics of anthropogenic disturbances in shaping the population distribution and habitat preferences of the giant panda and other wildlife to enhance the efficacy of conservation management practices. This study employed a species distribution model and a daily activity model to quantify variations in the potential suitable habitat and daily activity rhythms of giant pandas in response to anthropogenic disturbance. We evaluated the degree to which different disturbances affect giant pandas and determined if the combined effects of multiple disturbances produced a compounded impact. image

Land-use changes lead to habitat loss and fragmentation, which poses a further threat to the survival of species. Therefore, it is crucial to analyze how land-use change affects its habitat. 37 counties in Sichuan Province, China, where giant pandas are distributed, were selected as the subjects. Through analyzing land-use change, habitat suitability and connectivity characteristics over the past 20 years, and establishing a correlation between them, the impacts of land-use change on the habitat suitability and connectivity of giant pandas were explained. The results showed that from 2000 to 2020, the different land-use areas in the study area showed a pattern of change with an increase in forest area, built-up area and water area, and a decrease in grassland area and cropland area. There were significant differences in the characteristics of land-use dynamics changes among counties. Changes in land-use dynamics have a significant impact on the habitat suitability and connectivity of giant pandas, which is manifested in the fact that the conversion of forestland to grassland and grassland to cultivated land significantly reduces habitat suitability, while the conversion of grassland to forestland and cultivated to forestland significantly increases the connectivity of giant panda habitats. Changes in the habitat suitability index were significantly and positively correlated with the land-use dynamics index and the land-use degree index. Our findings emphasize the importance of balancing socio-economic development, land-use, and conservation efforts to maintain giant panda habitat. Therefore, the development of rational land-use patterns in future management is key to maximizing the comprehensive social, economic and ecological benefits.

Climate change will impact the distribution of species and their preferred habitat, thereby influencing the ecological processes intrinsic to these species. To investigate these phenomena, we analyzed the habitat distribution, structure, and connectivity of 6 forest ungulate species in Southwest China under current and future climate scenarios. Habitat projections indicate that forest ungulates will migrate to the southwest at higher elevations and the northwest at higher latitudes and elevations in the study area under climate change. The extent to which climate change affects the 6 forest ungulates is quite different. By 2050, there will still be a certain range of habitats for migration in the study area, but the habitat quality of species will have decreased to varying degrees after migration. By 2070, most forest ungulates will begin to experience significant habitat loss and habitat quality decline. The migration of species habitat also leads to a change in species habitat structure. Habitat landscape quality declines for most forest ungulate species. The loss of patches at the junction habitat has a huge impact on species habitat connectivity. The number and distance of corridors between the marginal habitat patches and the core habitat patches increase to a certain extent. To better achieve biodiversity conservation, we should strengthen the restoration and connectivity management of fragmented habitats to protect and restore the current habitats of species. Examples include the management of specific key areas and the establishment of large-scale integrated protected areas such as the Giant Panda National Park.

Climate change can pose a significant threat to terrestrial ecosystems by disrupting the circulation of soil nitrogen. However, experimental analyses on the effect of climate change on soil nitrogen cycles and the implications for the conservation of key wildlife species (i.e., the giant panda, Ailuropoda melanoleuca) remain understudied. We investigated the effects of a 1.5 °C, 3 °C, and 4.5 °C temperature increase on nitrogen distribution in different soil layers of bamboo forest via an in-situ experiment and assessed the implications for the growth and survival of arrow bamboo (Bashania faberi), a critical food resource for giant pandas. Our results showed that warming treatments generally increased soil N content, while effects differed between surface soil and subsurface soil and at different warming treatments. Particularly an increase of 1.5 °C raised the subsurface soil NO3-N content, as well as the content of N in bamboo leaves. We found a significant positive correlation between the subsurface soil NO3-N content and the N content of arrow bamboo. An increase of 3-4.5 °C raised the content of total N and NO3-N in the surface soil and led to a reduction in the total aboveground biomass and survival rate of arrow bamboo. Limited warming (e.g., the increase of 0-1.5 °C) may promote the soil N cycle, raise the N-acetylglucosaminidase (NAG) enzyme activity, increase NO3-N in subsurface soil, increase the N content of bamboo, and boost the biomass of bamboo - all of which could be beneficial to giant panda survival. However, higher warming (e.g., an increase of 3-4.5 °C) resulted in mass death of bamboo and a large reduction in aboveground biomass. Our findings provide a cautiously optimistic scenario for bamboo forest ecosystems under low levels of warming over a short period of time, but risks from higher levels of warming may be serious, especially considering the unpredictability of global climatic change.

为了解大熊猫保护地土地利用变化及其对生境质量的影响,本文以四川大熊猫栖息地所属的37个县(市、区)为研究区域,基于2000-2020年的土地利用数据和生境威胁因子数据,运用土地利用转移矩阵、土地利用动态度、景观格局指数及InVEST模型等研究方法,从土地利用变化视角对大熊猫保护地生境质量变化进行分析.结果表明:2000-2020年,研究区域土地利用变化主要为林地(+1.49％)、建设用地(+59.72％)和水域(+27.79％)面积增加,草地(-2.44％)和耕地(-2.14％)面积减少,变化类型以草地、林地相互转化以及耕地转为建设用地为主;研究区域生境质量变化与景观破碎度变化范围在空间上大致相同,景观破碎度高的地区,生境质量明显较低;生境质量空间上呈现"西高东低"的分布格局,生境质量改善(952.35 km2)的区域面积小于下降(1562.38 km2)的区域,但大熊猫栖息地范围内生境质量保持稳定;整体生境退化程度呈现上升的趋势,生境退化程度指数均值由2000年的0.018上升至2020年的0.022,且生境退化程度高和生境质量低的空间分布格局较为一致,主要分布在研究区域东部和南部地区.研究结果可以为大熊猫的栖息地保护与修复提供科学参考.

Habitat suitability assessment is the basis for wildlife conservation management and habitat restoration. It is a useful tool to understand the quality of wildlife habitat and its potential spatial distribution. In order to reveal the habitat suitability and connectivity of sambar ( Rusa unicolor ) to promote species and biodiversity conservation, this study collected records of sambar ( Rusa unicolor ) from over 2,000 camera traps in the forests of Southwest China in the past 5 years to assess the overall situation of their habitat. The results of the species distribution model revealed that the suitable habitat area for sambar in the five major mountain ranges (Minshan, Qionglai, Daxiangling, Xiaoxiangling, and Liangshan) in Southwest China is 18,231 km 2 , accounting for 17.02% of the total area. The most suitable habitat of sambar is primarily distributed in Qionglai, as well as the intersection areas of Daxiangling, Xiaoxiangling, and Minshan. The temperature annual range, temperature seasonality, elevation, and distance to road were important factors affecting the distribution of suitable habitat for sambar. Analysis of landscape pattern shows that there were 273 habitat patches, with a maximum patch area of 9,983 km 2 , accounting for 54.8% of the total suitable habitat area. However, the segmentation index and separation index of each habitat patch were 0.99 and 106.58, respectively, indicating a relatively high habitat fragmentation in the study area. The results of habitat connectivity analysis showed that the Qionglai mountains have the largest suitable habitat area and the highest connectivity among habitat patches. However, habitat connectivity between the five mountains is very low, suggesting that gene flow among these mountain ranges is probably limited. We therefore recommend strengthening protection of sambar and their habitat, with special attention to the establishment of corridors between the different mountain populations.

The giant panda (Ailuropoda melanoleuca) and the Chinese red panda (Ailurus styani) are distributed in the same region in the mountain forest ecosystem on the eastern edge of the Qinghai Tibet Plateau and share the same food sources. In order to understand how sympatric giant pandas and Chinese red pandas maintain interspecific relationships to achieve stable coexistence, we used species distribution models and diurnal activity rhythms to analyze the spatial and temporal niche characteristics of giant pandas and Chinese red pandas in the Daxiangling Mountain system based on 187 camera traps data. The results show that: (1) In the Daxiangling Mountains, the total area of suitable habitats for giant pandas and Chinese red pandas is 717.61km(2) and 730.00km(2), respectively, accounting for 17.78% and 18.25%, respectively, of the study area. (2) The top five environmental factors contributing to the model of giant panda and Chinese red panda are precipitation seasonality, temperature seasonality, distance to the road, and elevation and vegetation type. (3) The total overlapping area of suitable habitats for giant pandas and Chinese red pandas is 342.23 km(2), of which the overlapping area of highly suitable habitats is 98.91 km(2). The overlapping index of suitable habitats is 0.472, and the overlapping index of highly suitable habitats is 0.348, which indicates that the two achieve spatial niches are separated to achieve stable coexistence. (4) The overlapping index of the daily activity rhythm of giant panda and Chinese red panda is 0.87, which is significantly different (p < .05). The existence of Chinese red panda will significantly affect the daily activity rhythm of giant panda (p < .001). This research can provide scientific reference for the researches about population and habitat protection of giant pandas and Chinese red pandas, so as to understand the driving mechanism of resource allocation and population dynamics of sympatric species.

由于环境条件的异质性和可变性,生活在不同环境中的各物种经过长期的自然选择与进化,出现了体色变异现象.其中,黑化与白化是最显著和普遍的生物体色变异现象,广泛存在于众多动物类群中.True(2003)将黑化定义为"表皮呈现大部分或完全变黑的变异个体或群体现象,这种现象可认为是种群内多型现象或近似种内的固定变异".黑化原因多种多样,如在寒冷的环境中增加运动量、吸引异性、逃避天敌以及充当警戒色等(江幸福等,2007).在黑化现象发生较少的动物类群中,对黑化现象的理解不足容易导致物种分类系统的混淆(Ge et al.,2012).因此,揭示黑化、白化等体色变异现象的发生频率以及变异后的清晰影像等信息对于揭示物种黑化的本质、黑化在生物进化适应中的功能以及完善和修订相关分类系统十分重要.

为了解同域分布有蹄类在环境复杂的山地森林生境中以何种方式维持种间关系以实现稳定共存,基于物种分布模型与日活动模式分析了四川省岷山、邛崃、大相岭、小相岭和凉山五大山系同域分布中华鬣羚(Capricornis milneedwardsii)与中华斑羚(Naemorhedus griseus)的时空生态位特征.结果显示:(1)在四川省五大山系,中华鬣羚的适宜栖息地面积为28006.07 km2,占研究区总面积的26.18％,其中高适宜栖息地面积为10015.90 km2,中华斑羚的适宜栖息地面积为21073.32 km2,占研究区总面积的19.71％,其中高适宜栖息地面积为8396.22 km2;(2)中华鬣羚与中华斑羚在生境因子选择上相似性高、栖息地重叠面积大,其空间生态位重叠度指数D=0.776,I=0.949,其适宜栖息地的主要重叠区域位于岷山和邛崃山系;(3)中华鬣羚与中华斑羚的日活动节律重叠指数为0.812;(4)中华鬣羚与中华斑羚属于同域分布的资源利用型竞争物种,中华鬣羚的存在会显著影响中华斑羚的日活动节律(P=0.016);二者同域分布时都会增加其昼间活动强度,并增加活动高峰期的强度及持续时间.本研究初步分析了中华鬣羚与中华斑羚的时空生态位特征,揭示了二者在空间、时间生态位上种群共存及种间竞争的耦合关系.研究有利于深入理解同域分布动物时空生态位特征、近缘物种的共存机制及种间竞争关系,为有蹄类等珍稀野生动物种群及栖息地的保护提供科学参考.