摘要
利用对不同沙漠化程度的6个沙质草地群落样地的调查资料,并通过构建恢复力指数,尝试性地对沙漠化过程草地群落在经历约为0.5个生长季的短时间尺度极端干旱事件干扰后、在当年后0.5个生长季表现出的恢复力稳定性进行了定量测定与比较。结果表明:6个不同退化程度沙质草地群落在降水条件恢复后具有反应快速和补偿生长的能力,从而表现出良好的恢复力,即使最严重沙漠化程度的群落也恢复到甚至超过了其在干旱前的状况。各群落恢复力综合指数在2.21—1.16之间,分别以多度、高度、盖度和生物量指标计算的恢复力分指数在4.69—1.23,1.21—0.98,1.59—1.15和1.28—1.00之间,基本呈随沙漠化程度提高而减小的趋势。恢复力指数的计算结果表明,在经历短时间尺度干旱事件干扰后,所研究的退化沙质草地群落具有以较强的恢复力维持植被稳定的倾向和能力。群落之间的比较显示,恢复力随沙漠化程度的发展而降低。对群落恢复力来源与构成进行的分析表明,以多度指标计算的恢复力分指数最大,显示各群落都有充足的种源条件和土壤种子库为群落恢复力提供基本保障条件;群落恢复力不仅来源于1年生植物,也来源于多年生植物;一些群落的优势物种在恢复过程中发生了快速转换。通过综合分析本研究以群落内部生态过程为基础对群落恢复力进行的数量测定结果以及对该群落在同一干旱事件干扰下的抵抗力进行的已有研究结果,认为退化沙质草地群落较低的抵抗力和较高的恢复力都说明了植被稳定性对降水条件的依赖不可替代和无法超越。因而,群落在短时间尺度上具有随降水波动的必然性和不稳定性,而在较长时间尺度上又具有主要由群落恢复力所维持的稳定性;恢复过程中发生的群落优势物种快速转换现象是生物多样性的表现形式之一,进一步证明生物
Ecological stability,changes of eco-system under natural and human-induced disturbances such as fire,grazing,cultivation etc.,involved in how and to what extent human can utilize natural resources but without inducing eco-system degradation or collapse,is a problem worthy of study.From the reaction of an ecosystem to disturbances,it has been concluded that ecological stability could be defined as resistance and resilience.Because of many complicated factors such as the type,the intensity,the temporal scale and spatial scale of disturbances,it has been difficult to make qualified measurements for a real community.Therefore,researches related to resistance and resilience has been stopped at concepts,and studies on qualified resistance and resilience about a real community were scarce.In order to make a tentative example for study on this topic,6 communities in different desertification stage were sampled in a sandy desertified region,and community investigation was done one time for every half month from the beginning to the end of growth season.With the investigation data obtained at the same time in continual two years before and during a special period when climate was extremely arid,a resistance index,which indicates the resistance stability of the 6 communities,were defined and calculated as the ratio of vegetation data at the same time of two years in one study we have done in an earlier time.In this study,with investigation data of the same 6 sandy desertification communities after undergoing the same arid disturbance,a resilience index which indicates the resilience stability of communities was defined and calculated.It could be expressed as： resilience index = the vegetation data at the end of the year during which the aridity event took place / the vegetation data in the early year that was just before the aridity event took place.Results showed that,the resilience indice of the 6 desertified communities calculated with abundance,highness,coverage,and biomass were between 4.69—1.23,1.21—0.98,1.59—
出处
《生态学报》
CAS
CSCD
北大核心
2011年第20期6060-6071,共12页
Acta Ecologica Sinica
基金
国家973资助项目(G2000048704)
甘肃省教育厅硕士研究生导师项目(1005ZTC116)
甘肃省自然科学基金项目(1014RJZA034)
关键词
稳定性
恢复力
多样性
植被
沙漠化过程
stability
resilience
biodiversity
vegetation
desertification
