摘要
通过对岷江干旱河谷植被及其环境因子的系统取样调查 ,采用β多样性指数 - Cody指数 ,从海拔、样带、群系、地形以及土壤养分、水分梯度上研究了该地区植物群落的物种周转速率。结果表明 :随海拔的升高 ,物种周转速率表现出“高 -低 -高”的变化规律。在海拔 130 0～ 16 0 0 m和 190 0～ 2 2 0 0 m这两个海拔段 ,物种平均替代速率均较高 ;而在 16 0 0～ 190 0 m海拔段 ,物种平均替代速率较低。β多样性在样带梯度上的变化表现为干旱河谷核心区的样带较南部和北部过渡区的样带有较高的物种周转速率 ,这与样带所处的环境条件有关。群系之间的β多样性表现为 :华帚菊 -小黄素馨灌丛、金花小檗 -忍冬灌丛、黄花亚菊灌丛、子栎灌丛、小花滇紫草灌丛、莸灌丛、绣线菊灌丛与其它灌丛之间有着较高的物种周转速率。坡面不同地形上的物种周转速率 :不同坡向 ,阴坡 >半阴半阳坡 >阳坡 ;不同坡形 ,凹坡 >平坡 >凸坡 ;不同坡位 ,下坡位 >上坡位 >中坡位。β多样性在土壤水分和养分梯度上的变化表现为与土壤水解 N、速效 K、全 N含量、全 P含量以及土壤含水量成显著的二次曲线关系 ,与土壤有机质和全 K含量也呈现出二次曲线关系 ,但关系不显著 ,与 p H值和速效
The arid valley of the upper reaches of the Minjiang River is located in the transition zone between the Qinghai-Tibet plateau to the Sichuan Basin. It has a typical arid valley climate with complex topography and variable water and heat conditions. A long history of anthropogenic influences combined with severe natural environments resulted in degraded vegetations dominated by xeric shrubs. The objective of this study was to relate the plant community species turn over rates to their environments to provide a basic scientific data for ecosystem restoration and management in the region. In the arid valley of the Minjiang River, we established six transects along altitude gradients where vegetation compositions and fourteen environmental factors that describe the topography, soil water and nutrient status, were measured. The β diversity, calculated by the Cody index, was used as species turnover rate of plant community in the study area. We found that altitude gradient had great influence on the distribution of biodiversity. The β diversity values showed a “high-low-high” trend with the increasing of altitude in the area. Both herbs and shrubs layers had high species turnover rates at the 1300～1600 m and 2000～2200 m altitudes, while low species turnover rate were found at the 1600～1900 m altitude. The central area of the valley had higher β diversity than the north and south transition zones, presumably due to the differences of environmental conditions. There were 11 typical plant formations in the study area. Our study suggested that Form. Pertya sinensis, Jasminum humile、Form. Berberis wilsonae,Lonicera japonica、Form. Ajania breviloba、Form. Quercus cocciferoides、Form. Onosma farrerii、 Form. Caryopteris spp.、Form. Spiraea Spp had higher species turnover rate than other plant formations. Topography plays an important role in the distribution of vegetation as well as biodiversity. We also found that species turnover rate varied according to slope directions with a trend: north facing slope> half south facing and half north facing slope>south facing slope. Species turnover rates also varied among slope positions and slope shapes with ranking in an order lower slope >middle slope> upper slope, and concave slope>straight slope >convex slope,respectively. Soil water and nutrient status were found to be the most important limiting factors for plant growth and development in the area. We found that except for soil pH value and available P, significant quadratic relationships exited between hydrolyzable N、available K、total P、total N、soil water content and β diversity. Soil organic matter content and total K were also correlated with β diversity in the form of a quadratic curve, but correlation was not significant. Changes of β diversity did not have significant correlations with soil pH and available P.
出处
《生态学报》
CAS
CSCD
北大核心
2004年第11期2367-2373,共7页
Acta Ecologica Sinica
基金
国家重点基础研究发展规划资助项目 ( G2 0 0 0 0 4680 7)~~
关键词
植物群落
环境梯度
物种周转速率
Β多样性
岷江干旱河谷
Plant community
environmental gradient
species turnover rate
β diversity
the arid valley of Minjiang River
