物种多样性和功能群多样性与生态系统生产力的关系——以内蒙古短花针茅草原为例

生物多样性与生态系统生产力之间的关系是当前生态学领域的热点问题。短花针茅(Stipa breviflora)草原是内蒙古荒漠草原的主要类型, 生态系统脆弱, 气候波动剧烈, 研究内蒙古短花针茅草原生物多样性与生产力的关系具有十分重要的意义。该研究在内蒙古短花针茅草原区设置了202个样地进行群落调查, 在干旱区及半干旱区两种资源供给下, 分析了物种丰富度、功能群丰富度与生产力的关系, 旨在解决两个科学问题: 1)物种多样性和功能群多样性中, 哪一种与生产力关系更为密切?2)资源供给对多样性和生产力关系的影响。结果表明: 1)物种丰富度、群落生产力与年降水量呈正相关关系, 而功能群丰富度与年降水量之间不存在显著相关性; 2)群落生产力随物种丰富度的增加而增加, 且两者间呈正线性关系, 功能群丰富度与生产力之间不存在显著相关关系; 3)资源供给会影响多样性与生产力之间的关系, 资源供给低时, 多样性对生产力贡献较低, 资源供给高时, 多样性对生产力的贡献较高。该研究丰富了多样性与生产力关系的研究, 同时, 考虑到植物功能性状的研究在近几年受到生态学家的重视, 且多数研究集中于小尺度的人工控制实验, 因此, 在大尺度自然生态系统中开展功能性状多样性与生态系统功能关系的研究将十分必要。

Relationship of ecosystem primary productivity to species diversity and functional group diversity: evidence from Stipa breviflora grassland in Nei Mongol

Aims The relationship between biodiversity and ecosystem functioning has been a central issue in ecology. However, this relationship is poorly understood for the Stipa breviflora grassland, which is a major community type of desert steppe in Nei Mongol. With unpredictably fluctuating climate conditions, these desert steppe ecosystems are fragile and provide a unique opportunity to test our current understanding of the relationship between biodiversity and ecosystem functioning. This study has two objectives: (1) to examine if species diversity and functional group diversity affect ecosystem primary productivity in the desert steppe of Nei Mongol and (2) to explore how resource supply levels affect the relationship between diversity and productivity.
Methods Based on life forms, species were classified into five functional groups: shrub and semishrub, perennial bunchgrass, perennial rhizome grass, perennial forb, and annual and biennial. Species richness and functional group richness were used to represent species diversity and functional group diversity, respectively. Based on the dryness coefficient, 202 sites across the S. breviflora grassland in Nei Mongol were sampled, and divided into two resource supply levels: arid and semiarid zones. In order to tease out the effect of precipitation, partial regression analysis and partial correlation analysis were used for exploring the relationship of ecosystem primary productivity to species richness and functional group richness, respectively. According to the determination coefficient of regression analysis, the effect of resource supply levels on the diversity-productivity relationship was evaluated.
Important findings Species richness and ecosystem primary productivity were both positively and linearly correlated with precipitation, but no significant correlation was found between functional group richness and precipitation. Ecosystem primary productivity increased significantly with species richness, but not with functional group richness. Resource supply levels could affect the diversity-productivity relationship in that plant species diversity generally had a weaker effect on ecosystem primary productivity at the lower resource supply level and a stronger effect at the higher resource supply level.