Fig. 9. (a) The shifts of habitat population centroid and(b) the percent
contribution of the environment variables in 3 climate zones.
The constraint of STZ distribution is LUCC accounting for 34.3%
importance. The distribution in
STZ
is also influenced by bio14 and bio15 accounting for 21.6% and
11.4%,respectively.
Seasonal
rainfall significantly affected the distribution in this region. NDVI is
the most important variable in the distribution of MSZ and MTZ which the
percent contribution is 51.6% and 55.5% in 2 regions. Alt also plays a
great role accounting for 24.6% in MSZ and LUCC accounts for 19.7% in
MTZ.
The result shows that the reduction of the habitat area and the movement
of the population centroid will cause an increase in the distance and
the consumption, which forces the birds change their migration time and
route. Moreover, some birds may be not even able to achieve migration.
The habitat of migratory birds in central China trends to move towards
east in future, and the habitat of migratory birds in the southern China
trends to move towards south.
The result shows that NDVI is an important variable in southern China.
The variable shows a great percent contribution to the distribution of
migratory birds in southern China, which means the food is the
constraint of birds. In the middle China, LUCC plays a great role to the
distribution. Especially in the Haihe River Basin and Yellow River
Basin, the importance of LUCC accounts for over 30%, which means human
activities influence the distribution greatly. In the Yangtze River
Basin of the middle subtropical zone, we can see alt is an important
variable to the distribution. Because of the wide area, the altitude
varies greatly in the regions.
Implications of birds
protection
4.2.1 The status of birds protection in
China
Species
with
broad
tolerance may persist or even
expand in the changing environments, but migratory birds are sensitive
to the environment (Huang et al., 2017; Runge et al., 2015). It is not
effective to protect the biodiversity in China though the country has
committed great contribution in the remission of biodiversity loss
(Young et al., 2014). The main measure of protecting the species is
establishing the protected area in China.
The
identification and delineation of habitat is considered as the
cornerstone of the establishment of protected areas.
Whether
nature reserves works well under climate change has been more important
to protect species. Although the number of nature reserves increases
recent year, the protective effect is not obvious. For there is no
complete system to estimate the effectiveness of nature reserves (Liang
et al., 2018c; Ma et al., 2019; Sang et al., 2011). It is more difficult
to ensure the effectiveness of protected areas since they move to
different places each year.
Considering
the
climate change and the distribution of the migratory birds, we compared
the differences between the nature reserves and the suitable
areas(Fig.10).
Endangered
species are more environmentally sensitive and the population of these
species is rare. The migration of these endangered species makes it more
difficult for human to protect them effectively.