放牧和围封对干旱区草地生态系统的影响

研究了10a短期围封对贺兰山西坡哈拉乌一带短花针茅群落植被组成及土壤水分、养分的影响.结果表明,10a围封使短花针茅群落的植被盖度从围封前的30％增加到80％,旱生灌丛由2种增加到3种,1a生、多年生草本分别从0种和3种增加到2种和5种.围封区的物种丰富度指数(1.46)、多样性指数(2.84)和均匀度指数(0.81)...

Effects of Grazing and Enclosure on Desert Grassland Ecosystem

The effects of enclosure on the vegetation composition and soil properties of Stipa brevifloria community were studied in the west slope of Halawu section of the Helan Mountain,China.The results showed that 10-year enclosure increased the vegetation coverage of Stipa brevifloria community from 30% to 80%.The species of xerophyte shrub increased from 2 to 3,and the species of both annual and perennial herbs increased by 2,from 0 and 3 to 2 and 5,respectively.The species richness(1.46),diversity(2.84),and evenness(0.81) under the enclosure condition were significantly higher than those of the control,which were 1.02,1.77 and 0.76,respectively.The Jaccard similarity index was 0.25 between the enclosure and the control,which suggested that the species composition was significantly different.The enclosure resulted in the increase of soilorganic matter,total nitrogen and sand contents at depth of 0-20cm from(1170±360)g/kg,(580±140)g/kg and(15.0±2.8)% to(2890±310)g/kg,(880±180)g/kg and(20.3±2.6)%,but resulted in the decrease of silt and clay contents from(69.7±9.6)% and(15.3±4.2)% to(67.0±6.8)% and(12.7±3.3)%.Based on these results,a conceptual model of the desert grassland ecosystem stability under grazing disturbance was developed,which indicated that the degradation process resulting from grazing and the restoration process resulting from enclosure wereirreversible process.Finally,a management method of seasonal enclosure and rational use of grassland resources was proposed.