Fire regimes in mountain landscapes and global environmental change: top-down versus bottom-up controls

虽然火是驱动植被动态和本地物种的进化的一个中心过程，在加拿大西部的山林火制度的空间和时间变化仍然知之甚少。火灾状况受到气候、燃料和人类的强烈影响。气候被认为是火灾状况的"自上而下"驱动因素，在广泛的空间尺度和从几天到几年到几十年的时间尺度上影响有利于火灾的条件。燃料的可用性和可燃性是一种"自下而上"的火灾控制，并受到当地地形的强烈影响，如坡度和海拔。此外，在许多干旱森林类型中，由于土地使用的变化以及随后的灭火而导致的防火，燃料已经积累。自上而下和自下而上控制火灾的相对重要性因地理和森林类型而异，但我们需要进一步了解具体机制、相互作用和人类影响。我的长期科学目标是建立预测模型，量化山林中不同火灾制度的特征（频率，严重程度，范围），并区分气候，燃料和人类土地使用对这些制度的相对重要性。在短期内，我和我的研究生将使用树木生态学（树轮）重建来调查落基山脉南部海沟（SRMT）山地（1100 - 1600 masl）和亚高山（> 1600 masl）森林在多个空间和时间尺度上的火灾历史变化。 我们的实地研究的目标是：（1）区分自下而上的燃料与自上而下的气候控制对历史火灾频率/严重性的相互影响，（2）确定人类土地利用（LU）对这些控制的影响。更好地了解火灾机制和控制，将使我们能够预测未来的火灾制度的影响下，全球气候变化，确定部分景观显着改变过去的土地利用和需要生态恢复，并建立生态恢复和燃料缓解的优先事项和目标库特奈国家公园。

Although fire is a central process driving vegetation dynamics and the evolution of native species, the spatial and temporal variation in fire regimes of mountain forests in western Canada remains poorly understood. Fire regimes are strongly influenced by climate, fuels and humans. Climate is considered a "top-down" driver of fire regimes, influencing conditions conducive to fire at broad spatial scales and at a range of time scales from days to years to decades. Fuel availability and combustibility is a "bottom-up" control of fire and is strongly influenced by local topography such as slope aspect and elevation. Moreover, in many dry forest types, fuels have accumulated due to fire exclusion resulting from land use changes followed by fire suppression. The relative importance of top-down and bottom-up controls on fire varies geographically and by forest type, but we need further understanding of specific mechanisms, interactions and human impacts. My long-term scientific objective is to build predictive models that quantify the characteristics (frequency, severity, extent) of different fire regimes in mountain forests and distinguishes the relative importance of climate, fuels and human land use on those regimes. In the short-term, my graduate students and I will use dendroecological (tree-ring) reconstructions to investigate variation in fire history at multiple spatial and temporal scales in montane (1100-1600masl) and subalpine (>1600 masl) forests of the southern Rocky Mountain Trench (SRMT).  The objectives of our field-based research are: (1) differentiate the interacting impacts of bottom-up fuels versus top-down climate controls on historic fire frequency/severity and (2) determine the impacts of human land use (LU) on these controls. Improved understanding of the mechanisms and controls of fire regimes will allow us to predict of future fire regimes under the influence of global climate change, identify segments of the landscape significantly altered by past land use and requiring ecological restoration, and establishment of priorities and targets for ecological restoration and fuels mitigation in Kootenay National Park.