Effects of stream flow intermittency on riparian vegetation of a semiarid region river (San Pedro River, Arizona)
Effects of stream flow intermittency on riparian vegetation of a semiarid region river (San Pedro River, Arizona)
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DOI：
10.1002/rra.858
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发表时间：
2005-10-01
影响因子：
2.2
通讯作者：
Makings, E
中科院分区：
文献类型：
--
作者：
Stromberg, JC;Bagstad, KJ;Makings, E
位于美国西南部的圣佩德罗河保留了天然的洪水状态，并有几个河段有常年的溪流和浅层地下水。然而，大部分河流间歇性地流动。与城市化有关的区域地下水位下降引起了人们对河流某些部分河流生态系统未来状况的关切，而与干旱有关的农业地下水抽水减少预计将增加其他部分的河流流量。这项研究描述了河边草本植被的响应，在溪流流量持久性的变化。在初夏旱季，河边，草本植物覆盖和物种丰富度下降不断流动持久性的空间梯度，和组合物转移到中间物种的网站，更多的间歇性流动。水文阈值是明显的一个植物功能组：Schoenoplectus尖，灯心草，和其他含氢河岸植物急剧下降，覆盖与常年流损失。与此相反，覆盖的梅西奇河岸多年生植物（包括狗牙根，引进物种）增加的网站与间歇性流动。水文和梅西奇河岸一年生植物的模式随季节而变化：在初夏旱季，他们的覆盖不断下降，流量变得更加间歇性，而在夏末雨季，他们的覆盖增加，流量变得更加间歇性。在间歇性站点的周期性干旱可能会增加在季风洪水季节建立这些一年生植物的机会。在夏末的洪水季节。溪流流量是目前在大多数网站，和较少的植被特征与流动的持久性;覆盖和丰富度与其他环境因素，包括网站海拔和基质硝酸盐水平和颗粒大小。虽然常年流和不稳定流网站支持不同的河边植物群落，所有的植物功能群是丰富的，在更广泛的空间和时间尺度上观察生态系统时，在常年流网站：中质河岸多年生植物是常见的河漫滩区相邻的河道和夏末潮湿和中质一年生植物定期丰富的大洪水后。版权所有（c）2005年约翰威利父子有限公司。
The San Pedro River in the southwestern United States retains a natural flood regime and has several reaches with perennial stream flow and shallow ground water. However, much of the river flows intermittently. Urbanization-linked declines in regional ground-water levels have raised concerns over the future status of the riverine ecosystem in some parts of the river, while restoration-linked decreases in agricultural ground-water pumping are expected to increase stream flows in other parts. This study describes the response of the streamside herbaceous vegetation to changes in stream flow permanence. During the early summer dry season, streamside, herbaceous cover and species richness declined continuously across spatial gradients of flow permanence, and composition shifted from hydric to mesic species at sites with more intermittent flow. Hydrologic threshold values were evident for one plant functional group: Schoenoplectus acutus, Juncus torreyi, and other hydric riparian plants declined sharply in cover with loss of perennial stream flow. In contrast, cover of mesic riparian perennials (including Cynodon dactylon, an introduced species) increased at sites with intermittent flow. Patterns of hydric and mesic riparian annuals varied by season: in the early summer dry season their cover declined continuously as flow became more intermittent, while in the late summer wet season their cover increased as the flow became more intermittent. Periodic drought at the intermittent sites may increase opportunities for establishment of these annuals during the monsoonal flood season. During the late summer flood season. stream flow was present at most sites, and fewer vegetation traits were correlated with flow permanence; cover and richness were correlated with other environmental factors including site elevation and substrate nitrate level and particle size. Although perennial-flow and intermittent-flow sites support different streamside plant communities, all of the plant functional groups are abundant at perennial-flow sites when viewing the ecosystem at broader spatial and temporal scales: mesic riparian perennials are common in the floodplain zone adjacent to the river channel and late-summer hydric and mesic annuals are periodically abundant after large floods. Copyright (c) 2005 John Wiley & Sons, Ltd.