高寒草甸植物群落结构组建和生产力对施肥的响应机制

发布时间：2019-03-29 14:23

【摘要】：群落构建一直是生态学研究的核心问题,在生态学研究中具有久远的历史。然而关于群落构建的机制却一直都不是很清楚。从很久以前的机体论和个体论之间的论战,发展成本世纪初生态位理论和中性理论的论战,一直困扰研究者的问题是:群落构建到底是确定性的过程还是随机性的过程?研究群落构建机制的最终目的是解释和预测生态系统功能的变化,特别是与人类生活息息相关的生产力的变化。青藏高原高寒草甸的生产力到底是氮限制还是磷限制?在气候变化背景下高寒草甸的生产力会如何变化?导致这种变化背后的群落构建机制是什么?这些都是我们迫切需要解答的问题。为了研究上述问题,我们在位于青藏高原东部的高寒草甸中设置了包含不同肥料和不同梯度的两个施肥实验。我们测定不同处理中24个主要组分种的六个功能性状(高度、比叶面积、叶片干物质含量、种子大小、叶片氮含量和叶片磷含量),测定群落内物种的多度、盖度和生物量并测定土壤的主要理化性质(速效氮、速效磷、pH、土壤含水量和土壤温度)。单因素方差分析、标准主轴回归、一般线性模型、结构方程模型和系统发育独立性分析等分析方法被用来系统地分析我们的数据。研究结果表明:1、高寒草甸群落生产力受到氮磷两种养分的共同限制,其中氮为第一限制性养分,当解除氮限制以后磷成为限制性养分。高寒草甸的生产力不受钾的限制。2、施氮肥显著影响物种相对多度和功能性状之间的关系,磷肥对性状-多度关系的影响很小。以光竞争为代表的竞争过程在高寒草甸群落内普遍存在,尤其是在施氮肥以后的群落构建中发挥了重要的作用。我们的研究结果表明:在高寒草甸群落中可以使用简单但是具有重要生态学意义的功能性状去解释和预测施肥以后的物种多度变化。3、竞争-扩散权衡是高寒草甸群落构建的一种重要机制。群落内的大部分物种要么是竞争上的优势者要么是扩散上的优势者,但不会同时在竞争能力和扩散能力上都占据优势。竞争-扩散权衡对物种多度分布的影响依赖于空间尺度。4、在高寒草甸植物群落中最好的去解释群落施肥以后的生产力变化需要把物种多样性、系统发育多样性和功能多样性这三种不同类型的多样性指标结合起来。质量比假说和生态位互补假说这两种解释生产力与多样性关系的重要学说同时在施肥后的群落内发挥作用,他们之间的关系是相互补充而非相互排斥。5、无论是在施肥后的群落中还是在对照群落中都普遍地存在着确定性的性状-多度关系,说明基于性状的确定性过程在自然群落和施肥群落的构建中都扮演着非常重要的角色。6、在施肥以后的群落构建中环境筛选和竞争排除这两个相对的过程同时发挥作用。在低浓度的氮添加处理中环境筛选起到主要作用,但是随着氮肥添加梯度的增加,竞争排除过程在不断的增强,最终这两个相反的过程在高浓度氮添加中达到平衡。施磷肥对高寒草甸群落的构建几乎没有影响。
[Abstract]:Community construction has been a core problem of ecological research and has a long history in the study of ecology. However, the mechanism on the construction of the community has not been very clear. The controversy between the theory of ecology and the theory of neutral in the beginning of this century has always been a problem for researchers, from a long-time theory of body theory and individual theory. The problem of the researchers has been that the process of community construction is the process of certainty and the process of randomness. The ultimate purpose of the study community construction mechanism is to explain and predict the change in the ecosystem function, in particular the change in productivity associated with human life. The productivity of the alpine meadow in the Qinghai-Tibet plateau is the nitrogen limitation or the phosphorus limitation? How can the productivity of the alpine meadow change in the context of climate change? What is the community construction mechanism behind this change? These are the questions we urgently need to answer. In order to study the above problems, we set up two fertilization experiments with different fertilizers and different gradients in the alpine meadow located in the eastern part of the Qinghai-Tibet Plateau. Six functional traits (height, specific leaf area, leaf dry matter content, seed size, leaf nitrogen content and leaf phosphorus content) of 24 major component species in different treatments were determined to determine the abundance of species in the community, The main physical and chemical properties of the soil (quick-acting nitrogen, quick-acting phosphorus, pH, soil moisture content and soil temperature) were measured. The analysis methods such as single factor analysis of variance, standard principal axis regression, general linear model, structural equation model and phylogenetic independence analysis are used to analyze our data systematically. The results showed that:1. The productivity of the alpine meadow community was limited by both nitrogen and phosphorus, and the nitrogen was the first limiting nutrient, and the phosphorus became a limiting nutrient after the nitrogen limitation was released. The productivity of the alpine meadow is not limited by the potassium. The competition process represented by the light competition is common in the alpine meadow community, especially in the community construction after the application of the nitrogen fertilizer. The results of our study show that in the alpine meadow community, simple but important ecological functional traits can be used to explain and predict the multi-degree change of species after fertilization.3. The competition-diffusion trade-off is an important mechanism for the construction of the alpine meadow community. Most of the species in the community are either competitive or competitive, but not both competitive and proliferation. The influence of the competition-diffusion trade-off on the abundance distribution of species depends on the spatial scale. The diversity and functional diversity of the three different types of diversity are combined. The important theory of the relationship between the productivity and the diversity of the hypothesis of mass ratio and the complementary hypothesis of the niche is to play a role in the community after fertilization, and the relationship between them is complementary rather than mutually exclusive. In the community of fertilization and in the control community, there is a generally deterministic trait-multi-degree relationship, which indicates that the deterministic process based on the character plays a very important role in the construction of the natural community and the fertilization community. In the community construction after fertilization, the two opposite processes play a role in environmental screening and competition. The environmental screening plays a major role in the low-concentration nitrogen addition treatment, but with the increase of the addition gradient of the nitrogen fertilizer, the competition and elimination process is continuously enhanced, and the two opposite processes are balanced in the high-concentration nitrogen addition. The application of P fertilizer has no effect on the construction of the alpine meadow community.
【学位授予单位】：兰州大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：Q948.1

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