Knowledge Resource Center for Ecological Environment in Arid Area
| 科尔沁沙地凋落物分解的若干生物影响因素研究 | |
| 其他题名 | Study on the biotic factors affecting the decomposition of litter in the Horqin sandy land |
| 毕京东 | |
| 出版年 | 2016 |
| 学位类型 | 硕士 |
| 导师 | 李玉霖 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 凋落物作为养分的基本载体，在养分循环中是连接植物与土壤的“纽带”，其分解不仅是生态系统重要的生物地球化学循环过程，也是生态系统内部物质与能量循环的关键环节，对于土壤的理化性质，土壤肥力和植物生产力等均起着决定性的作用。凋落物分解速率主要受非生物因素如温度和降水等和生物因素如凋落物质量和土壤微生物等的直接影响，而且一些生物影响因素的作用也受非生物因素的控制，不同气候类型、生态系统类型、微生境控制凋落物分解的控制因素不同。本文以我国北方半干旱区科尔沁沙地和沙丘草地优势植物叶凋落物为研究材料，针对科尔沁沙地强烈风蚀造成的凋落物二次混合以及远离凋落物栖息地的现象，通过室内培养的方法，研究凋落物化学成分、凋落物混合及栖息地间凋落物互移对凋落物碳矿化和干物质损失的影响，以期为深入认识区域陆地碳循环全球对气候变化的贡献以及区域尺度碳收支平衡提供科学依据。本研究的主要目的是解决以下三个问题：（1）在凋落物自身化学性质对凋落物分解的速率的影响中，哪些物质是凋落物分解速率的控制因素？（2）凋落物碳矿化速率对混合效应有怎样的响应？（3）主场效应对凋落物分解及碳矿化的影响是怎样的？主要研究结论如下：1) 科尔沁沙地 27种植物叶凋落物化学成分存在较大差异。经过66天的实验室培养，27种植物叶凋落物的培养样品共矿化有机碳总量在9.0 mg C/g干土至12.7 mg C/g干土之间，干物质损失量在14.7%- 40.4%之间。叶凋落物矿化分解释放的CO2总量及干物质损失量在27种植物之间存在显著差异。分布在严重退化沙丘生境中的优势物种具有较快的矿化分解速率，可以加快退化沙丘土壤C和N周转速率，有利于退化植被的快速恢复。2）科尔沁沙地27种植物叶凋落物矿化分解速率与凋落物的N含量、木质素含量、C/N、木质素/N、LOMⅠ和RP等指标存在密切关系。回归分析结果说明叶凋落物的矿化分解主要受凋落物木质素/N和极易分解有机物（LOMⅠ）的控制。3）科尔沁沙地豆科植物达乌里胡枝子凋落物与禾本科植物凋落物混合后，凋落物分解过程中CO2累计释放量和干物质损失量显著大于其组成凋落物单独分解得出的期望值，说明豆科植物与禾本科植物混合凋落物分解具有明显的协同效应；但是禾本科植物凋落物相互混合后，凋落物分解没有表现明显的协同效应，并且部分凋落物组合（芦苇+狗尾草和芦苇+糙隐子草混合）表现一定程度的拮抗效应。说明高质量凋落物与低质量凋落物混合可以产生明显的协同效应，这可能与凋落物化学成分之间的互补作用有关，但低质量凋落物之间混合不仅没有发生协同效应，甚至产生拮抗效应，这可能与凋落物化学成分相似或凋落物中某种化学物质的他感作用有关。4）科尔沁沙地优势灌木差巴嘎蒿和小叶锦鸡儿叶凋落物分解过程中，差巴嘎蒿叶凋落物具有明显的正向主场效应，但是小叶锦鸡儿叶凋落物并没有表现明显的主场效应；两种灌木根际微生物组成以及两种灌木的分布生境土壤微生物多样性的差异可能是主场效应的形成原因。5）科尔沁沙地差巴嘎蒿和小叶锦鸡儿叶凋落物混合后，凋落物分解过程中CO2累计释放量和干物质损失量显著大于基于其组成凋落物单独分解得出的期望值，说明化学成分相似的凋落物混合也会产生明显的混合效应，而凋落物混合对分解微环境的改变是引起混合效应的可能原因。 |
| 英文摘要 | As the basic carrier of nutrients, plant litter is considered as the "bridge" connecting plants and soil in the nutrient cycling. The decomposition of litter is not only an important process of biogeochemical cycle, but also a key part of mass turnover and energy flow in terrestrial ecosystem. Therefore, it determines the physical and chemical properties in the soils, soil fertility, and the primary productivity in terrestrial ecosystem. The rate of litter decomposition is controlled directly by abiotic factors (e.g. temperature, precipitation ) and biotic factors (e.g. litter quality, soil microorganism). Moreover, some biotic factors is substantially affected by abiotic factors. As a result, main controlling factors varies greatly between climate zones, between ecosystems, even between micro-habitats. In consideration of litter re-mixing and carrying away from home-habitat by strong wind erosion in Kerqin Sandy Land, we detected the effects of litter chemistry, litter mixture, and home-field advantage on CO2 release and mass loss during litter decomposition by indoors incubation method in this study. Our purposes is to: 1) reveal the relationship between litter decomposition and litter chemistry and determine which is the main controlling index of litter chemistry; 2) detect if there is additive or non-addition effects after litter mixing; 3) detect if there is home-field advantage in litter decomposition after litter exchange between habitats. The main results are as follows: Litter chemistry differed greatly among 27 dominant plant species in Kerqin Sandy Land. After 66 days of litter incubation, the cumulative CO2 release of 27 dominant plant species varied between between 9.0 mg C g-1 dry soil and 12.7 mg C g-1 dry soil, and dry matter loss of 27 dominant plant species ranged from 14.7% to 40.4%. There are significant differences in the cumulative CO2 release and dry mass loss among 27 dominant plant species. The results showed that litters from the species with mainly distributed in severe degraded sand dunes was decomposed relatively faster with higher cumulative CO2 release and dry mass loss during incubation. This will facilitates C and N turnover of litter on severe degraded sand dune and subsequently accelerate vegetation recovery in such habitat.There are close relationships between litter decomposition rate and N content, lignin content, C/N, lignin/N, LOMⅠand PR of 27 plant leaf litter in Kerqin Sandy Land. Regression analysis suggested that the C mineralization and mass loss of leaf litter is mainly affected by lignin/N ratio and LOMⅠ.Cumulative CO2 release and dry mass loss of mixing litter of legume Lespedeza davurica and graminaceous plant were significantly greater than expectations based on their litter decomposition alone, suggesting that there is obvious synergistic effect after litter legumes and grasses mixing. However, we did not detect synergistic effect after litter of graminaceous plant mixed each other. Moreover, we even detected antagonism effect in some litter mixtures of graminaceous plant (e.g. Setaria viridis + Phragmites australis,and Cleistogenes squarrosa + Phragmites australis). The results suggested that mixture of high quality litter and low quality litter would exert synergistic effect during litter decomposition. The reason of such effect is probably due to complementarities between chemical composition of high quality litter and low quality litter. In contrast, mixing of litter with similar quality would not exert synergistic effect but even exert antagonism effect during litter decomposition. We speculated that the reason was high similarity of chemical composition or allelopathy between litter.The results showed that CO2 release and dry mass loss were faster when leaf litter of Artemisia halodendron decomposed in soils under own canopy than in other soils, suggesting there is obvious home-field advantage during litter decomposition of Artemisia halodendron. In contrast, CO2 release and dry mass loss of Caragana microphylla remained steadily in three soil during incubation, suggesting no home-field advantage for leaf litter of Caragana microphylla. Variation in rhizosphere microorganisms and soil microbial diversity of two shrub may contribute the differences of home-field advantage in this study.Cumulative CO2 release and dry mass loss of mixing litter of Caragana microphylla and Artemisia halodendron were significantly greater than expectations based on their litter decomposition alone, suggesting that there is also obvious synergistic effect for litter with similar chemical decomposition. The main reason is probably due to the change of microenvironment during mixing litter decomposition. |
| 中文关键词 | 凋落物分解 ; 碳矿化速率 ; 化学性质 ; 主场效应 ; 混合效应 |
| 英文关键词 | litter decomposition carbon mineralization chemical properties home-field advantage mixing effect |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生物工程 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287724 |
| 推荐引用方式 GB/T 7714 | 毕京东. 科尔沁沙地凋落物分解的若干生物影响因素研究[D]. 中国科学院大学,2016. |
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