围封对内蒙古中东部草原植物群落和土壤线虫群落的影响

2007年8月在中国科学院内蒙古草原生态系统定位研究站的退化样地（对照）、围封5 a样地和围封24 a样地,调查地上部植物群落、土壤性质和地下部土壤线虫群落。结果表明,围封处理能显著提高土壤水分质量分数,土壤深度和围封处理对土壤pH的交互作用显著。随着围封年限的增加,地上植物的多度、生物量和单株生物量都显著增加,而3个样地的多样性和均匀度均为围封24 a样地〉退化样地〉围封5 a年样地;随着围封年限的增加,大针茅（Stipa grandis）、苔草（Carex duriuscula）、羊草（Leymus chinensis）、锦鸡儿（Cleistogenes squarrosa）、双齿葱（Allium bidentatum）的生物量都呈现递增的趋势;围封5 a样地上冰草（Agropyron cristatum）和野韭（Allium ramosum）的生物量最大,围封24 a样地上苔草、羊草、双齿葱的生物量最大。调查样地线虫的密度平均为9.79 g-1（以干土计）,分别隶属于线虫动物门的90个属。植物寄生类线虫和食细菌类线虫分别占到总数的35%和40%,优势类群是丽突属（Acrobeles）和矮化属（Tylenchorhynchus）,二者共占总捕获个体数量的31.4%。围封24 a样地的结构指数显著高于退化样地,其它指标差异不显著。由此可知,围封有助于改善土壤理化性质;从围封角度来看,植物群落比线虫群落的反应明显得多,二者并未出现同步反应。

Effect of fencing on plant and nematode communities in the grassland in mid-and eastern Inner Mongolia,China

The objective of the present study was to evaluate the effect of fencing on plant community,soil characters and soil nematode community in grassland.The investigation was performed in the Inner Mongolia Grassland Ecosystem Research Station（IMGERS） in August 2007.The experiment consisted of three treatments： the degraded plots（control）,plots with fencing for 5 years,and plots with fencing for 24 years.The results showed that soil moisture content increased in the treatment of fencing as compared to the control plots.The interactive effect of fencing treatment and soil depth on soil pH was significant.The abundance of plants,total plant biomass and biomass per plant increased with increasing length of time for fencing.The patterns of diversity and evenness were similar with the following order： fencing for 24 years degraded plots fencing for 5 years.The biomass of Stipa grandis,Carex duriuscula,Leymus chinensis,Cleistogenes squarrosa,and Allium bidentatum appeared to be increased by fencing.The largest biomass of Agropyron cristatum and Allium ramosum presented in the plots with fencing for 5 years,whereas the largest biomass of Stipa grandis,Carex duriuscula and Leymus chinensis presented in the plots with fencing for 24 years. The average abundance of nematodes in all tested samples was 979 individuals per 100 g dry soil.Among all of the nematodes belonging to 90 genera found at the site,the plant-parasitic nematodes and bacterivorous nematodes were dominant,accounting for 35% and 40% of total nematodes,respectively.Acrobeles and Tylenchorhynchus were the most dominant genera of bacterivorous and plant-parasitic nematodes,respectively.The structural index,but not other indexes,of nematode community was higher in plots with 24-years fencing than degraded plots.Our study suggests that fencing improved soil properties.The plant community had greater response to fencing than did the nematode community,and the two communities did not show a synchronous response.