Abstract:

Bryophytes are an indispensable part of biodiversity and play important ecological roles in terms of water balance, erosion control, nitrogen budget, etc. In order to reveal the factors which affect the variability of geographic components of bryophytes, we compiled a bryophyte dataset of 27 national nature reserves from 19 provinces and 2 municipalities and analyzed the dataset to explore the contribution of spatial and environmental variables to the variability of bryophytes’ geographic components using distance-based Moran’s eigenvector maps (dbMEM). The analysis was conducted on environmental variables, coordinates of the centroids, climate records, clay proportion and elevation of these nature reserves. The results present that (1) in total, 1962 species (including 21 subspecies and 94 varieties) were recorded in the 27 national nature reserves, belonging to 130 families and 445 genera. Of these, there were 3 key national protected wild bryophytes and 62 threatened species. (2) The dominant distribution type was Temperate. There were two gradients for the distribution pattern of these bryophytes, a significant latitudinal increasing gradient of Temperate elements along with a decreasing gradient of Tropical elements and Asia-Australian-Oceania elements from south to north while East Asian elements peaked in the middle, and a longitudinal increase of East Asian elements from west to east, while Tropical elements and Asia-Australian-Oceania elements peaked and Temperate elements decreased down to the bottom in the middle. (3) Variation partitioning showed that the unique effect of environmental factors (18.04%) composed of the min temperature of coldest month, mean annual temperature and clay percentage obtained by forward selection was higher than that of spatial factors (3.30%) which were composed of dbMEM1 and dbMEM3 obtained by forward selection. The common effect of environmental and spatial factors was 49.15%. The results suggest that environmental factors and spatial distance affected the similarity of bryophytes geographical elements among the 27 nature reserves together, and the contribution of environmental factors was higher than that of spatial factors. This study reveals preliminarily the factors influencing the similarity of geographic elements among 27 nature reserves from the perspective of modern environmental factors and spatial distance, providing a theoretical basis for the study of bryoflora.

Key words: bryophyte, area type, climate factor, spatial distance, clay proportion, variation partitioning, nature reserve

摘要：

苔藓植物是生物多样性的重要组成部分，在水分平衡、侵蚀防治和氮收支等方面发挥着重要功能。为了揭示苔藓植物地理成分构成差异的影响因素，该研究基于19个省和2个直辖市内27个国家级自然保护区内的苔藓植物物种数据，以及中心地理坐标、气候因子、黏土含量和海拔等参数，利用中心经纬度坐标通过基于距离的Moran特征向量图（distance-based Moran’s eigenvector maps，dbMEM）构建空间变量，分析了空间因子和环境因子对苔藓植物地理成分分异的贡献。结果表明，（1）27个国家级自然保护区共有苔藓植物130科445属1962种（包含21个亚种和94个变种），其中有国家重点保护野生植物3种，受威胁物种62个。（2）分布区类型以温带分布为主。在纬度上，温带成分自南向北显著增加，东亚成分在中部达到最大值，热带成分和亚洲-澳大利亚-大洋洲成分均显著减少；在经度上，温带成分在中部处于最低值，东亚成分自西向东显著增加，热带成分和亚洲-澳大利亚-大洋洲成分在中部达到最大值。（3）变差分解显示由前向选择得到的最冷月最低温、年均温和黏土含量组成的环境因子（18.04%）的独自效应（unique effect）高于由前向选择得到的dbMEM1和dbMEM3组成的空间因子（3.30%），环境因子和空间因子的共同效应（common effect）为49.15%，表明环境因子和空间因子共同影响27个保护区间地理成分的相似性，并且环境因子的贡献要高于空间因子。该研究基于现代环境因素和空间距离，初步揭示了影响27个保护区间地理成分相似性的因素，为苔藓植物区系研究提供了一定的理论基础。

关键词: 苔藓植物, 分布区类型, 气候因子, 空间距离, 黏土含量, 变差分解, 自然保护区