Sensitivity of a Sandy Area to Climate Change Along a Rainfall Gradient at a Desert Fringe
Sensitivity of a Sandy Area to Climate Change Along a Rainfall Gradient at a Desert Fringe
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沙漠边缘降雨梯度沙区对气候变化的敏感性
DOI：
10.1007/978-3-540-75498-5_29
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
S. Breckle
中科院分区：
文献类型：
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作者：
A. Yair;M. Veste;R. Almog;S. Breckle
过去几十年来，全球气候变化已成为一个备受关注且经常讨论的问题。这对于占全球陆地总面积约三分之一的旱地地区至关重要。年平均降雨量与环境变量之间的关系引起了许多科学家的关注。气候学家使用干旱指数来表达气候和环境变量之间的关系（Köppen 1931；Budyko 1974；Wallen 1967；Bailey 1979）。这些指数基于纯粹的气候变量，如年降水量、温度、蒸发和辐射，往往意味着干旱的严重程度与年降水量成反比。尽管意识到土壤含水量取决于当地土壤类型和降水状况，Walter（1939，1960）断言，在更大的全球范围内，常备生物量与年平均降雨量呈正相关。许多研究人员仍然遵循这种方法，他们假设年平均降雨量与环境变量之间存在正相关关系，例如植物的可用水量、植被覆盖、生产力、物种多样性、土壤特性、人类活动以及半湿润到干旱地区的侵蚀率（Issar and Bruins 1983；Shmida 1985；Seely 1991；Lavee et al. 1991；Kutiel et al. 2000；Meron et al. 2000）。 2004）。这种方法在全球范围内当然是正确的，对于旱地地区的非灌溉一年生作物也是如此。然而，对于通常被认为对气候变化高度敏感的干旱和半干旱地区，尤其是多年生植物来说，这一点是值得怀疑的。随着年降雨量的减少，暴雨次数和暴雨量减少。在这种条件下，植物的可用水量可能高度依赖于降雨量和地表性质之间的关系，这极大地影响水渗透或转化为径流的程度，从而显着影响水资源的空间重新分配。例如，众所周知，缺乏广泛土壤和植被覆盖的岩石山坡的特点是入渗率极低，并且地表径流很快形成。由于大多数个别阵雨的持续时间较短，水流距离较短，导致附近下坡位置的水集中和深水渗透(Yair and Danin 1980; Yair 1983, 1994,
Global climate change has become a strongly and frequently addressed issue in the last decades. The aspect is crucial in dry-land areas, which cover approximately one third of the globe’s total land area. The relationship between average annual rainfall and environmental variables has attracted the attention of many scientists. Climatologists use aridity indices to express relationships between climatic and environmental variables (Köppen 1931; Budyko 1974; Wallen 1967; Bailey 1979). These indices, based on purely climatic variables such as annual precipitation, temperature, evaporation and radiation, tend to imply that the acuteness of aridity is inversely related to annual precipitation. Although aware that soil water content depends on local soil type and precipitation regime, Walter (1939, 1960) asserted that at a larger, global scale, standing biomass is positively correlated to average annual rainfall. This approach is still followed by many researchers who assume a positive relationship between average annual rainfall and environmental variables such as water availability for plants, vegetation cover, productivity, species diversity, soil properties, human activity, and erosion rates for sub-humid to arid areas (Issar and Bruins 1983; Shmida 1985; Seely 1991; Lavee et al. 1991; Kutiel et al. 2000; Meron et al. 2004). This approach is certainly correct at the global scale, as well as for non-irrigated annual crops in dry-land areas. It is, however, questionable for arid and semi-arid areas, usually regarded as highly sensitive to climate change, especially for perennial plants. With decreasing annual rainfall, the number of rainstorms and storm rain amounts decrease. Under such conditions, water availability for plants may be highly dependant on the relationships between rainfall and surface properties which greatly influence the degree to which water will percolate or will be transformed into runoff, thereby significantly affecting the spatial redistribution of water resources. For example, it is well known that rocky hill slopes devoid of extensive soil and vegetation cover are characterized by extremely low infiltration rates, and quickly develop surface runoff. Due to the short duration of most individual rain showers, flow distances are short, resulting in water concentration and deep water percolation at nearby down-slope positions (Yair and Danin 1980; Yair 1983, 1994,