Turning up the heat in a northern hardwood: Response of soils and trees to summer and winter climate change

气候变化正威胁着森林提供各种服务的能力，除其他外，气候变化造成了更温和的冬季和土壤中冻融循环的增加，以及更干燥和更温暖的夏季，给植物造成水分压力。加拿大致力于维护森林，使其能够抵御当前和即将发生的全球变化。为了预测森林对气候变化的反应，科学家们最近认识到，不仅需要根据区域气候，而且还需要根据树种之间、树木与土壤之间的相互作用以及可能的反馈来建立模型。这项研究计划的长期目标是在不断变化的气候条件下，加拿大东部温带落叶林的土壤-植物相互关系和养分循环的特点。在接下来的5年里，该研究计划将继续加强森林对气候变化响应的预测框架，通过运行新的操纵性实地实验来评估生长季节土壤变暖和冬季积雪减少如何影响温带落叶林北方界限的土壤碳动态。为此，将在各种处理下测量土壤有机碳水平、形式和稳定性、来自土壤微生物生物量的有机碳、土壤呼吸、落叶分解率、细根生物量生产和微生物群落以及溶解有机碳浸出率的变化，这些处理包括仅生长季节土壤升温、仅冬季除雪、两者结合和参考（对照）地块。还将评估使用离子交换树脂和传统土壤化学提取方法获得的土壤养分以及种子发芽率、幼苗存活率、生长、用水、叶片营养和根菌根真菌协会。这些实验是不匹配的其他地方，由于网站的位置，复制的地块，事实上，生长季节和冬季气候变化的实验测试和树木和土壤之间的相互作用在招聘和少年生长阶段进行了调查实验气候变化领域。因此，这项研究计划是一项非常独特和重要的研究：（1）衡量和估计森林的现状和未来动态，（2）改进森林对气候变化反应的模拟模型，从而确定适应气候变化的最佳可能战略，以及（3）培训HQP，以进一步了解气候变化下的森林功能，并将这一知识传授给参与森林管理的公共和私营森林部门;管理决策。

Climate change is threatening the capacity of forests to provide its various services by causing, among other events, milder winters and increased freeze-thaw cycling in the soil and drier and warmer summers that create water stress for plants. Canada is committed to maintaining forests that are resilient to current and imminent global change. To forecast forest response to climate change, scientists have recently recognized the need to develop models not just based on regional climates, but also based on the reorganization of interactions between tree species and between trees and soils as well as possible feedbacks. The long-term objective of this research program is to characterize soil-plant interrelationships and nutrient cycling in eastern Canadian temperate deciduous forests under a changing climate. In the next 5 years, the research program will continue to strengthen the predictive framework of the response of forests to climate change by running novel manipulative field experiments to assess how soil warming during the growing season and decreased snow cover during winter affect soil carbon dynamics at the northern limit of temperate deciduous forests. To do so, changes in soil organic carbon levels, forms and stability, organic carbon from soil microbial biomass, soil respiration, leaf litter decomposition rates, fine root biomass production and microbial communities and dissolved organic carbon leaching rates will be measured under various treatments which include growing season soil warming only, winter snow removal only, a combination of both and reference (control) plots. Soil nutrient availability using ion-exchange resins and conventional soil chemical extraction methods as well as seed germination rates, seedling survival, growth, water use, foliar nutrition and root mycorrhizal fungi associations will also be assessed. These experiments are not matched elsewhere due to site location, number of replicated plots, the fact that both growing season and winter climate change are experimentally tested and that interactions between trees and soils at recruitment and juvenile growth stages are investigated under experimental climate change in the field. This research program is thus a very unique and essential piece of research for: (1) measuring present and estimating future states and dynamics of forests, (2) improving simulation models of forest response to climate change and thus pin-pointing the best possible adaptation strategies to climate change, and (3) training HQPs to gain further understanding of forest functioning under a changing climate and transfer this knowledge to the public and private forest sectors involved in forest management decision-making.