沙源的供给形式和丰富度是控制沙丘形态的直接因子。在内蒙古高原阴山北麓,以洪积扇下风向、农耕地下风向和残积地内的小叶锦鸡儿(Caragana microphylla)灌丛沙堆为研究对象,用典型样方法对沙堆的分布及形态进行系统测量。结果显示:相同样地面积内,相比内源型供给的残积地内的灌丛沙堆,外源型供给的洪积扇和农耕地下风向灌丛沙堆数量少,但单体沙堆的平均尺度大;洪积扇下风向样地沙堆的各项形态参数顺风向急剧递减,残积地内沙堆的水平形态参数顺风向缓慢递增,灌丛及沙堆高度顺风向保持不变,这一结果是对沙源相对位置不同导致沙粒运移方式和沙源量产生差异的响应;内源型、外源型供给的沙堆长、宽间均存在极显著的线性关系(p<0.01),且拟合线斜率均顺风向呈递增趋势,两种供给形式下的沙堆高度与灌丛高度间均存在显著的线性关系(p<0.05),洪积扇下风向和残积地内沙堆的水平尺度与高度间存在极显著的幂函数关系(p<0.01),其中残积地内沙堆水平尺度与高度间的拟合曲线顺风向几乎无变化,洪积扇下风向样地的则顺风向逐步产生差异。

The sand supply and its richness have long been considered the direct factors in influencing dune morphology. The targeted Caragana microphylla nebkhas are located at three different sites(downwind of alluvial fans, downwind of cultivated land and residual-depositional land) in northern foot of Yinshan Mountain of Inner Mongolian Plateau of China, and its distribution pattern and morphology were systematically measured with a typical quadrat sampling method. The results show that compared with those nebkhas locating at exogenous alluvial fans and cultivated land, the dunes at endogenous residual-depositional land are less in unit area, but the average size is larger. In downwind direction, the morphological parameters in horizontal direction of nebkhas at residual-depositional land are increased slowly and both the height(at vertical direction) of the vegetation and nebkhas has little change, while the parameters are decreased sharply at alluvial fan site. It is believed that the phenomenon is response to the difference of sand movement and quantity caused by relative location between the nabkhas and sand resource. There is an extremely significant linear relationship between the length and width of nebkhas at both endogenous and exogenous area(p<0.01), and the fitting lines' slope is increased in the downwind direction. A good correlation also exists between nebkhas height and vegetation height in the two supplying form(p<0.05). An extremely significant power function relationship was found between the horizontal parameters and height of the nebkhas on downwind of alluvial fan and residual-depositional land(p<0.01), and the fitting curves of horizontal parameters and height of nebkhas change slightly in wind direction at residual-depositional land, while that shows a gradually large variation in wind direction at alluvial fans.