Evaluating the role of local and landscape factors on the resilience of mixed-species forest ecosystems under climate uncertainty

点击翻译按钮获取中文摘要

In boreal and sub-boreal mixed-species forests, interactions between coniferous and deciduous trees entail competition for limiting resources, such as light, water and nutrients. However, under some conditions the presence of multiple species is hypothesized to facilitate tree growth. My research aims to improve our understanding of the conditions under which competition or facilitation will occur, and what the concomitant impacts on long-term forest dynamics, the resilience of forests to disturbances, and the provision of forest ecosystem services, such as timber production, carbon storage and biodiversity will be. In particular, I will focus on testing how interactions between species are projected to change under novel future climate conditions. My students and I will examine how forest composition and structure impacts the availability of resources essential for tree growth. By evaluating how resource availability changes within and between years, we will gain insights into where and when competition for resources will be most important, and how projected changes in climate will alter the prevalence of competition or facilitation. Tree and forest development is expected to be influenced not only by the current growth environment, but also by past environmental conditions. We will test for differences in the sensitivity of conifers and deciduous species to past environmental conditions to improve our understanding of how current growth conditions will influence the vulnerability of forests to disturbances and climate-dependent stress, such as drought. Specifically, we will test the hypothesis that under some conditions, mixed-species forest will be more resilient to environmental change and extreme weather events. The long-term dynamics of mixed-species forests are hypothesized to be driven by the interplay of landscape disturbances, environmental conditions including climate, and the developmental state of the forest at the time of disturbance. However, climate change will likely alter the relative competitive ability of species, and the prevalence and intensity of different disturbance types. Therefore, large uncertainty remains regarding how the relative importance of each of these factors, and their interactions, will change under future climate conditions. Using process-based forest models we will examine the mechanisms that drive mixed-species forest dynamics, and project how these processes will change in the future. We will also test how the timing and intensity of different forest management practices influences the dynamics of mixed-species forests at stand and landscape scales. Specifically we will evaluate if forest management can increase the resilience of forests to climate changes, and test how to most effectively trade-off short- and long-term management goals to maintain a diversity of forest ecosystem services under future climate uncertainty.