半干旱黄土区自然恢复与人工造林恢复植被群落对比研究

为研究半干旱黄土区高效植被恢复途径,选取陕西省吴起县境内的合沟封禁流域和柴沟人工造林流域为研究区,在两流域内,沿顺坡和横坡方向,选择一系列20 m×20 m的样地,各组成2条样带。在每个样地内的对角线交点和对角线四分之一处选取5个样方进行植被调查,草本样方和乔灌样方的尺寸分别为1 m×1 m和5 m×5 m。共获得草本样方185个、乔灌木样方80个,其中,合沟封禁流域105个,均为草本样方,柴沟人工造林流域草本样方与乔灌样方各80个。运用植物生态学和植物群落学方法,调查各样方内的植物种类、株数、株高、盖度、地上生物量以及树木基茎、树高、冠幅等植被群落特征指标,并在此基础上对两流域的植被群落特征进行对比分析。结果表明：（1）两流域的植被种类共61种,其中柴沟人工造林流域46种,合沟封禁流域51种,共存物种36种;（2）经过10年生态恢复,柴沟人工造林流域已形成乔-灌-草群落,合沟封禁流域仍为草本群落,且两流域草本群落均以铁杆蒿（Artemisia sacrorum Ledeb.）和茭蒿（Artemisiagiraldii Pamp.）为主要建群种;（3）柴沟人工造林流域的植被盖度、平均高、生物量均明显高于合沟封禁流域的相应指标。两流域植物群落Simpson指数和Shannon-Weiner指数差异较小,Sorensen指数为0.742,主要草本植物种的指标差异不显著。以上特征反映出,在半干旱黄土区,适宜的人工造林可加速该区植被恢复的进程。

Comparison of vegetation community between natural recovery and artificial restoration in semiarid loess area

Aimed to study the effective approach of vegetation restoration in semiarid loess area,two watersheds in Wuqi county,Shannxi province,one of which used the vegetation restoration methods of enclosed and another artificial afforestation,were taken as survey area.In growing season,two transect lines consisted of plots of 20×20 m,and along the direction of down and cross slope respectively,were set up in each of the two survey watershed.In each plot,five square quadrates were selected,which located in the center and quadrant of diagonals respectively,and with the size of 1×1m for herbaceous vegetation and 5×5m for tree vegetation.The total 185 herbaceous quadrates and 80 tree-shrub quadrates were obtained,105 herbaceous quadrates of which in Hegou watershed,the rest all in Chaigou watershed.Using the method of phytoecology and phytocoenology,vegetation community attributes including plant species,number,height,cover of every species,aboveground biomass,basal diameter,tree height and crown diameter were measured in each quadrate.Based on this,vegetation communities in the two watersheds were compared and analyzed.The results show：（1） There are 61 species altogether in two surveyed watersheds,51 of which in Hegou watershed and other in Chaigou watershed.Besides,36 species are in the tow watersheds meanwhile.（2） After 10 years restoration,trees-brushes-grasses community has formed in Chaigou watershed while still herbaceous community in Hegou.The main constructive species of herbaceous community in the tow watersheds all are Artemisia sacrorum Ledeb.and Artemisiagiraldii Pamp.（3） The average cover,average height and total biomass of vegetation community in Chaigou are significantly larger than Hegou watershed.Simpson index and Shannon-Weiner index of vegetation community in two watersheds are similar,and Sorensen index between two watersheds is 0.742.Differences of importance index of the main herbaceous plant species between two watershed were not significant.All of this suggests that the process of vegetation restoration in semiarid loess area can be accelerated by appropriate artificial afforestation.