民勤沙区人工梭梭林自然稀疏过程研究

通过实地样方调查,对民勤沙区人工梭梭林的自然稀疏过程进行分析,以探讨其自然稀疏机理。结果表明:(1)民勤沙区梭梭经过自然稀疏,15~32 a林龄的密度为387.14株.hm-2。(2)梭梭林内乔木、灌木、草本植物对不同层次土壤水分利用的分异比较明显,草本植物和灌木分别主要利用0~20 cm和0~100 cm的土壤水分,梭梭主要利用60~120 cm的土壤水分。(3)在梭梭林成长过程中,沙丘水分递减,梭梭因水分亏缺而自然稀疏化,且在10 a林龄以内自然稀疏过程最明显。(4)当林龄达到15 a以上时,植株普遍枯梢,生长不良,植株个体增大缓慢。(5)对于15 a及其以上成龄梭梭林进行人工补灌没有显著恢复效果,只是增加草本植物的密度和盖度。

Self Thinning Process of Haloxylon ammodendron Planted Forest in Desert Area of Minqin

This article has studied the self thinning process of Haloxylon ammodendron planted forest through the establishment plots.The result indicated that:(1) with the self thinning process,the density of H.ammodendron planted forest is 387.14 hm(-2) from 15 a to 32 a age.(2) It is distinct that the tree and shrub,annual herbaceous plant use the different level soil moisture in the H.ammodendron planted forest,The herb herbaceous plants mainly use the soil moisture in 0~20 cm,the shrub plants mainly use the soil moisture in 0~100 cm,the H.ammodendron plants mainly use the soil moisture in 60~120 cm.(3) Sand dune moisture decreases progressively and H.ammodendron is sparse with H.ammodendron growing from infancy to maturity,the self thinning process is most obvious in 10 ages of forest.(4) The top of adult plant universally is withered and the individual adult plant grows slowly when the age of forest achieved 15 a.(5) Artificial irrigation does not remarkably restore the H.ammodendron forest.The only change is the increase of the annual herbaceous plant density and coverage.