Calculating for wildlife tree patch areas
A fundamental premise for maintaining biological diversity is to implement strategies at both the landscape and stand scales. There is a linkage between
There are two tables that are used to calculate the percentage required as wildlife tree patches.
Table 1-A — When landscape units are designated and landscape level biodiversity objectives are established, then the requirement for maintaining biodiversity in individual stands can be reduced and the appropriate retention levels determined from Table 1-A.
Table 1-B — When no landscape unit biodiversity objectives is established, then appropriate retention levels are determined from Table 1-B.
The use of Table 1-A is a one-time calculation (within a harvest rotation length) for each biogeoclimatic subzone within the landscape unit unless the landscape unit objectives change, a new landscape unit is designated, or operability limits change (changing the area available for harvest).
A separate objective is made for each subzone within the landscape unit.
Explanation for tables
Columns: The proportion of the subzone within the landscape unit (or forest development plan) that is identified as available for harvest. The Y-axis.
Rows: The proportion of the available landscape (by subzone) that has already been harvested without application of the Landscape Unit Planning Guidebook (LUPG) and/or Provincial Wildlife Tree Policy and Management recommendations or similar prescriptions. The X-axis.
For each biogeoclimatic subzone in the landscape unit (Table 1-A), calculate the area available for harvest (the X-axis).
An example using Table 1-A
For example:
If 30% of the SBSmc subzone area* is available for harvest, then, using the 30% column, the recommended minimum proportion of each cutblock to be managed for wildlife trees is between 1 and 9%.
* SBSmc subzone area — Sub Boreal Spruce (moist continental)
If 50% of the available area in the subzone were already harvested without application of these or similar guidelines (Y-axis), then 5% of each new cutblock would need to be left for wildlife tree patches.
Where landscape units have not been designated, the same calculation can be done using Table 1-B.
No-work zones (NWZ)
The purpose of a no-work zone is to protect workers from tree hazards in situations where the danger tree or parts thereof have not been removed. NWZs are generally 1.5 times the height of the danger tree length. This length can be modified (larger or smaller) depending on site-specific conditions.
When the decision has been made to retain a valuable wildlife tree that has been assessed as dangerous to workers, a no-work zone must be clearly identified and marked on site. The no-work zone must include all the area on the ground that could be reached by any dislodged portion of the tree.
No-work zones will take into account the nature of the hazard and the lean of the tree. On steep ground, the no-work zone will be extended downhill to protect workers. No-work zones can be adjusted in size depending on the size of surrounding live timber (e.g., a small tree surrounded by much larger trees that shield the adjacent area have a NWZ radius less than 1.5 defect lengths. A kickback area should be included for semicircular no-work zones. The size and shape of this area is determined by tree lean, condition, and form (branching).
See the Wildlife/Danger Tree Assessor's Course (No-Work Zones (NWZ)) for detailed information.
Wildlife tree committee
The Wildlife Tree Committee (WTC) is a multi-agency committee composed of representatives from the government ministries as well as the BC Workers' Compensation Board, industry and labour, and public interest groups from across the province. Formed in 1985, the WTC is the advisory body acting on behalf of the three signatory agencies and representing all wildlife matters in British Columbia.
The Wildlife Tree Committee mandate is:
To promote the conservation of wildlife trees and associated stand-level biodiversity in a safe and operationally efficient manner, in forest, park, and urban environments.
Two major objectives of the WTC are:
The WTC believes that managed forests, high standards of worker safety, and maintenance of valuable habitat for wildlife tree-dependent species are mutually compatible if cooperative action is taken to integrate these goals.
Stand level components - conclusion
Recall
There are two parts to recall — modifying the mind map and answering the set of questions some which are listed at the beginning of the module. Begin by returning to the mind map that you started at the beginning of this module and using a different colored pen add what you have learned during this module. This may mean that you add facts or ideas, modify some, or correct others. This is an important step in your learning process. You need to recognize what you learned, what you have modified, and what you had to correct because of misinformation.
If you completed the three application assignments (or fewer), answer these questions:
How successful were you in assessing an old growth forest using the stand level components tools?
Transfer of learning
Reflections