Biophysical diversity on landslides in the Peace River region of British Columbia

The aim of this dissertation is to investigate and quantify biophysical diversity on landslides in the boreal forest of the Peace River Region of northern British Columbia (BC), sampling three landslides that occurred in the last 50 years. Landslides are increasing in the boreal forest, likely driven by climate changes such as increased precipitation and permafrost thaw, and as a derivative of large wildfires. An understanding of ecosystem recovery on landslides is important for conservation and management purposes. Several studies have been done in southern parts of the world to elucidate processes of landslide recovery. However, few studies have addressed landslide recovery in northern climates, and little is known about the biophysical diversity of landslides in this region. This research investigates whether landslides are more biophysically diverse than the surrounding relatively undisturbed terrain, and whether microsite variables or geomorphic diversity are predictors of plant community diversity. Using a series of field sampling campaigns and GIS (geographic information system) mapping exercises, I show that landslides are more biophysically diverse than the surrounding terrain in some respects, while the surrounding undisturbed terrain is more diverse in other aspects. The age and size of landslides also appear to influence diversity. Microsite diversity does not necessarily predict plant diversity. The research highlights the role of invasive plant species in slope stabilisation and plant community makeup. I also show that landslide ponds are disproportionately concentrated on rotational landslides, and that most ponds on landslides occur in the body and toe. I note post-slide modifications such as drainage of landslide ponds and lowering of landslide ridges, but many geomorphic features are expected to endure for decades to millennia. Overall, the research shows that vegetation recovery is complex and may take decades to fully manifest. This study contributes knowledge about plant community and site diversity on landslides by providing quantitative data and comparing those traits with those found on surrounding terrain. These findings can be used as guidance when identifying conservation and management practices for ecological restoration of disturbed slopes.