Status of the riparian ecosystem in the upper San Pedro River, Arizona: Application of an assessment model
Status of the riparian ecosystem in the upper San Pedro River, Arizona: Application of an assessment model
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DOI：
10.1007/s10661-006-6549-1
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发表时间：
2006-04-01
影响因子：
3
通讯作者：
Watts, Joseph M.
中科院分区：
文献类型：
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作者：
Stromberg, Juliet C.;Lite, Sharon J.;Watts, Joseph M.
亚利桑那州圣佩德罗河的一部分被管理为国家河岸保护区，但可能受到保护区边界以外地下水抽取的影响。我们将一个评估模型应用于保护区，作为监测河流可用水量变化导致的河岸生态系统状况长期变化的基础，并收集了一些最敏感的生物指标的多年数据。该评价模型基于对地表水或地下水变化敏感的9个植被生物指标。场地指数得分允许放置在三个条件类别之一，每个类别都反映了场地水文和植被结构的特定范围。我们收集了分布在14个河段的26个站点的生物指标数据，这些河段具有相似的河流水文（空间流量间歇性）和地貌（河道弯曲度、洪泛平原宽度）。总体而言，39%的河岸走廊属于第3类条件（最潮湿的条件），55%属于第2类条件，6%属于最干燥的条件。条件3级河段沿多年生河道有较高的草本湿地植物覆盖度（例如，榕树和schoenplectus spp.），洪泛平原上有密集的、多龄的杨柳林地，由河流冲积层的浅层地下水维持。在2级条件下，间歇水流导致滨水湿地草本植物盖度较低，但杨柳类植物在洪泛平原上仍然丰富。多年生湿地植物在条件1级中缺失，反映了高度间歇的水流；泛滥平原上长满了柽柳，这是一种小树，可以忍受这种河流类型的深而波动的地下水位。草本湿地植物的丰度和黄柳的生长速率在不同年份随流量的变化而变化，表明这些指标在跟踪水文变化的短期响应方面的实用性。所有生物指标的重复测量将表明水生植被条件的长期趋势。
A portion of Arizona's San Pedro River is managed as a National Riparian Conservation Area but is potentially affected by ground-water withdrawals beyond the conservation area borders. We applied an assessment model to the Conservation Area as a basis for monitoring long-term changes in riparian ecosystem condition resulting from changes in river water availability, and collected multi-year data on a subset of the most sensitive bioindicators. The assessment model is based on nine vegetation bioindicators that are sensitive to changes in surface water or ground water. Site index scores allow for placement into one of three condition classes, each reflecting particular ranges for site hydrology and vegetation structure. We collected the bioindicator data at 26 sites distributed among 14 reaches that had similar stream flow hydrology (spatial flow intermittency) and geomorphology (channel sinuosity, flood-plain width). Overall, 39% of the riparian corridor fell within condition class 3 (the wettest condition), 55% in condition class 2, and 6% in the driest condition class. Condition class 3 reaches have high cover of herbaceous wetland plants (e.g., Juncus and Schoenoplectus spp.) along the perennial stream channel and dense, multi-aged Populus-Salix woodlands in the flood plain, sustained by shallow ground water in the stream alluvium. In condition class 2, intermittent stream flows result in low cover of streamside wetland herbs, but Populus-Salix remain abundant in the flood plain. Perennial wetland plants are absent from condition class 1, reflecting highly intermittent stream flows; the flood plain is vegetated by Tamarix, a small tree that tolerates the deep and fluctuating ground water levels that typify this reach type. Abundance of herbaceous wetland plants and growth rate of Salix gooddingii varied between years with different stream flow rates, indicating utility of these measures for tracking short-term responses to hydrologic change. Repeat measurement of all bioindicators will indicate long-term trends in hydro-vegetational condition.