The role of distrubance in catalyzing ecological change in boreal forests

全球气候正在发生变化。与此同时，人类正在极大地改变陆地表面覆盖的模式，改变干扰制度，并引入新物种。气候变化和人类活动的综合影响意味着，大多数生态系统已经进入了一个环境条件快速定向变化的时期，这在历史上是没有类似的。我们应该期待生态系统如何应对这种快速变化？北方森林是地球上第三大陆地生物群落，占加拿大森林面积的90%。这些森林可能特别容易受到气候变化的影响，因为北方的许多物理过程和生物对温度很敏感，而气候变化预计在高纬度地区首先和最快发生。气候变化还可能刺激森林火灾和虫害爆发范围的增加，再加上人类活动，可能导致森林受到更大程度的干扰。扰动的变化将如何与持续的气候变化相互作用，从而驱动加拿大北方森林的未来变化？这个问题是拟议研究的重点，该研究利用实地观察和实验来检查当地气候和干扰对北方森林植被的影响。育空地区的研究范围将从干旱胁迫对干旱北方森林火灾后森林再生的影响的实验，到检查干扰对北部林木线入侵物种开辟通道的作用。本文研究了气候变化与干扰之间的三种相互作用及其对北方森林生态系统的潜在影响：a)干扰对植物物种迁移模式的调节作用；b)干扰类型和严重程度变化对森林恢复的影响；c)气候变暖对森林更新的直接影响。对这些主题的研究将提供关于干扰如何作为北方森林对未来气候变化反应的催化剂的新信息。

The global climate is changing. At the same time, humans are dramatically altering patterns of land surface cover, changing disturbance regimes, and introducing new species. Combined effects of climate change and human activities mean that most ecosystems have entered a period of rapid directional change in environmental conditions that has no historical analogue. How should we expect ecological systems to respond to this rapid change?     Boreal forests are the earth's third largest terrestrial biome and comprise about 90% of Canada's forest land cover. These forests may be particularly vulnerable to climate change, as many physical processes and organisms in the North are sensitive to temperature, and climate changes are predicted to occur first and fastest at high latitudes. Climate change is also likely to stimulate increases in the extent of forest fires and insect outbreaks, which combined with human activities, could lead to much greater rates of forest disturbance. How will changes in disturbance interact with ongoing climate change to drive future changes in Canada's boreal forests?     This question is the focus of the proposed research, which uses field observations and experiments to examine the effects of local climate and disturbance on vegetation in the boreal forest. Research in Yukon Territory will range from experiments on the effects of drought-stress on forest regeneration after fire in dry boreal forests, to examining the role of disturbance in opening avenues for invading species at the northern treeline. The research addresses three types of interactions between climate change and disturbance and their potential effects on boreal forest ecosystems: a) the role of disturbance in regulating patterns of plant species migration, b) impacts of changes in disturbance type and severity on forest recovery, and c) direct effects of climate warming on forest regeneration. Studies on these themes will provide new information on how disturbance may act as a catalyst of boreal forest responses to future climate change.