Fact Sheet: What Are the Consequences of Cutting Old Ponderosa Pine Trees? A Systematic Review

In ponderosa pine forests, restoration treatments (including thinning and prescribed burning) are being implemented to reduce the threat of stand-replacing fire and to restore ecosystem structure, composition, and function to within the natural range of variability. In implementing treatments, old trees (>150 years) are typically retained due to their relative rarity and as-sumed ecological importance, and because old trees take centuries to replace. The oldest ponderosa pine have unique morphological and presumably functional characteristics and can exceed 700 years in age (Huckaby et al. 2003). The morphology of such trees often includes large trunks and branches, deeply furrowed bark, deformities in crown structure, epicormic branching, big mistletoe brooms, or external fire scars (Harrington and Sackett 1992; Huckaby et al. 2003; Morgan et al. 2002; Swetnam and Brown 1992), and thus they may have different functions than younger trees related to these different structures. As treatments are implemented at increasingly larger scales, a wide variety of thinning treatments, including cutting old trees, have been proposed. We used systematic review methodology to specifically address the question: What are the consequences to ecosystem function of cutting old ponderosa pine trees; particularly, do old trees serve a different function than younger trees?