塔里木河中游植物群落与环境因子的关系

应用数量分类和排序方法，对新疆塔里木河中游地区植被进行了多元统计分析。结果表明，该地区共有植物23种，隶属于11科21属。其中，多数植物种类在样方中的出现频次较低，说明该地区植物物种丰富度较低。TWINSPAN结果表明，该地区3个断面19个样地可分为3个主要类型，与实际调查结果一致。CCA排序结果同TWINSPAN分类结果基本一致，反映出植物群落分布格局的一般规律及其随环境因子梯度变化的趋势。分析了不同环境因子间的关系，并从定量的角度，以CCA排序图直观地揭示了决定塔里木河中游地区植物群落分布的环境因子主要是地下水位和土壤含水量，其回归模型分别为：X1＝-9.5991L 100.86（R^2=0.6459)；X2＝1.65W 43.011(R^2=0.7646)。

Plant Communities and Their Interrelations with Environmental Factors in the Middle Reaches of the Tarim River

Plant communities were sampled in the lower reaches of t he Tarim River, Xinjiang. The results showed that among the 475 sampled quartets from 19 sites, 23 plant species were identified, which belong to 21 genera in 11 families, most of which have low occurrence freque ncy in quadrats. The most common species of this study, Tamarix ramosi ssima occurred in 17 sites (89.47% of the total investigated sites), fol lowed by Phragmites communis, which occurred in 12 sites (63.15% of the total investigated sites). Populus euphratica and Lycium ruthenicum were fou nd in 11 sites respectively, accounting for 57.89% of the total sites. Quan titative classification (TWINSPAN) and ordination (CCA) methods were used to study the distribution patterns of 23 plant species at 19 sites in this study area. The TWINSPAN analysis identified three site groups. Site group 1 contains 7 sites, which were located in Shazihe transect. Site group 2 contains 5 sites, which were located in Wusman transect. Site group 3 contains 7 sites, which were located in Aqihe transect except for site 10. The site group 3 separated firstly from all the 19 sites by TWINSPAN showed evident difference with other two site grou ps. The 23 plant species could be also divided into 3 ecological speci es groups using TWINSPAN analysis. CCA results were consistent with TW INSPAN results. The distribution patterns of plant species were most str ongly associated with underground water table, soil moisture and soil pH value. To a lesser extent, distribution of species was associated with soil alkalinity, underground water mineralization and altitude. The major en vironmental variables are ground water level and soil moisture, and th e regression model as below respectively: X 1 =-9.5991L + 100.86 (R 2 = 0.6459);X 2 = 1.65W + 43.011 (R 2 = 0.7646). Although the species did not cluster into well-defined groups, loose arrangements of species can be identified which were ass ociated in a similar way with the environmental variables.