Introduction
Wildlife trees are very important for the biodiversity as there are over 70 species in British Columbia dependent on these natural structures. Therefore it is of highest priority to manage these trees properly to maintain the natural environmental diversity. The policy direction released in 1985 was revised and re-released in 200 as the Provincial Wildlife Tree Policy and Management Recommendations.
The Forest and Range Practices Act and Regulations states in the Forestry Planning and Practices Regulations that the aim is to protect wildlife trees without excessively limiting the timber supply.
Results and Strategies for Wildlife Tree Retention
When planning wildlife tree retention strategies it is important to know all the details about the trees and the areas beforehand. An individual Forest Stewardship Plan has to either follow the default practice requirement or give specific details about their own strategy for the wildlife tree retention.
Wildlife Tree Retention Practice Requirement
Wildlife tree retention is at a minimum of 7% of the whole area of all the cutblocks that are harvested by one license holder in one year and a minimum of 3.5% for every individual cutblock.
In some cases the percentage of wildlife tree retention can be lower, however, this has to be balanced out by a higher percentage in another area. Lower percentages can be allowed on cutblocks adjacent to protected areas which already have a sufficient number of wildlife trees and on cutblocks that contain a low amount of such high-value structures and are within a low-risk watershed. A higher percentage of wildlife tree retention is necessary when the area carries a large amount of diverse and valuable ecological attributes, on cutblocks where more than one objective has to be met and on cutblocks that are bigger than 100ha adding 1% per 100ha.
Alternative Results or Strategies for Wildlife Tree Retention
If a licensee decides to have an alternative strategy for the wildlife tree retention they need to include some factors into their plan including structure, size, location, characteristics and amount. There are likely numerous reasons for a licensee to create a new strategy or aim for new results.
Locating Wildlife Tree Retention
When locating wildlife tree retention there are three things to be considered. First, the trees with valuable wildlife tree attributes need to be protected. Second, if the area does not show many valuable characteristics of wildlife trees then the retention must be placed in a more suitable area for long-term wildlife tree recruitment. Third, if the area shows no valuable signs of wildlife tree area then the retention area needs to be located to be the representative of the pre-harvest stand. The retention is needed to maintain the stand-level biodiversity and habitat for wildlife. It also provides the environment with coarse woody debris which is important to wildlife and native mycorrhizal fungi. It also makes it easier to recolonize the area of the cutblocks again.
A less preferred but still applicable strategy would be to have a retention area around the cutblock at the distance of one-tree height. This should only be done if there are only limited options to manage habitat within the cutblock or if it would impact worker safety too much to have wildlife trees in the harvested area. The wildlife trees around the cutblock should have high wildlife tree value and be located on the post-harvest map as wildlife tree retention areas.
Selecting the Location and Type of Wildlife Tree Retention
When assessing the stand-level biodiversity attributes before harvest to identify the best retention area it is important to consider already existing areas with high-value wildlife trees or biodiversity and areas that show operational constraints but have attributes of wildlife trees of high value. Considering these two factors will decrease the impact on the timber supply.
The first type of retention is patch retention where a patch of wildlife tree retention is selected which is anchored on valuable ecological attributes like veteran trees, bear dens, bat hibernacula, wildlife use areas and resource features that need to be protected. If there are no such attributes either the largest trees need to stay or trees that are representative of the pre-harvest stand should be kept and the ecological inter-patch spacing needs to be maintained. In general, trees that show signs of developing wildlife tree attributes or trees with large branches are the ones to look for. Uncommon tree species and stand structures need to be retained as they are very important to the biodiversity. If in a harvest area there is a smaller area with wildlife tree attributes which is not operational then this area should be considered a retention zone in order to reduce impacts on the timber supply.
The next type is dispersed retention where only single trees or clumps of trees too small to be mapped are left. This strategy provides structural diversity, feeding opportunities and coarse woody debris within the cutblock. Stubbing can also be used as a strategy but is not recommended. If it has to be done then trees with an existing heart-rot are the best candidates, however, they should be trees that are greater than 30 cm diameters at breast height.
In order to have a larger biodiversity it is possible to use patch and dispersed retention if the site conditions allow it.
Attributes of High-value Wildlife Tree Retention at the Management Unit Level
To have an ecologically successful wildlife tree retention it is recommended to utilize different types of retention and create site plans that favour the conservation of ecological values.
Windthrow and Forest Health
In order to decrease windthrow design, selection and layout of the retention areas are very important, however, windthrow cannot be stopped completely as it is a natural occurrence and for example creates coarse woody debris.
When planning a retention area it is also important to consider forest health and leave patches with multiple tree species to prevent too much damage from insects or diseases.
Future Coarse Woody Debris
Coarse woody debris is a very important structure for wildlife habitat. It is very helpful to leave the debris on the ground in cutblock areas unless it poses a threat to the safety of the workers or to the health of the forest.
Worker Safety
In order to ensure safe working conditions an assessment of dangerous trees has to be conducted. The level of assessment can vary according to the intensity of work that will be done in the area. If there are dangerous trees there should be a no-work zone around them, they should be assessed again by a qualified assessor or they should be removed if possible.
Time Frame for Wildlife Tree Retention
The retention area will stay unharvested until the other trees in the cutblock have grown mature seral attributes. After the area will be re-assessed to determine if the same areas will stay retention areas or if a better area has been created and a re-location of the retention area could be considered.
Tracking and Monitoring Wildlife Tree Retention
All license holders have to monitor their own wildlife tree retention areas. This will include the determining of the percentages of wildlife tree retention areas and cutblock area left on each cutblock, the sum of all retention areas or the harvested area and the ecological attributes.
Conclusion
Wildlife trees are important structures for over 70 vertebrate wildlife species. Forest Stewardship Plans need to be created to ensure the protection of wildlife tree structures and maintain the timber supply at a sufficient amount. In each cutblock the percentage of wildlife tree retention areas should be at least 3.5% ,and 7% regarding the total area of all cutblocks.
The retention areas serve as a protection for wildlife trees and other valuable ecological structures. These retention areas are located within or adjacent to cutblocks. For patch retention it is helpful to have the patches around anchors that are ecologically valuable. In general, leaving rare or uncommon tree species or other structures is of utmost importance to the biodiversity. There are different retention strategies and not all of them can be implemented for all the harvesting sites, so proper assessment is important and utilizing multiple strategies will also increase the biodiversity. Other factors to consider are windthrow and forest health. If coarse woody debris is on site it is recommended to leave it if possible as it serves as important habitat for wildlife. Proper assessment of dangerous trees will ensure safe working conditions and the wildlife tree retention areas are maintained until the new cutblock trees have mature seral attributes.
About wildlife tree retention in:
- Evergreen Stewardship Plan for Lillooet Sub Region
- Evergreen Stewardship Plan for South Chilcotin Sub Region
- Source Wildlife Tree Retention: Management Guidance. May 2006. Available at : https://www2.gov.bc.ca/assets/gov/environment/plants-animals-and-ecosystems/conservation-habitat-management/wildlife-conservation/wildlife-tree-committee/wt-guidance-05-2006.pdf [Accessed 03/2021].