【作者】 陶军；

【导师】 李辉信；

【作者基本信息】 南京农业大学 ， 生态学， 2009， 博士

【摘要】 蚯蚓作为陆地生态系统最重要的大型土壤动物,通过影响土壤物理、化学和生物学等性质在物质循环及能量流动过程中起着极其重要的作用。蚯蚓在土壤中穿行和取食形成蚓穴以及排泄土内和土表的蚓粪等活动将不可避免的影响到土壤栖息者-土壤生物(微生物和微动物)的种群数量和群落结构。当前,国际上有关蚯蚓影响土壤微生物和微动物以及土壤酶活性的研究也很多,但大部分的研究是通过短期培养或室内模拟试验而获得,且关于蚯蚓活动对土壤生物在土壤中空间分布的影响研究也很少。尤其在自然的稻、麦轮作土壤生态系统中蚯蚓活动对土壤生物影响的报道就更为少见。据此,选取在农田中常见的威廉腔环蚓(Metaphire guillelmi),以长期小区和室内培养试验相结合的方式来研究蚯蚓与其它土壤生物之间的关系。主要研究目标如下：(1)小区试验条件下蚯蚓活动对农田土壤微生物数量和活性的影响；(2)小区试验条件下蚯蚓活动对农田土壤微生物群落和功能群以及它们的空间分布的影响；(3)小区试验条件下蚯蚓活动对农田土壤线虫、原生动物种群数量和群落结构以及它们的空间分布的影响；(4)培养试验条件下研究蚯蚓活动对土壤微动物(线虫、原生动物和线蚓)种群数量的影响机制。结果表明：1玉米秸秆表施和混施促进了土壤细菌、真菌、放线菌、氨化细菌、固氮菌、纤维素分解菌、无机磷分解菌数量和微生物生物量碳的增加。在秸秆表施方式下,接种蚯蚓使得细菌、放线菌和真菌数量减少,而氨化细菌、固氮菌、纤维素分解菌、无机磷分解菌4种细菌生理菌群的数量增加；秸秆混施方式下,接种蚯蚓增加细菌、放线菌、氨化细菌和无机磷分解菌数量。不论秸秆以何种方式施用,接种蚯蚓使得微生物量碳增大,但均未达到显著性差异。另外,蚓粪中三大菌和4种细菌生理菌群的数量都远远高于其周围土壤；蚓粪中微生物量碳显著高于其周围土壤。2在秸秆表施条件下,接种蚯蚓促进了5-10 cm层土壤微生物群落碳源总利用活性的增加(用平均颜色变化AWCD值表示)；而在秸秆混施条件下,接种蚯蚓促进了0-5 cm和10-20 cm层土壤微生物群落碳源总利用活性的增加；与秸秆混施且接种蚯蚓处理相比秸秆表施且接种蚯蚓处理在0-5 cm和10-20 cm两层土壤有较高的微生物群落碳源总利用活性。通过对不同碳源类群利用的主成分分析,结果表明,秸秆两种施用方式下接种蚯蚓改变了0-20 cm层土壤微生物群落对不同碳源类群的利用。Shannon多样性指数结果表明：秸秆两种施用方式下,接种蚯蚓使0-20 cm各层土壤微生物碳源利用多样指数升高,但差异显著性仅表现在秸秆表施的5-10 cm层土壤中。蚓粪相比其周围0-5 cm层土壤的微生物群落碳源利用活性和多样性均降低；但与10-20cm层土壤相比,微生物群落碳源利用活性和多样性均升高。3在稻麦两季收获后,与对照处理相比,玉米秸秆两种施用方式均显著地增加土壤蛋白酶、脲酶、蔗糖酶、碱性磷酸酶和脱氢酶活性；不论秸秆以何种方式施用,接种蚯蚓进一步增加了稻、麦两季土壤的蛋白酶活性；在稻季的秸秆混施处理下,接种蚯蚓显著地增加土壤碱性磷酸酶的活性；在稻、麦两季的秸秆混施处理下,接种蚯蚓显著地增加土壤蔗糖酶的活性；不论秸秆以何种方式施用,接种蚯蚓没有改变两季土壤的脱氢酶活性。另外,本试验通过收集土壤表面新鲜蚓粪,测得蚓粪的五种酶活性显著地高于其周围土壤,特别是蔗糖酶和脱氢酶的活性。除了土壤脱氢酶活性外,麦季收获后各处理的土壤和蚓粪的酶活性都高于稻季。4玉米秸秆的施用强烈地影响土壤线虫和原生动物的数量和群落结构；与对照比较,玉米秸秆两种施用方式增加了土壤总线虫和各营养功能群的数量,但显著性仅仅表现在秸秆混施处理上。玉米秸秆混施方式下,接种蚯蚓显著地减少了各土层(0-5 cm、5-10cm和10-20 cm)土壤的总线虫数量；而玉米秸秆表施方式下,接种蚯蚓降低了表土层(0-5 cm和5-10 cm)土壤的线虫总数量,但差异不显著。线虫总数的减少以食细菌性线虫数量的减少为主。同时接种蚯蚓也强烈影响到总线虫及食细菌性和植食性线虫两营养功能群数量在土壤深度上的分布。在玉米秸秆两种施用方式下,接种蚯蚓显著地增加了所有土层土壤的总原始动物和鞭毛虫数量,而土壤变形虫数量仅在玉米秸秆表施且接种蚯蚓的处理中增加。另外,在土壤表面的新鲜蚓粪中总线虫数量显著地高于其周围0-5 cm层土壤,且以食细菌性和食真菌性线虫的增加为主；而蚓粪中总原始动物的数量显著地低于其周围0-5 cm层土壤,且以鞭毛虫和变形虫减少为主。5利用土壤线虫和线蚓能自由穿过1mm孔径网而不能穿过5μm孔径网的特点,在1mm、5μm孔径的网内接种蚯蚓,研究蚯蚓活动对网内、外土壤线虫、线蚓和原生动物的种群数量变化,以期揭示蚯蚓活动影响土壤微动物种群数量的机制。研究结果表明：在整个试验培养期,玉米秸秆施用使土壤原生动物、线虫和线蚓的数量随着培养时间而增加,且高于对照(未添加玉米秸秆和蚯蚓)处理。在整个培养期,lmm、5μm孔径的内圈土壤的线虫和线蚓总数均显著低于对应孔径外圈土壤；尽管1mm、5μm孔径的内圈土壤微生物量碳在整个培养期均低于1mm、5μm孔径的外圈土壤,但它们在第1、3周时显著地高于单独玉米秸秆处理。lmm的内圈土壤原生动物总数在第7周时显著地高于1mm孔径的外圈土壤；而1mm、5μm孔径的内圈土壤原生动物总数在第3、7培养期显著地高于单独玉米秸秆处理土壤；无论与单独玉米秸秆处理或5μm孔径的外圈土壤比较,1mm孔径的外圈土壤有较低的土壤线虫和线蚓数量。总之,农田土壤中蚯蚓活动改变土壤微生物数量和酶活性,造成土壤微生物群落碳源利用的差异；同时蚯蚓活动也改变了土壤线虫和原生动物的种群数量和群落结构,这种影响还取决于有机物物料的施用方式。蚯蚓排泄的产物-蚓粪显著地增加了微生物和微动物的种群数量,改变了它们的群落结构组成。更多还原

【Abstract】 Earthworms are the most important macro-animal in soil and they play an important role on the substance cycling and the energy flow through modifying soil physical, chemical and biological properties in terrestrial ecosystem. Earthworms directly or in directly influence soil habitation (soil organisms) via their comminution, feeding, burrowing, casting activities and dispersal. However, much of the current studies about the effect of earthworms on the populations of soil microorganism and microfaunal and enzyme activities were concluded from either short duration or laboratory simulations. Few extended studies were carried out about the effects of earthworms on the distribution of soil organisms in soil profile under field conditions, particularly far less in the upland rice-wheat rotation agro-ecosystem with corn residues manipulations. In order to confirm the relation between earthworms and soil organisms, a long-term and laboratory experiments were conducted and Metaphire guillelmis was chosen to focus on. The main objectives of these experiments are as follows:(1) Earthworm effects soil microbial population and acitivity in a long-term plot experiment; (2) earthworm effects on the functional communities of soil microorganisms and its distribution on soil profiles in a long-term plot experiment; (3) earthworm effects on the abundance and community structure of soil nematodes protozoan in a long-term plot experiment; (4) how to earthworm affects on the abundance of soil protozoa, nematode and enchytraied in a laboratory incubation experiment. The main results as follows:1 The application of corn residues (mulching and incorporation) to soil gave higher number of bacteria, fungi, actinomyces, ammonifiers, nitrogen-fixing bacteria, cellulose-decomposing microbes, inorganic phosphorus-decomposing bacteria and microbial biomass carbon (MBC) than control soil. When corn residue was mulched, the presence of earthworms had lower number of bacteria, fungi and actinomyce, and higher number of four bacterial physiological groups than the same treatment without earthworms. The presence of earthworms had higher number of bacteria, actinomyces, ammonifiers and inorganic phosphorus-decomposing bacteria in corn residue incorporation than the same treatment without earthworms. The presence of earthworms enhanced MBC in soil with corn residue mulching or incorporation. Additionally, in earthworm casts the number of bacteria, fungi, actinomyces and four bacterial physiological groups and MBC was significantly higher than those in the surrounding soil.2 BIOLOG analysis results showed that the presence of earthworms had higher microbial ability of carbon source utilization in 5-10 cm layer soil with corn residue mulching than the same treatment without earthworms and in 0-5 cm and 10-20 cm layer soil with corn residue incorporation than the same treatment without earthworm. The results of principal component analysis showed that the presence of earthworms changed carbon sources utilization by different soil microbial community at all soil depths following corn residue mulching or incorporation. In two methods of corn residue application, the presence of earthworms gave higher Shannon diversity of BIOLOG substrate utilization at all soil depths, showing a significant difference in 5-10cm layer soil with corn residue mulching. In earthworm casts, there were higher microbial ability of carbon source utilization and significantly lower Shannon diversity than those in the surrounding soil.3 The application of corn residues to soil without earthworms significantly enhanced the five soil enzyme activities compared with the control treatment during rice and wheat cultivation. The presence of earthworms further significantly enhanced protease activity in the soils with both incorporated and mulched corn residues during two cultivation seasons, but only significantly increased alkaline phosphatase activity in the soil with incorporated corn residue during the rice cultivation season. Invertase activity was significantly enhanced by the presence of earthworms in the soil with corn residue incorporation during two cultivation seasons. There were no changes in dehydrogenase activity when earthworms were present. Additionally, the five enzyme activities in earthworm casts were significant higher than those in the surrounding soil, especially dehydrogenase and invertase activities. Whatever the treatment, the values obtained for the enzyme activities in both soil and casts, except for dehydrogenase activity in earthworm casts, were significantly higher under wheat than those in rice-cultivated soil. These results indicate that the presence of earthworms strongly affected soil enzyme activities, depending on the method of organic residue application, and the enhanced enzyme activities of earthworm casts probably contributed to the surrounding soil enzyme activities.4 The addition of corn residues to soil strongly affected the abundance and community structure of nematodes and protozoa in the absence of earthworms. The presence of earthworms gave significantly lower total nematode numbers at all soil depths following corn residue incorporation than that in the same treatment without earthworms, and also gave lower (although not significantly) total nematode numbers in the upper soil layer following corn residue mulching than the same treatment without earthworms. This was mainly due to a significant decrease in bacterial-feeding nematode numbers. Earthworms also strongly affected the distribution of the number of total nematodes and two trophic groups (bacterial and plant feeders) with soil depth. In the presence of earthworms, total protozoan and flagellate numbers significantly increased at all soil depths following both incorporation and mulching of corn residues, while numbers of amoebae increased only when corn residues were mulched. Additionally, in earthworm casts total nematode numbers (mainly bacterial and fungal feeders) were significantly higher, whereas total protozoa numbers (mainly flagellates and amoebae) were significantly lower than that in soil from the 0-5cm layer. These results indicated that earthworm activity could affect the abundance and community structure of microfauna, and change their distribution between soil layers and cast material, depending on the mode of application of organic residues.5 The lmm diameter mesh would allow nematodes, enchytraeids and soluble nutrients, which developed in the inoculum soil, to migrate to the surrounding soil, while the 5μm diameter meshwould prevent the migration of nematodes and enchytraeids but still allow soluble nutrients to pass into the surrounding soil. Experimental results showed that the number of soil protozoa, nematode and enchytraeid increased with increasing of incubation time and was higher in the soil with corn residues than in the control soil. With earthworms present in inner soil of lmm and 5μm diameter mesh, the number of nematodes and enchytraeids was significantly lower than in outer soil of lmm and 5μm diameter mesh during 7 weeks; Although soil microbial biomass carbon in inner soil of lmm and 5μm diameter mesh was lower by earthworms than that in outer soil of them without earthworms, it was significantly higher than in the soil of treatment with maize residues. The presence of earthworms in inner soil of lmm diameter mesh had a higher total protozoan numbers than in outer soil of it at 7 weeks, while total protozoan numbers in inner soil of 1mm and 5μm diameter mesh were significantly higher than in outer soil of them at 3 and 7 weeks. Compared with the soil of treatment with maize residues or the outer soil of 5μm diameter mesh, the outer soil of lmm diameter mesh had a lower number of nematodes and enchytraeids. In general, the presence of earthworm affects on the number and activities of soil microorganisms in soil with corn residue; earthworm activities also changes the abundance and community structure of nematodes and protozoan, depending on the methods of corn residue application. Earthworm casts, as production of earthworm indigestion, significantly increased the number of soil microorganisms and microfaunal and enzyme activity.更多还原