Since 1991, the PROBE (PRotocol for Operational Brushing Evaluations) project has studied the effects of operational brushing treatments on conifer seedlings and vegetation (Simard et al. 2001). It currently includes experiments on 96 sites across the southern interior of BC, and 10-year data is being collected at many of these sites. The results are providing forest managers with valuable guidance regarding a) where brushing is and is not required, b) the selection of appropriate treatments, c) expected conifer and vegetation responses, d) the effects of treatment on forest health, and e) the effects of treatment on non-timber site values. Information regarding broadleaf complexes is particularly important because of the long time period during which conifers and broadleaves interact, because of the controversy that currently exists regarding appropriate levels of broadleaves that can be retained at free-growing, and because these complexes occur in some of the most productive ecosystems in BC. PROBE sites that have already yielded 10 years of data now have the potential to provide valuable information about the long-term effects of brushing on conifer growth and yield, stand dynamics, and plant community development and diversity at relatively low cost. This can be accomplished through the installation of permanent measurement plots (PMPs) that will be assessed at approximately 5 year intervals. This project best meets the FSP strategic goal of 'improving timber growth and value', under the theme of 'tree growth and stand development'. It currently includes two components: (1) installation of PMPs on existing PROBE sites, and (2) remeasurement of high priority PROBE sites, many of which are now yielding 10-year data. The objectives for Component 1 are: 1. To study the long-term effects of brushing on growth and yield and stand development (and to provide an infrastructure for collection of this information at regular intervals). 2. To study the ongoing effects of brushing on plant community development and diversity. 3. To identify forest health problems (e.g., increases in the spread of Armillaria) that may be occurring as a result of brushing treatments. The objectives of Component 2 are: 1. To quantify the effects of operational brushing treatments on: (a) conifer seedling survival, growth, health, and free-growing status, (b) plant species abundance and (c) the structure, diversity, and condition of plant communities. 2. To identify, wherever possible, competition thresholds for conifer growth. 3. To discuss possible effects of brushing treatments on various ecosystem attributes. 4. To determine whether or not brushing treatments are meeting biological and economic management objectives. This project makes cost-effective use of the existing broad-based PROBE study, which is unique in scope and longevity. Ongoing data collection at high-priority sites is providing valuable insight into the effects of brushing treatments 5-10 years post-treatment, and the installation of PMPs is establishing the infrastructure for collection of long-term data regarding the effects of these treatments on stand development. Although stand development information will be useful for all vegetation complex/ecosystem/conifer species/treatment combinations studied by PROBE, our highest priority is to establish PMPs on sites dominated by broadleaf complexes because of the urgent need for information regarding the development of mixed stands.
Consulting, J. Heineman Forestry. 2007. Long-term effects of vegetation management treatments on growth and yield and stand development : a summary of PMP installation methods, location, and baseline statistics. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report