Forested riparian buffers are an integral part of the managed forest landscape. Riparian forests impact many ecological processes, both terrestrial and aquatic. Previous research has examined upland forest structure through time or compared current conditions in riparian buffers and upland forests, but the relationship between riparian forest structure and changing conditions of adjacent upslope managed forests is poorly understood. We investigated the relationship between riparian and upland managed forest structure as affected by environmental attributes and time since harvest. We examined a chronosequence of 75 sites. Each site consisted of a riparian buffer and adjacent upslope managed stand. Sites represented 8 age classes (time since harvest of the upslope stand). Tree (100 m2) and herb (1 m2) plots were established along transects located in the buffer and harvest area. Cover of tree seedlings (< 1 m tall) was collected in each herb plot. Within each tree plot, overstory tree (> 5 cm diameter at breast height) and snag data were collected, including stem density, basal area, and decay class (snags). Cover of saplings (>1 m tall and < 5 cm diameter at breast height) and coarse woody debris (CWD) volume and decay class were collected using the line-transect method. Environmental characteristics, including elevation, aspect, and slope, were collected at each of the study sites.
Results/Conclusions
Many structural characteristics changed with time as expected: structural characteristics within buffers were little influenced by time since harvest, but in adjacent harvest areas, tree seedling cover, sapling cover, and snag and overstory tree characteristics (basal area and density) increased with time since harvest. Environmental characteristics seemed to influence larger structural characteristics (CWD, trees, and snags) but not seedling or sapling structure. Our data suggest that that in a managed landscape, structural characteristics change over time as expected as trees grow in harvest areas, but in riparian buffers, environmental attributes may be more influential to forest structure than adjacent harvest activities.