Stand Dynamics and Conservation of an Old-Growth Engelmann Spruce-Subalpine Fir Forest in Colorado

Old-growth studies normally emphasize structural characteristics, but it is also critical to understand the underlying processes that shape old-growth forests. In Colorado, the issue of old-growth forest management recently came to a head in Bowen Gulch, one of the last extensive, high-quality, old-growth spruce-fir forests in the Front Range. The area was originally slated for logging, but public pressure led to its protection. We examined the physiognomy and stand dynamics of Bowen Gulch and report the results ofthat study here. Structurally, Bowen Gulch is an exceptional old-growth forest with high densities of large, old trees, snags, and logs and complex vertical stratification. However, age data and tree-ring chronologies reveal that much of the forest is probably in a transitional phase of development. Studies of forest dynamics have demonstrated the importance of fire, spruce beetle outbreaks, and windthrow in the subalpine zone, which brings into question the feasibility of old-growth preservation. Unfortunately, policies that balance preservation with the inevitability of disturbance have been lacking. The rarity of some old-growth types necessitates that natural areas be dedicated to old growth, but prudence and forest dynamics also dictate that we should plan for renewal of old growth on a landscape basis.