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

以生态系统为基础的管理的发展是美国西部原生森林研究和管理的主要范式转变。这种新的科学管理范式的一个关键组成部分是认识到过去干扰过程和森林条件中自然和人为引起的变异性。了解影响森林组成和结构的气候敏感干扰（如火灾）的空间范围和时间变化，作为生态机制，对自然区域的管理至关重要。然而，在大多数生态系统中，我们缺乏对火灾等生态机制的行为和影响的详细研究。这个博士论文研究项目将利用火灾历史数据，结合密集的树木年龄数据，来确定过去的火灾类型和火灾对科罗拉多北部前山脉黄松海拔范围的影响。研究的目的是：1)确定黄松带内过去火灾行为的变化与地形位置和海拔的关系；2)通过详细重建黄松带不同生境类型的森林年龄结构，确定过去火灾对森林更新的影响；3)综合目标1和目标2的结果，构建黄松带主要生境类型的林分发展模型。为了描述火灾行为及其对北科罗拉多前山脉山区的影响，将采用多尺度采样方法。采样和综合将在三个尺度上进行：1)对北部前线山脉的火灾状况和栖息地类型进行大尺度GIS分析；2) 30 ~ 100 ha区域森林结构和火灾历史的中尺度采样；3)在约100 ~ 500平方米的地块上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，我们有必要更好地了解过去几个世纪以来黄松林和林地火灾类型（地表、林分或混合）的空间变异性。本研究将通过对过去火种类型和森林年龄结构的多尺度重建，建立一系列基于生境特征的上、下山地火种和林分发展模型。这些模型可供资源管理人员在制订特定类型生境的火灾和植被管理目标时使用。我们知道，山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。对山区不同生境类型的火灾行为进行分类，将使管理人员能够在历史变化范围内制定适当的火灾管理方案。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.