关键词: 极小种群野生植物, 种群特征, 濒危机制, 人为干扰, 保护遗传多样性

Abstract

Aims: It is important to clearly identify the mechanisms that leads Wild Plants with Extremely Small Populations to become endangered as a way to effectively protect these WPESP.
Progresses: Here, we review the population characteristics, internal causes, and external threat factors for the first-class protected WPESP (28 species in China) and accordingly discuss the mechanisms leading to plants becoming endangered. Most WPESP displayed at least one of four population characteristics that likely resulted in their current endangered status. First, 20 WPESP species (such as Parakmeria omeiensis, Abies beshanzuensisand Cycas changjiangensis) had a narrow distribution area. Combining a narrow distribution area with low fertility and weak competitive capacity as intrinsic factors results in WPESP species to become endangered. Second, the distribution structure for 11 WPESP species was aggregated (e.g., Abies ziyuanensis, Kmeria septentrionalis, Metasequoia glyptostroboides). Third, there was declining population structures for 11 WPESP (e.g.,Thuja sutchuenensis,Metasequoia glyptostroboides, Pinus squamaia). This declining population structure has a negative role in maintaining stable population growth. The fourth population characteristic was that the genetic diversity of 13 WPESP species (46%) was low (e.g., Manglietia decidua, Abies yuanbaoshanensis, Cycas debaoensis). Low genetic diversity is unfavorable for these species to adapt to a changing environment and leads them to face risks of extinction. Twenty-one WPESP species (75%) exhibited low fertility, such as Acer yangjuechi and Abies beshanzuensis. The poor seed quality and low yield of WPESP species leads to a difficult regeneration of populations. The competitive capacity of 57% WPESP species (16) is relatively weak (e.g., Shaniodendron subaequaleandCathaya argyrophylla), which decreases growth and reproduction for these species. External factors that threaten WPESP mainly include overexploitation decreasing abundance (15 species), human activities and natural disasters destroying habitats (25 species), and geological movements plus climate change affecting the survival of WPESP.
Prospects: In addition to protecting WPESP against destruction from human activities, conservation strategies should focus on the maintenance of population size and the conservation of genetic diversity of WPESP.

Key words: Wild Plants with Extremely Small Populations (WPESP), population characteristics, endangered mechanism, human disturbance, conservation of genetic diversity