Integrated Vegetation Management: Is it Right for You?
by Dusty Cooper

Vegetation Management (VM) controls vegetation where it is undesirable or where it has become competitive or detrimental to desirable plant species or may even pose a safety or health risk. Many individuals relate VM to the forest and in particular the silviculture industry. However, VM is widely used throughout Canada in many different industries including rail, hydro, oil and gas, transportation, transmission, and many others.
VM took on a new look in the early 1990s when the BC Ministry of Environment helped define the purpose of Integrated Vegetation Management (IVM) throughout BC to control vegetation growth using a more systematic approach. Now the industry in BC is working under the Integrated Pest Management Act & Regulation that was introduced in 2005. The Act provides the statutory authority to use Integrated Pest Management Plans (PMPs) as an authorization vehicle for pesticide use on crown and some types of private land. 
IVM is the selection of treatment options that involve a decision making process based on integrated vegetation management concepts, which include several factors. This process should include an evaluation of the site, an examination of the need for IVM as well as what type of treatment that may be necessary i.e. herbicide/mechanical, choosing an approved method available for the control you are trying to achieve, what is required to meet your objectives, the potential for any negative impact on the environment or human health and safety, monitoring, post evaluation, and the economics of the IVM treatment. Safety is without a question one of the biggest concerns when developing a vegetation control program. You will have to decide what safety measures are adequate for your program. Some data has shown that there is an increased risk to workers using chain saws vs herbicides, while other data may support the opposite. 
IVM requires you to do your research to find the best method of controlling vegetation, considering what is most economical, what provides the best efficacy, and what is safest for your workers and the environment.
A PMP involves strategies to develop an integrated vegetation management program, which may include mechanical, manual, biological, cultural, and herbicide control measures. Mechanical methods include excavators, brush saws, mowers, and chain saws. Manual methods include hand weeding, girdling, and manual cutting. Biological methods usually refer to biological agents (bugs) used for the control of invasive alien plants (noxious weeds). Cultural control methods include burning or sheep grazing to control undesirable vegetation. Herbicides are used in many different techniques such as basal bark, cut stump, cone, and hack and squirt, and can be applied using backpacks, truck mounted sprayers, or airplanes, depending on whether you require a selective, spot, or broadcast treatment. 
In the forest industry VM or IVM is generally used for 2 different reasons. Research shows that intense, unmanaged vegetation competition elevates seedling mortality to much higher levels, and this can have serious implications on planted stands. Research also shows that without some form of vegetation control of competitive species, sustainable harvest can be reduced on most planted stands. When undesirable, competitive vegetation is a problem, it will influence conifer seedling growth by different factors such as low light, soil moisture, and air and soil temperatures. Vegetation managers recognize that it is very important to protect plant species’ diversity to maintain healthy ecosystems and forest productivity while controlling competitive species.
Vegetation cover may benefit or interfere with the growth and development of a crop species. Benefits may be thermal cover, protection of soil from erosion, and retention and accumulation of nutrients. Detrimental effects include competition for light, water, and nutrients, along with physical, chemical, and environmental interferences.
Treatment thresholds are developed and implemented to determine whether a treatment is required or not. All brush, broadleaf tree, and non-broadleaf tree vegetation including herbaceous/low shrub and tall/woody shrub species, which are found within the 1 m radius effective growing space of a crop tree, must be considered when assessing levels of competition. This includes competing vegetation originating inside and outside of the 1 m radius cylinder. To be declared free growing, trees must also be free from damage or infection from insects, disease, mammals, or abiotic agents as outlined in the free growing damage criteria for BC.
A treatment may be implemented when one or more of the following are present and are negatively affecting the crop trees:
Snow press - Crop tree damage or mortality is evident due to snow press.
Shading - The competing vegetation complex shades the crop trees to a degree where the crop trees vigorous growth and development is suppressed, or is likely to be suppressed, resulting in poor growth or possible mortality.
Soil temperature - The competing vegetation complex is such that the soil temperature is reduced or is likely to be reduced, thereby suppressing the growth level to poor or possibly causing mortality.
Nutrients - The competing vegetation complex is such that the nutrient level required by crop trees for vigorous or normal development and growth is suppressed, or likely to be suppressed, resulting in poor growth or possible mortality.
Moisture - The competing vegetation complex is such that competition for limited moisture represses the crop trees, reducing or likely reducing vigorous or normal development, and possibly causing mortality.
Allelopathy - The competing vegetation complex releases chemicals, which interfere with vigorous or normal crop tree development and growth, resulting in poor growth or possible mortality.
Free Growing - The free growing criteria as established in operational plans cannot be met.

Cost comparisons have shown that when controlling vegetation on planted blocks in the forestry sector, there is generally a substantial cost reduction for herbicidal over mechanical or manual treatments. For example, in BC, the average backpack herbicidal treatment may cost $400.00 per ha to treat a planted block, and only one treatment is required to meet free to grow, while the average cost of a mechanical treatment could be approximately $800.00 per ha and multiple treatments are required before establishing free to grow. 
Invasive plant species are a major problem in BC. Timber is the primary product of our forests, however range management is also important. The ranching industry relies on crown forage for grazing livestock, even though many foresters believe that cattle grazing poses a problem for some silviculture plantations. Grazing cattle on crown land is considered a non-timber forest product and faces just as many threats as the timber industry. Invasive weeds are a very large threat to the ranching industry on crown land as well as on private land, so IVM is being used to help contain the spread of these alien plant species. 
The BC Weed Control Act specifies that land occupiers must control noxious weeds on private or public land. Noxious weeds impact agriculture where they displace or reduce the quality of crop and forage species and natural environments where they take over native plant species, thereby reducing biodiversity and forage for wildlife.
If invasive (noxious) weeds are not contained and are allowed to spread, the province stands to lose good productive land and forage for wildlife as well as experience degradation of riparian areas, which will be a huge potential economic loss. The spread of invasive plant species is the second most significant threat to biodiversity after urban development, and in some cases if the site is heavily infested it may never be restored to its natural habitat. 
The Fraser Basin Council has shown that knapweed in Glacier National Park has reduced elk winter forage by 50-90%. Large infestations of knapweed have also resulted in the loss of water quality and fish habitat. Native grasses, wildflowers, and endangered species are being destroyed throughout BC by alien invasive weeds such as dalmatian toadflax, oxeye daisy, rush skeleton weed, purple loosestrife, orange hawkweed, hoary alyssum, and several others. 
These alien, invasive weeds are brought into BC and Canada primarily from foreign countries where the indigenous plant species have predators that keep the plants in check. However, those predators are not naturally present here in Canada and the invasive plants must be contained with other measures. One of these measures is bio-control, where biological agents are released in the infested areas and the bugs eat the plant or root. Several biological agents such as L. minutus and S. jugoslavica are currently being used on knapweed, while other agents are being distributed in trials on new, invasive plant species and the results are being monitored at this time. Early indication shows promising results with bio-control for some invasive plant species.
Whether to control invasives or undesirable native competition, the systematic rigor required by IVM has improved both the efficacy, cost, and public acceptance of vegetation management for all users.
For more information on IVM, go to www.ivma.com

Dusty Cooper is current president of the Integrated Vegetation Management Association of BC and is President and General Manager of DJ Silviculture Enterprises Ltd.