Late quaternary paleoecology and paleoclimatology of the Pacific Coast of Canada

为了更好地了解未来的气候变化及其对不列颠哥伦比亚省森林的潜在影响，我们的研究考察了数千年来沉积在湖泊沉积物中的证据，以研究过去气候的自然变化如何影响植物群落。我们研究的主要目标是：1）了解自上一个冰河时代以来加拿大太平洋沿岸植被群落的发展; 2）确定气候在那段时间内如何变化; 3）了解气候以外的因素的作用（例如，树种的生态差异，如耐荫性），在如何和为什么植被群落在长期尺度上变化。我们从不列颠哥伦比亚省沿海沿着的湖泊中收集沉积物核心，并识别过去沉积在这些湖泊中并保存在今天沉积物中的花粉和种子等植物遗骸。这使我们能够确定自湖泊沉积物沉积以来周围植物群落的组成是如何变化的。我们还分析了其他化石，如昆虫遗骸以及湖泊沉积物的物理性质，以确定过去的环境变化，包括气候，水文状况和侵蚀速率的变化。通过结合几个湖泊的数据，我们可以确定过去气候变化的区域模式，包括这些变化的速率和幅度，并利用这些来了解森林如何应对过去的气候变化。例如，先前的研究发现，大约7000年至10,000年前温暖干燥的夏季改变了许多植物物种的地理分布，森林火灾比今天更常见。通过了解过去的环境变化，我们可以预测未来气候变化的影响，从而更好地做好准备。这项研究对加拿大社会有许多重要的社会和经济影响，从提供管理和保护我们今天的森林和其他生态系统的相关知识，到为考古学家和原住民提供人类过去经历的生态和环境背景的重建。

To better understand future climate change and its potential impacts on British Columbia's forests, our research examines evidence deposited in lake sediments over thousands of years to study how natural variability in climate affected plant communities in the past. The main objectives of our research are: 1) to understand the development of vegetation communities on the Pacific coast of Canada since the last ice age; 2) to determine how climate has changed during that time; and, 3) to understand the role of factors other than climate (e.g., ecological differences in tree species such as shade tolerance) in how and why vegetation communities change on long-time scales. We collect cores of sediment from lakes along the coast of British Columbia and identify plant remains such as pollen and seeds that were deposited in those lakes in the past and are preserved in their sediments today. This allows us to determine how the composition of surrounding plant communities has changed since deposition of the lake sediments. We also analyze other fossils such as insect remains as well as the physical properties of the lake sediments to identify past environmental changes, including changes in climate, hydrological regimes and erosion rates. By combining data from several lakes, we can identify regional patterns in past climate change, including the rates and magnitudes of those changes, and use these to understand how forests have responded to past changes in climate. For example, previous research found that warmer and drier summers between about 7000 and 10,000 years ago changed the geographic distribution of many plant species, and that forest fires were more common than today. By understanding past environmental changes like these, we can predict and thus better prepare for the impacts of future climate change. This research has many important social and economic implications for Canadian society, ranging from providing relevant knowledge for management and conservation of our forests and other ecosystems today, to providing archaeologists and First Nations peoples with reconstructions of the ecological and environmental context that human populations experienced in the past.