低覆盖度行带式固沙林对土壤及植被的修复效应

在我国干旱、半干旱地区由于水分条件的制约,经过漫长的自然演替过程,逐步发育形成了广泛分布的低覆盖度植被,这些低覆盖度植被类型中存在大量的天然乔木疏林或稀疏灌丛,地表处于半流动状态,而配置成行带式后,能够完全固定流沙,并且不同配置模式下行带式固沙林土壤与植被自然恢复程度不同.因此,通过对不同带宽的低覆盖度行带式固沙林对土壤及植被修复的影响研究,揭示了不同带宽行带式固沙林带间土壤因子与植被因子的变化过程,从而阐明行带式固沙林对带间植被自然恢复和土壤发育的促进作用.结果表明,行带式杨树固沙林能够明显的促进带间土壤与植被修复；带间距离的宽窄影响植被恢复及土壤发育效果；宽带间距固沙林带间植被多样性指数高,地上生物量大,根系生物量,总长度及表面积均高,土壤水分养分条件好,微生物数量大植物残体分解快,有利于植被的生长；模糊综合评估结果表明,不同带间距行带式固沙林土壤植被恢复程度不同,宽带间距20m的恢复效果＞带间距15m＞带间距10m.行带式固沙林通过带间宽度的变化可以调节植被与土壤之间的相互作用,窄带间距固沙林土壤与植被的相互作用则由于造林密度大而受到抑制.宽带间距可以明显加快土壤及植被修复的速度,进而缩短土壤及植被修复的时间.

The effect of low-covered sand-fixing forest belts on restoration of the soil and vegetation

Low-covered vegetation is one of typical vegetation patterns in arid and semi-arid areas of China through a long term nature succession. These vegetation types consist of a lot natural sparse woodland and shrubbery, the sandland is under semi-shifting and semi-fixing. However, we found that at low vegetation coverage, the horizontal distribution pattern of trees and shrubs can have marked effects on fixation of shifting sands, and different horizontal distribution patterns have the different restoration degrees of the soil and vegetation. In this paper, for clarify impacts of low-covered sand fixing forest belts on natural vegetation restoration and soil development, the variation and rule of soil nutrients and vegetation with different distribution patterns were researched in Aohan, Chifeng City, Inner Mongolia. The characteristics of community and structure, the physical and chemical characteristics of soil, the amount of soil microbes in different distribution patterns were investigated. The data obtained from the experiment were analyzed with the principal components, the canonical correlation and fuzzy comprehensive evaluation, which obtain coefficient of different recovery scale. Results show: Belt scheme of populus sand fixing forest could improve the interband vegetation and soil rehabilitation effectively; vegetation and soil rehabilitation depend on distance between neighboring belts, and interval distances of neighboring belts can adjust the effect between the vegetation and soil, due to sand-fixation forest planting of narrow spacing with a higher density would inhibited this effect. In wide distance scheme forest, the silt and clay content of soil significantly increased; the soil coarse particle content and bulk density were significantly decreased, soil moisture content was increased; the soil nutrient content was higher in wide distance between the belts than in narrow distance between the belts, and the pH of wide distance between the belts is more closer to the zonal soil. The total number of microorganisms was significantly higher in wide distance between the belts than in narrow, which was conducive to growth of vegetation; the variation trend of root biomass, total length and surface area showed 20m>15m>10m.When the distance between the belts increased, the composition of community species was gradually complex and quantity increased; the index of diversity and above-ground biomass of community increased gradually, and the similarity coefficient of community in the different recovery scale was a rising trend with grassland recovery, which was showed that 20m>15m>10m. Suitable distance between the belts will rehabilitate significantly, the effect on vegetation recovery of distance between bands of 20m sanded forest was better than those others of 15m and 10m; according to the fuzzy comprehensive evaluation of vegetation and soil, the vegetation and soil restoration scale between the belts of 20m interval,15m interval and 10m interval populus forest were current control 68.63%,55.01% and 42.04%.So belt scheme can significantly speed up the soil and vegetation restoration, thereby shortening the time of the soil and vegetation restoration if the distance between neighboring belts is appropriated.