Restoration of a Rocky Mountain Spruce-Fir Forest: Sixth-Year Engelmann Spruce Seedling Response With or Without Tree Shelter Removal

This paper presents results following 6 growing seasons of a project designed to examine the use of tree shelters as a means to provide initial shade for planted Engelmann spruce seedlings. Seedlings were planted in 1996 on a 48-ha (119-ac) high-elevation site with different colors of tree shelters providing various degrees of shading. A control treatment, consisting of shading using debris within the site, was also included. Results following 2 years were presented previously (Jacobs and Steinbeck 2001). To examine the response of seedlings to shelter removal following seedling establishment, 50% of shelters were removed in 2000 and all seedlings were remeasured in 2002. Shelter removal did not result in mortality, indicating that seedlings are able to grow in full sun after 4 years. Survival to 2002 of all shelter treatments (with or without shelter removal) was ≥ 88%, while survival of the control was 45%. For all 3 shelter colors, shelter removal resulted in less mean height growth but greater mean diameter growth. The lightest color tree shelter (with or without removal) produced the best overall response. Because shelters showed little sign of deterioration after 6 years, it was suggested that shelters could be removed at 4 years and reused at a different site. Tree shelters appear to provide a viable and cost-effective option to restore high-elevation spruce-fir sites where reforestation has proven difficult in the past.