【摘要】 中国北方典型草原的地上生物量与气候的相关性已经有很多研究,多数注意到草原地上生物量的波动性,但尚未分析典型草原系统又能长期维持相对稳定的生产力机制,而该方面的研究有助于了解草地对全球气候变化的响应机理。本研究根据中国北方广泛分布的羊草大针茅草原24年的定点监测数据,分析降水量变化引起草地地上生物量的波动性,其波动幅度不如降水量波动幅度大,说明群落生物量存在一定的稳定性。为研究草地生态系统稳定性机制,本文进一步分析了24年样方中出现77种植物的相对生物量,结果表明有31种植物之间存在着负相关,可能在这些种对之间存在着生物量的补偿性。通过分析这些种对间的补偿性,可以看出优势种与亚优势种、优势种与其他非优势种、非优势种之间均存在着补偿性;发生在多年生草与多年生草之间或多年生草与半灌木之间生物量互补较多,说明群落的稳定成分之间的补偿性较强;补偿性主要发生在典型草原群落中的旱生与中旱生植物之间,发生在中旱生与中旱生植物之间的生物量补偿性位于第二,而中生对于中旱生的补偿性位于第三位,这与草原植被组成、降水量变动均有关;种之间的补偿性发生在最多的是禾本科与其它科的种之间,其次是菊科与其它科种之间。总而言之,羊草大针茅草原的地上生物量随降水量的波动性较强,而其又能维持相对稳定性,依赖于群落中的植物种类之间的补偿性。更多还原

【Abstract】 There were many studies on the climate and its effect on the grassland biomass of typical steppe in the Northern China,which showed that the biomass fluctuate seasonably with precipitation change.On long-time observation the grassland ecosystem could maintain the relatively stable biomass,thus it is imperative to study the mechanism of the stability of the grassland biomass.Here we present the results of a long-term(1981～2004) study of the natural steppe communities in the Northern China grassland.The seasonable fluctuation of the community biomass is not as sharp as precipitation change.It implies that the community biomass maintains a relative stability.It is assumed that if an ecosystem in a changing environment has compensatory mechanism,at least some of its components would show negative correlations in biomass over time.At the species level,correlation analyses for 77 species showed that a negative correlation existed for 31 species(compensation information).Importantly,the negative correlation existed between dominant and sub-dominant species,between dominant and non-dominant species,and between non-dominant and non-dominant species in the Leymus chinensis and Stipa grandis grassland.This indicates that a species will be increased in its abundance in response to the reduction of others in a fluctuating environment,it called compensatory effects.In addition,the negative correlation exists between perennial plant and perennial plant,between perennial plant and semi-shrubs or shrubs,while it was less between annual plant and perennial plant,between annual plant and semi-shrubs or shrubs.From the above analysis,we could see that compensation came mostly from those stable components in the grassland community.The most negative correlation existed Xerophytes and midxerophytes which were the master components of the grassland community because the rainfall was not more than that in the semiarid region.The compensatory effects occurred between the gramineous plants and another plants(added to 19 times),most of which were dominant species in the grassland community.In a word,although the community production fluctuated seasonably in the Leymus chinensis and Stipa grandis grassland,the ecosystem could maintain relative stability in a long term for compensatory effects between species and species as well as between species and functional group.Therefore,the study would redound to the advanced research in the stable mechanism of the grassland ecosystem not only in the productivity of the ecosystem.更多还原