Multiscale ecology and dynamics of the forest-tundra ecotone

北极和高山地区从森林到冻土带的过渡——被称为“森林-冻土带过渡带”，树木生长的上限被称为“树线”——预计将随着气候变暖的持续而显著推进，对生物多样性和地球系统过程产生严重影响。研究影响其动态的生态过程以及对过去气候变化的反应，对于改进对景观变化的预测和了解其生态后果至关重要。该项目将野外生态学与地理空间分析相结合，在多个时空尺度上研究加拿大西北部的森林苔原。未来五年的研究将努力回答两个主题问题：(1)森林苔原过去是如何对气候变化和变异作出反应的？(2)影响整个交错带树木和灌木的建立和生长的一系列物理和生物变量是什么？重要的是，它们如何相互作用以影响树线动态？调查将重点放在育空地区西南部的纬向交错带和西北地区中部的纬向交错带，并比较两种类型的过渡。方法和技术包括植物水平的生长和生理测量，种群动态和物种相互作用的社区水平调查，以及使用遥感和地理信息系统的空间格局和生态系统过程的景观尺度测量。学生的跨学科训练是研究计划的重要组成部分。资助期间将资助至少5名硕士生和2名博士生，每年至少聘请2名本科生担任现场和实验室助理。个别项目可能侧重于特定规模，并将作为学生培训的基础。该计划最新颖的科学贡献将是将这些项目以分层方式整合在一起，以阐明创建和塑造过渡带并影响其动态的跨尺度模式过程关系。

The transition from forest to tundra in arctic and alpine regions - referred to as the 'forest-tundra ecotone' and punctuated by the upper limit of tree growth, known as 'treeline' - is expected to advance significantly as climate warming continues, with serious implications for biodiversity and earth-system processes. Research on the ecological processes that influence its dynamics, as well as responses to past climate change, is critical for improving forecasts of landscape change and understanding its ecological consequences. This program integrates field ecology with geospatial analysis to study the forest-tundra of northwestern Canada at multiple spatial and temporal scales. Research over the next five years will endeavour to answer two thematic questions: (1) How has the forest-tundra responded to climatic change and variability in the past?, and (2) What are the suite of physical and biological variables that influence the establishment and growth of trees and shrubs across the ecotone and, importantly, how do they interact to influence treeline dynamics? Investigations will focus on the altitudinal ecotone of southwest Yukon and the latitudinal ecotone of central Northwest Territories with the ancillary goal of comparing the two types of transitions. Methods and techniques range from plant-level measures of growth and physiology within experimental treatments, community-level investigations of population dynamics and species interactions, and landscape-scale measures of spatial pattern and ecosystem processes using remote sensing and GIS. Interdisciplinary training of students is a significant component of the research program. At least five Master's students and two Ph.D. students will be supported during the grant period and at least two undergraduate students will be hired annually as field and lab assistants. Individual projects are likely to focus on a specific scale and will act as the foundation of student training. The most novel scientific contribution of the program will be the integration of these projects in a hierarchical fashion to elucidate the cross-scale pattern-process relationships that create and shape ecotones and influence their dynamics.