Conservation and Management Strategy
The search for suitable and unsuitable cedar habitat
Recommendations on the conservation or active management of yellow-cedar are based on current and future habitat suitability of yellow-cedar in the context of its vulnerability to climate. Partitioning of the landscape into suitable-unsuitable areas is achieved by blending yellow-cedar decline surveys, yellow-cedar habitat modeling from inventory plots, and climate and snow forecasting. In a mapping and modeling project with The Nature Conservancy we are using about 40,000 plots from eight inventories to provide a detailed distribution map of yellow-cedar. We expect to elucidate key habitat features where yellow-cedar is dying, stable, and regenerating—an approach consistent with the shifting climate envelope conceptual figure below.
Our conservation and management strategy incorporates the bioclimatic envelope concept. As the climate warms, there is a shift of suitable habitat away from the existing range of yellow-cedar. This creates zones of unsuitable habitat where the tree is dead and dying, and areas of suitable habitat where the tree already occurs, or potentially could occur. Specific management actions can then be tailored to each zone. The actual landscape partitioning model is accomplished by integrating cedar decline surveys, cedar habitat modeling and mapping, and climate and snow forecasting.
Conservation and active management in suitable habitat for cedar
Managers need to know where conservation or active management will either protect or promote yellow-cedar without losses owing to the climate-induced decline mortality problem. The landscape modeling project above will produce maps that show habitat suitable for yellow-cedar promotion. Until then, our current guidance to managers is to plant and thin for yellow-cedar at higher elevation and on better-drained soils. Snow at higher elevations buffers late-winter soil temperatures, and roots grow deeper to avoid lethal temperatures on well-drained soils. Active management through planting or thinning is often needed to ensure the initial regeneration and competitive status of yellow-cedar.
Planting projects using yellow-cedar seedlings and rooted cuttings (stecklings) with partners on the Tongass National Forest show that yellow-cedar can be successfully regenerated. Yellow-cedar has low reproductive capacity, and its ability to regenerate naturally (i.e., without planting) on harvested sites needs to be evaluated. Further, silvicultural techniques to reduce the effects of deer browse and enhance its competitive status are needed to ensure its long-term survival and productivity in managed forests. See our webpage on cedar regeneration for more information.
Management in unsuitable habitat for cedars—
Wood recovery, natural succession, and favoring other tree species
The distribution of dead cedar forests totaling more than a half-million acres is well documented and available now in GIS format. Our vegetation plots indicate the zones and related site features where dead cedar trees of commercial size can be found. We have completed a line of research on the value of wood from dead yellow-cedars. For trees dead up to 30 years, wood volume and grade recovery, and concentration of heartwood chemical compounds were all comparable to wood from live trees. Only modest reductions in these values were detected in wood from trees dead 80 years. Remarkably, all strength properties were retained, even in wood from trees dead up to 80 years.
In sum, these studies demonstrate that dead cedar forests represent an astonishingly valuable wood resource for salvage recovery. See the Wood Products webpage for more information. Shifting a portion of the timber harvest to dead cedar forests would divert some of harvest away from areas where yellow-cedar is healthy (i.e., suitable habitat). To predict the future composition and productivity in these declining forests, more knowledge is required on the vigor of remaining trees and successional trajectories after the death of yellow-cedar overstory. Such information is needed on how these forests are changing, whether or not salvage harvest activities occur.