CAS Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Tianshui Middle Road 18, Lanzhou, 730000, Gansu, China.
MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshui South Road 222, Lanzhou, 730000, Gansu, China.
Environ Sci Pollut Res Int. 2018 Oct;25(29):28998-29005. doi: 10.1007/s11356-018-2893-2. Epub 2018 Aug 14.
As alpine plants, cushion species are particularly susceptible to environment changes. Thus, understanding population structure and community diversity variation of cushion plants along elevational gradients is crucial for estimating their response to predicted climate changes. In this study, Thylacospermum caespitosum populations from three elevations (low, medium, and high) in three climate zones of China (the Kunlun, Qilian, and Tianshan Mountains) were selected to evaluate the effect of elevation on the structure of T. caespitosum populations and species diversity of cushion communities. Results showed that elevation substantially influenced T. caespitosum populations (size structure, density, and death rate), as well as richness (α-diversity) and microhabitat species pool (species pool) of cushion communities. In the low elevations, T. caespitosum populations were in decline due to a lower ratio of small plants and higher mortality compared with populations at medium and high elevations. The α-diversity and species pool in cushion communities were significantly increased with decreased elevation, but the importance value of T. caespitosum decreased accordingly. Moreover, there was a significant positive correlation between elevation and relative importance value (the importance of one species in the community) of T. caespitosum (r = 0.883; P < 0.01). Elevation was significantly negatively correlated with the mortality rate of T. caespitosum (r = - 0.855; P < 0.01), α-diversity (r = - 0.933; P < 0.001), and species pool (r = - 0.885; P < 0.01). The declining characters of T. caespitosum population structure were obvious in low elevation populations. This decline may directly or indirectly relate to environmental change. Effects of elevation can provide an early indication of range contractions and population declines of cushion species with future climate warming. We call for more mechanistic studies of climate change impacts on cushion populations, particularly in alpine systems near the snow line.
作为高山植物，垫状植物特别容易受到环境变化的影响。因此，了解垫状植物种群结构和群落多样性沿海拔梯度的变化对于估计它们对预测气候变化的响应至关重要。本研究选择了中国昆仑、祁连和天山三个气候带三个海拔高度（低、中、高）的绵刺种群，以评估海拔对绵刺种群结构和垫状群落物种多样性的影响。结果表明，海拔高度显著影响绵刺种群（大小结构、密度和死亡率）以及垫状群落的丰富度（α-多样性）和小生境物种库（物种库）。在低海拔地区，由于小型植物的比例较低和死亡率较高，绵刺种群呈下降趋势，与中、高海拔地区的种群相比。随着海拔的降低，垫状群落的 α-多样性和物种库显著增加，但绵刺的重要值相应降低。此外，海拔与绵刺的相对重要值（群落中一种植物的重要性）呈显著正相关（r=0.883；P<0.01）。海拔与绵刺死亡率（r=-0.855；P<0.01）、α-多样性（r=-0.933；P<0.001）和物种库（r=-0.885；P<0.01）呈显著负相关。在低海拔地区，绵刺种群结构的衰退特征明显。这种下降可能直接或间接与环境变化有关。海拔的影响可以提供垫状物种范围收缩和种群减少的早期迹象，随着未来气候变暖。我们呼吁对气候变化对垫状种群的影响进行更多的机制研究，特别是在接近雪线的高山系统中。
