黄土丘陵区弃耕地恢复过程中土壤与植物恢复特征

采用对比分析以及空间代替时间的方法,根据黄土丘陵区5个恢复年限(0-5、6-10、11-15、16-20和21-25年)弃耕地的调查数据,研究其在植被恢复过程中随着弃耕年限的增加植物群落生物量及其土壤养分的变化特征。结果表明,在5个恢复阶段内黄土丘陵区主要的优势物种依次为赖草(Leymus scalinus)、猪毛蒿(Artemisia scoparia)、达乌里胡枝子(Lespedeza davurica)、长芒草(Stipa bungeana)、白羊草(Bothriochloa ischaemun)。期间,Simpson多样性指数(D)、Shannon-Wiener多样性指数(H)、Pielou均匀度指数(Jsw)、Margalef丰富度指数(Dma)总体上均呈先增大后减小的趋势,其植被覆盖度呈逐渐增加的趋势,这表明黄土丘陵区的植被生物量在自然和人工恢复方式下可以逐渐增加。随着植被恢复年限的增加,黄土丘陵区地上生物量总体上呈现先减少后增加的趋势。土壤养分含量随土层深度(0-20、20-40、40-60cm)的增加而下降,随植被恢复年限的增加土壤有机质、全N和速效K含量呈先减少后增大的趋势,土壤全P含量呈先增大后减小的趋势。植被恢复过程中,21-25年的土壤有机质和全N含量达到峰值,16-20年的土壤全P含量达到峰值,这表明在植被恢复过程中黄土丘陵区土壤养分含量能够得到一定改善,但改善速度缓慢。

The characteristics of plant species and soil quality in the restoration process of the Loess Hilly Region

Using the methods of comparative analysis and substituting temporal serial with spatial serial,the changing characteristics of plant communities biomass and soil nutrient in the process of plant restoration were studied based on the survey data of abandoned lands in the Loess Hilly Region with the five different ecological restoration periods (0—5,6—10,1 1 —15,1 6 —20,and 21 —25 years).The results showed that the main domi-nant species in the Loess Hilly Region with these five plant restoration periods were Leymus scalinus ,Artemis-ia scoparia ,Lespedeza davurica ,Stipa bungeana and Bothriochloa ischaemun ,respectively.Generally, Simpson index,Shannon-Wiener index,Pielou index and Margalef index increased firstly and then decreased which suggested that the ecological system in the Loess Hilly Region can gradually improved by both natural and artificial restoration modes.With the increase of restoration period,the aboveground biomass,soil organic matter,total nitrogen and available nitrogen content decreased firstly and then increased,however,the total phosphorus content changed in opposite way.The soil nutrient contents in different layer decreased with soil depth (0—20 cm,20—40 cm,40—60 cm)increased.Soil organic matter and total nitrogen reached the peak in area with the 21 —25 years restoration period and total phosphorus content reached the peak in area with the 1 6—20 years restoration period which indicated that the content of soil nutrient in the Loess Hilly Region can be gradually improved with low speed.