Lake sediment records of artic ecosystem responses to holocene climatic changes

加拿大的自然环境目前正经历着迅速的变化。全球变暖和生物多样性的丧失威胁着加拿大人赖以经济繁荣、健康和农业的生态系统。因此，有必要更好地了解生态系统对气候变化作出反应的机制。为了获得这种认识，有必要在长时间和大空间尺度上对生态系统进行研究。古气候记录表明，自上一个冰河期以来，发生了重大的气候变化。该研究项目的目标是利用古生态科学的长期视角，在长时间尺度上量化生物系统对气候变化的响应；这些发现提供了这些反应的案例研究，并将有助于预测全球变暖和生物多样性丧失的影响。古生态科学包括对湖泊或湿地沉积物岩心的研究，这些岩心包含了数千年来环境变化的详细记录。这里使用的主要技术是分析保存在沉积物中的微观生物遗骸，包括花粉粒和水生生物，如硅藻。这些指标显示了陆地植被和水生群落是如何随时间变化的，这些记录可以叠加在古气候数据上，以量化气候与生态变化之间的相关性。该研究项目将集中在加拿大北极地区，因为该地区对气候变化高度敏感。实地工作将集中于跨生物多样性和生物生产力梯度取样，以确定生态系统的特性如何调节对气候变化的反应。这一战略将有助于确定最敏感的北极生态系统类型，还将显示生物多样性的丧失如何加剧气候变化的影响。

Canada's natural environment is presently undergoing rapid change. Global warming and losses of biodiversity threaten the ecosystems that Canadians depend upon for economic prosperity, health and agriculture. Therefore, there is a need for a better understanding of the mechanisms through which ecosystems respond to climatic change. In order to gain this understanding, it is necessary to study ecosystems on long temporal and large spatial scales. Paleoclimatic records indicate that since the last ice age, significant climatic changes have occurred. The goal of the research program is to use the long-term perspective given by paleoecological science to quantify the responses of biological systems to climatic changes on long time scales; the findings supply case studies of these responses, and will aid in predicting the impacts of global warming and losses of biological diversity. Paleoecological science involves the study of lake or wetland sediment cores that contain detailed records of environmental change over thousands of years. The major technique used here is the analysis of the microscopic biological remains preserved in the sediments, including pollen grains and aquatic organisms such as diatoms. These indicators show how terrestrial vegetation and aquatic communities have changed over time and these records can be superimposed on paleoclimatic data to quantify the correlations between climatic and ecological changes. The research program will be focussed on Arctic Canada as this region is highly sensitive to climatic change. Field work will concentrate on sampling across gradients of biodiversity and biological productivity to determine how the properties of ecosystems modulate responses to climatic change. This strategy will enable the identification of the most sensitive types of Arctic ecosystems, and will also show how losses of biodiversity might exacerbate the impacts of climatic change.