荒漠绿洲边缘区泡泡刺种群对风沙干扰的响应

研究了位于黑河中游荒漠绿洲外缘 (荒漠与绿洲过渡带 )戈壁与沙漠两种生境下泡泡刺种群对风沙干扰的响应。结果表明 ,因风沙干扰的响应 ,泡泡刺种群以斑块状格局形式存在 ;独立灌丛沙堆的形成途径主要有 4种 :种子发育、根蘖繁殖、较大的沙堆退化 (生境破碎化 )和邻近沙堆的兼并。水分条件是泡泡刺种群生长的重要制约因素 ,长期对有限的水分资源竞争 ,使其大小和空间分布都形成了明显的特征。绿洲与戈壁交错带 (类似戈壁生境 )样地的泡泡刺种群的沙埋深度、种群高度、种群盖度、种群大小、生物量都小于绿洲与沙漠交错带 (类似沙漠生境 )样地的泡泡刺种群的相应的种群特征变量 ,而绿洲与戈壁交错带样地的泡泡刺种群密度却大于绿洲与沙漠交错带样地的相应的种群特征变量。绿洲与戈壁交错带样地的泡泡刺种群密度为33.3株 / m2 ,而绿洲与沙漠交错带样地的泡泡刺种群密度为 2 5 .4株 / m2 。两样地泡泡刺种群的沙埋深度、种群高度、盖度、密度及大小存在着显著差异 ,只有生物量无显著差异。两样地中泡泡刺的沙埋深度对泡泡刺种群特征的影响明显 ,无论戈壁还是沙漠生境 ,沙埋深度与种群高度、种群大小、种群生物量明显正相关。适度沙埋可以促进泡泡刺种群的生长 ,但当沙埋深度超过10 0 cm时 ,又会对泡泡刺种群

Responses of Nitraria sphaerocarpa Maxim. population to disturbance of blown sand in the edge of Desert Oasis

Nitraria sphaerocarpa Maxim. is one of the major sand binding species in the sand lands, which mainly distributes in the arid and semi-arid area of China. The study was conducted to evaluate how the Nitraria sphaerocarpa Maxim. population responds to the disturbance of blown wind, and to establish the relationships between the depth of sand burial and the population height, coverage, density, size, and biomass, respectively. The results show as follows: Nitraria sphaerocarpa Maxim. population shows patchy and discontinuous distribution pattern. Sand burial makes the population relative independent shrub coppice dune. And the independent shrub coppice dunes can be formed by four ways, that is: 1) seedling reproduction; 2) sprouting reproduction; 3) habitat fragmentation; 4) combination of neighboring shrub coppice dunes. Water condition is one of the most important factors to control the growth of Nitraria sphaerocarpa Maxim. population, which has significant characters in size and spatial distribution, due to competing for the limited water resource. Except for the biomass, there are significant differences between population height, coverage, density, and size in Gobi and those of the population in the desert, respectively. The height, coverage, size, and biomass of the population in the desert are bigger than those in Gobi, however, the density of the population in desert is less than that in Gobi. The population height, density, size and biomass are significantly correlated with the depth of sand burial in Gobi, and the height, coverage, size and biomass are significantly correlated with the depth of the sand burial in the desert, respectively. Population height increases with increasing sand depth. Population coverage increases with increasing sand depth in desert. Also the density increases with increasing depth of sand burial in the desert, however, there is a steady decrease when the depth of sand burial is more than 100cm. The result illustrates that the depth of sand burial that is fittest for the growth of Nitraria sphaerocarpa Maxim. population is 100cm. In Gobi, the population density increases with increasing depth of sand burial. The size of the population is significantly correlated with the sand depth, which increases with increasing depth both in Gobi and the desert. The conclusion can be drawn that the characteristics of Nitraria sphaerocarpa Maxim. population are significantly correlated with the depth of sand burial due to the disturbance of blown wind and the limited water resource. Sand burial can improve its growth, however, when the depth of sand burial is more than 100cm, its growth will be gradually restrained.