陕北黄土高原丘陵沟壑区植被恢复中的障碍分析与应对策略——以子长县为例

Barriers and countermeasures to them in vegetation rehabilitation in hilly and gully regions of the Loess Plateau located in North Shaanxi——A case study of Zichang County

通过对子长县退耕还林、植被恢复重建中出现的具体问题进行实地调查研究,并结合研究区自然环境条件和前人有关人工植被建设中的研究结果进行分析,以探讨黄土高原丘陵沟壑区植被恢复重建的技术体系。结果表明,在陕北黄土高原丘陵沟壑区退耕还林植被恢复建设中,应充分考虑当地降水条件并结合生态效益与经济效益,具体实施过程中要注意:(1)依据当地原生态植被结构合理配置乔、灌、草,在以刺槐为主的乔木林内应适当搭配当地适生树种(杨、柳、山杏、榆、杜梨等);(2)在沟谷及部分阴坡水分条件较好的地方种植耐旱乔木树种,在墚峁坡顶种植灌木和草本植物,半灌木和灌木种植在沟坡上部,坡度大的地方尽量不要人为干扰,自然封育恢复;(3)秋季植树,初植乔木林密度不要超过2300株/hm2,成林密度应控制在1100株/hm2左右;(4)建立苗圃,提高种苗质量,造林种苗尽量在本地解决,以提高植树成活率。

Concrete problems occurring in farmland conversion into forestland and grassland and vegetation rehabilitation of Zichang County were field investigated and analyzed in combination with the local natural environmental conditions and previous research results in vegetation construction, and we discussed the technique system of vegetation rehabilitation in hilly and gully regions of the Loess Plateau. The results showed that farm conversion into forestland and grassland in hilly and gully regions of the Loess Plateau should pay adequate attention to local rainfall as well as combining economic benefits with ecological benefits. Its implementation should stress that （1） the compositions of arbors, shrubs and grasses should be arranged according to the local original vegetation compositions, and locally adaptable tree species （poplar, willow, apricot, elm and bireh-leaf pear） should be arranged in acacia-dominated arbor forests; （2） Drought-tolerant arbor species should be planted in valley lands and north-facing slope lands, which have relatively favorable moisture, shrub and herbaceous plant species should be planted on ridge and mound tops, sub-shrubs and shrubs should be planted in upper valley and slope sections, and human disturbances should be avoided as much as possible on slope lands with a high gradient so that the vegetations will recover naturally; （3） Where trees are planted in autumn, the initial planting density of arbor trees should not surpass 2 300 trees/hm^2 and the density of adult forests should be kept at about 1 100 trees/hm^2; （4） Sapling nurseries should be constructed to improve sapling qualities and realize local supply of saplings necessary for afforestation so that the survival rates of planted trees will be increased.