Restoration of plant communities to red-burned soils

Fire, natural or anthropogenic, is a common occurrence in the open forests and grasslands of Western North America. The effects of fire on soil and vegetation depend largely on the soil temperatures and the residence time of the burn. Generally, the more severe the fire, the more significant the changes are to soil and vegetation. The relationship between the most severe fires, or where the soil has been oxidized to a red colour, and invasive species is unknown. Resource availability may increase on these soils, leading to favourable conditions for invasive species, or the disturbance may be so severe that nothing is able to grow indefinitely. I performed two studies to investigate the relationship between invasive species and red-burned soil. To reduce the threat of interface fires near Kamloops, BC, excess timber was harvested, piled and burned on site (pile burning), created multiple burn scars denuded of vegetation and large areas of red soil. In the first study, I investigated soil nutrient flux differences between red-burned and unburned soil using ion-exchange resin technology. I also investigated three restoration methods to control invasive species: the addition of agronomic or native seed, the addition of arbuscular mycorrhizal fungi (AMF) inoculum, and the addition of soil cover. Non-native species cover was high on red soil 2 years post-burn, which may be linked to measured increased nutrients. Only the addition of agronomic seed was successful at suppressing non-native species cover. The second study compared the growth of native, agronomic and invasive species on unburned and red-burned soil in a greenhouse study. Soil was collected in the field and transferred to a greenhouse. Treatments were soil burning, AMF, and watering. Burning increased aboveground biomass for the native species. AMF addition increased invasive species aboveground biomass for the invasive species, but decreased biomass for agronomic and native species. Watering increased aboveground biomass for the agronomic and invasive species. The findings here suggest that pile burning creates areas that are susceptible to colonization of non-native species. Restoration efforts should be directed at these sites as soon as possible to ameliorate the effects of invasive species colonization.Science, Faculty ofBotany, Department ofGraduat