古尔班通古特沙漠南缘羽毛针禾种群年龄结构分析

Analysis on the Population Structure of Stipagrostis Pennata in the Southern Fringe of Gurbantunggut Desert

利用种群生态学中的年龄(植丛大小)结构的研究方法,比较了沙漠内(处于沙漠较深处———距农田边缘500m以外)和农田边(500m内相邻于农田)羽毛针禾种群年龄结构的特征。结果表明,从总体比较,农田边羽毛针禾种群植丛密度、数量分布显著高于沙漠深处;如果将种群中的植丛大小按从小到大分成30级,沙漠中和农田边的羽毛针禾种群年龄结构中幼年植丛(1,2,3,4级)显著多于其它级别的植丛,都属于增长型;羽毛针禾种群的老年植丛的存活率在这两个区域都比较低,这可能是沙漠极端干旱环境条件下植物种群动态的基本特征,同时也说明,增长型羽毛针禾种群应是其能在沙漠中长期续存的基本要素。从研究的结果看,似乎人类农业活动并不损害羽毛针禾种群的发育,反而提高了其幼年植丛补充更新的成功率与成活的比率,推测可能是农业活动改善了局域小环境,增加了局域降水,从而提高了羽毛针禾幼苗成活率及幼年植丛的成活率。另一方面,羽毛针禾是活化沙地上的先锋植物,人类的扰动使沙地活化程度增加,这一点可能也是使农田边羽毛针禾种群相对较为繁荣的原因之一。

By analyzing the two types population structure of S. pennata in Gurbantungut desert, which one is dis- tributing in the deeply desert （ not less than 500m away from farmland） and another is nearby farmland. The result showed that if we divided the plant clumps to 30 grades, the population of S. pennata in these two areas is all in- creasing. Generally, the population density in farmland edge, the number of plant clumps are significantly higher than the deeply desert. The older population survival rate in these two area are all low, this may be the commom feathers under the extreme environment, while the increasing population maybe the long-term renewal elements in the desert. The results also showed that, human activity does not block the farmland edge population development, but to enhance its young plants recruitment rate and survival rate. while human disturbance quicken the desertifiea- tion, this maybe the reason why farmland edge population are more prosperous.