Understanding the past and planning for the future: Changes in spatial dynamics and regeneration in a southwestern mixed conifer forest
Office: Bldg 82, Rm 220
Hometown: Colorado Springs, CO
Bachelor of Arts in Geography and Environmental Studies with a minor in Sustainable Development
University of Colorado, Colorado Springs
Increases in forest density due to fire exclusion, grazing, and logging have led to many large and catastrophic fires in the southwestern United States in recent years. Ecological restoration offers a potential solution to this problem. By re-creating prior form and function of an ecosystem, we may be able to improve long-term health and resiliency, reduce fire hazard and manage for a wide range of ecological and human needs. The need for restoration in frequent fire ecosystems in the West is well documented, but for restoration treatments to be properly implemented, a greater knowledge of reference conditions is necessary. Many studies have focused on past conditions within the ponderosa pine forests of northern Arizona, but relatively few have focused on spatial pattern or mixed conifer forests in the region. Ponderosa pine and mixed conifer forests differ in many ways. They have slightly different fire regimes and a very different species composition. Unfortunately, the differences between these two ecosystems in regards to historic spatial pattern are largely unknown. With upcoming restoration treatments, there is a danger of reducing landscape-scale biodiversity by managing dry mixed conifer forests based on reference conditions from ponderosa pine forests.The mixed conifer ecosystem type is prevalent in the Southwest, covering over 1,000,000 hectares. It is also quite complex, having a wide variation of tree species, moisture levels and fire histories. The variability inherent in mixed conifer forests makes study of this ecosystem, perhaps, even more important than study of ponderosa pine dominated forests. Reference conditions in these forests include disturbance regime, species composition, and structure. Overstory spatial pattern, a part of the structure of an ecosystem, can influence conditions that affect fire behavior, understory microclimate, understory vegetation, and regeneration patterns. Forest spatial patterns have become increasingly homogeneous since Euro-American settlement of the Southwest and we are interested in the severity and extent of this change.
The objective for our study is to develop a greater understanding of the spatial dynamics and reference conditions of dry mixed conifer forests in the Southwest, and to understand the impacts of future restoration treatments on species composition and regeneration patterns. Through mapping the spatial location of overstory trees, dendrochronology, regeneration surveys (of seedlings and saplings), and collection of environmental variables in the understory (such as canopy closure and soil moisture) we hope to answer the following questions:
- What are the historical spatial patterns, density, species composition and age distribution of southwestern mixed conifer forests on the Mogollon Rim, and how do they differ from contemporary patterns?
- How do the different tree species and components of spatial pattern (Groups, single trees, and openings) influence microsite conditions in the understory?
- How do these microsite conditions impact tree regeneration patterns of the different species present?
This study will develop reference conditions for future restoration treatments that can be used by land managers in the Southwest to better treat mixed conifer forests. The study will also help to develop a greater understanding of important processes involved in mixed conifer stand dynamics, such as disturbance regimes, overstory-understory interactions, and regeneration patterns