民勤绿洲荒漠交错带三种沙丘类型的自然植被特征

基于对民勤沙井子地区植被调查数据,研究了固定沙丘、半固定沙丘和流动沙丘3种沙丘类型的自然植被特征.结果表明:从固定沙丘、半固定沙丘到流动沙丘,总盖度、灌木盖度下降,草本盖度增加.物种丰富度减小是物种多样性下降的主要原因.从植物的生活型来看,多年生草本和灌木类植物受沙丘类型的影响最大,而一年生草本和半灌木可存活于不同沙丘类型.白刺的生态优势度(重要值)由小到大依次为固定沙丘、半固定沙丘、流动沙丘.植物多样性与白刺的生态优势度呈负相关.不同沙丘类型白刺地上生物量变化明显,半固定沙丘白刺生物量最大.

Natural vegetation characteristic of three sand dune types in the Minqin oasis-desert ecotone

On the basis of vegetation investigation data at Shajingzi region in the Minqin County,the natural vegetation characteristics of three dune types were analyzed.The results showed that the total vegetation coverage,shrub and undershrub coverage decreased;herbage coverage increased.The decline of the species richness was the main reason of species diversity decreasing.Change in life-form composition indicated that perennial herbage and scrubby plants were severely affected,but annual herb and semi-shrub species occured on all dune types.Ecological dominance(importance value) of Nitraria tangutorum enhanced.Negative correlation between ecological dominance of Nitraria tangutorum and species diversity.The change of biomass on different Nitraria tangutorumdune was evident,among which the biomass of semi-fixed dune was maximum.