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/G018367/2
• 负责人: Richard Bardgett
• 金额: $ 1.42万
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FG018367%2F2
• 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二氧化碳排放影响的能力。这项工作将是第一个在生物多样性和碳生物地球化学循环非常高的热带地区解决大海拔梯度问题的此类工作。生态系统的碳平衡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，目前陆地上的呼吸作用比光合作用略小，这意味着陆地生态系统被认为是大气二氧化碳的“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，分解速度可能会加快，可能会加速本世纪的气候变化，因此我们迫切需要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，海拔从3000米到220米不等。土壤碳储量很大，特别是在高海拔地区，因此在气候变暖的情况下，这些碳可能会分解并以二氧化碳的形式排放，因此存在风险。我们的初步数据表明，这些森林土壤二氧化碳排放的温度敏感性存在较大差异，高海拔地区敏感性较高。该项目旨在通过检查对物理环境、根部以及土壤中分解微生物施加的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，因为它的自然温度梯度为 12-26 摄氏度。我们将以两种方式利用这一点：（i）观察不同海拔和温度下二氧化碳排放的自然差异，（ii）检查从一个海拔移植土壤并在另一个海拔“重新种植”的效果。我们已经在海拔梯度上的 4 个地点进行了第 (ii) 部分，现在有一个绝佳的机会来研究其影响，并加深我们对土壤二氧化碳排放的短期和长期气候变暖的理解。我们的方法是观察天然土壤和移植土壤中土壤二氧化碳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测量，进一步操纵土壤，以观察从分解系统中去除根和菌根真菌的效果。我们将测量物理环境和土壤碳的化学复杂性。我们还将使用领先的基于膜和 DNA 的技术来测量土壤中微生物的生物多样性。最后，我们将使用实验室实验来追踪研究样带不同地点不同微生物使用的碳化合物的类型。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位置，即排放了多少标记的二氧化碳以及哪些生物体在新陈代谢中使用它。这将为我们提供有价值的信息，以便我们分析从现场测量中获得的数据。在我们的分析中，我们将统计检查哪些微生物/根功能对于限制土壤呼吸对气候变化的反应最重要，并使用我们的实验室数据为我们的统计分析提供机械解释。结合起来，我们将对土壤呼吸对气候变暖的反应有一个新的认识，我们将测试生物多样性对于控制和限制这种反应的重要性及其对气候变化的影响。

项目成果

Microbial community composition explains soil respiration responses to changing carbon inputs along an Andes-to-Amazon elevation gradient.

微生物群落组成解释了土壤呼吸对沿安第斯山脉至亚马逊高度梯度沿线不断变化的碳输入的反应。

• DOI: 10.1111/1365-2745.12247
• 发表时间: 2014-07
• 期刊: The Journal of ecology
• 作者: Whitaker J;Ostle N;Nottingham AT;Ccahuana A;Salinas N;Bardgett RD;Meir P;McNamara NP;Austin A
• 通讯作者: Austin A

Temperature sensitivity of soil enzymes along an elevation gradient in the Peruvian Andes

• DOI: 10.1007/s10533-015-0176-2
• 发表时间: 2016-02
• 期刊: Biogeochemistry
• 影响因子: 4
• 作者: A. Nottingham;Benjamin L Turner;J. Whitaker;N. Ostle;R. Bardgett;N. McNamara;N. Salinas;P. Meir

Soil microbial nutrient constraints along a tropical forest elevation gradient: a belowground test of a biogeochemical paradigm

• DOI: 10.5194/bg-12-6071-2015
• 发表时间: 2015-10
• 期刊: Biogeosciences
• 影响因子: 4.9
• 作者: A. Nottingham;Benjamin L Turner;J. Whitaker;N. Ostle;N. McNamara;R. Bardgett;N. Salinas;N. Salinas-N.-Sal