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

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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.