（2）两种荒漠生态系统季节变化中土壤微生物量与有机碳、全氮均显著（p < 0.05）相关，但不同生态系统则还具特有的影响因子：柽柳生态系统与土壤总含盐量呈显著负相关，而梭梭生态系统与土壤湿度存在显著正相关。柽柳生态系统土壤微生物量空间动态中，土壤微生物量与土壤水分、土壤温度显著（p < 0.05）正相关。
（3）两种荒漠生态系统土壤呼吸表现出强烈的时空动态，且与土壤温度表现出显著正相关（p < 0.05）。
（4）将土壤微生物量对土壤呼吸的影响进行分析，构建了土壤微生物量影响土壤呼吸时空变化的定量模型，结果表明荒漠生态系统土壤微生物量对土壤呼吸有显著（p < 0.05）影响。
|其他摘要||Accurate assessment of carbon budget in variable ecosystems is vital to our understanding and accurate estimation of the global carbon balance. However, the carbon cycle details of desert ecosystems are still poorly understood because the carbon budget of deserts is largely driven by availability of water to vegetation and soil microbes. Improving our knowledge of spatiotemporal pattern of soil microbial biomass and its effects on soil respiration under various water and salt stress levels in desert ecosystems is hence critical for clarifying both temporal and spatial variations of soil respiration. The conclusion will be useful to assess carbon budget and furthermore to mitigate the impacts of global changes in arid land.
This research focused on two typical desert ecosystems (Tamarix chinensis and Haloxylon ammondendron) at the southern edge of Junggar Desert, soil microbial biomass and other various environmental factors were continuously monitored, combining the control experiments in laboratory to reveal the temporal and spatial variations of soil microbial biomass and its responses to different water and salt stress levels. In the meantime, soil respiration was simultaneously measured using an automatic soil CO2 flux system to clarify the influences of soil microbial biomass on soil respiration.
The main results indicated that:
(1) Soil microbial biomass in desert ecosystems had significant seasonal variations, and also had significant spatial variation in Tamarix chinensis ecosystem.
(2) Environmental factors analysis showed that the temporal distributions of soil microbial biomass were significantly related with the soil organic carbon and soil total nitrogen in the two desert ecosystems, and significantly related with total salt (negative, p <0.05) in Tamarix chinensis ecosystem, while significantly correlated with soil moisture (positive, p <0.05) in Haloxylon ammondendron ecosystem. Spatial distributions of soil microbial biomass in Tamarix chinensis ecosystem were significantly related with the soil moisture and soil temperature (positive, p <0.05).
(3) Soil respiration had clear heterogeneous patterns on the both spatial and temporal contexts in the two desert ecosystems, which were positively significantly correlated with soil temperature (p <0.05).
(4) Soil microbial biomass was positively significantly correlated with soil respiration (p <0.05), and the model for quantitatively assessing the impact of soil microbial biomass on soil respiration was established.
The results obtained in this study should help us to elucidate both temporal and spatial variations of soil microbial biomass and their effects on soil respiration in arid land, and also to provide a basis for better understanding carbon cycle in arid zone.|
管海英. 荒漠生态系统土壤微生物量动态及其对土壤呼吸的影响[D]. 北京. 中国科学院大学,2015.