沙生植物对沙丘动态的影响
The effects of psammophilous plants on sand dune dynamics
摘要：
沙生植物是一种特殊的植物，生长在流沙环境中。风对这些植物的影响主要有两种机制：（i）流沙暴露根和覆盖枝-暴露的根变成新的植物，被覆盖的枝变成新的根;这两种机制都导致沙丘的沙生植物覆盖物的生长速度加快;（ii）强风，通常伴随着沙的移动，撕裂树枝并在附近的地方播种，导致新的植物和沙丘的沙生植物覆盖物的增长率提高。尽管沙生植物在沙丘动力学中具有重要作用，但据我们所知，沙生植物从未被纳入沙丘的数学模型中。在这里，我们试图模拟这些植物对沙丘动态的影响。我们构造了一组三个常微分方程的分数的表面覆盖的常规植被，生物土壤结皮和沙生植物。后者在（i）特定的流沙或（ii）特定的风力下达到其最佳生长。我们表明，沙生植物丰富的沙丘动态。根据气候条件的不同，有可能获得一个、两个或三个稳定的沙丘状态。沙丘的活动可能与表面覆盖有关-裸露的沙丘是活动的，而有大量植被、生物土壤结皮或沙生植物覆盖的沙丘是固定的。我们的模型表明，在适当的降水率和风力，不同的覆盖类型的动态是符合共同的观点，沙丘最初是稳定的沙生植物，减少沙活动，从而提高了生长的经常植被，最终占主导地位的覆盖沙丘，并决定他们的活动。
英文摘要：
Psammophilous plants are special plants that flourish in sand moving environments. There are two main mechanisms by which the wind affects these plants: (i) sand drift exposes roots and covers branches--the exposed roots turn into new plants and the covered branches turn into new roots; both mechanisms result in an enhanced growth rate of the psammophilous plant cover of the dunes; (ii) strong winds, often associated with sand movement, tear branches and seed them in nearby locations, resulting in new plants and an enhanced growth rate of the psammophilous plant cover of the dunes. Despite their important role in dune dynamics, to our knowledge, psammophilous plants have never been incorporated into mathematical models of sand dunes. Here, we attempt to model the effects of these plants on sand dune dynamics. We construct a set of three ordinary differential equations for the fractions of surface cover of regular vegetation, biogenic soil crust and psammophilous plants. The latter reach their optimal growth under (i) specific sand drift or (ii) specific wind power. We show that psammophilous plants enrich the sand dune dynamics. Depending on the climatological conditions, it is possible to obtain one, two, or three steady dune states. The activity of the dunes can be associated with the surface cover--bare dunes are active, and dunes with significant cover of vegetation, biogenic soil crust, or psammophilous plants are fixed. Our model shows that under suitable precipitation rates and wind power, the dynamics of the different cover types is in accordance with the common view that dunes are initially stabilized by psammophilous plants that reduce sand activity, thus enhancing the growth of regular vegetation that eventually dominates the cover of the dunes and determines their activity.
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