4.3 Prospective geographical distribution and conservation
The two profiles of the suitable distribution for the macaques in the 2050s proposed with SSP2 and SSP5 emission scenarios and presented in Figures 2 and 3 demonstrate that macaques would be distributed in the southern and eastern Southwest, southeastern Northwest, and southeastern Coastal. Compared to the current profiles, the highly suitable distribution would be slightly increased referring to SSP2 but continue reducing considering SSP5 (Figure 3), implying that the greenhouse emission patterns would play a significant role in shaping macaques’ future distribution and conservation.
The trend of moving to lower elevations in some areas in the following years (Figure 4) could be closely related to what has been done by the Chinese Government over the last two decades after realizing the seriousness and urgency of conservation and environmental protection. Such as implementing the six Key Forestry Projects (SKFPs), targeting 76 million ha of land for afforestation and reforestation, covering 97% of China’s counties (Wang et al., 2007). As a result, total forest coverage in China increased from 16.55% in the 1990s to 22.9% in 2018 (Song and Zhang, 2010; Cui and Liu, 2020). Most significantly, logging natural forests for commercial purposes has been banned in some places bearing remarkable diversity of hot spots, such as the upper reaches of the Yangtze River and the upper and middle reaches of the Yellow River, involving 13 provinces (Xu et al., 2006). On the other hand, Pas have gained substantial attention; as of 2018, 11,800 Pas have been established in China, covering about 18% of China’s terrestrial area and 4.1% of its marine area (Feng et al., 2021).
Unfortunately, referring to Table S3, macaques are left out of such PA promotion: more than 87% of their suitable habitats from now on to the 2050s are not covered by Pas, indicating their conservation prospect is facing the challenge, and the implementation of the conservation strategies proposed (please see below) in this study is urgent.
On the other hand, migration corridors for the macaques would be noticeably reduced, referring to SSP2, corresponding to further fragmented habitats. Such passages would be more condensed in the southern Central, featured by shorter and isolated, considering SSP5 (Figure 5), indicating that their expected migration space would be further confined. That especially applies to some threatened taxa, such as the Arunachal macaque, distributed only in southeastern Tibet (Kumar et al., 2020), at the edge of extinction due to hunting and retaliatory killing in response to crop damage (Sinha et al., 2006). The other species having reduced habitats and less moving corridors are the northern pig-tailed macaques restricted to southwestern Yunnan, west of the Yuanjiang River and east of the Nujiang River (Sun et al., 2020), and the white-cheeked macaques, a newly discovered in southeastern Tibet (Li et al., 2015).
According to Figure 5, more potential habitat corridors for macaques are currently distributed in the Southwest and Central regions, with poor connectivity in the southern Central region, following highly suitable habitats being fragmented in the 2050s, referring to SSP5 (Figure 5C). Besides macaques, other wildlife would be suffered in this area, e.g., the Chinese giant salamanders (Andrias davidianus ) (Zhang et al., 2020), and black-faced spoonbill (Platalea minor ) (Hu et al., 2010).
The proposed macaque distribution trajectories assume that seven species’ conservation situations are equally weighted. However, there is a significant variation among species regarding their differences in ecology, environment, geographic contour, elevation, and human activities. In general, the following three groups should be considered differently:
  1. Macaca cyclopis in Twain and M. mulatta in the mainland are featured by stable population sizes and broad distribution (the latter). Their main threat is the conflicts with humans for cropland feeding (Lu et al., 2018; Wu and Long, 2020).
  2. Macaca arctoides, M. thibetana and M. assamensis . They primarily face the pressures of habitat fragmentation and degradation caused by expanded urbanization, rising human activity, and global climate change (Li, 1999; Boonratana et al., 2020).
  3. Macaca leucogenys, M. munzala and M. leonina , whose biological and distribution issues are still less understood, with narrow distribution and small population sizes. The main threats are hunting, land conversion, hydroelectric power station construction, and habitat fragmentation (Ma and Wang, 1988; Sinha et al., 2006; Li et al., 2015).