【作者】 杨阔；

【导师】 王传宽； 杨金艳；

【作者基本信息】 东北林业大学 ， 生态学， 2010， 硕士

【摘要】 以往的土壤呼吸(Rs)研究绝大多数集中于生长季,而对非生长季Rs的研究很少。冬季Rs是生态系统呼吸中的重要组成部分,并且能显著地影响碳收支。春季土壤解冻过程是中高纬度地区森林生态系统Rs年内变化的一个关键时期,但此期间Rs的时间动态规律及其控制机理尚不清楚。本研究以我国东北东部5种温带森林(蒙古栎(Quercus mongolica)林、杨桦(Populus davidiana—Betula platyphylla)林、硬阔叶林、红松(Pinus koraiensis)林和落叶松(Larix gmelinii)林)为研究对象,采用静态箱—气相色谱法测定非生长季时期Rs动态及其相关的环境因子。主要研究结果如下：冬季不同林型的Rs变化没有明显的规律,基本上在冬季末期达到最大值,其中只有硬阔叶林的Rs与土壤温度的变化一致,其余林型的Rs变化格局与土壤温度的关联性不大。与生长季相比,冬季的Rs与土壤温度和含水量的之间的关系不是很紧密(R2=0.266—0.422)。Rs年通量从大到小依次为：硬阔叶林2114.90 g·m-2yr-1；杨桦林1989.66 g·m-2yr-1；蒙古栎林1860.88 g·m-2yr-1；红松林1435.56 g·m-2yr-1和落叶松林1934.59 g·m-2yr-1。各自对应的冬季Rs通量在年通量中所占的比例分别为：9.63%；10.19%；13.08%；12.78%和10.13%。冬季时期不同林型Rs的Q10值从大到小依次为：硬阔叶林12.5；落叶松林10.5；杨桦林6.8；红松林4.6和蒙古栎林2.4。除了蒙古栎林和红松林冬季和全年的Q10值比较接近外,其余林型的Q10值在冬季时普遍大于生长季的。在土壤解冻过程中,Rs受林型、解冻时期及其交互作用的显著影响。红松林、落叶松林、硬阔叶林、杨桦林和蒙古栎林的Rs变化范围依次为：10.0—196.0 mg·m-2·h-1,5.8—217.1 mg·m-2·h-1,9.7—382.1 mg·m-2·h-1,15.8—269.0 mg·m-2·h-1和35.9—262.5mg·m-2·h-1。Rs的平均值随着解冻的进程而增大,其变化趋势大致与土壤温度的变化相吻合。土壤温度极显著地影响Rs(R2=0.46—0.77),而土壤含水量对Rs的影响则因林型和土壤深度而异。5种林型的土壤呼吸温度系数(Q10)依次为：落叶松林10.9,硬阔叶林7.1,红松林6.5,杨桦林4.3和蒙古栎林2.3。进一步的研究应该集中研究非生长季时期Rs的控制机制,尤其是Rs与土壤微生物种群动态及其活性之间的关系。更多还原

【Abstract】 Most previous studies on soil respiration (Rs) are for growing seasons, while few for non-growing seasons. Winter CO2 efflux from soils is a significant component of annual carbon budges and can greatly determine carbon balance of ecosystems. Spring soil thawing period is critical in the intra—annual dynamics of Rs in mid—and high latitudes forest ecosystems, in which the frequently occurring alternate freezing and thawing events strongly influence the availability and dynamics of soil carbon and nutrients. However the temporal changes of Rs and involved mechanisms are poorly understood. Especially in situ measurements of Rs in spring soil thawing process are needed. In this study, a static closed chamber—gas chromatograph technique was used to measure the Rs and related biophysical factors in representative temperate forests of Northeast China during the non-growing season. The experimental design included five forest types, three random plots in each forest type, and three randomly installed static chambers in each plot. The forests were oak forest dominated by Quercus mongolica, poplar—birch forest dominated by Populus davidiana and Betula platyphylla, hardwood forest dominated by Fraxinus mandshurica, Juglans mandshurica and Phellodendron amurense, Korean pine (Pinus koraiensis) plantation, and Dahurian larch (Larix gmelinii) plantation. The results showed:During winter period, there were no obvious temporal trends for the Rs. We found the highest CO2 fluxes in late winter and patterns of Rs for different forest types were independent of soil temperature except for hardwood forest. Compared with growing seasons, soil temperature and water content did not significantly influence the Rs (R2=0.266—0.422) The annual fluxes for the hardwood, poplar—birch, and oak, pine and larch forests were 2114.90 g·m-2yr-1,1989.66 g·m-2yr-1,1860.88 g·m-2yr-1,1435.56g·m-2yr-1, and 1934.59 g·m-2yr-1,respectively; the ratio of winter fluxes for those were 9.63%,10.19%,13.08%,12.78%, and 10.13%, correspondingly. In winter, the temperature coefficients of Rs (Q10) for the hardwood, larch, poplar—birch, pine, and oak forests were 12.5,10.5,6.8,4.6, and 2.4, respectively. Q10 during winter time were much higher than those in the whole year except for pine and oak forests.During the soil thawing period, the forest types, thawing periods and their interaction significantly affected the Rs. The Rs for the pine, larch, hardwood, poplar—birch, and oak forests varied from 10.0—196.0 mg·m-2·h-1,5.8—217.1 mg·m-2·h-1,9.7—382.1 mg·m-2·h-1, 15.8—269.0 mg·m-2·h-1, and 35.9—262.5 mg·m-2·h-1, respectively. The mean Rs, T2 and W2 differed significantly among the five forest types(P<0.001). The Rs for broadleaved forests were generally higher than coniferous plantations. The mean values of RS increased as the soil thawing proceeded, and were largely consistent with the changes in soil temperature. Soil temperature significantly influenced the Rs, while the effect of soil water content on the Rs varied with forest types and soil depths. The Rs was significantly affected by W2 for all forests except for the oak forest. The statistical models of the Rs against T2 and W2 explained 60%—77% of the variability in the Rs measurements. The Q10 during the spring soil thawing period were much higher than those in the growing season, and changed with forest types. The Q10 for the larch, hardwood, pine, poplar—birch, and oak forests were 10.9,7.1,6.5,4.3, and 2.3, respectively. Further studies should focus on the mechanisms controlling Rs in the in situ soil, especially on temporal dynamics of soil microbial population in non-growing seasons and the relationship between soil respiration and soil microbial activity and composition.更多还原