汉丰湖入湖支流河岸带植物群落特征及其环境影响分析

Effects of Environment on Riparian Plant Community in the Inflow Branches of the Hanfeng Lake

为探究三峡库区汉丰湖入湖支流河岸带植物分布格局及其环境特征,2013年6月在4条主要入湖支流——南河、桃溪河、头道河和东河设置12个站点,从纵向分布格局(沿河岸带上游至下游)和侧向分布格局(沿水面到高地)开展调查。结果显示,共采集到维管束植物69科、155属、171种;其中禾本科、菊科和蔷薇科种类数较多,分别为19种、16种和9种,占总种数的11.1%、9.4%和5.3%,生活型以草本为主(68.4%),其次为灌木(12.9%);草本植物鲜重、盖度和高度均值依次为(1 951.6±3 076.2)g/m2、(79.9±34.7)%和(34.2±18.3)cm;重要值较大的植物主要有枫杨(Pterocarya stenoptera)、牛筋草(Eleusine indica)和金发草(Pogonatherum paniceum)。河岸带土壤容重、p H值、有机质、碱解氮、有效磷、有效钾的含量均值依次为(1.32±0.19)g/cm3、(7.91±0.38)、(18.22±21.45)g/kg、(60.58±68.67)mg/kg、(6.51±5.21)mg/kg和(59.42±34.33)mg/kg。典范对应分析(CCA)表明,影响河岸带植物重要值的环境因子主要是高程和土壤有机质。

The riparian zone regulates the flux of energy, nutrients, and biotic interchange between aquatic and ter- restrial ecosystems and provides many important ecological services critical to maintaining watershed productivity and sustainability. This area of research has attracted increasing attention among ecologists and environmental sci- entists both at home and abroad. In this study the riparian plant communities and riparian habitats were investigated across the four rivers flowing into Hanfeng Lake （Nanhe, Taoxi, Toudao, and Donghe） and the distribution of the plant communities and their relationship with environmental factors were analyzed. The study will provide scientific data for the management and restoration of the riparian ecosystems. Twelve transects along the longitudinal gradient from upstream to downstream were established in the four rivers and three study areas along the lateral gradient from the river bank to the adjacent upland were established for each transect （at 0 -1 m, 2 -5 m and 6 -10 m above water level）. The height, cover and biomass above ground of all herbaceous plants were measured in a 1 m×1 m plot of each study area in June 2013. The cover and branch diameter of the trees and shrubs were determined in a 5 m （vertical）×10 m （horizontal） plot of each study area. The soil bulk density of each plot was measured using the cutting-ring method and soil cores （0 -20 cm） for each plot were collected for measurement of moisture, pH, organic matter, available nitrogen, available phosphorous and available potassium in the laboratory. A total of 171 species of vascular plants belonging to 155 genera and 69 families were observed with high species richness of As- teraceae（ 19 species ） , Gramineae （ 16 species） and Rosaceae （ 9 species）, accounting for 11. l%, 9.4% and 5.3% of total plant species. The plant communities were mainly composed of herbs （68. 4% ） and shrubs （ 12. 9% ） in terms of biotype. The mean values of fresh weight, cover and height of the herbaceous plants were （ 1 951.6 ±3 076.2） g/m2, （79.9 ±34.7 ）% and （34.2 ± 18.3） cm. Plant species with high importance values were Pterocarya stenoptera, Eleusine indica and Pogonatherum paniceum. The mean values of soil density, pH, or- ganic matter, available nitrogen, available phosphorus and available potassium were （1.32 ±0.19） g/cm3, （7.91 ±0.38）, （18.22 ± 21.45 ） g/kg, （60.58 ± 68.67） mg/kg, （6. 51 ± 5. 21） mg/kg and （59.42 ± 34.33） mg/kg, respectively. Canonical correspondence analysis （CCA） revealed that the main environmental var- iables affecting the importance value of species were elevation and soil organic matter.