【作者】 鲁顺保；

【导师】 郭晓敏； 徐志红； 陈成榕；

【作者基本信息】 江西农业大学 ， 森林培育， 2011， 博士

【摘要】 土壤可溶性有机质是研究陆地生态系统中碳氮循环不可忽视的组分,土壤微生物是土壤的分解者,参与土壤生物地球化学过程,在维持土壤生态系统平衡中具有重要的作用。澳大利亚昆士兰州属于典型的亚热带地域单元,是澳大利亚森林比较集中的分布区,对气候变化十分敏感,在澳洲气候乃至全球气候变化中扮演重要角色,其独特的自然环境和生态系统在全球占有特殊的地位,但人们对森林土壤有效态碳氮库及微生物活性方面的认识还非常有限。湿地松(Pinus elliottii Engelm. var. elliotttii)、南洋杉(Araucaria cunninghamii)和贝壳杉(Agathis australis)是澳大利亚南昆士兰州最主要的3种森林类型,本文以这3种森林类型为研究对象,利用生化和分子生物学方法对其土壤可溶性有机碳氮、微生物生物量、酶活性、土壤呼吸和微生物群落功能及结构多样性进行研究,探讨不同森林类型土壤有效碳氮库及相关的微生物过程,对于进步研究土壤生态系统结构和功能具有重要的理论指导意义。主要研究结果如下：1.对土壤11种重要金属元素进行分析,得出不同森林类型对土壤Al、Cu、Fe、K、Mg和Mn含量差异影响显著。不同森林类型SOCHW含量在552-1154 mg·kg-1之间变化,SOCHW含量大小顺序为湿地松>南洋杉>贝壳杉。SONHW含量则以南洋杉最高,为46.2 mg·kg-1,占可溶性全氮含量(SONHW/TSN)的65.38%,占全氮(SONHw/TN)的0.82%；其次是贝壳杉为39.2 mg·kg-1;湿地松林土壤SONHW含量最低,为26.7mg·kg-1。且南洋杉和贝壳杉林地土壤SONHW含量显著(P<0.05)高于湿地松。不同森林类型土壤SONHW和(?)SONHW/TSN差异达极显著(P<0.01)。不同森林生态系统NH4+-NHW含量均高于21.4 mg-kg-1,而NO3--NHW含量均低于8.02 mg-kg-1, NH4+-NHW的变化趋势跟SONHW和(?)SOCHW不一样,有机态碳氮比(C:NHW)的变化趋势跟SOCHW的变化趋势一样,并且C:NHW在不同森林类型之间的差异达极显著(P<0.05)。两种不同提取方法所得的土壤可溶性有机质含量相差较大。SONKCl比SONHW要低,均值为9.93 mg·kg-1, SONKCl占TSN的24.6-33.5%,占TN的0.14-0.25%。在湿地松林地, SONKCl含量占TSNKCl的比例最高,为29.3-32.1%；但占TN的比例最低,为0.14-0.16%,说明湿地松林地的TSN含量偏低。南洋杉林地土壤SOCKCl含量最高,而湿地松林地SOCKCl含量最低。由于NH4+-NKCl主要来自于无机态氮库,其含量与热水提取物的变化一致,并且在不同森林类型土壤之间的差异达显著(P<0.05),而各森林类型土壤NO3--NKCl含量偏低,都在7.7 mg·kg-1以下。SOCKCl和C:NKCl有相同的变化趋势,不同森林类型土壤SOCKCl和SONKCl含量之间的差异均未达显著差异。2.贝壳杉林地土壤MBC含量最高,为188.2 mg-kg-1,其次是湿地松林地为112.8mg-kg-1,南洋杉林地MBC含量最低,其含量为77.1 mg-kg-1,不同森林类型土壤MBC含量差异显著(P＜0.05), MBC含量占全碳含量(MBC/TC)在0.48-1.55%之间,且不同森林类型土壤MBC/TC差异显著。MBN含量均值为18.0 mg-kg-1, MBN有着和MBC同样的变化趋势和规律,且不同森林类型各土壤MBC的含量差异显著。δBC在-28.5--27.5%o,其中南洋杉林地土壤的δ13C含量较高,均值为-27.8%o,湿地松林与其他两种林地土壤δ13C含量差异显著；δ15N含量在-2.1-3.4‰之间,其中贝壳杉林δ15N含量最高,为2.33%o,不同森林类型土壤δ15N含量之间差异不明显。不同森林土壤PMN和PMN/TN具有相似的变化趋势,其中南洋杉林PMN最高,为77.19mg·kg-1, PMN/TN为0.138%；其次为贝壳杉林,PMN为71.87 mg-kg-1, PMN/TN为0.14%；而湿地松林最小,PMN为43.55 mg-kg-1, PMN/TN为0.082%,方差分析表明湿地松林地土壤PMN和PMN/TN均与其他两种森林之间差异显著。3.63 d的室内培养实验结果表明,贝壳杉林地土壤呼吸程度最强,为680.28 gCO2-C kg-1,显著强于湿地松林277.73 g CO2-C kg-1 (P<0.05)。对土壤呼吸潜在碳排放进行模拟,得出贝壳杉最大潜在碳排放(C0)为1117.8 g CO2-C kg-1;其次为南洋杉林土壤为1082.1 g CO2-C kg-1;而湿地松林土壤最低,为783.0 g CO2-C kg-1,并且湿地松与其他两种森林土壤最大潜在碳排放差异显著,模拟的相关系数均在0.99以上,说明拟合效果很好。底物对不同林地土壤呼吸所产生的CO2影响格局基本一致。底物Glucose的添加对土壤呼吸产生CO2的量影响较对照均有显著的提高(P<0.000), Glucose和Na2HPO4以及Glucose、NH4NO3和Na2HPO4共同作用与对照相比,均在不同程度上提高了土壤的呼吸强度。但是在底物Na2HPO4或H4NO3和Na2HPO4共同作用下,气体排放均减少,尤其是Na2HPO4在一定程度上抑制了土壤呼吸。添加底物与对照相比其土壤呼吸速率均呈现显著的时间性变化(P<0.001)基本一致,总体上三种森林类型土壤呼吸速率曲线格局相似,均呈现单峰型。底物的添加对微生物生物量碳氮的影响并不一致,其影响与底物对土壤呼吸基本相似。4.微生物活性随培养时间的延长而提高,培养24 h后,微生物对底物的利用迅速增加。在96h的培养过程中,不同生态系统土壤微生物利用单一碳源能力的大小顺序为：南洋杉林>贝壳杉林>湿地松林,其中南洋杉林土壤微生物群落具有最强的代谢能力,湿地松与其他两种森林类型的碳源利用差异显著(P<0.05)。南洋杉林地土壤的Shannon指数为4.391,均匀度为0.046, Simpson指数为67.9,Mclntosh指数为14.07,均匀度为0.979,均高于其他两种森林类型,湿地松林最低,并且均与南洋杉和贝壳杉林地土壤的多样性指数和均匀度均达差异显著(P<0.05)。同一森林类型下土壤微生物对不同类型碳源的利用程度差异非常显著,在Biolog微平板整个培养期内,土壤微生物比较偏好的碳源类型为糖类和聚合物类。5.不同森林类型土壤几丁质酶和亮氨酸氨肽酶(LAP)活性表现为：湿地松林>南洋杉林>贝壳杉林。酸性磷酸酶和p-葡萄糖苷酶活性表现为：湿地松>贝壳杉>南洋杉；碱性磷酸酶则表现为：贝壳杉>湿地松>南洋杉。土壤几丁质酶与TC, pH与几丁质酶、LAP、β-葡萄糖苷酶、TC和碱性磷酸酶之间差异显著(P<0.01)。冗余分析结果表明碱性磷酸酶与南洋杉、LAP和p-葡萄糖苷酶与贝壳杉以及微生物生物量与湿地松之间关系更密切。几丁质酶和酸性磷酸酶与湿地松成负相关。6.湿地松林地土壤PLFAs的单体数为45个,南洋杉和贝壳杉林地的PLFAs单体数分别为39和35个。湿地松林地的PLFAs单体个数和含量均较其他两种林地土壤的要高。PCR-DGGE分析表明三种森林类型土壤样品的电泳条带数量从17到28条,其中湿地松林地土壤的电泳条带数量平均为25.5条,南洋杉为17条,贝壳杉为23条,这说明细菌丰度湿地松林地最高,其结果与PLFA技术分析的结果相吻合。更多还原

【Abstract】 Soil soluble organic matter was components which should not be ignored in carbon and nitrogen cycles of terrestrial ecosystems, and the soil microbes were the decomposers of ecosystems. They were involved in soil bio-geochemical processes, and played an important role in maintenance of soil ecological equilibrium. There had been main distribution of forest and typical subtropical geographical unit in southeast Queensland, Australia. It was very sensitive to climate change in Australia and global climate, and played an important role, and its unique natural environment and ecosystems occupied a special place in the world, but our knowledge about this versatile microbial community was very limited. In this paper, soil samples under the slash (Pinus elliottii Engelm. var. elliotttii), hoop pine(Araucaria cunninghamii) and kauri pine(Agathis australis) populations for 90 years test plots were collected to investigate the effects of forest types on soil soluble organic matter, microbial biomass C (MBC) and nitrogen (MBN), enzyme activities, soil respiration as well as microbial community structural and functional diversity by bio-chemical and molecular biological methods. We discuss soil available carbon and nitrogen pools and related microbial process under different forest types. Furthermore, some suggestions are important theoretical significance for further study of the soil ecosystem structure and function. The main results were described as follows:(1) The 11 main soil metal elements were analyzed that the difference of soil Al, Cu, Fe, K, Mg and Mn contents were significantly. The soil SOC and SON contents were different by different extraction methods. SONHW and SOCHW were higher than that of 2 mol L-1KCl extract. The SONHW contents of soil in slash pine, hoop pine and kauri pine were 26.7 mg kg-1,46.2 mg kg-1 and 39.2 mg kg-1, respectively. The differences between forest types and soil SONHW, SONHW/TSNHW were significant (P<0.01). The NH4+-NHW contents were more than 21.4 mg kg-1, and NO3--NHW content was no less than 8.02 mg kg-1. The NH4+-NHW content was not consistent with that of SOCHW with SONHW, while the organic carbon and nitrogen ratio (C:NHW) was consistent with SOCHW, and the difference of C: NHW were significant among different forest types (P<0.05). The SOCHW content was 552-1154 mg kg-1 in different forest types, and the order of SOCHW content was slash pine> hoop pine> kauri pine, but the difference was not significant. The order of SONHW content was hoop pine> kauri pine> slash pine, and the soil SONHW in hoop pine was significantly (P<0.05) higher than that of slash pine. The SONKCl contents were lower than that of SONHW, the mean was 9.93 mg kg-1, and the SONKCl content accounting for TSN was 24.6-33.5%, and accounting for TN was 0.14-0.25%. The SONKCl content was 29.3-32.1% and the highest accounting for TSNKCl in the slash pine, but was the lowest to account for TN and 0.14-0.16%. The results suggested that the TSN content of slash pine was low. The soil SOCKCl content of hoop pine forest was the highest, and lowest that of slash pine SOCKCl-The NH4+-NKCl was mainly from inorganic nitrogen pools, and the changes of its content was similar to that of hot water extract. The differences of soil NH4+-NKCl content were significant among different forest types (P<0.05). The NO3--NKCl content was lower than 7.7 mg kg-1 in the forest types. The change of SOCKCl was similar to C:NKCl and the differences of SONKCl and SOCKCl were not significant among different forest types.(2) The soil MBC content was 188.2 mg-kg-1 and highest in kauri pine, following in slash pine was 112.8 mg kg-1. Its in hoop pine forest MBC was the lowest, and their content was 77.1 mg kg-1, MBC content were significantly different among forest types (P<0.05). MBC /TC ranged from 0.48% to 1.55% under three forest soil, and MBC/TC was significantly different among three forest types. MBN average content was 18.0 mg kg-1, and MBN content was similar to MBC under three forest types. The differences of MBC were significant. Theδ13C content ranged from-28.5‰to -27.5‰. Theδ13C in hoop pine was high, and mean was -27.8‰. The differences ofδ13C content in slash pine were significant with hoop pine and kauri pine. Theδ15N contents ranged from-2.1‰to 3.4‰, and theδ15N content in kauri pine was the highest, accounting for 2.33‰. There was no significant difference of 815N among three forest types. The change of PMN was similar to PMN/TN under three forest types. The PMN in hoop pine was highest 77.19mg kg-1, and PMN/TN was 0.138%. The following PMN and PMN/TN in Kauri pine were 71.87 mg kg-1 and 0.14%, respectively. The PMN and PMN/TN in slash Pine were the lowest 43.55 mg kg-1 and 0.082%, respectively. The analysis of variance showed that there were significant difference of PMN and PMN/TN between in slash pine and other two forest types.(3) The soil respiration for 63 days lab incubation in kauri pine was strongest, was 680.28 g CO2-C kg-1, which was significantly stronger than that of slash pine, was 277.73 g CO2-C kg-1 (P<0.05). We obtained the maximum potential carbon emissions (Co) in kauri pine which was 1117.8 g CO2-C kg-1 by simulated soil respiration, and following was 1082.1 g CO2-C kg-1 in hoop pine, and 783.0 g CO2-C kg-1 in slash pine, the lowest. The difference of Co was significant between slash pine and other two forest types, and the correlation coefficients were above 0.99. This indicated that Co was simulated to a good fitting effect. The changes for soil CO2 production by respiration were similar by adding substrate. Adding Glucose substrate on the amount of soil respiration of CO2 compared with the control (CK) were significantly increased (P= 0.000). Adding Glucose and Na2HPO4 with Glucose, NH4NO3 and Na2HPO4 interaction could increase soil CO2 production compared with the control. But soil CO2 production was reduced in the substrate H4NO3 or Na2HPO4 and Na2HPO4 interaction, especially Na2HPO4 inhibited soil respiration to some extent. The change of soil CO2 production under added substrate was consistent with the control (P 0.001), and the pattern of soil respiration rate curves was similar and showed a single peak under three forest types. Substrate addition on microbial biomass carbon and nitrogen is not uniform to different forest types, and its impact was similar to soil respiration by adding substrate.(4) Microbial activity increased with incubation time increased. After incubating 24h, microbial utilization substrate was increasing rapidly. The order of different soil microorganism utilize carbon source during 96h incubation was hoop pine> kauri pine> slash pine. The metabolism of microbial communities in hoop pine was the strongest, and the difference of utilization carbon sources was significant between slash pine and the others (P<0.05). Shannon index in hoop pine was 4.391, evenness was 0.046, Simpson index was 67.9, Mclntosh index was 14.07, and evenness was 0.979, which were higher than that of the other forest types, and that of slash pine was lowest, and the difference of diversity and evenness was significant to hoop pine and Kauri pine (P<0.05). The difference of carbon source utilization under the same forest type was significant. The microorganism prefers to utilization carbohydrate and polymer during the Biolog Microplate incubation.(5) The order of soil chitinase and LAP activity in different forest types was slash pine> hoop pine>kauri pine. The order of soil acid phosphatase and (3-glucosidase activity as follows:slash pine> kauri> hoop pine, and alkaline phosphatase as follows:kauri pine> slash pine> hoop pine. The difference of relationship was significant between soil chitinase and TC, pH and chitinase, LAP and (3-gluocosidase, TC and alkaline phosphatase (P<0.01). Redundancy analysis showed that the relationship between alkaline phosphatase and hoop pine, LAP andβ-gluocosidase and kauri pine, microbial biomass and slash pine were closer. There was negatively related between Chitinase and acid phosphatase to slash pine.(6) There were 45 PLFAs in slash pine soil, and 39 and 35 PLFAs, respectively, in the hoop pine and kauri pine. The number of PLFAs in slash Pine was higher than that of hoop pine and kauri pine. PCR-DGGE analysis showed that the number of bands ranged from 17 to 28, and the average number of bands under slash pine, hoop pine and kauri pine were 25.5,17 and 23, respectively. The results indicated that abundance of soil bacterial in slash pine was the highest, and was similar to the results by PLFA.更多还原