【作者】 于建光；

【导师】 胡锋；

【作者基本信息】 南京农业大学 ， 生态学， 2007， 博士

【摘要】 蚯蚓作为陆地生态系统最重要的大型土壤动物,在物质循环及能量流动过程中起极其重要的作用。蚯蚓通过影响土壤结构、土壤通气保水性能等物理性质而影响土壤有机碳的呼吸与淋失等,通过改变土壤中养分的供应状况及组成而影响土壤有机碳的含量与组成,通过改变土壤微生物的组成、结构、活性等而影响土壤有机碳的循环和转化。目前国际上有关蚯蚓影响土壤养分及物质循环、微生物活性等的研究很多,但多数均涉及单一方面,没有综合性地开展蚯蚓对土壤有机碳循环及转化的研究,特别是全面考虑蚯蚓对光合产物、植物残体、有机碳呼吸、植物生长、微生物群落动态、土壤团聚作用等信息的综合。据此,为了进一步明确蚯蚓与土壤有机碳间的关系,选取在农田中常见的成廉腔环蚓（Metaphire guillelmi）,设置了一系列的小区、盆钵及培养试验,主要研究目标如下:（1）长期小区试验下蚯蚓活动对土壤有机碳更新的影响;（2）长期小区试验下蚯蚓对土壤活性有机碳的影响;（3）秸秆施用下接种蚯蚓对农田土壤微生物特性的影响;（4）不同植物残体施用下接种蚯蚓对土壤团聚体及有机碳分布的影响;（5）蚯蚓对结构破坏土壤恢复过程中微生物群落的影响;（6）新鲜蚓粪与老化蚓粪的有机碳呼吸动态特征;（7）蚯蚓在植物-土壤系统中对水稻光合产物分布的影响。研究结果表明:通过小区长期试验6年后,施用秸秆增加了土壤中来自玉米秸秆碳的含量,而减少了来自原土壤与植物碳的含量;表施秸秆更利于秸秆有机碳向土壤有机碳的转化,同时减少来自原土壤与植物碳的比例。在两种秸秆施用下接种蚯蚓均使土壤中来源于秸秆的碳含量增加,而使来源于原土壤与植物的碳含量下降。在施用秸秆条件下接种蚯蚓使不同活性有机碳的响应各异,秸秆的施用方式是影响土壤有机碳与活性有机碳的主要因素,而蚯蚓活动则并非对所有的土壤活性有机碳有显著影响。在连续六年稻麦轮作后,不同秸秆施用下接种蚯蚓均对土壤微生物生物量、微生物生物活性和群落碳源利用能力产生显著影响:两种秸秆施用方式下接种蚯蚓均增加微生物生物量;秸秆表施并接种蚯蚓导致微生物活性、碳源利用丰富度和多样性指数均降低,而在秸秆混施下则均升高;BIOLOG碳源测定表明在秸秆施用下接种蚯蚓后土壤的微生物群落组成发生明显变化。不同土壤、不同植物残体施用下,蚯蚓对土壤水稳性团聚体的分布、微团聚体分散性及土壤有机碳分布的作用不同;在潮土中,接种蚯蚓使微团聚体分散性降低,但不对水稳性团聚体分布产生影响,而在红壤中,接种蚯蚓使微团聚体分散性降低,同时使水稳性大团聚体的比例增加,而且使更多的土壤有机碳分布于大团聚体中。两种土壤在施用植物残体且接种蚯蚓时均可显著增加土壤有机碳的含量。在不同土壤不同植物残体施用下,接种蚯蚓均对土壤基础呼吸（Basil Respiration,BR）和微生物代谢熵（qCO₂）产生显著影响,二者均趋于增大,特别是在潮土中不施植物残体与施用三叶草接种蚯蚓时的作用最显著;与上述不同,接种蚯蚓对微生物生物量碳（MBC）影响不大。接种蚯蚓时,Biolog测定中表征微生物对碳源利用能力的平均吸光值（average well color development,AWCD）在接种蚯蚓时均增大,同时接种蚯蚓也使微生物群落的基质利用丰富度（S）与多样性指数（H）增大;主成分分析（PCA）也表明接种蚯蚓后土壤微生物群落组成与结构发生了明显变化。进一步分析表明蚯蚓的作用与土壤类型及不同植物残体间有交互作用。新鲜蚓粪中有机碳的呼吸量均大于相应土壤中的,特别是施用玉米残体形成的蚓粪;老化蚓粪中,除红壤不施植物残体形成的老化蚓粪的呼吸量低于相应土壤外,其它老化蚓粪的呼吸量均大于相应土壤的。蚓粪的呼吸量与土壤质地、有机碳含量、植物残体及蚓粪老化程度等均有关。蚯蚓抑制早期水稻的生长,在后期抑制消失。分蘖期光合的¹⁴C在15天后分布于植株根中的比例由于蚯蚓活动而显著增加,该效应在收获时消失。抽穗期光合的¹⁴C在15天后分布于植株根中的比例也因蚯蚓活动而显著增加,同时收获时也可观察到土壤中¹⁴C比例的增加。在所有采样期,接种蚯蚓均使土壤微生物量¹⁴C与总有机¹⁴C的比值下降,而使可溶性有机¹⁴C与总有机¹⁴C的比值增大。蚯蚓可能影响植物光合产物在植-土系统中的分布,并影响土壤活性碳库。总之,蚯蚓活动可加快土壤有机碳的更新,显著影响土壤活性有机碳的含量,使土壤团聚作用增强,促使土壤微生物群落发生变化,影响光合产物在植物-土壤系统中的分布。在农田及退化土地中接种蚯蚓对于保持与扩大土壤有机碳库有重要的生态意义。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 in terrestrial ecosystem.Earthworms affect the mineralization and leaching of soil organic carbon through modifying the structure,aeration,moisture of soil.Earthworms affect the content and composition of soil organic carbon through modifying the nutrition supply and component of soil.Earthworms affect the cycling and turnover of soil oranic carbon through modifying soil microbial structure and activity.Most works of earthworm effects on the soil nutrition cyclying, microbial activity were simplex.The all-around information of earthworm effects on soil organic carbon cycling and turnover are essential,especially take into account the synthesis of knowledge about earthworms and photosynthate,straw residue,organic carbon mineralization,plant growth,microbial community dynamic,soil aggregation.In order to confirm the relation between earthworms and soil organic carbon,a series of experiments were conducted and Metaphire guillelmi was chosen to focus on.The main objectives of these experiments are as follows:（1） Earthworm effects on the renewal of soil oranic carbon in a long-term plot experiment.（2） Earthworm effects on soil labile organic carbon in a long-term plot experiment.（3） Earthworm effects on soil microbial properties under straw application.（4） Earthworm effects on soil aggregation and organic carbon distribution under different straw residue input.（5） Earthoworm effects on soil microbial properties during the renewal of structure-degenerated soil.（6） The mineraliztion dynamics of organic carbon of fresh cast and ageing cast.（7） Earthworm effects on rice photysynthates distribution in plant-soil system.The main results as follows:After six years straw input in plots,soil organic carbon originating from maize straw increased,meanwihile,soil oranic carbon originating from original soil and plant decreased Compared with straw incorporated,straw mulching was more beneficial to the transfer of straw carbon to soil carbon and decreased the proportion of carbon originating from original soil and plant.Earthworm activities increased the content of soil organic carbon originating from straw,and decresed the content of soil organic carbon originating from original soil and plant.Earthworm inoculation showed different effects on diverse soil labile organic carbon under two straw application methods.Straw application method was the major factor on affecting soil organic carbon and labile organic carbon,and earthworms didn’t show significant effects on all soil labile organic carbon.The presence of earthworms had significant effects on soil microbial biomass, microbial activity and the microbial ability of carbon source utilization.Microbial biomass increased in the presence of earthworms irrespective of the way of straw application.Soil microbial activity,richness and biodiversity all decreased in the presence of earthworms under straw mulching method,and the reverse was true under straw incorporation method. It was indicated that soil microbial community composition changed significantly under straw application using BIOLOG carbon utilization analysis.The experiment of earthworms and aggregates stability indicated that earthworms affected water-stable aggregates distribution and micro-aggregate dispersion and soil organic carbon distribution differently under different soil substrate and straw residue input. Earthworms decreased the dispersion of micro-aggregate and didn’t affect the distribution of water-stable aggregates in silt soil.Meanwhile,earthworms decreased the dispersion of micro-aggregate and increased the percentage of water-stable macro-aggregate and the distribution of soil organic carbon in macro-aggregate in silt clay loam soil.Earthworm inoculation with straw residue input increased soil organic carbon content in the two soils.Earthworms significantly affected soil basil respiration（BR） and qCO₂,both of them increased under earthworm activities,especially under no straw residue input and white clover straw input in silt soil.Differently,earthworms had less effect on soil microbial biomass carbon.The AWCD（average well color development） and substrate richness（S） and biodiversity index（H） all increased with earthworm activities through Biolog test.It was indicated that the composition and structure of soil microbial community changed significantly under earthworm activities through principal component analysis（PCA）. Earthworms had interactive effects with soil and straw residue types.The mineralization in fresh cast was more than those in corresponding soil,especially the cast originating form soil with maize residue input.The mineralization of ageing casts was more than those in corresponding soil except that the cast originating from clayed soil with no straw residue input.The mineralization of cast was related to soil texture,soil oranic carbon content,straw residue,and the ageing degree of cast.The ¹⁴C pulse-labelling experiment indicated that rice growth was inhibited by earthworms（Metaphire guillelmi） at early stage,but the inhibition disappeared at later stage. Earthworms significantly increased the ¹⁴C percentages in root at day 15 after tillering stage labelling,but the effect disappeared at harvest.Earthworms（Metaphire guillelmi） significantly increased the ¹⁴C percentages in root at day 15 after heading stage labelling, and increased ¹⁴C percentage in soil at harvest.Earthworms decreased the ratios of microbial biomass ¹⁴C(MB¹⁴C) to total organic ¹⁴C(TO¹⁴C) and increased the ratios of dissolved organic ¹⁴C(DO¹⁴C) to total organic ¹⁴C(TO¹⁴C) at all sampling times.It is suggested that earthworms might alter the transfer of plant photosynthates from the aboveground to the belowground and thus soil active C pool.In general,earthworm activities accelerated the turnover of soil organic carbon,and affected the content of soil labile organic carbon significantly.Earthworms enhanced the soil aggregation and induced the change of soil microbial community.Earthwoms increased the transfer of photosynthate from aboveground to belowground.It is indicated that earthworm inoculation in cropland and degenerate field to maintain and enlarge soil organic carbon pool are of ecological significance.更多还原