一项研究发现，原生海滩草的分布控制着沿海受风暴侵害的脆弱性。Orencio Duran 和Laura Moore利用数学建模研究了植被与沙的相互作用如何形成了面向海的沙丘。海滩植物帮助俘获沙，因此也就积累和稳定了沙丘。这些沙丘反过来又作为天然屏障，保护内陆生态系统不受海洋和风暴的冲击。这组科研人员确定了植被的类型以及它的分布影响着沙丘的尺寸，一些植物的分布形成了与海岸平行的长沙丘脊，另一些植物形成了更具流动性、较不连续的沙丘，而还有一些植物妨碍沙丘的形成。这些植物的动态再加上风流和地貌，限制了面向海洋的沙丘的增长。这组作者报告说，大型沙丘倾向于在远离水边的平坦的细沙丘上形成，因为靠近水边，大浪干扰了植物，让沙丘的形成偏向陆地。相反，小型沙丘倾向于在更接近水边的陡峭的粗砂滩上出现，在那里海浪较小。在风暴中，沙丘的尺寸影响着侵蚀。这项研究发现通过控制沿海沙丘的最大尺寸，植物在修改栖息地和改变沿海脆弱性方面起到了比以前认为的更积极的作用。(生物谷 Bioon.com)
生物谷推荐的英文摘要
PNAS doi: 10.1073/pnas.1307580110
Vegetation controls on the maximum size of coastal dunes
Orencio Durán1,2 and Laura J. Moore
Coastal dunes, in particular foredunes, support a resilient ecosystem and reduce coastal vulnerability to storms. In contrast to dry desert dunes, coastal dunes arise from interactions between biological and physical processes. Ecologists have traditionally addressed coastal ecosystems by assuming that they adapt to preexisting dune topography, whereas geomorphologists have studied the properties of foredunes primarily in connection to physical, not biological, factors. Here, we study foredune development using an ecomorphodynamic model that resolves the coevolution of topography and vegetation in response to both physical and ecological factors. We find that foredune growth is eventually limited by a negative feedback between wind flow and topography. As a consequence, steady-state foredunes are scale invariant, which allows us to derive scaling relations for maximum foredune height and formation time. These relations suggest that plant zonation (in particular for strand “dune-building” species) is the primary factor controlling the maximum size of foredunes and therefore the amount of sand stored in a coastal dune system. We also find that aeolian sand supply to the dunes determines the timescale of foredune formation. These results offer a potential explanation for the empirical relation between beach type and foredune size, in which large (small) foredunes are found on dissipative (reflective) beaches. Higher waves associated with dissipative beaches increase the disturbance of strand species, which shifts foredune formation landward and thus leads to larger foredunes. In this scenario, plants play a much more active role in modifying their habitat and altering coastal vulnerability than previously thought.
