Doctoral Dissertation Research: The Historic Range of Variability of Ponderosa Pine in the Northern Colorado Front Range: Past Fire Types and Fire Effects

基于生态系统的管理的发展是美国西部原生森林研究和管理的重大范式转变。这一新的科学管理模式的一个关键组成部分是认识到过去干扰过程和森林状况中的自然和人为变化。了解火灾等对气候敏感的干扰的空间范围和时间变化，作为影响森林组成和结构的生态机制，对于管理自然区至关重要。然而，在大多数生态系统中，我们缺乏对火等生态机制的行为和影响的详细研究。这项博士论文研究项目将利用火灾历史数据结合密集的树龄数据来确定过去的火灾类型和对科罗拉多州北部前缘山脉黄皮松海拔范围的火灾影响。该研究的目的是：1)确定黄松林内过去火灾行为随地形位置和海拔的变化；2)通过详细重建黄松林带内各种生境类型的林龄结构，确定过去火灾对森林更新的影响；3)将目标1和2的结果综合成黄松林带内主要生境类型的一系列火情-林分发展模型。为了描述科罗拉多前锋山脉北部山区的火灾行为和由此产生的影响，将采用多尺度抽样方法。采样和综合将在三个尺度上进行：1)对整个北部前锋范围的火情和生境类型进行广泛的地理信息系统分析；2)对30至100公顷地区的森林结构和火灾历史进行中尺度采样；以及3)在大约100至500平方米的地块中进行密集的年龄结构和火灾历史分析。在生态恢复的背景下，重要的是我们必须更好地了解火情类型(地表、林分替代或混合)的空间变异性，因为它在过去几个世纪中在黄松林和林地中发生了变化。通过多尺度重建过去的火情类型和林龄结构，本研究将产生一系列特定生境的火情和林分发育模式。这些模型可供资源管理人员在制定特定类型生境的火和植被管理目标时使用。我们知道，山地地区的火灾状况在时间和空间上都有很大的变化，但我们缺乏根据栖息地类型对过去的火灾状况进行有用的分类。对山地不同生境类型内的火灾行为进行分类，将使管理人员能够在历史变异性范围内预测适当的火灾管理处方。作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立研究生涯。

The development of ecosystem-based management is a major paradigm shift in the study and management of native forests in the western United States. A key component of this new scientific-management paradigm is the recognition of past natural and human-caused variability in disturbance processes and forest conditions. Understanding the spatial extent and temporal changes of climatically-sensitive disturbances such as fire as ecological mechanisms that have affected forest composition and structure is essential for managing natural areas. However, in most ecosystems we lack detailed studies on the behavior and effects of ecological mechanisms such as fire. This doctoral dissertation research project will utilize fire history data in combination with intensive tree age data to determine past fire types and fire effects across the elevational range of ponderosa pine in the northern Colorado Front Range. The objectives of the study are: 1) to determine variation in past fire behavior in relation to topographic position and elevation within the ponderosa pine zone; 2) to determine the effects of past fires on forest regeneration through detailed reconstruction of forest age structure over a range of habitat types within the ponderosa pine zone; 3) to synthesize the results of objectives 1 and 2 into a series of fire regime-stand development models for major habitat types within the ponderosa pine zone. In order to characterize fire behavior and the resulting effects across the montane zone in the northern Colorado Front Range, a multi-scale sampling approach will be applied. Sampling and synthesis will be conducted at three scales: 1) broad-scale GIS analysis of fire regimes and habitat types across the northern Front Range; 2) meso-scale sampling of forest structure and fire history in areas of 30 to 100 ha; and 3) intensive age structure and fire history analyses in plots of approximately 100 to 500 m2. In the context of ecological restoration, it is important that we have a better understanding of the spatial variability of fire regime type (surface, stand-replacing, or mixed) as it has changed over the past several centuries in ponderosa pine forests and woodlands. Through a multi-scale approach of reconstructing past fire regime types and forest age structure, this study will produce a series of habitat-specific models of fire-regimes and stand development for the lower through the upper montane zone. These models can be used by resource managers in formulating the goals of fire and vegetation management in particular types of habitats. We know that fire regimes have varied significantly over both time and space in the montane zone, but we lack a useful classification of past fire regimes according to habitat type. A classification of fire behavior within different habitat types of the montane zone will allow managers to project appropriate fire management prescriptions within the historic range of variability. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.