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:
- 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).
- 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).
- 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).