Conserv Biol. 2015 Sep 15. doi: 10.1111/cobi.12584. [Epub ahead of print]
Abstract
Xishuangbanna
is on the northern margins of tropical Asia in southwestern China and
has the largest area of tropical forest remaining in the country. It is
in the Indo-Burma hotspot and contains 16% of China's vascular flora in
<0.2% of the country's total area (19,690 km2 ). Rapid
expansion of monoculture crops in the last 20 years, particularly
rubber, threatens this region's exceptional biodiversity. To understand
the effects of land-use change and collection on orchid species diversity and determine protection priorities, we conducted systematic field surveys, observed markets, interviewed orchid collectors, and then determined the conservation status of all orchids. We identified 426 orchid species in 115 genera in Xishuangbanna: 31% of all orchid species that occur in China. Species richness was highest at 1000-1200 m elevation. Three orchid
species were assessed as possibly extinct in the wild, 15 as critically
endangered, 82 as endangered, 124 as vulnerable, 186 as least concern,
and 16 as data deficient. Declines over 20 years in harvested species
suggested over-collection was the major threat, and utility value (i.e.,
medicinal or
ornamental value) was significantly related to endangerment. Expansion
of rubber tree plantations was less of a threat to orchids than to other
taxa because only 75 orchid
species (17.6%) occurred below the 1000-m-elevation ceiling for rubber
cultivation, and most of these (46) occurred in nature reserves.
However, climate change is projected to lift this ceiling to around 1300
m by 2050, and the limited area at higher elevations reduces the
potential for upslope range expansion. The Xishuangbanna Tropical
Botanical Garden is committed to achieving zero plant extinctions in
Xishuangbanna, and orchids are a high priority. Appropriate in and ex
situ conservation strategies, including new protected areas and seed
banking, have been developed for every threatened orchid species and are being implemented.
© 2015 Society for Conservation Biology.
© 2015 Society for Conservation Biology.
