Changing requirements for land reclamation in Alberta has led to the need for revegetation of disturbed lands with native woody and herbaceous species. Our study involves “Hitchhiker Planting” which is similar to companion cropping in agriculture, with the goal of improving native forb establishment on reclamation sites through mixed-species plugs. We grew white spruce (Picea glauca) in plugs with either fireweed (Chamerion angustifolium) or showy aster (Eurybia conspicua). We evaluated the success of this approach with reference to other landscape-level disturbance types (wildfires and forest harvesting). The initial objective of this study was to determine if we could produce a mixed-species container stock that is comparable or better than single species stock in terms of spruce development without negatively effecting forb development. The secondary objectives were to study if the presence of a forb had an effect on vegetation dynamics aboveground, or microbial function belowground. We collected standard vegetation measurements aboveground (% cover, species richness, biomass), as well as root egression belowground (distribution, biomass). We also collected data for plant available nutrients, soil temperature, soil moisture and soil microbial characteristics (biomass carbon and nitrogen, respiration, and community level physiological profiles (CLPP)).
Results/Conclusions
After two growing seasons, this study clearly showed that it is possible to successfully co-establish native forbs with white spruce seedlings. Where site conditions are good (adequate soil and site preparation, low initial vegetation competition during year of establishment), both species of forb (fireweed and aster) demonstrated excellent growth and survival with fireweed spreading substantially beyond the point of planting. This has allowed us to determine idealized stocktypes based on forb, plug volume, and sow delay for different site conditions. Initial analysis of rhizosphere soils indicates that hitch hiker planting increased the similarity of belowground function to sites recovering from harvesting and wildfire.