The importance of phytogenic mounds (nebkhas) for restoration of arid degraded rangelands in northern Sinai
The importance of phytogenic mounds (nebkhas) for restoration of arid degraded rangelands in northern Sinai
复制标题
DOI：
10.1046/j.1526-100x.2003.00222.x
复制
发表时间：
2003-09-01
影响因子：
3.2
通讯作者：
Khedr, AHA
中科院分区：
文献类型：
--
作者：
El-Bana, MI;Nijs, I;Khedr, AHA
植物冠层内部或周围的风载沉积物的自然积累在许多沿海和沙漠生态系统的生态和进化动力学中起着重要作用。这些植物丘（nebkhas）的形成形成了能够强烈影响植物和土壤资源空间分布的斑块。在干旱和半干旱环境的土地恢复中，研究这种生物斑块的潜在作用是很重要的，它可能为不同生命和生长形式的物种提供共存的场所。我们的主要目的是测试一种豆科灌木Retama raetam（白帚）的nebhas是否能促进西奈半岛北部退化牧场的草本植被和土壤的恢复。比较了未放牧地和放牧地网带内及网带间的植被、小气候和土壤特征。草本植物的丰度和丰富度与nebha面积呈正相关，说明放牧样地的丰度和丰富度差异大于未放牧样地。对放牧的保护，特别是对nebkhas的保护，与草本植物丰度和丰富度的增加、土壤小气候的改善以及土壤细颗粒和养分浓度的增加有关。结果表明，对多年生木本灌丛nebhas的管理（作为放牧保护）改变了草地条件，改善了资源调控过程。此外，在过度放牧的植物群落中，有害植物的nebkhas具有保护植物多样性的潜力，因为它们可以有效地捕获和保留水、土壤物质和来自附近地区的繁殖体，否则这些资源将会丢失。
Natural accumulation of wind-borne sediments within or around the canopies of plants plays an important role in the ecological and evolutionary dynamics of many coastal and desert ecosystems. The formation of such phytogenic mounds (nebkhas) creates patches that can strongly influence the spatial distribution of plant and soil resources. In land restoration of arid and semiarid environments it is important to study the potential role of such biological patchiness that may provide sites for coexistence of species with different life and growth forms. Our main objective was to test whether the nebkhas of a leguminous shrub, Retama raetam (white broom), promote restoration of herbaceous vegetation and soil in the degraded rangelands of northern Sinai. Vegetation and microclimatic and edaphic characteristics within the nebkhas, as well as within internebkha spaces, were compared for ungrazed and grazed sites. Abundance and richness of herbaceous plants were positively related to nebkha area, which explained more of the variance of abundance and richness in the grazed site than in the ungrazed one. Protection from grazing, especially on nebkhas, was associated with an increase in abundance and richness of herbaceous plants, improved soil microclimate, and increased soil fine particles and nutrient concentrations. The results suggest that management (in casu protection from grazing) of nebkhas of woody perennial shrubs changes rangeland conditions and improves the resource regulatory processes. Furthermore, nebkhas of unpalatable plants have the potential to preserve plant diversity in overgrazed plant communities, because they are effective in capturing and retaining water, soil materials, and propagules within and from nearby areas, resources that would otherwise be lost.