Thibault James R, Cleverly James R, Dahm Clifford N
Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA.
Terrestrial Ecohydrology Research Group, School of Life Sciences, University of Technology Sydney, P.O. Box 123, Broadway, NSW, 2007, Australia.
Environ Manage. 2017 Dec;60(6):1101-1115. doi: 10.1007/s00267-017-0945-x. Epub 2017 Oct 9.
Hydrological processes drive the ecological functioning and sustainability of cottonwood-dominated riparian ecosystems in the arid southwestern USA. Snowmelt runoff elevates groundwater levels and inundates floodplains, which promotes cottonwood germination. Once established, these phreatophytes rely on accessible water tables (WTs). In New Mexico's Middle Rio Grande corridor diminished flooding and deepening WTs threaten native riparian communities. We monitored surface flows and riparian WTs for up to 14 years, which revealed that WTs and surface flows, including peak snowmelt discharge, respond to basin climate conditions and resource management. WT hydrographs influence the composition of riparian communities and can be used to assess if potential restoration sites meet native vegetation tolerances for WT depths, rates of recession, and variability throughout their life stages. WTs were highly variable in some sites, which can preclude native vegetation less adapted to deep drawdowns during extended droughts. Rates of WT recession varied between sites and should be assessed in regard to recruitment potential. Locations with relatively shallow WTs and limited variability are likely to be more viable for successful restoration. Suitable sites have diminished greatly as the once meandering Rio Grande has been constrained and depleted. Increasing demands on water and the presence of invasive vegetation better adapted to the altered hydrologic regime further impact native riparian communities. Long-term monitoring over a range of sites and hydroclimatic extremes reveals attributes that can be evaluated for restoration potential.
水文过程驱动着美国西南部干旱地区以棉白杨为主的河岸生态系统的生态功能和可持续性。融雪径流使地下水位升高并淹没洪泛区，从而促进棉白杨的发芽。一旦扎根，这些深根植物就依赖于可获取的地下水位。在新墨西哥州的中里奥格兰德走廊，洪水减少和地下水位加深威胁着当地的河岸群落。我们对地表径流和河岸地下水位进行了长达14年的监测，结果表明地下水位和地表径流，包括融雪径流峰值，对流域气候条件和资源管理有响应。地下水位过程线影响河岸群落的组成，可用于评估潜在的恢复地点是否满足本地植被在其整个生命周期内对地下水位深度、下降速率和变异性的耐受性。一些地点的地下水位变化很大，这可能会排除那些在长期干旱期间不太适应深度下降的本地植被。不同地点的地下水位下降速率各不相同，应根据植被恢复潜力进行评估。地下水位相对较浅且变异性有限的地点可能更适合成功恢复。随着曾经蜿蜒的里奥格兰德河受到限制和水量减少，合适的地点已大幅减少。对水的需求不断增加，以及存在更适应改变后的水文状况的入侵植被，进一步影响了当地的河岸群落。在一系列地点和极端水文气候条件下进行的长期监测揭示了可用于评估恢复潜力的特征。
