【作者】 宋博；

【导师】 殷秀琴；

【作者基本信息】 东北师范大学 ， 自然地理学， 2008， 博士

【摘要】 凋落物分解是生态系统过程的一个重要环节。本论文在对国内外土壤动物生态学研究历史回顾的基础上,分析了当前对土壤动物生态分布及其对环境的指示意义、土壤动物多样性及其在分解和养分循环中的作用等方面的现状。其中对土壤动物功能作用相关研究多集中在森林生态系统,而草地生态系统相对缺乏。由于土壤动物在草地生态系统分解及养分循环中的作用不同于森林生态系统。因此,亟需相关研究丰富土壤动物生态学的基础和理论。众多学者越来越关注土壤动物功能作用,但对土壤动物多样性作用的结论并不一致。特别是国内还没有对草地生态系统中土壤动物在分解过程中的作用进行研究。因此本论文对温带草甸草原凋落物分解过程中土壤动物功能作用的长期定位研究,能够获得松嫩平原羊草草甸凋落物分解速率、养分释放动态,了解土壤动物作为分解者对凋落物分解的影响,并对凋落物性质、环境因子等的影响进行讨论。不仅具有重要的理论价值,而且可以为松嫩草地生态恢复提供管理学依据。论文得到了国家自然科学基金的资助,项目编号:40871120。本研究采用凋落物袋法对东北松嫩平原(44°40′- 44′N,123°44′-47′E)羊草草甸中羊草、虎尾草、拂子茅、碱茅、碱地肤5种植物地上部分的凋落物分解和养分动态进行了连续野外研究。采用4mm、2mm、0.15mm和0.01mm四种规格凋落物袋控制参与分解的土壤动物类群,研究凋落物的分解速率和养分动态,并对分解过程中土壤动物群落进行分类和统计;在此基础上分析了土壤动物群落多样性特征及其在凋落物分解及养分释放中的作用,并讨论了凋落物性质、环境因子对分解的影响和土壤动物群落与环境因子的关系。研究发现,各种网袋凋落物中的土壤动物群落随着温、湿度变化而具有明显的季节性动态。2007年6月~9月之间土壤动物的密度和多样性均高于2006年11月~2007年5月的冬春季节。4mm网孔的开放网袋处理中,凋落物中土壤动物数量由大到小依次分别为虎尾草、羊草、拂子茅、碱茅和碱地肤凋落物。典型生境凋落物中土壤动物的个体数量高于退化生境。凋落物中土壤动物群落数量较少,大部分为植食性、腐食性和杂食性群落,而缺乏捕食性类群。研究期间各种凋落物在不同网孔凋落物袋的处理中,分解速率也表现出季节性动态。退化生境中碱地肤和碱茅凋落物的分解速率高于典型生境中的羊草、拂子茅和虎尾草凋落物。凋落物分解过程中,不同网孔凋落物袋处理中,凋落物分解速率不是简单的随凋落物袋网孔的变小而降低。这说明由于参与分解的土壤动物类群不同,不同物种凋落物的分解速率产生了变化。开放处理中各种凋落物分解近一年后N、P、K绝对含量有所减少。其中退化生境中凋落物的养分元素绝对量的减少较典型生境中显著。而在限制了土壤动物分解作用的较小网孔凋落物袋处理中,凋落物养分元素绝对量的减少变化较大。这说明土壤动物活动对于凋落物养分释放具有较大的影响,不同类群动物对养分释放的影响具有差异。土壤动物对凋落物分解损失率具有较大的贡献,对元素循环也具有重要意义。凋落物袋中土壤动物的多度和多样性与袋内凋落物损失率呈显著的正相关性。冬春季节参与分解的土壤动物主要有蜱螨类、缨翅目,此外双翅目、啮虫目和鞘翅目也有出现;到夏秋季节土壤动物数量和多样性都有较大的增加,其中啮虫目和螨类的个体数量最多,半翅目、弹尾目、同翅目、蜘蛛目、膜翅目、等足目和腹足纲等类群开始出现;秋末土壤动物的数量和类群有一定的减少。分析表明,凋落物的种类、凋落物袋网孔差异、取样时间及其交互作用对凋落物损失率都具有显著的影响,此外三者对凋落物中P、K元素的绝对量的释放也具有显著的影响。凋落物物种、取样时间及两者之间的交互作用对凋落物袋内土壤动物的群落数量也具有显著影响。典型生境中土壤动物群落的总个体数量与土壤中的TN含量呈极显著的正相关,退化生境中温度因子的影响更为显著。更多还原

【Abstract】 Litter decomposition is an important part of ecosystem progress. Based on the review of history of soil fauna ecology, the thesis summarized the four topics, including ecological distribution of soil fauna community and the relationship between soil fauna community and environmental factors; bioindictor of soil fauna; the function of the diversity of soil fauna in litter decomposition and nutrient cycle as well. As the case of function of soil fauna in the litter decay and element cycle, most researches were performed in forest ecosystem, and few of them carried in grassland ecosystem. The characteristics of vegetation, soil and other environmental factors in grassland ecosystem are different from those in forest ecosystem. And the function of soil fauna in litter decomposition and nutrient release in grassland ecosystem should be different from that in the forest ecosystem. Consequently, soil fauna’s function in litter decomposition and nutrient cycle in grassland ecosystem should be eager to perform more researches, which will enrich the fundamental and theoretics of soil fauna ecology. The results that had gotten in a few researches about the function of the diversity of soil fauna were not consisted. There are few studies on the longer time of litter decomposition in grassland ecosystem that performed to study the function of soil fauna, especially in China. The goal of this study is discussing the function of different groups of soil fauna in litter decomposition and nutrient cycle in grassland ecosystem. And the effects of litter qulities and environmental factors on the litter decomposition rate and nutrient release are also discussed in the thesis. The present study will not only be a great performance of the theory of soil fauna ecology, but also give leading help in ecological restoration and management of Songnen grassland ecosystem. The thesis was financially supported by National Natural Science Foundation of China (No. 40871120 ).The thesis had been studied the decomposition and nutrient release of the above-ground litter of the Leymus chinensis, Chloris virgata, Calamagrostis epigejos, Puccinellia chinampoensis, and Kochia sieversiana by litterbag standard method in Leymus chinensis steppe ecosystem in Songnen plain(44°40′- 44′N and 123°44′-47′E). The four different mesh sizes of litterbag, including 4mm, 2mm, 0.15mm, and 0.01mm, were used to control the different body size of soil fauna in the litterbag. The litterbags of L. chinensis, C. virgata, C. epigejos are located in their situ (called typical situ), and the litterbags of P. chinampoensis and K. sieversiana are located in their situ (called degraded situ). Starting from 23rd October 2006 to 23rd September 2007, at monthly intervals, litter samples were carefully retrieved from the field to laboratory. Based on the data of decay rate and dynamics of the N, P, K of litter and soil fauna community, the thesis discussed the function of different fauna groups in litter decomposition and nutrient release and analysized the relationship between soil fauna community and environmental factors at the same time.The results showed that soil fauna community in litter had seasonal dynamics with the seasonal fluctuation of temperature and moisture. The density and diversity indexes of soil fauna community in June 2007~ September 2007 were higher than those in November 2006~ May 2007. In the open (mesh size=4mm) litterbag, the individual numbers of soil fauna in the five litter were in the sequence of C. virgata> L. chinensis > C. epigejos > P. chinampoensis > K. sieversiana. The individual numbers of soil fauna in the litter of typical situ are higher than that of in degraded situ through all litterbags. The phytophagous, saprophagous, and omnivorous groups of soil fauna were more common in litter than those in soil. But the number and dominance of predacious group of soil fauna were lower than those in soil.The decay rate of litter also showed seasonal dynamics in all mesh size litterbags. The loss rate of litter in summer and autuman are higher than that in winter and spring. After decomposition of eleven months, the percent of litter mass remained from 61% to 84%. The decay rates of P. chinampoensis and K. sieversiana litter in the degraded situ are higher than those of C. virgata, L. chinensis and C. epigejos litter in the typical situ. The decay rates of litter in litterbags were not consistent with the mesh size of the litterbag, which indicated that the different groups of soil fauna in litterbags had different effects on the litter decomposition.The remaining percent of N, P, K in the open litterbags of litter were all decreased to 4%~45%, 26%~63%, 72%~89%, respectively, at the end of study stage. There are great changes in the other mesh size litterbags had great changes. The loss percent of N, P, K of litter in degraded situ were higher than that of in typical situ. The different groups of soil fauna in litterbags had different effects on the nutrient release of litter.Soil fauna had great contribution on litter decay rate. There were significant positive relations between density, diversity of soil fauna community and litter decay rate. Soil fauna have great influences on the element cycle in ecosystems. The decay rate and loss percent of nutrient of litter in the open litterbags were higher than that in the other mesh size litterbags, which also indicated that soil fauna community had great effects on litter decomposition and nutrient release. The groups of soil fauna as decomposers in litter had changes in different seasons. In winter and spring, Prostigmata, Thysanoptera were the main decomposers, and Diptera, Psocoptera, Araneae, Coleoptera as well. In summer and autumn, the groups included Collembola, Hemiptera, Lepidoptera larvae, Hymenoptera, Homoptera, Coleoptera larvae, Oribatida, Astigmata, Isopoda, Gastropoda were also founded in the litter. The number and diversity of soil fauna in litter in summer & autumn are higher than those in winter & spring. At the end of autumn (September 2007), the number of soil fauna in litter decreased than before (August 2007). The effects of physical and chemical leaching on litter decay and nutrient release possibly explained that the decay rates and dynamics of nutrient concentration in litter were not consistent with the mesh size of litterbag. The results of ANOVA analysize showed that there are significant effects of litter species, mesh size of litterbag, sampling time and the interactions of them on litter decay rates. Litter species, mesh size of litterbag, sampling time had significant effects on P and K release.The density of soil fauna in litter were influenced significantly by litter species, sampling time and their interactions. There were little relativity between temperature, precipitation and the individual number and group number of soil fauna. There was positive relationshiop between the individual number of soil fauna and total N in soil in typical situ. And the individual number of soil fauna was mainly influenced by temperature in degraded situ.更多还原