祁连山中段狼毒入侵退化草甸群落格局及环境解释

Spatial pattern of degraded alpine communities invaded by Stellera chamaejasme and environmental interpretation in the central Qilian Mountain

中文关键词:双向指示种分析  除趋势对应分析  典范对应分析  地理信息系统  环境因素  狼毒

keywords:TWINSPAN  DCA  CCA  GIS  environmental factor  Stellera chamaejasme

中文摘要:为明确狼毒Stellera chamaejasme入侵退化草甸的群落分布格局及其与环境因子之间的关系，在青海省祁连县选取典型研究区，综合运用双向指示种分析（two-way indicator species analysis，TWINSPAN）分类方法、除趋势对应分析（detrended correspondence analysis，DCA）和典范对应分析（canonical correspondence analysis，CCA）排序方法，结合地理信息系统（geographic information system，GIS）空间分析技术，在区域尺度上分析狼毒型退化草甸群落的分类特征及环境响应。结果表明：研究区草甸群落中共调查到18科30属37种植物，其中早熟禾Poa annua、狼毒、高山嵩草Kobresia pygmaea、委陵菜Potentilla chinensis、花苜蓿Medicago ruthenica和麻花艽Gentiana straminea等为优势种，蒲公英Taraxacum mongolicum、异叶米口袋Gueldenstaedtia diversifolia、肉果草Lancea tibetica、草玉梅Anemone rivularis和披针叶野决明Thermopsis lanceolata等为主要伴生种。TWINSPAN分类将退化草甸群落划分成6种群落，分别是早熟禾+高山嵩草+披针叶野决明+二裂委陵菜Potentilla bifurca群落、狼毒+早熟禾+委陵菜+披针叶野决明群落、狼毒+早熟禾+麻花艽+花苜蓿群落、早熟禾+狼毒+草玉梅+花苜蓿群落、垂穗披碱草Elymus nutans+花苜蓿+蒲公英+鹅绒委陵菜Argentina anserina群落、金露梅Potentilla fruticosa+早熟禾+车前Plantago asiatica+鹅绒委陵菜群落。其中，狼毒入侵群落中毒杂草类植物占比明显高于原生草甸群落，莎草科植物不具有生长优势，入侵群落中狼毒平均盖度随着入侵程度的加重而增加。对土壤、地形、气候因子以及综合环境因子的DCA和CCA排序结果显示，影响狼毒入侵草甸群落分布的主要环境因子为土壤含水量，其次为年均温和经度，表明研究区内植物群落的分布格局受水分、热量和空间因子共同影响。

Abstract:To determine the spatial pattern of Stellera chamaejasme invaded alpine communities and its relationship with environmental factors, a typical study area in Qilian County of Qinghai Province was selected, the classification of degraded alpine communities and the corresponding environmental response at the regional scale were analyzed with integrating two-way indicator species analysis (TWINSPAN) classification, detrended correspondence analysis (DCA)/canonical correspondence analysis (CCA) and geographic information system (GIS) technology. The results showed that 18 families, 30 genera, and 37 species was examined in the study area. The dominant species of communities in the region were Poa annua, S. chamaejasme, Kobresia pygmaea, Potentilla chinensis, Medicago ruthenica, and Gentiana straminea, and the companion species include Taraxacum mongolicum, Gueldenstaedtia diversifolia, Lancea tibetica, Anemone rivularis, and Thermopsis lanceolata. TWINSPAN classification divides alpine meadow communities into six groups: Poa annua+K. pygmaea+Thermopsis lanceolata+ Potentilla bifurca community, S. chamaejasme+Poa annua+Potentilla chinensis+Thermopsis lanceolata community, S. chamaejasme+Poa annua+Gentiana straminea+M. ruthenica community, Poa annua+S. chamaejasme+Anemone rivularis+M. ruthenica community, Elymus nutans+M. ruthenica+Taraxacum mongolicum+Argentina anserina community, Potentilla fruticosa+Poa annua+Plantago asiatica+ Argentina anserina community. Compared with native communities, the proportion of the forbs and poisonous plants in S. chamaejasme communities notably increased, and cyperaceous plants did not exhibit significant growth advantages. As invasion aggravated, the average coverage of S. chamaejasme invaded communities increased. Hierarchical CCA ordination of soil, topographic and climatic factors, and subsequent comprehensive ordination showed that key environmental factors affecting spatial distribution of S. chamaejasme communities in the study area were soil moisture content, followed by mean annual temperature and longitude, indicating that the distribution pattern of plant communities is controlled by a combination of moisture, heat and spatial factors in the degraded alpine meadow.