Naumburg Elke, Mata-Gonzalez Ricardo, Hunter Rachael G, McLendon Terry, Martin David W
Pacifica Services, Inc., 106 S. Mentor Avenue, Suite 200, Pasadena, California 91106, USA.
Environ Manage. 2005 Jun;35(6):726-40. doi: 10.1007/s00267-004-0194-7.
Although changes in depth to groundwater occur naturally, anthropogenic alterations may exacerbate these fluctuations and, thus, affect vegetation reliant on groundwater. These effects include changes in physiology, structure, and community dynamics, particularly in arid regions where groundwater can be an important water source for many plants. To properly manage ecosystems subject to changes in depth to groundwater, plant responses to both rising and falling groundwater tables must be understood. However, most research has focused exclusively on riparian ecosystems, ignoring regions where groundwater is available to a wider range of species. Here, we review responses of riparian and other species to changes in groundwater levels in arid environments. Although decreasing water tables often result in plant water stress and reduced live biomass, the converse is not necessarily true for rising water tables. Initially, rising water tables kill flooded roots because most species cannot tolerate the associated low oxygen levels. Thus, flooded plants can also experience water stress. Ultimately, individual species responses to either scenario depend on drought and flooding tolerance and the change in root system size and water uptake capacity. However, additional environmental and biological factors can play important roles in the severity of vegetation response to altered groundwater tables. Using the reviewed information, we created two conceptual models to highlight vegetation dynamics in areas with groundwater fluctuations. These models use flow charts to identify key vegetation and ecosystem properties and their responses to changes in groundwater tables to predict community responses. We then incorporated key concepts from these models into EDYS, a comprehensive ecosystem model, to highlight the potential complexity of predicting community change under different fluctuating groundwater scenarios. Such models provide a valuable tool for managing vegetation and groundwater use in areas where groundwater is important to both plants and humans, particularly in the context of climate change.
尽管地下水位的变化是自然发生的，但人为改变可能会加剧这些波动，从而影响依赖地下水的植被。这些影响包括生理、结构和群落动态的变化，特别是在干旱地区，地下水可能是许多植物的重要水源。为了妥善管理受地下水位变化影响的生态系统，必须了解植物对地下水位上升和下降的反应。然而，大多数研究仅关注河岸生态系统，而忽略了地下水可供更广泛物种利用的地区。在这里，我们综述了干旱环境中河岸物种和其他物种对地下水位变化的反应。虽然地下水位下降通常会导致植物水分胁迫和活体生物量减少，但地下水位上升的情况不一定如此。最初，地下水位上升会使被淹没的根系死亡，因为大多数物种无法耐受相关的低氧水平。因此，被淹没的植物也会经历水分胁迫。最终，单个物种对这两种情况的反应取决于耐旱性和耐淹性以及根系大小和水分吸收能力的变化。然而，其他环境和生物因素在植被对地下水位变化反应的严重程度中也可能起重要作用。利用综述的信息，我们创建了两个概念模型，以突出地下水位波动地区的植被动态。这些模型使用流程图来识别关键的植被和生态系统属性及其对地下水位变化的反应，以预测群落反应。然后，我们将这些模型的关键概念纳入EDYS（一个综合生态系统模型），以突出在不同波动地下水位情景下预测群落变化的潜在复杂性。此类模型为管理对植物和人类都很重要的地下水地区的植被和地下水利用提供了有价值的工具，特别是在气候变化的背景下。
