Predictors of plant diversity in a hyperarid desert wadi ecosystem
Predictors of plant diversity in a hyperarid desert wadi ecosystem
复制标题
DOI：
10.1006/jare.2000.0631
复制
发表时间：
2000-07-01
影响因子：
2.7
通讯作者：
Murphy, KJ
中科院分区：
文献类型：
--
作者：
Ali, MM;Dickinson, G;Murphy, KJ
本研究的目的是确定植物多样性的趋势，并研究它们与环境变量（水分胁迫、风帆质地和放牧强度）和植被特征（总植被和单个物种覆盖）之间的预测关系，该研究沿着埃及南部一个超干旱沙漠地区340公里的样带进行。该样带的主要部分位于瓦迪阿拉奇人与生物圈（MAB）保护区的边界内。样带共记录到55种植物。TWINSPAN对数据的分类确定了Springuel等人（1997年）先前在该地区确定的七种主要植被类型中的四种。I型植被主要分布在Wadi Allaqi系统的最低段，受纳赛尔湖的洪水和渗漏影响最大，其特征是柽柳（Tamarix nilotica）林分密集。wadi系统中上层以IIIb型植被为主，植被较少，以金合欢、金合欢为主。raddiana (Savi) Brenan和Aerva javanica （Burm）。f。)汁液。Schult交货。iii - ia型植被分布在瓦迪-阿拉齐中部地区，其特征为灰杉。和Cullen plicatum （Delile）。物种最丰富的植被类型为IV型，主要分布在Wadis Allaqi和Eiqat上游。利用Whittaker’s beta(w)指数对样带各样点间的植物β多样性（物种更替）进行了评估，结果表明，植物物种更替从河系下游样点向河上游样点呈上升趋势。这些植被类型内的植物α多样性（物种丰富度R：每500 m(2)单位面积存在的物种数量）与辛普森指数(D)测量的植物多样性呈线性相关。从植被覆盖、土壤湿度和放牧强度三个变量（遵循三阶多项式模型）可以较好地预测R。该模型对原始数据集R的预测成功率为52.9% （R = 0.73, p < 0.001）。研究表明，植被覆盖估算与生境压力强度（水分有效性）和干扰强度（放牧强度）的简单估算相结合，可以快速显示荒漠生境的生物多样性支持能力。(C) 2000年学术出版社。
The aim of this study was to identify trends in plant diversity, and examine their predictive relationships with environmental variables (water stress, sail texture and grazing intensity) and Vegetation characteristics (total vegetation and individual species cover), along a 340 km transect through an area of hyper-arid desert in southern Egypt. The major part of the transect is located within the boundaries of the Wadi Allaqi Man and Biosphere (MAB) Reserve. In total 55 plant species were recorded from the transect. A TWINSPAN classification of the data identified four of the seven main vegetation types, previously identified as present in the area by Springuel et al. (1997). Sites dominated by Vegetation type I occurred exclusively in the lowest stretch of the Wadi Allaqi system, most heavily influenced by flood and seepage from Lake Nasser, and characterized by dense stands of Tamarix nilotica (Ehrenb.) Bunge and Glinus lotoides L. Vegetation type IIIb was represented at sites higher up the wadi system, characterized by sparser vegetation dominated by Acacia ehrenbergiana Hayne, Acacia tortilis subsp. raddiana (Savi) Brenan and Aerva javanica (Burm. f.) Juss.ex Schult. Vegetation type IIIa occurred in the middle region of Wadi Allaqi and was characterized by Salsola imbricata Forssk. and Cullen plicatum (Delile) C. H. Stirt. Vegetation type IV, the most species rich, was limited to upstream sites of Wadis Allaqi and Eiqat. Plant beta-diversity las species turnover between individual sites along the transect, assessed using Whittaker's beta(w) index) showed a rising trend of plant species turnover from sites low in the wadi system to sites located in the upper part of the wadi. Plant alpha-diversity within these vegetation types (as species richness R: number of species present per 500 m(2) unit area) was linearly correlated with plant diversity measured using Simpson's index (D). R was reasonably well predicted from three variables: plant cover, soil moisture and grazing intensity (following a third order polynomial model). This model predicted R in the original data set with 52.9% success ( r = 0.73, p < 0.001). The study suggested that vegetation cover estimates, in association with simple estimates of intensity of habitat stress (water availability) and disturbance (grazing intensity), can provide a rapid indication of the biodiversity support capacity of desert habitats. (C) 2000 Academic Press.