Retention Flashcards
What are the multiple values that Silvi perscriptions must consider?
regeneration, growth, forest health, potential damage to leave trees, windthrow, soil disturbance, wildlife habitat, streams and fish, CMTs, visuals.
What are some examples of biological anchors?
- Snag patches or large old trees
- Riparian areas
- Rock outcrops
- Unique ecosystems
What are the different retention types?
Dispersed, Group, Mixed
What are the steps in choosing retention areas?
- Set Objectives
- ID critical habitats or species at risk
- Determine what you want to leave and why
- Locate biological control points on map
- Integrate with engineering control points
- Determine final design (including visual aesthetics)
Why is group retention typically the most desirable?
- Adequate space to grow the new forest (less growth impact vs. dispersed)
- More habitat features than single trees (undisturbed understory, buffers for streams and wetlands)
- Easier falling and yarding
What are some considerations for group size
Usually a minimium size
Use larger patches for issues such as: Windthrow, forest health, or cable Yarding.
Small groups useful for small openings where large groups are not feasible
When would dispersed retention be desired?
- Seed tree or shelterwood objectives
- Retain specific habitat trees (dens, nests)
- Distribute important habitat features (large old “vets”, cavities, arboreal lichens & mosses)
- Maintain mycorrhizal fungi distribution
- Retain understory redcedar
What are some rules and guidelines for retention planning?
Rule: retention must be distributed “over the area of the cutblock” (retention system definition)
Guidelines: At least 5% of the retention is “internal” (includes peninsulas equivalent to 1.5 tree lengths, riparian areas included.
How is percent retention represented?
As a % ratio of the area retained to the area logged
Ex. If the target is 10%, for every 10 ha logged, 1 ha is retained. (40ha logged would require 4 ha retention.)
The other way to express it is as a ratio of (ha retained / NAR + NP roads)
What is the minimum stand level retention?
10-20 % for every retention system Cutblock. This number is determined by Res. Mgt. Zone - Ecosection - BEC subzone.
For clearcut with reserves, 3.5% is the minimum but an average of 7% must be achieved throughout a year unless otherwise specified in FSP.
For dispersed retention targets are % basal area
How is forest influence calculated?
Long term retention area + cut area within 1 tree length of standing timber / Total area under prescription (TAUP)
Where Tree heights are the average dom/codom for the edge
- Adjacent areas must be free growing to count for influence
- Cut area is NAR + NP roads
- Long-term defined as at least one rotation
What are the goals for retention system cutblocks?
- Safe and cost-effective
- Leave a legacy of mature and old forest attributes
(Examples: large and old trees, snags, multi-canopy structure, large woody debris, unique features) - Maintain over 50% forest influence
- Practice good stewardship
What things define forest influence?
Seed fall, litter fall, humidity, temperature, soil moisture, shade. Usually defaults to 1 tree length for management purposes
What are the mapping and layout codes?
- Wildlife Tree (WT)
- Long-Term (LT, rotation +)
- Short-Term (ST,
What are the dangers of high grading?
- Removes trees with the best genes
- Promotes low quality or unhealthy trees and species
- Undesirable trees interfere with the growth of desirable trees
Leading to: Degraded stand quality and growth potential, or
Uneconomical future harvesting + Reduced future opportunities
