退化沙质草地自然恢复过程中土壤-植物系统的变化特征

研究了科尔沁沙地封育5a后退化沙质草地自然恢复过程中土壤—植物系统的变化特征,同时分析了土壤性状与植物特征之间的相互影响程度。(1)从流动沙地恢复到固定沙地,沙质草地植物群落的物种多样性、植被盖度、地下根量和地表枯落物残留量均趋于增大。β多样性测度值表明,在半流动沙地恢复到半固定沙地阶段,植物种周转速率大,群落结构变化明显。(2)在退化沙质草地的自然恢复过程中,表层土壤的结构性能明显改善,土壤养分的有效性相应提高。(3)相关分析显示,沙质草地表层土壤的理化性状与植物特征值之间存有密切的相关性(R2=0.33～0.84,P<0.01,n=20),表明退化沙质草地的恢复过程实质上是土壤—植物系统协同演变的过程,在该过程中,植物多样性的关键恢复期滞后于土壤环境的关键恢复期。

Features of Soil-Plant System Changes in Different Restorative Stages of Degraded Sandy Grasslands

The variation features of soil- plant system in the natural restoration processes of deg raded sandy grassland in the Horqin sandy land af ter 5 years of exclusive grazing by a nimals are studied.In the mea ntime, the interacting deg ree between soil properties and plant cha racteristics are analyzed.The result s show that: (1) As moving sand was turned into fixed sandy land, the species diversity in plant communities, vegetatio n cov er, underg round root volume and surface litter residue tended to increase.The measured values of β diversity demo nst ra te tha t as semi fluid sand was restored to semi fixed sand, The turnover rate of plants increased and the chang es in plant community structure became evident.(2) In the natural restoration processes of degraded sandy grassland, the structure of surface soil layer significantly improved and the availability of soil nutrients correspondingly enhanced.(3) Correlation analy ses show that there is a close correlation between to psoil physiochemical properties and plant cha racteristic values of the sandy grassland.This shows that the restoration processes of degraded sandy grassla nd are virtually a synergi stically evolutional processes of soil-plant system, the key restoration phase of plant diversity lags behind the key restoration phase of soil environment in the processes.