Ecological Impacts of clear cutting in BC Flashcards
what kind of harvesting systems should we use in BC
- Depends on species, climate, etc.
what is clear cutting
- Removal of all trees from an area that is large
- The forest influence removed from majority of that area
- vary in size and shape
- reserves around 8-10% of blocks left as a reserve area
what is forest influence
the modified microclimate, the occupancy of the soil by living tree roots, and processes of organic matter turnover and nutrient cycling that characterize the forest environment
what is theDefinition of Clearcut in BC Silvicultural Systems
- Removes an entire standoff tree from more than one hectare and more than 2 tree heights in width in a single harvest
- A new even aged crop is obtained by planting, natural or advance regeneration, and/or direct seeding
- > 1 hectare
- > 2 tree heights in width
- > 50% open area climate (not influenced by edge)
- Can include green tree or patch regeneration
what caused the Bowron River Valley Clear-cuts and how much was cut
- Response to large spruce bark beetle outbreak in 1980s
o 48 00ha harvested
o 3000ha burned
what was the replanting operation for the Bowron River Valley Clearcuts
o 70% Interior space
o 28% Lodgepole pine
o 2% Douglas fir
what was the largest conflict in BC forestry
Clayoquot Sound: The War of the Woods (1994)
- Large progressive clearcuts resulting from road building policies
- Large public protests forced government and forest companies to use alternative harvesting methods
- Logging watersheds in Vancouver Islands
what are ecological effects of clear-cutting
- Soil environment and ecology
- Long term productivity loss
- Alteration of stream hydrology and morphology
- Habitat and biodiversity loss
o Terrestrial and aquatic - Loss and fragmentation of old growth forests
- Many others such as carbon and climate change and spiritual values
- Effects soil invertebrates and ectomycorrhizas
o More fugus is better health
how does clear-cutting affect decomposition rates
- Soil temperature and moisture increase
- Decomposition rates faster in clear-cutted areas than in forests
- Faster decomposition in clear-cuts can cause accelerated leaching of nitrate and other nutrients
what is fragmentation
- The loss and isolation of natural habitats
- One of the greatest threats to regional and global biodiversity
- Division the remaining forest into small blocks
- Unconnected blocks
what are differences between harvesting and wildfire
- Quality and quantity of woody debris
- Sizes and structures of woody debris
- Nutrient removal
- Long term implications
- Landscape matters
- Return interval and severities
- Ransom and deterministic
why should we support clear-cutting
- Efficiency
- work safety
- Low road densities
- God for regenerations of even aged stands
- Good for some BC interior forests requiring large and high intensity disturbance
what are some Recent changes in BC forest Management
- Greater social and scientific constraints
- Greater governance by higher level plans and regulations
- Focused more on what we leave behind
- Attempt to manage under guiding principle of “range of natural variability”
- Most sites on BC coast now harvested with “variable retention” systems
what are new management directions
- Close to nature forestry
- Range of variability: considering disturbances
- Variable retention
- Difference between BC costal and interior
what is green tree retention
Green tree replaced clearcutting on federal forestlands subject to timber harvest regulations
