DO ARCTIC PLANT-SOIL COMMUNITIES ACCLIMATE TO LONG TERM ELEVATED CO2 EXPOSURE?

由于持续的工业活动，温室气体浓度正在上升，这对我们未来的气候产生了影响。生物圈被认为是减缓大气变化的一个重要因素，因为它有能力通过封存额外的碳来应对这种变化。我们理解和评估这些过程的关键是了解生态系统适应二氧化碳升高的程度。一些研究表明，只有对二氧化碳升高的短期增长反应，但这些研究往往专注于生产反应，而忽视了整个生态系统功能的更微妙的变化。即使在已经发生驯化的地方，确定任何新的平衡状态是否会导致生态系统功能的改变，特别是在碳的损失或获得方面，这一点也很重要。北极生态系统对全球保护至关重要，储存了高达全球土壤碳储量的三分之一。它们在未来大气二氧化碳情景下的稳定性将对全球生物多样性和变暖产生重大影响。在这项研究中，我们想要测试北极植物群落是否即使长期暴露在高二氧化碳环境中也不能完全适应，地下反应滞后于地上反应，以及高二氧化碳暴露对影响生态系统稳定性、抵抗力和复原力的生态系统属性具有累积效应。由于人为气体排放，北极地区的气候可能会发生变化，特别是在温度和降水方面。这些变化，以及其他周期性的扰动，将挑战当前植被和土壤微生物过程的稳定性。亚北极的卫生系统也会受到周期性的大规模食草性事件的影响，例如，由于飞蛾的大规模侵扰。因此，我们将研究田间对模拟落叶事件的反应(叶片再生和土壤呼吸)。在受控环境设施中，我们还将调查土壤温度和水分的变化是否会与未来北极土壤在未来高二氧化碳浓度下保留固定碳的能力相互作用。如果我们能够根据气候模型改进的预测做出有效的管理决策，来自该研究计划的信息是至关重要的。具体地说，在预测和模拟未来情景时，整个生态系统适应二氧化碳浓度升高的程度是一个关键的不确定性领域。研究成果还将大大促进我们对北极生态系统对未来气候变化下的扰动的稳定性以及对全球生物多样性影响的重要潜在影响的理解。

Concentrations of greenhouse gases are rising as a result of continued industrial activity with consequences for our future climate. The biosphere has been suggested as a significant factor mitigating atmospheric change, through its capacity to respond to this change by sequestering additional carbon. Key to our understanding and evaluation of these processes is knowledge about the extent to which ecosystems acclimate to elevated CO2. Some research has indicated only short-term growth responses to elevated CO2, but these studies have often focussed on production responses ignoring more subtle shifts in whole ecosystem function. Even where acclimation has occurred, it is important to determine whether any new state of equilibrium results in altered ecosystem function, especially with regard to C loss or gain. Arctic ecosystems are of critical importance to global conservation and store up to one-third of global soil carbon reserves. Their stability under future atmospheric CO2 scenarios will have major influences on global biodiversity and warming. In this study we want to test whether arctic plant communities do not acclimate fully even with extended exposure to elevated CO2, that below-ground responses lag those above-ground and that exposure to elevated CO2 has a cumulative effect on ecosystem properties that influence ecosystem stability, resistance and resilience. As a result of anthropogenic gaseous emissions, the climate of Arctic regions is likely to alter, in particular with regard to temperature and precipitation. These changes, and other periodic perturbations will challenge the stability of current vegetation and soil microbial processes. Sub-arctic heath systems are also subject to periodic mass herbivory events, for example due to mass infestation by the moth Epirrita autumnata. We will therefore investigate field responses (leaf regrowth and soil respiration) to a simulated defoliation event. In a controlled environment facility, we will also investigate whether variations in soil temperature and moisture content will interact with the future capacity of Arctic soils to retain sequestered C under future elevated CO2. The information from this research programme is vital if we are to be able to make effective management decisions based on improved predictions from climate models. Specifically, the extent to which whole ecosystems acclimate to elevated CO2 is a key area of uncertainty in predicting and modelling future scenarios. Research findings will also significantly advance our understanding of the stability of Arctic ecosystems to perturbations under future climate change and important potential impacts on global biodiversity impacts.