Module 3 — Stand level components
of biodiversity
British Columbia
Ministry of Forests
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 Module 3G — Related topics In this part Related topics include:

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

• How much retention of stand structure is required at the stand scale;

• How much should be retained at the landscape scale

There are two tables that are used to calculate the percentage required as wildlife tree patches.

1. 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.

2. 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 of 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.

An example using Table 1-A   For each biogeoclimatic subzone in the landscape unit
(Table 1-A), calculate the area available for harvest (the X-axis).

 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.
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