沙丘微地形生境蚁丘分布特征及其对恢复过程的响应

为了阐明沙丘微地形生境蚁丘特征及分布规律对沙丘固定过程的响应规律，以科尔沁沙地为研究区，选择不同固沙阶段沙丘的4个方位（西北、东南、西南、东北）布设调查样地，测定了不同样地的蚁丘密度、直径和高度，分析了不同样地蚁丘特征及空间分布规律。结果表明：（1）流动沙丘背风向（即东南方位）蚁丘密度显著高于其他方位，但从流动沙丘到半流动沙丘，背风向（即东南方位）蚁丘密度显著低于其他方位；从半固定沙丘开始，半固定和固定沙丘微地形对蚁丘密度分布的影响较小。（2）在流动沙丘、半流动沙丘、半固定沙丘，不同微地形生境中蚁丘直径和高度均呈现出相似的分布规律，即东南方位均小于其他方位。在固定沙丘，蚁丘高度表现为东南方位亦较低，但蚁丘直径表现为西南和东北方位显著小于西北方位。（3）在流动沙丘，西北、西南和东南方位上蚁丘空间分布均表现为均匀分布型，而在半流动、半固定和固定沙丘，4个方位上蚁丘空间分布均表现为聚集分布型。（4）相关性分析表明，不同固沙阶段不同微生境下蚁丘密度、高度、直径与植物密度、多样性间的相关性不同。随着固沙阶段演替，不同微生境下蚁丘特征与植物密度、多样性的相关性增强。研究表明，在科尔沁沙地，随着流动沙丘固定和生境逐渐恢复，沙丘不同空间方位上蚁丘密度分布差异缩小，而蚁丘直径和高度仍存在沙丘微地形间显著差异性，并且蚁丘空间方位上均呈现聚集分布状态。

Distribution of ant mounds in sand dune microtopographic habitats and their responses to the restoration process

The objective of this study was to clarify the distribution of ant mounds in sand dune microtopographic habitats and their responses to the restoration process. In Horqin sandy land, four dune aspects (i.e., northwest, southeast, southwest, and northeast) of dune were selected as sampling sites in mobile sand dune, semi-mobile sand dune, semi-fixed sand dune, and fixed sand dune. The density, diameter and height of ant mounds were measured, and the distribution of ant mounds sand dune microtopographic habitats were analyzed. The results showed that:(1) from mobile dune to semi-mobile dune, there was an opposite distribution of ant mound density between the four habitats of dune aspects. The density of ant mounds in mobile dunes was significantly higher on leeward aspect (i.e., southeast direction) than that on other aspects, whereas the density of ant mounds in semi-mobile dunes was significantly lower on leeward aspect (i.e., southeast direction) than that on other aspects. However, there was a little effect of dune aspects on ant mound density in both semi-fixed and fixed sandy dunes. (2) There was a similar distribution of ant mound diameter and height between dune aspects in mobile dune, semi-mobile dune, and semi-fixed dune; the ant mound diameter and height was significantly lower on the southeast aspect than on the other aspects. In fixed sand dune, the height of ant mounds was significantly lower on the southeast aspect, but the diameter of ant mounds was significantly lower on the southwest and northeast aspects than on the other aspects. (3) The spatial distribution of ant mounds indicated a pattern of uniform in the northwest, southwest and southeast dune aspects in mobile sand dune. However, it indicated a pattern of clumped distribution in the four dune aspects in semi-mobile, semi-fixed, and fixed sand dunes. (4) The correlation analysis showed that the correlation coefficients between the density, height and diameter of ant mounds and the plant density and diversity in different dune aspects differed between mobile, semi-mobile, semi-fixed, and fixed sand dunes. The correlation coefficients in different dune aspects increased along with the ecological restoration process of mobile sand dunes. In conclusion, with the fixation of mobile dunes, the differences of ant mound density between dune aspects decreased from mobile and semi-mobile sand dunes toward semi-fixed and fixed sand dunes in Horqin sandy land. The distribution of ant mount diameter and height was still significantly different among the four micro-topography of sand dunes. The spatial distribution of ant mounds indicated a similar pattern of clumped distribution during the restoration process.