Biological controls on soil respiration and its climatic response across a large tropical elevation gradient

大热带海拔梯度土壤呼吸及其气候响应的生物控制

• 批准号: NE/G018278/1
• 负责人: Patrick Meir
• 金额: $ 46.98万
• 依托单位: University of Edinburgh
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FG018278%2F1
• 关键词: Biological; controls; soil; respiration; its

This project will advance our ability to quantify the influence of climatic warming on the emission of CO2 from soil by investigating how soil biological and functional diversity (roots and microbes), and soil chemical properties, limit respiration processes in soil. This work will be the first of its kind to address this question over a large elevation gradient and in a tropical region where biodiversity and biogeochemical cycling of carbon are very high. The carbon balance of an ecosystem is strongly dependent on the balance between photosynthesis and respiration. Globally, respiration on land is at present very slightly smaller than photosynthesis, meaning that terrestrial ecosystems are thought to be a 'sink' for atmospheric carbon dioxide, slowing the continual rise in carbon dioxide (CO2) concentration in the atmosphere. The largest fraction of total respiration from land comes from the decomposition of organic matter in soil. This decomposition leads to emissions of CO2 to the atmosphere. The rate of decomposition may increase under climatic warming, possibly accelerating climate change over this century, so we need urgently to understand what the risk of this happening is. Our study site is in the tropical rain forests of Peru, ranging in altitude from 3000 m to 220 m above sea level. The soil carbon stock is large, particularly at high elevation and so represents a risk in the sense that this carbon could be broken down and emitted as CO2 under climatic warming. Our preliminary data suggest that there are large differences in the temperature sensitivity of soil CO2 emissions in these forests, with high sensitivity at high elevations. This project aims to understand these differences in sensitivity by examining controls over the decomposition of organic matter that are exerted by the physical environment and also by roots, and by the decomposing microbes in soil. Our study site is ideally suited to address this question because it spans a natural temperature gradient of 12-26 degrees Celsius. We will use this in two ways: (i) to observe natural differences in CO2 emissions at different elevations and temperatures and (ii) to examine the effects of transplanting soil from one elevation and 're-planting' it at another. We have performed part (ii) for 4 sites across our elevation gradient and now haave an exceptional opportunity to study the effects, and to advance our understanding of short- and long-term climatic warming of soil CO2 emissions. Our approach will be to observe the temperature response characteristics of soil CO2 emission in natural and transplanted soil. We will make high temporal resolution measurements over 2.5 years, further manipulating the soil to see the effects of removing roots and mycorrhizal fungi from the decomposing system. We will measure the physical environment and the chemical complexity of the soil carbon. We will also measure the biological diversity of microbes in the soil using leading edge membrane- and DNA-based techniques. Finally we will use a laboratory experiment to trace the types of carbon compound that different microbes use from different sites along the study transect. Here we will 'feed' the soil with a stable (safe) carbon isotope and trace where that carbon is used and emitted - ie how much labeled CO2 is emitted and which organisms use it in their metabolism. This will give us valuable information to inform our analysis of the data we get from field measurements. In our analysis we will statistically examine what microbes/root functions are most important for constraining the response by soil respiration to climatic change and use our laboratory data to provide mechanistic interpretations of our statistical analysis. Combined we will develop a new understanding of the response by soil respiration to climatic warming and we will test how important biological diversity is for controlling and constraining that response, and its effect on climatic change.

该项目将通过研究土壤生物学和功能多样性（根和微生物）以及土壤化学特性的如何限制土壤中的呼吸过程，从而促进我们量化气候变暖对土壤中二氧化碳排放影响的能力。这项工作将是第一个在较大的海拔梯度上解决这个问题的第一个工作，以及在碳生物多样性和生物地球化学循环非常高的热带地区。生态系统的碳平衡在很大程度上取决于光合作用和呼吸之间的平衡。在全球范围内，目前在陆地上的呼吸比光合作用略小，这意味着陆地生态系统被认为是大气二氧化碳的“下水道”，从而减慢了大气中二氧化碳（CO2）浓度的持续上升。土地总呼吸中最大的一部分来自土壤中有机物的分解。这种分解导致二氧化碳排放到大气中。在气候变暖的情况下，分解速度可能会增加，可能会在本世纪加速气候变化，因此我们需要紧急了解发生这种情况的风险是什么。我们的研究地点位于秘鲁的热带雨林中，海拔高于海拔3000 m至220 m。土壤碳的储备很大，尤其是在高海拔地区，因此在气候变暖下可以分解并以二氧化碳的形式分解并排放为二氧化碳。我们的初步数据表明，在这些森林中，土壤二氧化碳排放的温度敏感性存在很大差异，高海拔高度较高。该项目旨在通过检查对物理环境以及根部以及土壤中分解微生物所施加的有机物分解的控制来了解敏感性的这些差异。我们的研究地点非常适合解决这个问题，因为它覆盖了12-26摄氏度的自然温度梯度。我们将以两种方式使用它：（i）观察不同高度和温度下的二氧化碳排放量的自然差异，以及（ii）检查从一个高程中移植土壤的影响，然后将其“重新种植”到另一个高度。我们已经在海拔梯度的4个地点进行了部分（ii），现在有了一个出色的机会来研究这种影响，并促进我们对短期和长期气候对土壤二氧化碳排放的理解的理解。我们的方法是观察自然和移植土壤中土壤CO2发射的温度响应特征。我们将在2。5年内进行高度的时间分辨率测量，进一步操纵土壤，以查看从分解系统中去除根和菌根真菌的影响。我们将测量土壤碳的物理环境和化学复杂性。我们还将使用前缘膜和基于DNA的技术来测量土壤中微生物的生物多样性。最后，我们将使用一个实验室实验来追踪研究样带中不同位点中不同微生物使用的碳化合物类型。在这里，我们将以稳定的（安全的）碳同位素为“喂”土壤，并追踪该碳的使用和发射的位置 - 即发出了多少标记的二氧化碳，哪些生物在其代谢中使用了它。这将为我们提供有价值的信息，以告知我们对现场测量数据获得的数据的分析。在我们的分析中，我们将统计检查哪些微生物/根功能对于通过土壤呼吸对气候变化来限制反应最重要，并使用我们的实验室数据来提供我们统计分析的机械解释。结合在一起，我们将通过土壤呼吸对气候变暖的呼吸进行新的理解，我们将测试生物学多样性对于控制和限制该反应的重要性以及对气候变化的影响。

项目成果

Density-body mass relationships: Inconsistent intercontinental patterns among termite feeding-groups

• DOI: 10.1016/j.actao.2015.01.003
• 发表时间: 2015-02-01
• 期刊: ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY
• 影响因子: 1.8
• 作者: Dahlsjoe, Cecilia A. L.;Parr, Catherine L.;Eggleton, Paul
• 通讯作者: Eggleton, Paul

Annual variation in soil respiration and its component parts in two structurally contrasting woody savannas in Central Brazil

• DOI: 10.1007/s11104-011-0984-7
• 发表时间: 2012-03-01
• 期刊: PLANT AND SOIL
• 影响因子: 4.9
• 作者: Butler, Andre;Meir, Patrick;Grace, John
• 通讯作者: Grace, John

First comparison of quantitative estimates of termite biomass and abundance reveals strong intercontinental differences

白蚁生物量和丰度定量估计的首次比较揭示了巨大的洲际差异

• DOI: 10.1017/s0266467413000898
• 发表时间: 2014
• 期刊: Journal of Tropical Ecology
• 影响因子: 1.4
• 作者: Dahlsjö C

Describing termite assemblage structure in a Peruvian lowland tropical rain forest: a comparison of two alternative methods

• DOI: 10.1007/s00040-014-0385-z
• 发表时间: 2015-05
• 期刊: Insectes Sociaux
• 影响因子: 1.3
• 作者: C. Dahlsjö;C. Dahlsjö;C. Dahlsjö;Catherine L. Parr;Y. Malhi;Patrick Meir;Patrick Meir;P. Eggleton

Termites promote soil carbon and nitrogen depletion: Results from an in situ macrofauna exclusion experiment, Peru

• DOI: 10.1016/j.soilbio.2014.05.033
• 发表时间: 2014-10
• 期刊: Soil Biology & Biochemistry
• 影响因子: 9.7
• 作者: C. Dahlsjö;C. Parr;Y. Malhi;P. Meir;Omayra V.C. Chevarria;P. Eggleton