摘要
研究林下植被对不同密度林地土壤水分环境的指示作用 ,可以为造林营林中的密度调控、提高林分生产力和林分稳定性等 ,提供理论根据。为此 ,对山西黄土丘陵沟壑区的 14年生人工刺槐 (Robiniapseudoacacia)林 6种造林密度 (1 5m× 2m、1 5m× 3m、1 5m× 4m、1 5m× 5m、1 5m× 6m、1 5m× 7m)林分的土壤水分、林下光照强度等环境因子进行观测 ,同时 ,采用样方调查法 ,对不同密度林内的树木生长情况和林下植物的类型、数量、分布及发育状况进行了研究。结果表明 :密度小的林分内 ,各小环境指标均优于密度大的林分 ,其中土壤水分、光照强度有显著的随林分密度增大而减小的趋势 ,刺槐林地内随着林分密度的增大 ,渐渐出现干旱、半干旱地区成龄人工林土壤干化的现象 ,林下植被的种类和数量相应减少 ,物种丰富度和物种多样性指数也降低 ,且逐步由以鹅观草 (Roeg neriakamoji) ,小菅草 (Themedaminor)为典型的中生植物 ,向以角蒿 (Incarvilleasinensis) ,灰绿藜 (Chenopodiumglaucum)为典型的旱生植物过渡 ,反映出林分内的小环境条件随林分密度变化的特征。因此 ,在半干旱区造林和营林中 ,密度不可过大 。
During months of 510 in 2002, radiation, temperature and soil moisture in the forests, the biodiversity and productivity of undergrowth, and the growth of trees in 9 year old Robinia pseudoacacia forests with 6 densities of 3?330 trees·hm -2 , 2?220 trees·hm -2 , 1?750 trees·hm -2 , 1?330 trees·hm -2 , 1?110?trees·hm -2 and 950 trees·hm -2 , and with the canopy density of 1 0, 1 0, 0 9, 0 8, 0 8, and 0 6 respectively were analyzed comparatively. Research can be used to study the indicatory function of undergrowth vegetations with different stand densities. The results showed that the growing condition of trees and undergrowth with low density is prior to that of high density, particularly soil moisture and radiation have a decreasing trend with the increasing density. It also showed the phenomenon of soil desiccation with the density increasing in the woodland of Robinia pseudoacacia like the matured stand of the arid and semiarid regions. Accordingly, the species and quantity of undergrowth are gradually reduced with the increase of stand densities. And it will evolve from the mesophyte, Roegneria kamoji and Themeda minor as the typical ones to xerophil, Incarvillea sinensis and Chenopodium glaucum which showed that the growing conditions will vary with different stand densities in forests.
出处
《中国水土保持科学》
CSCD
2004年第2期62-67,79,共7页
Science of Soil and Water Conservation
基金
国家自然科学基金项目 (30 371172 )
教育部科学技术研究重大项目 (10 4 0 7)
