不同退耕年限撂荒地植物多样性及生物量分析

Investigation into the Species Diversity and Biomass of Plants in the Abandoned Farmlands with Different Restoration Years

退耕还林(草)作为黄土高原水土流失综合治理的主要生态建设措施,经过几十年的开展,黄土高原生态环境得到极大恢复,林草覆盖率明显增加。以安塞县纸坊沟流域为研究区,选取坡耕地(0a)为对照,研究了退耕年限(3～5,10,18,28,37a)对撂荒地植物多样性和生物量的影响。结果表明,随退耕年限的延长,物种丰富度指数、多样性指数、均匀度指数、相同土层根长密度都表现为增大—减小—增大的趋势;植被盖度和地上生物量表现为37a>28a>18a>3～5a>10a>0a;撂荒地植被根系生物量、根长密度均随土层深度增加而减少;不同退耕年限撂荒地,相同层根系生物量表现为28a>37a>18a>3～5a>10a>0a。

As one of the major ecological construction measures for comprehensive control of soil and water losses on the Loess Plateau,the implement of the ＇conversion of cropland to forest or grass land＇ project has greatly improved the eco-environmental condition and the vegetation coverage significantly during the past decades.It was conducted to investigate the potential effects of vegetation restoration years（3-5 a,10 a,18 a,28 a,37 a） on species diversity and biomass of plant in Zhifanggou watershed.The results indicated that indices of species richness,species diversity,community evenness and root length density in the same soil layer increased at the initial period,afterward those parameters decreased,and finally increased as the restoration age increased from 0 to 37 a.The variations in vegetation coverage and aboveground biomass followed the order： 37 a28 a18 a3-5 a10 a0 a.Both of root biomass and root length density decreased with the increase of soil depth.The root biomass also increased with restoration years significantly.