民勤荒漠草场植物群落自然更新和退化演替初探

Preliminary study on the natural regeneration and degenerated succession of the plant community of desert grassland in Minqin

目前,甘肃民勤沙区荒漠植被正在严重退化。梭梭Haloxylon ammodendron、柠条Caragana korshin-skii、花棒Hedysarum scoparium不能自然更新,白刺Nitraria tangutorum、沙蒿Artemisia arenaria、沙拐枣Calligonum mongolicum、麻黄Ephedra przewalskii等可进行自然更新。自然更新能力强弱排序为沙拐枣、白刺、沙蒿、麻黄、泡泡刺N.sphaerocarpa,沙拐枣和沙蒿自然更新的速度最快,麻黄最为缓慢。当地植物主要围绕种源(母株)进行更新,更新幼苗的数量与土壤之间存在一定关系。除白刺外,幼苗普遍出现在当地主风向西北向的下风向。除梭梭人工林群落外,生态位宽度大的植物种其繁殖更新能力亦较强。幼苗成活低的限制因子主要是降水量及其分布。尤其是沙蒿、沙米Agriophyllum squarrosum的自然更新对降水最为敏感。当地梭梭人工林大面积衰退,梭梭人工林内沙拐枣植株明显增多,存在梭梭人工林向沙拐枣群落演替的趋势。

At present, the degradation of desert vegetation in Minqing was still in severe situation. Nitraria tangutoru, Artemisia arenaria, Calligonum mongolicum and Ephedra przewalskii could regenerate naturally, but Haloxylon ammodendron, Caragana korshisrii and Hedysarum scoparium could not. The research result indicated that the order of the natural regeneration ability was C. mongolicurn 〉 N. tangutoru 〉A. arenaria 〉E. przewalskii 〉 N. sphaerocarpa, the speed of the natural regeneration of C. mongolicum and A. arenaria were the fastest and E. przewalskii was the slowest. The local plant mainly regenerated around the mother plants. And there was a certain rela- tionship between the number of regenerating seedlings and soil. Except for N. tangutoru, the seed- lings generally appeared in the downwind direction of local main NW wind. Except for the artificial forest communities （H. arnmodendron）, the ability of breeding and regeneration growth of the species with broad niche was strong. The limiting factors of seedling survival rate were mainly the precipitati- on and its seasonal distribution. Especially the natural regeneration of A. arenaria and Agriophyllum squarrosum was most sensitive to precipitation. The area of local artificial forest （H. ammodendron） greatly reduced and C. mongolicum obviously increased.