Carbon Storage in Old-Growth Western Larch (Larix occidentalis) Forests of Western Montana

Abstract

Over the last 30 years, the structural development of western old-growth ecosystems has been of great interest in ecological research. As the loss of historical forested acreage in western Montana became more widely recognized, the preservation of frequent-fire old-growth stands became a focus of forest management. And, although old-growth studies are commonly found in the literature, few studies focus on long-term carbon (C) storage associated with interior old-growth. This limited understanding of the C storage capacity and patterns in old-growth forests of western Montana leaves little ability to evaluate the role of old-growth forests in ecosystem level C storage capacity. Further, there is a disconnect between old-growth definitions and old-growth management. Forest Service definitions for interior old-growth ecosystems inadequately describe the structure, composition, and function of these ecosystems, and definitions applied from the Pacific Northwest do not capture the unique qualities of old-growth of the Northern Rockies. In this thesis, I first present a review of existing literature on definitions and characteristics of old-growth ecosystems of the Pacific Northwest and contrast these with old-growth forests of the Northern Rockies. In the second chapter, I present studies undertaken to generate empiric data on C storage in old-growth forests of this region. Specifically, studies were conducted to compare ecosystem C of old-growth western larch (Larix occidentalis) stands to that of paired 30-40 year old second growth stands in western Montana. Old-growth forests were found to store nearly three times more C than second growth forests, with most of the difference coming from C stored in the overstory. Finally, the third chapter describes a web-based plant guide that simplifies the challenge of plant identification by eliminating the use of technical vocabulary, focusing instead on visually recognizable plant characters and providing students with a more user-friendly means of identifying specimens and obtaining species-specific information