Grant: CCI Applied Research and Development Grants

In Alberta, herbicides (and manual removal to a lesser extent) are the conventional methods for controlling or eliminating noxious weeds on reclaimed industrial sites. However, this approach may be counterproductive to re-establishing forest vegetation, as overspray on non-target native forest vegetation may impede the recovery of desirable species. Currently, limited data support alternative methods for noxious weed management. It is also unclear if this practice is truly achieving, and sustaining, the intended objective of removing undesirable plant species to allow desirable plant development. Retrospective data in Alberta supports the assertion that noxious weeds tend to decrease over time; however, these analyses are complicated by a lack of early site intervention data. While it may seem implicit that most weedy species will diminish as the forest canopy develops, there is a scarcity of long-term datasets to further substantiate the existing retrospective analyses. This project aims to overcome these knowledge gaps via two corresponding objectives. Objective 1 will evaluate the effectiveness of herbicide application as a long-term control of weeds in recently reclaimed well pads in Alberta. Objective 2 will evaluate the success of planting tree density as a long-term method of noxious weed control. We propose a long-term, large-scale experiment, where 80 study sites in northern Alberta across different ecological subregions within the Boreal Forest will randomly receive one of two treatments, herbicide application and control (i.e. no herbicide application). Within a subset of sites, 16 sites will be planted with a higher-than-usual density (4,000 stems ha-1) of broadleaf tree/shrub species to speed the pace of forest canopy closure. While the present proposal encompasses a 3-year timeframe, allowing for the setup and short-term data collection of vegetation dynamics, we anticipate continued measurement in the longer term as forest growth and plant community succession are long-term endeavours. This project offers significant environmental and social benefits by addressing the efficacy of herbicide application and planting tree density in managing weed populations on reclaimed well pads in Alberta.