The work was supported by Science and Technology Plan Projects of Zhejiang Province [grant numbers 2019C02024].
Abstract: Satyrium is an endangered and rare genus of plant that has various pharmacodynamic functions. The prediction of potentially suitable habitat of Satyrium species and to analyze their changes, the model MaxEnt niche was applied; furthermore, the receiver operating characteristic curve was applied to analyze accuracy. The results provided an available reference for implementation of long-term conservation and management approaches for the species. Under the current climatic conditions, the area of the total suitable habitat forSatyrium ciliatum (S. ciliatum ) in China is 32.51 × 104 km2, the total suitable habitat area for Satyrium nepalense (S. nepalense ) in China is 61.76 × 104 km2, and the area of the total suitable habitat for Satyrium yunnanense (S. yunnanense ) in China is 89.73 × 104km2. The potential suitable habitat ofSatyrium is mainly distributed in Southwest China. The major environmental changes influencing the geographical distribution ofS. ciliatum were temperature seasonality (Bio4), isothermality (Bio3), and mean temperature of coldest quarter (Bio11). The geographical distribution ofS. nepalense was mainly affected by environmental variables like temperature seasonality (Bio4), isothermal environment (Bio3), and precipitation of the coldest quarter (Bio19); and the geographical distribution of the species S. yunnanense were mainly affected by the environmental variables such as temperature seasonality (Bio4), isothermality (Bio3) and lower temperature of the coldest month (Bio6). The distribution range of Satyrium’s extended with global warming increased, in both situations’ emissions of greenhouse gases with lower concentration (SSP1-2.6) and the emission of greenhouse gases with higher concentration (SSP5-8.5). According to the study, the distribution of suitable habitat would shift with change to higher elevated areas in the coming time.
Keywords: Satyrium , MaxEnt niche, the potential suitable habitat, environmental variables.
Global warming is one of the crucial environmental problems facing the world today (1). The global temperature has risen by about 1℃ in the past century, especially in the past 30 years, causing some florae species to move to higher altitude areas, as reported by the Fifth Assessment Report (AR5) of the United Nations Intergovernmental Panel on Climate Change (2). According to the different suggestions that the future change in climate has an impact on the distribution range of species, resulting in the loss of biodiversity and the endangered species will be extinct (3). After climate change, the prediction of the appropriate habitat of species was considered important in the future (4). In research on the geographical distribution range of plants affected by climate change, the species distribution model (SDM) uses the distribution data of species and environmental variables in their habitat to predict the basic niche of species. These data are combined with environmental data in different periods for simulating the potential distribution areas of species in those periods (5). Among many SDMs, the maximum entropy model (MaxEnt) has the advantages of fast modeling, wide use and high accuracy, and stability even with a small sample size (6, 7). It can better anticipate the possible distribution of species compared with other SDMs (8).
Satyrium (Orchidaceae) is rare and endangered plant genus with about 92 species, mostly found on continents of Africa, 5 species found in Madagascar and 4 species are found in Asian countries (9). Just 3 species are found in China alone, namely, Satyrium ciliatum(S. ciliatum ), Satyrium nepalense (S. nepalense ), and Satyrium yunnanense (S. yunnanense ) (10).Satyrium is also used for traditional herbal medicinal purposes; such as the traditional healthcare centers in India used the tubers ofS. nepalense to make energy tonics and it is mostly used for curing different types of fevers.
The number of Satyrium resources has been rapidly diminishing. Its population has a fragmented distribution and is in a rare and endangered state. It is facing extinction because of the value of herbal medicine and the serious deterioration of the ecological environment in recent times (9). The changes in climate will result in changes in the biological phenology period. This in turn will result in changes in the geographical distribution of species and a quickening of the rate of species extinction. Therefore, it is necessary to adequately understand the changing trends of the geographical distribution of species under the conditions of climate change and to develop relative protection strategies.
The diversity of Satyrium species were predicted by employing the MaxEnt model:
(1) In current climatic conditions, the geographical diversity ofSatyrium species in China were studied, and relationship between these distributions and environmental changes were studied. The main environmental variables limiting their potential geographically diversity was outlined.
(2) The potential geographical distribution and shifting trend of the centroid of suitable areas in China were predicted under the scenario of future climate change. To offer a scientific foundation for the appropriate protection and utilization of Satyrium, the conceivable geographical distribution, dynamic change features, and affecting environmental elements in China under different climate conditions were defined.