The Structure of Mixed Species Stands of the Moist, Warm Subzones of the Interior Cedar-Hemlock Biogeoclimatic Zone
A wide variety of stand structure types can be found in the forest stands of the Interior Cedar-Hemlock biogeoclimatic zone (ICH). The ICH is home to 14 tree species, which can grow together in many different combinations. Disturbance agents, such as fire, insects, diseases and wind, contribute to the variation in stand structure at stand initiation and throughout stand development.
In the moist, warm subzones (ICHmw2 and ICHmw3), most stands have regenerated as single-cohort, mixed-species stands following large, stand-replacement fires. Remnant survivors, particularly western redcedar, are common. The numbers and proportions of the constituent species are highly variable, even for stands initiated by the same disturbance. Interspecific differences in height-growth rate and shade tolerance promote stratification of the species into layers. The tree species also vary in their susceptibility to the native root diseases Armillaria ostoyae and Phellinus weirii.
The complexity of stand structure types is depicted here in a series of images of sample stands from within the ICHmw2 and ICHmw3 subzones in the Kamloops Forest Region. All the stands were between 40 and 60 years old when sampled. The stand structure images are 2-dimensional projections of actual stem-mapped plots. A scale rule is incorporated into each image. The tree locations, height and crown depth are based on field measurements of each tree. The horizontal distances between trees have been expanded by a factor of two for easier viewing. Crown profiles are based on measured profiles of selected trees. Each species has been assigned a different colour and branching pattern, as shown in the Species Image Key. While the simulated crowns convey some of the crown characteristics of the various species, they do not faithfully duplicate the real branching patterns of trees. Dead trees have been drawn simply as stems without crowns.
The images are indexed by geographic area and stand structure type. The four geographical areas are different drainage systems in the Kamloops Forest Region. Stand structure types correspond to different combinations of tree species.