Abiotic Factors
Windthrow
Blowdown on
Gilford Island
Licensees can manage for
the effect of wind damage on trees by:
- feathering the
cutblock edge
- removing the trees
with the most windthrow potential
- designing the cutblock as to disperse
the force of the wind
- tree topping and pruning to make the
surrounding timber windfirm. Tree topping and pruning are usually done
to protect high value features (such as streams) as the treatment is quite
expensive.
Yellow Cedar Decline
Yellow Cedar decline, Owikeno Lake
Yellow Cedar decline extends over 200,000
hectares in Alaska and the extensive mortality has recently been mapped in parts
of coastal BC. This problem is thought to be caused by changing climatic
conditions. Yellow cedar is thought to be susceptible to spring frost injury in
areas where root systems are not protected by snow, resulting in fine root
death. An aerial survey of the mainland portion of the TSA in 2006 identified
Yellow Cedar decline in the several areas between Seymour and Kingcome Inlets,
including the Parson Creek, Rainbow Creek and Clear River areas. More
extensive areas were located in the mid coast during 2006 and 2007 surveys,
including operable areas near Rivers Inlet.
Deer Browse
Damage resulting from deer
browse can be reduced by using protectors such as wire cages or plastic cones on
all cedar and cypress seedlings. Protectors must be maintained until the
seedling is well out of the top, and then removed.
Common Diseases
Stefan Zeglen in Mistletoe stand (FH
Workshop 2007)
A major disease
impacting the forests in the NICCFD is
Hemlock Dwarf Mistletoe (Arceuthobium tsugense). Hemlock mistletoe
is managed for by avoiding partial cutting and not regenerating hemlock adjacent
to infected sites, cutting down all host trees within hemlock mistletoe infected
stands that are greater than or equal to 3 metres in height, and planting
non-host species such as cedar near stand edges.
Minor forest
diseases in NICCFD include:
Common Insects
This is a summary of the
most common insects of concern in the NICCFD:
Western Black headed budworm outbreak
During the years 1997-1999
the North Island was ravaged by a large outbreak of the western blackheaded
budworm (Acleris gloverana) affecting approximately 40,000 hectares of
both mature and immature hemlock/balsam forests. In subsequent years there
was a total collapse of the budworm populations as evidenced by various
provincial surveys. In 1956-57, 3
million acres were affected by this budworm on Vancouver Island. In 1957,
146,000 ha were sprayed with DDT in the "Englewood-Port Alice-Port Hardy
triangle." Over the past few decades though it has not been a big issue
(growth increment impacts only), but could resurface at some point in the
future.
Spruce Weevil
Spruce weevil is the most
damaging insect pest of young Sitka spruce within the Coast Forest Region.
Within high hazard sites it significantly hinders the establishment of Sitka
spruce regeneration. The success of weevil broods is strongly regulated by
temperature and heat accumulation. Weevil hazard zones have been delineated on
this basis. As the climate warms, areas currently considered to have a low or
moderate hazard will become increasingly more suitable for weevil broods.
Indeed, this has been observed in the Mid Coast TSA. Simple modelling shows
that an increase of only 1° in the average temperature adequately warms the
climate to support weevil broods at weather stations within the Mid Coast.
Fortunately the identification and propagation of weevil resistant spruce
genotypes is anticipated to largely resolve the weevil problem in regenerating
Sitka spruce on the BC coast.
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