Nutrient controls on the terrestrial carbon cycle: how does phosphorus deficiency influence plant respiration?

陆地碳循环的养分控制：磷缺乏如何影响植物呼吸？

• 批准号: NE/F002165/1
• 负责人: Jonathan Lloyd
• 金额: $ 18.25万
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FF002165%2F1
• 关键词: Nutrient; controls; terrestrial; carbon; cycle

This project will advance our ability to quantify the influence of phosphorus limitation and temperature on plant tissue respiration. The carbon balance of an organism and 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 concentration in the atmosphere. About 80% of respiration from land is thought to come from trees, so understanding what determines plant respiration is central to understanding how the terrestrial component of the Earth system works. However, despite its importance, only a limited amount of data are available to help us quantify plant respiration over large regions of the world. For example, although we know that the most important nutrients for plant growth - nitrogen and phosphorus - limit plant metabolism, we have almost no information on how phosphorus deficiency limits plant respiration, and hence the carbon balance. We also know only a little about how plant respiration responds to temperature: currently our global models of terrestrial ecosystems make large assumptions about this that may be wrong. When we consider that: (i) 30% of the global land surface may be phosphorus-deficient; (ii) the global phosphorus supply may seriously decline in under 100 years; and (iii) global climatic warming is likely to increase plant respiration this century (but by how much we don't know), there is clearly a strong and urgent need to address this issue. We will make measurements of respiration on a wide range of plant species. We will first use controlled-environment chambers to control the supply of nutrients to plants. We will then couple this with field measurements made in selected forested regions where phosphorus and nitrogen are differentially limiting, in order to compare the data from our experimental work to real ecosystems. The choice of our fieldsites in tropical South America and New Zealand makes use of existing knowledge about likely phosphorus limitations and will allow us to also address the issue of how biodiversity affects the phosphorus-respiration relationship. Finally we will analyse and model our data to enable us to incorporate our findings into mathematical models used to calculate how the land surface and our climate interact. Our project will enable us: (i) to quantify how phosphorus deficiency affects respiration; (ii) to quantify the influence of phosphorus deficiency on the temperature dependence of plant respiration. We will be able to link our results to existing work on the relationship between plant tissue metabolism and nitrogen concentration, and to incorporate the results into site-specific and global modelling frameworks. The project is highly cost efficient to NERC, making use of international facilities and project partner time supplied at zero cost to this project. This work will also link directly into existing research programmes funded by NERC of which the project investigators are already a part. The project will fill a signficant gap in our understanding of global ecology and the functioning of the Earth system.

该项目将提高我们量化磷限制和温度对植物组织呼吸影响的能力。生物体和生态系统的碳平衡强烈依赖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浓度的持续上升。大约80%的陆地呼吸被认为来自树木，因此了解植物呼吸的决定因素对于了解地球系统的陆地部分如何运作至关重要。然而，尽管它的重要性，只有有限的数据可用于帮助我们量化植物呼吸在世界大面积地区。例如，尽管我们知道植物生长最重要的营养素--氮和磷--限制了植物的新陈代谢，但我们几乎没有关于磷缺乏如何限制植物呼吸作用的信息，从而限制了碳平衡。我们对植物呼吸如何对温度作出反应也知之甚少：目前我们的全球陆地生态系统模型对此做出了大量假设，这些假设可能是错误的。当我们考虑到：（i）30%的全球陆地表面可能是缺磷的;（ii）全球磷供应可能在100年内严重下降;以及（iii）全球气候变暖可能会增加本世纪的植物呼吸（但我们不知道增加多少），显然有强烈和迫切的需要解决这个问题。我们将对多种植物的呼吸作用进行测量。我们将首先使用受控环境室来控制植物的营养供应。然后，我们将结合在选定的森林地区，磷和氮是不同限制的实地测量，以比较我们的实验工作的数据，真实的生态系统。我们在热带南美洲和新西兰的实地考察地点的选择利用了现有的关于可能的磷限制的知识，并将使我们能够解决生物多样性如何影响磷呼吸关系的问题。最后，我们将分析和模拟我们的数据，使我们能够将我们的发现纳入数学模型，用于计算地表和气候如何相互作用。我们的项目将使我们：（i）量化磷缺乏如何影响呼吸作用;（ii）量化磷缺乏对植物呼吸作用的温度依赖性的影响。我们将能够将我们的研究结果与现有的植物组织代谢和氮浓度之间的关系联系起来，并将结果纳入特定地点和全球建模框架。该项目对NERC来说具有很高的成本效益，利用了国际设施和项目合作伙伴以零成本为该项目提供的时间。这项工作还将直接与NERC资助的现有研究计划联系起来，项目调查人员已经是其中的一部分。该项目将填补我们对全球生态和地球系统运作的理解方面的一个重大空白。

项目成果

Contrasting photosynthetic characteristics of forest vs. savanna species (Far North Queensland, Australia)

• DOI: 10.5194/bg-11-7331-2014
• 发表时间: 2014-01-01
• 期刊: BIOGEOSCIENCES
• 影响因子: 4.9
• 作者: Bloomfield, K. J.;Domingues, T. F.;Lloyd, J.
• 通讯作者: Lloyd, J.