Soil Organic Matter Dynamics in Boreal Ecosystems in Eurasia

本研究对欧亚大陆北方生态系统土壤有机质动态进行了研究，主要结果如下：1）在欧亚大陆和北美的不同地区，即哈萨克斯坦东南部、芬兰、西西伯利亚和加拿大，考察了土壤和植被受气候条件影响的转变，这些气候条件沿着海拔或纬度变化。2）采用稳定同位素示踪法，对北方天山地区5种不同类型的土壤进行了野外试验，研究了~（13）<13>C标记植物材料的分解速率和植物材料中C向HF迁移的分解率。分解速率常数和分解率随分解速率常数的变化而变化，分解速率常数和分解率随分解速率常数的变化而变化。 ...更多信息 3）通过分析添加低水平葡萄糖C后土壤微生物对葡萄糖的利用模式，详细研究了北方天山土壤微生物对有机质的利用。实验结果表明，葡萄糖存在一个阈值浓度，超过该浓度，土壤微生物开始从贮藏化合物合成结构化合物，呼吸同化比开始增加，并且更高比例的底物可以容易地在酸中矿化，并且/或在较高浓度的基质中偶尔提供临时“C冲洗”的情况下，例如可能发生在根际或土壤中的扰动土壤，4）为了优化区域作物轮作系统以缓解土壤有机质的消耗，监测土壤有机质收支的时空变化是可行的选择，地统计学方法可用于模拟区域尺度土壤有机质动态，并考虑到土壤资源的空间异质性。少

The main results obtained in the present study, in which soil organic matter (SOM) dynamics in boreal ecosystems in Eurasia were investigated, are listed below:1) Transition of soils and vegetation influenced by climatic conditions that change along with elevation or latitude were surveyed in different regions of Eurasia and North America; that is, southeastern Kazakhstan, Finland, West Siberia and Canada. Generally a clear zonation was observed within respective study regions, indicating that the SOM dynamics would be formulated primarily by location data.2) A field experiment was conducted using the stable isotope tracer method at the five different soils in northern Tienshan to clarify the decomposition rate of ^<13>C labeled plant materials and the splitting ratio of C derived from the plant materials that migrates to HF on whole substrates utilized. Both the decomposition rate constant and splitting ratio of decomposed plant materials that migrate to either HF or CO_2 varied consi … More derably among the different slope directions.3) Utilization of SOM by soil microbes in the soils from northern Tienshan was investigated in detail by analyzing patterns of glucose utilization after addition of low levels of glucose C. The experimental results indicated that there was a threshold concentration of glucose over which structural compounds started to be synthesized from storage compounds in soil microbes and the ratio of respiration to assimilation started to increase, and that a higher proportion of substrates may be easily mineralized in acid and/or disturbed soils in situations where higher concentrations of substrates are occasionally supplied with temporal 'C flushes' such as may occur in the rhizosphere or in the vicinity of plant residues.4) To optimize regional crop rotation systems for mitigating SOM depletion, spatial and temporal variation of the SOM budget was monitored could be feasible options and that the methodology of geostatistics was useful to simulate SOM dynamics in a regional scale considering spatial heterogeneity of soil resources according to topography. Less