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.

该项目将通过调查土壤生物和功能多样性（根和微生物）以及土壤化学性质如何限制土壤呼吸过程，提高我们量化气候变暖对土壤CO2排放影响的能力。这项工作将是第一次在大海拔梯度和热带地区解决这个问题，那里的生物多样性和碳的地球化学循环非常高。生态系统的碳平衡很大程度上取决于光合作用和呼吸作用之间的平衡。在全球范围内，目前陆地上的呼吸作用略小于光合作用，这意味着陆地生态系统被认为是大气二氧化碳的“汇”，减缓了大气中二氧化碳（CO2）浓度的持续上升。陆地总呼吸的最大部分来自土壤中有机物质的分解。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，分解的速度可能会增加，这可能会加速本世纪的气候变化，因此我们迫切需要了解这种情况发生的风险是什么。我们的研究地点位于秘鲁的热带雨林中，海拔3000米至220米。土壤碳储量很大，特别是在高海拔地区，因此存在风险，因为在气候变暖的情况下，这种碳可能会分解并以二氧化碳的形式排放。我们的初步数据表明，这些森林中土壤CO2排放的温度敏感性存在很大差异，在高海拔地区具有高敏感性。本项目旨在通过检查物理环境和根系以及土壤中的分解微生物对有机物分解的控制来了解这些敏感性差异。我们的研究地点非常适合解决这个问题，因为它跨越了12-26摄氏度的自然温度梯度。我们将以两种方式使用这一点：（i）观察不同海拔和温度下二氧化碳排放的自然差异，以及（ii）检查从一个海拔移植土壤并在另一个海拔“重新种植”土壤的影响。我们已经在海拔梯度上的4个地点进行了第（ii）部分，现在有一个特殊的机会来研究影响，并提高我们对土壤CO2排放的短期和长期气候变暖的理解。本研究旨在观察天然和移植土壤CO2排放的温度响应特征。我们将在2.5年内进行高时间分辨率的测量，进一步操纵土壤，以观察从分解系统中去除根系和菌根真菌的效果。我们将测量土壤碳的物理环境和化学复杂性。我们还将使用先进的膜和DNA技术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跟踪碳化合物的类型，不同的微生物使用不同的网站沿着研究样带。在这里，我们将用稳定（安全）的碳同位素“喂养”土壤，并追踪碳的使用和排放-即排放了多少标记的二氧化碳，哪些生物在新陈代谢中使用它。这将为我们提供有价值的信息，为我们分析从现场测量中获得的数据提供信息。在我们的分析中，我们将统计研究什么微生物/根功能是最重要的约束土壤呼吸对气候变化的反应，并使用我们的实验室数据提供我们的统计分析的机械解释。结合起来，我们将开发一个新的理解土壤呼吸对气候变暖的反应，我们将测试生物多样性的重要性是控制和约束这种反应，及其对气候变化的影响。

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

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

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

Productivity and carbon allocation in a tropical montane cloud forest in the Peruvian Andes

• DOI: 10.1080/17550874.2013.820222
• 发表时间: 2014-01-01
• 期刊: PLANT ECOLOGY & DIVERSITY
• 影响因子: 1.5
• 作者: Girardin, Cecile A. J.;Silva Espejob, Javier E.;Malhi, Yadvinder
• 通讯作者: Malhi, Yadvinder