Natural Features of Sphagnum Bog, Crater Lake National Park

Franklin, Jerry

The Study of Sphagnum Bog at Crater Lake National Park was designed with these objectives in mind: (a) to characterize the bog's vegetation through description of the structure and composition of the major plant communities; (b) to characterize the major physical parameters differentiating these communities; and (c) to briefly investigate the vegetation and dynamics. Characterization of the present vegetation and future monitoring of its changes can provide the basis for establishment of management guidelines concerning visitor and animal use for minimal impact. The first summer's work consisted of sampling the vegetation through the use of microplots withing homogeneous areas. Ten community types were delineated, including two tall shrub border types, willow and alder; a widespread low shrub type, western bog huckleberry; and a variety of herbaceous types, dominated by sedges, with or without a moss mat, and ranging from relatively dry to having 20 or more centimeters of standing water; plus a community restricted to the deeper, moving water of the stream channels. In the second summer's research, representative sites within the different community types were chosen for testing various physical parameters. Depth to the water table was monitored across the different communities through the use of PVC pipes sunk vertically in the peat, and a strong seasonality in water table depths was exhibited , in addition to significant differences between the communities. pH was tested, but showed only a narrow range of variation between 5.5 and 7.0 Samples of peat were collected, and are being analyzed for nutrient status. Measurements of relative elevation and slope revealed that in general the wetter communities are less sloping and lower than the immediately surrounding vegetation types. Sampling with the peat borer revealed a ubiquitous substrate of pumice gravel, and that the bog has always been non-forested. The greatest depth of peat accumulation sampled was slightly over two meters, but depths decreased.