Revisiting salt marsh resilience to sea level rise: Are ponds responsible for permanent land loss?
Revisiting salt marsh resilience to sea level rise: Are ponds responsible for permanent land loss?
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DOI：
10.1002/2016jf003900
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发表时间：
2016-07
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影响因子：
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通讯作者：
G. Mariotti
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作者：
G. Mariotti
池塘是无植被的圆形洼地，通常存在于沼泽平台上。池塘对潮汐沼泽长期形态演变的作用尚不清楚-有时池塘扩大，但最终恢复沼泽平台，在其他时候池塘永远不会恢复，并导致永久性的沼泽损失。现有的实地观察表明，沼泽植被的间歇性扰动会导致形成小的（1 - 10米）孤立的池塘，即使植被平台与相对海平面上升（RSLR）保持同步，孤立的池塘往往会加深和扩大，直到它们最终连接到通道网络。在这里，我实现了一个简单的模型来研究一个单一的连接池塘的垂直和平面形状的演变。一个新连接的池塘恢复，如果它的床高于沼泽植物生长的限制，或者如果无机沉积速率大于RSLR率。一个不能比RSLR更快地增生的池塘将加深和扩大，最终进入一个失控的侵蚀波边缘撤退。大潮差，大量的沉积物供应，和RSLR率低有利于池塘恢复。该模型表明，无机沉积物沉积单独控制池塘恢复，即使在沼泽地中，有机物占主导地位的植被平台的增生。因此，阻止池塘坍塌造成的沼泽永久性损失需要增加无机沉积物沉积。因为池塘崩溃是可能的，即使植被平台跟上RSLR的步伐，我的结论是沼泽恢复RSLR是小于以前量化。
Ponds are unvegetated rounded depressions commonly present on marsh platforms. The role of ponds on the long‐term morphological evolution of tidal marshes is unclear—at times ponds expand but eventually recover the marsh platform, at other times ponds never recover and lead to permanent marsh loss. Existing field observations indicate that episodic disturbances of the marsh vegetation cause the formation of small (1–10 m) isolated ponds, even if the vegetated platform keeps pace with relative sea level rise (RSLR) and that isolated ponds tend to deepen and enlarge until they eventually connect to the channel network. Here I implement a simple model to study the vertical and planform evolution of a single connected pond. A newly connected pond recovers if its bed lies above the limit for marsh plant growth or if the inorganic deposition rate is larger than the RSLR rate. A pond that cannot accrete faster than RSLR will deepen and enlarge, eventually entering a runaway erosion by wave edge retreat. A large tidal range, a large sediment supply, and a low rate of RSLR favor pond recovery. The model suggests that inorganic sediment deposition alone controls pond recovery, even in marshes where organic matter dominates accretion of the vegetated platform. As such, halting permanent marsh loss by pond collapse requires to increase inorganic sediment deposition. Because pond collapse is possible even if the vegetated platform keeps pace with RSLR, I conclude that marsh resilience to RSLR is less than previously quantified.