兰州大学机构库 >生命科学学院
凋落物质量、土壤动物和牛粪添加对青藏高原高 寒草甸凋落物分解的影响
Alternative TitleThe effects of litter quality, soil fauna and dung addition on litter decomposition in a Tibetan alpine meadow
梁德飞
Thesis Advisor张世挺
2016-12-01
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name博士
Keyword凋落物分解 养分释放 土壤动物 牛粪添加 高寒草甸
Abstract

凋落物分解将植物光合产物转变成无机化合物和土壤有机质,是温室气体主要的源和全球碳平衡的关键环节;伴随着凋落物分解的养分动态是生态系统养分循环的主要进程,因此了解分解特征有助于全球碳和养分循环的预测。青藏高原高寒草甸已有数千年的牦牛放牧历史,放牧过程中产生的粪便作为碳和养分归还土壤的另一个重要方式,研究其沉积对凋落物分解的影响有助于更清晰全面的了解青藏高原高寒草甸生态系统功能,为草地管理提供理论依据。除了大型食草动物(如牦牛),土壤动物在放牧草地生态系统中,对凋落物分解会有怎样的影响?以及与牛粪交互作用如何影响凋落物分解的重量损失及养分释放?

基于以上,我们选择青藏高原高寒草甸优势种线叶嵩草(Kobresia capillifolia),垂穗披碱草(Elymus nutans)以及常见种黄帚橐吾 (Ligularia virgaurea),小花草玉梅(Anemone rivularis),瑞苓草(Saussurea nigrescens)和披针叶黄华(Thermopisis lanceolata)的叶片凋落物作为研究对象进行18个月的野外分解实验。将凋落物物种单种以及两两混合,用广泛采用的凋落物袋(3mm和0.01mm)分解法,通过土壤动物去除(不同大小网孔)和牛粪添加处理,观测6个月、12个月和18个月后凋落物重量损失和氮(N),磷(P)释放率,研究凋落物质量,牛粪添加以及土壤动物去除在不同分解时间上对凋落物重量损失以及养分释放的影响。主要研究结果如下:

1)凋落物初始C/N与凋落物分解速率以及养分释放呈显著负相关关系,可作为预测凋落物分解的指标。2)土壤动物对凋落物重量损失的促进效应随时间延长而减弱,且对低质量凋落物的促进效应更大;同时,土壤动物能降低凋落物N、P剩余量,此效应也随分解时间的延长而减弱,但和凋落物质量没有交互作用。3)牛粪添加能促进凋落物重量损失,能降低凋落物N、P剩余量,且与凋落物质量和分解时间存在交互作用。4)同质凋落物(相似C/N和Lignin/N)混合在3个分解时期重量损失和N释放均表现为加性效应。异质凋落物混合在分解6个月后的凋落物重量损失表现出正的非加性效应,但对N释放表现出负的非加性效应;分解12月后,凋落物重量损失和N释放均表现出加性效应;分解18个月后,凋落物重量损失表现出负的非加性效应。对于P释放而言,凋落物混合在分解6个月后表现出正的非加性效应,其它情况均表现为加性效应。5)土壤动物去除仅在分解6个月后能减弱混合凋落物重量损失和P释放的正非加性效应,并能增强混合凋落物N释放的负非加性效应。6)牛粪添加在分解6个月后增强凋落物混合重量损失的非加性效应,并使其加性效应转变为正的非加性效应,使N释放的负非加性效应变为加性,并能增强部分凋落物混合(P含量差异较大)P释放的正非加性效应;分解12个月后牛粪添加使混合凋落物重量损失的加性变为负的非加性效应,将不同质量混合N释放的加性效应变为负的非加性效应,并使P含量差异较大的凋落物混合P释放的加性变为正的非加性效应;分解18个月后,牛粪添加使混合凋落物重量损失的加性效应变成负的非加性效应。

Other Abstract

Litter decomposition, which converts the products of photosynthesis to inorganic components and soil organic matter, is the main source of greenhouse gases and regulator of global carbon balance.  Nutrient cycle of ecosystem is also affected by litter decomposition and nutrient release. Thus, through understanding of litter decomposition will greatly improve our understanding of global carbon and nutrient cycle process. There has been a long history (up to 1000 years) of yak grazing in the Tibetan Plateau, and yak dung is one of another important ways of returning back carbon and nutrient into soil. Thus, the effect of dung deposition on litter decomposition  need to be studied, which can help us to improve understanding of the function of alpine meadow ecosystem and to provide  theoretical foundation for grassland management. Except for herbivores, how did soil fauna affect litter decomposition, and its interaction with dung addition affect litter decomposition and nutrients release?

We selected six common leaf litter species, including Kobresia capillifolia, Elymus nutans, Ligularia virgaurea, Anemone rivularis, Saussurea nigrescens and Thermopisis lanceolata in an alpine meadow, and incubated leaf litter of six species in monocultures and all possible two species combinations in the field using litterbags of different mesh size (3mm and 0.01 mm)with and without dung addition. Our aims were to test the effect of litter quality, soil fauna and dung addition on litter decomposition, nitrogen (N) and phosphorus (P) release. Our results showed that:

1) Both initial litter C/N was negatively correlated with litter decomposition rates and nutrient release, respectively, and could be considered as effective predictors of litter decomposition.2) Soil fauna increased the litter mass loss and nutrient release, the strength of which weakened over incubation time. This positive effect was stronger for low-quality species than for high-quality species. In addition, soil fauna decreased the remaining of N and P, the strength of which also weakened over incubation time, but there were not interactions with litter quality.3) Dung addition promoted the mass loss of low-quality species and decreased the remaining of N and P, and significantly interacted with litter quality and incubation time, respectively.4) Additive effects on litter mass loss and N release both occurred in homogeneous litter mixtures (similar C/N and Lignin/N) in all of three incubation times. After 6 months, synergistic interactions appeared in heterogeneous litter mixtures for litter mass loss, and antagonistic interactions for N release. After 12 months, additive effects on both litter mass loss and N release occurred in heterogeneous litter mixtures. After 18 months, synergistic interactions appeared for litter mass loss. For P release, synergistic interactions appeared in all of litter mixtures after 6 months incubation, and additive effects occurred in other cases.5) After 6 months, soil fauna removal could weaken the magnitude of positive non-additive effects on litter mass loss and P release, and enhanced the magnitude of negative non-additive effects on N release.6) After 6 months, dung addition strengthened the magnitude of synergistic interactions and shifted synergistic interactions from additive effects for litter mass loss, shifted additive effects from antagonistic interactions for N release, and enhanced synergistic interactions for some of litter mixtures (contrasting  P content) ; After 12 months, dung addition shifted antagonistic interactions from additive effects for litter mass loss, antagonistic interactions from additive effects for heterogeneous litter mixtures for N release, and synergistic interactions from additive effects for some of litter mixtures (contrasting P content); After 18 months, dung addition shifted antagonistic interactions from additive effects for litter mass loss.

URL查看原文
Language中文
Document Type学位论文
Identifierhttp://ir.lzu.edu.cn/handle/262010/221534
Collection生命科学学院
Recommended Citation
GB/T 7714
梁德飞. 凋落物质量、土壤动物和牛粪添加对青藏高原高 寒草甸凋落物分解的影响[D]. 兰州. 兰州大学,2016.
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