高寒草甸不同群落类型土壤碳分布与物种多样性、生物量关系

Relationships between Soil Carbon Distribution and Species Diversity and Community Biomass at Different Alpine Meadows

利用2003年-2005年中国科学院海北站不同群落类型草地和土壤的实测资料,研究了高寒草甸不同群落类型土壤有机碳、微生物量碳的分布特征与物种多样性、生物量的关系。结果显示:不同群落类型物种多样性随土壤有机碳、微生物量碳的增加而降低;群落生物量随着土壤有机碳、微生物量碳含量的增加而增加;不同类型草地土壤中,藏嵩草沼泽化草甸不同土层土壤微生物量碳和土壤有机全碳均显著高于其它三个类型草地各层的土壤微生物量碳、土壤有机全碳(P<0.01),4种群落类型土壤剖面上土壤有机碳和微生物量碳随土层深度的增加而降低,同一土层、不同群落类型土壤有机碳和微生物量碳存在明显差异;相关分析表明,土壤有机碳和土壤微生物量碳与有机质、全氮呈显著相关,土壤有机碳和土壤微生物量碳含量可作为衡量土壤肥力和土壤质量变化的重要指标。不同类型草地其最初的植物群落物种组成、生产力水平和土壤养分条件影响着土壤微生物生物量、组成和活性。

Soil organic carbon is a critical component in the terrestrial carbon reservoir,and its storage,distribution,and conversion play a major role in the globe carbon budget. Better understanding the distribution pattern of soil carbon storage in different alpine meadows will facilitate the projection of global change on the terrestrial carbon cycling. The relationship between biodiversity and ecosystem functioning has aroused considerable interest and controversy in recent ecological literature. Heterotrophic microbial communities inhabiting soil dictate key processes that control the ecosystem carbon and nitrogen cycling,and they potentially represent a mechanistic link between plant diversity and ecosystem functions. Measurements of different plant community types and soils were used at the Haibei alpine meadow ecosystem station during the period 2003-2005. This study was conducted to examine characteristics of soil microbial biomass carbon （MBC）,soil organic carbon （SOC）,and their relationships with productivity and diversity at different alpine meadows. Results indicated that the plant diversity index （H＇） decreased with soil total organic carbon and soil microbial biomass carbon increasing. Community biomass increased with soil total organic carbon and MBC increasing in different alpine meadow communities. The MBC and organic total carbon at 0-10 cm,10~20 cm,20~40 cm,and 0~40 cm soil layer in Kobresia tibetica swamp meadow were found to be 2.99,1.78,0.38,and 1.72 g/kg dry soil,and 183.31,78.92,20.58,and 94.27 g/kg dry soil,respectively,which were significantly higher than other types of meadows （p0.01）. The SOC and MBC contents decreased with increasing soil depth,exhibiting differences at the same soil depth in different type communities. There existed a significant correlation of the two indices with soil organic and soil total N,indicating that both SOC and MBC could be used as the important indicators to measure changes in soil quality. The soil resources showed a stronger positive correlation with aboveground biomass of different grassland type communities. Changes in microbial composition and community biomass largely resulted from a higher level of plant production,rather than from plant diversity. It was found that the plant species differed in their biochemical composition. Changes in plant diversity could substantially change the production,thereby controlling the composition and function of heterotrophic microbial communities. The amounts of living plant biomass in alpine meadow communities affected soil microbial biomass carbon,soil organic carbon,and soil fertility. These results suggest that the original soil conditions,plant community composition,and community productivity play an eminent role in regulating plant community productivity and microbial biomass and activity in different alpine meadows.