Ecological consequences of altered hydrological regimes in fragmented ecosystems in southern Australia: Impacts and possible management responses
Ecological consequences of altered hydrological regimes in fragmented ecosystems in southern Australia: Impacts and possible management responses
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DOI：
10.1046/j.1442-9993.2002.01215.x
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发表时间：
2002-10-01
期刊：
影响因子：
1.5
通讯作者：
Hobbs, RJ
中科院分区：
文献类型：
--
作者：
Cramer, VA;Hobbs, RJ
尽管地下水位上升和次生盐碱化对澳大利亚南部农业用地的潜在影响已经被认识到了一段时间，但直到最近才考虑对本地植被的影响。尽管问题的范围和严重性可能很大，但迄今为止尚未尝试采用全面的方法来评估盐度对原生植被的影响。在本文中，我们讨论了地下水位和旱地盐度上升的原因和影响，评估了不同生态系统类型的风险水平，并考虑了维持濒危植被生物多样性和生态系统功能的可能性。我们研究了西澳大利亚 (WA) 小麦带林地植被的盐度风险，并考虑了大尺度背景和个别植被斑块内的更精细尺度变化。根据这些信息，我们开发了一套概念模型，研究浅层咸水位对农业区（特别是西澳小麦带）残余植被的生态系统结构和过程的潜在影响。首先，我们认为地表地形和土壤特征的细尺度变化可能在限制咸水位上升的影响方面发挥重要作用。结果将取决于影响的异质性、与小规模环境异质性相关的物种分布以及物种对水文变化的响应变化之间的相互作用。其次，我们建议可以认为浅层咸水位会引起“边缘效应”，即从原生植被残余物的边缘向内移动。最后，我们考虑盐地表流如何加剧浅层咸水位的影响并加速残余地区的植被衰退。我们将这些模型作为假设提出，以便在不同情况下进行测试。我们将澳大利亚植被的次生盐碱化情况与澳大利亚和其他地方的自然盐碱系统的情况进行了对比，并表明这些系统可能为制定濒危植被的管理方法提供重要的路标。总之，我们认为有必要根据对相对威胁和持续或恢复可能性的评估，确定保护和恢复因水文变化而面临风险的自然植被的优先顺序。我们强调采取行动保护原生植被免受地下水位上升带来的日益增加的风险的紧迫性。
Although the potential impacts of rising water tables and secondary salinization on agricultural land in southern Australia have been recognized for some time, it is only recently that the impacts on native vegetation have been considered. Despite the likely extent and severity of the problem, no comprehensive approach to assessing the impact of salinity upon native vegetation has been attempted to date. In the present paper, we discuss the causes and impacts of rising water tables and dryland salinity, assess the levels of risk in different ecosystem types and consider the possibilities for the maintenance of biodiversity and ecosystem function in vegetation at risk. We examine the salinity risk to woodland vegetation in the Western Australian (WA) wheatbelt, and consider both broad-scale context and finer-scale variation within individual patches of vegetation. From this information, we develop a set of conceptual models of the potential impacts of shallow saline water tables on ecosystem structure and processes in remnant vegetation in agricultural areas, particularly in the WA wheatbelt. First, we suggest that fine-scale variability in surface topography and soil characteristics may play an important role in limiting the impacts of rising saline water tables. The outcome will depend on the interaction of the heterogeneity of the impact, species distribution in relation to small-scale environmental heterogeneity and variation in species response to hydrological change. Second, we suggest that shallow saline water tables can be considered to cause an 'edge effect', which moves inwards from the edge of remnants of native vegetation. Finally, we consider how saline surface flows exacerbate the effects of shallow saline water tables and hasten vegetation decline in remnant areas. We put these models forward as hypotheses to be tested in different situations. We contrast the situation of secondary salinization in Australian vegetation with that of naturally saline systems in Australia and elsewhere, and suggest that these systems may provide important signposts toward developing management approaches for vegetation at risk. In conclusion, we consider the need to set priorities for the protection and restoration of natural vegetation at risk from altered hydrology, based on an assessment of relative threat and probability of persistence or recovery. We highlight the urgency for action that protects native vegetation from the increasing risks of rising water tables.