Alexander J. Smith, Glenn R. Guntenspergen, Joel A. Carr, David C. Walters, Matthew L. Kirwan
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引用次数: 0
Abstract
As global climate change alters the magnitude and rates of environmental stressors, predicting the extent of ecosystem degradation driven by these rapidly changing conditions becomes increasingly urgent. At the landscape scale, disturbances and stressors can increase spatial variability and heterogeneity — indicators that can serve as potential early warnings of declining ecosystem resilience. Increased spatial variability in salt marshes at the landscape scale has been used to quantify the propagation of ponding in salt marsh interiors, but ponding at the landscape scale follows a state change rather than predicts it. Here, we suggest a novel application of commonly collected surface elevation table (SET) data and explore millimeter-scale marsh surface microtopography as a potential early indicator of ecosystem transition. We find an increase in spatial variability using multiple metrics of microtopographic heterogeneity in vulnerable salt marsh communities across the North American Atlantic seaboard. Increasing microtopographic heterogeneity in vulnerable salt marshes mirrored increasing trends in variance when a tipping point is approached in other alternative stable state systems — indicating that early warning signals of marsh drowning and ecosystem transition are observable at small-spatial scales prior to runaway ecosystem degradation. Congruence between traditional and novel metrics of marsh vulnerability suggests that microtopographic metrics can be used to identify hidden vulnerability before widespread marsh degradation. This novel analysis can be easily applied to existing SET records expanding the traditional focus on vertical change to additionally encapsulate lateral processes.
随着全球气候变化改变了环境压力因素的强度和速率,预测这些快速变化的条件所导致的生态系统退化程度变得日益紧迫。在景观尺度上,干扰和压力因素会增加空间变异性和异质性--这些指标可作为生态系统恢复能力下降的潜在预警。盐沼在景观尺度上的空间变异性增加已被用于量化盐沼内部池塘化的传播,但景观尺度上的池塘化是跟随状态变化而发生的,而不是预测状态变化。在此,我们建议对通常收集的地表高程表(SET)数据进行新的应用,并探索毫米尺度的沼泽表面微地形作为生态系统过渡的潜在早期指标。我们发现,在北美大西洋沿岸的脆弱盐沼群落中,微地形异质性的多个指标的空间变异性都在增加。脆弱盐沼中微地形异质性的增加反映了其他替代稳定状态系统中临界点临近时方差的增加趋势--这表明在生态系统失控退化之前,可以在小空间尺度上观察到沼泽淹没和生态系统过渡的早期预警信号。沼泽脆弱性的传统指标和新指标之间的一致性表明,微地形指标可用于在沼泽普遍退化之前识别隐藏的脆弱性。这种新颖的分析方法可以很容易地应用于现有的 SET 记录,将传统的垂直变化扩展到横向过程。
期刊介绍:
Estuaries and Coasts is the journal of the Coastal and Estuarine Research Federation (CERF). Begun in 1977 as Chesapeake Science, the journal has gradually expanded its scope and circulation. Today, the journal publishes scholarly manuscripts on estuarine and near coastal ecosystems at the interface between the land and the sea where there are tidal fluctuations or sea water is diluted by fresh water. The interface is broadly defined to include estuaries and nearshore coastal waters including lagoons, wetlands, tidal fresh water, shores and beaches, but not the continental shelf. The journal covers research on physical, chemical, geological or biological processes, as well as applications to management of estuaries and coasts. The journal publishes original research findings, reviews and perspectives, techniques, comments, and management applications. Estuaries and Coasts will consider properly carried out studies that present inconclusive findings or document a failed replication of previously published work. Submissions that are primarily descriptive, strongly place-based, or only report on development of models or new methods without detailing their applications fall outside the scope of the journal.