Qian Hong, Grau Oriol
Research and Collections Center, Illinois State Museum, 1011 East Ash Street, Springfield, IL 62703, USA.
Parc Natural de l'Alt Pirineu, Llavorsí 25595, Catalonia, Spain.
Plant Divers. 2024 Jul 18;47(1):98-105. doi: 10.1016/j.pld.2024.07.005. eCollection 2025 Jan.
Understanding the underlying mechanisms driving species assembly along elevational gradients is of great interest in ecology and biogeography. The Himalaya is one of the world's hotspots of biodiversity, and the elevational gradient of the central Himalaya in Nepal is one of the longest elevational gradients in the world. Mosses are important constituents of vegetation in the Himalaya, and knowledge of geographic patterns and ecological causes of phylogenetic structure of mosses along elevational gradients in the Himalaya is critical to understanding the assembly of plant diversity in general, and moss diversity in particular, in the Himalaya. Here, we investigate the relationships of phylogenetic structure metrics reflecting different evolutionary depths with elevation and climatic variables representing mean temperature and precipitation conditions, climate extremes, and climate seasonality for mosses distributed along an elevational gradient spanning about 5000 m in the central Himalaya, Nepal. For a given climatic variable, different metrics of phylogenetic structure show different spatial and climatic patterns, but all phylogenetic metrics standardized for species richness show that phylogenetic dispersion in moss assemblages tend to increase with increasing elevation and decreasing temperature. The standardized effect size of mean pairwise distance of moss assemblages shows a triphasic (zig-zag) pattern, which is generally consistent with the triphasic patterns previously found in angiosperms and ferns along the same elevational gradient. Our study shows that temperature-related variables and climate seasonality variables are more important drivers of phylogenetic dispersion in mosses in Nepal, compared with precipitation-related variables and climate extreme variables, respectively.
了解驱动物种沿海拔梯度组装的潜在机制是生态学和生物地理学中备受关注的问题。喜马拉雅地区是世界生物多样性热点地区之一，尼泊尔中部喜马拉雅地区的海拔梯度是世界上最长的海拔梯度之一。苔藓是喜马拉雅地区植被的重要组成部分，了解喜马拉雅地区苔藓系统发育结构的地理格局和生态成因，对于理解整个喜马拉雅地区植物多样性的组装，特别是苔藓多样性的组装至关重要。在此，我们研究了反映不同进化深度的系统发育结构指标与代表平均温度和降水条件、气候极端情况以及气候季节性的海拔和气候变量之间的关系，这些苔藓分布在尼泊尔中部喜马拉雅地区约5000米的海拔梯度上。对于给定的气候变量，系统发育结构的不同指标呈现出不同的空间和气候格局，但所有针对物种丰富度进行标准化的系统发育指标均表明，苔藓群落中的系统发育离散度往往随着海拔升高和温度降低而增加。苔藓群落平均成对距离的标准化效应大小呈现出三相（锯齿状）模式，这与之前在相同海拔梯度上被子植物和蕨类植物中发现的三相模式总体一致。我们的研究表明，与降水相关变量和气候极端变量相比，温度相关变量和气候季节性变量分别是尼泊尔苔藓系统发育离散度更重要的驱动因素。
