Transcript Predators associated with hemlock woolly adelgid

Silvicultural treatments for
management of the hemlock
woolly adelgid in the
northeastern U.S.
Glenn Kohler
FS 533
Background photo: eastern hemlock mortality, Bill Ciesla
Hemlock woolly adelgid (HWA), an exotic
pest, is causing widespread mortality to
eastern hemlocks in the eastern U.S.
Connecticut Agricultural Experiment Station
Following HWA caused mortality
► sites
colonized by birches, oaks, and
maples; resulting in a more homogenous
hardwood dominated landscape
William M. Ciesla, Forest Health Management International
► exotic
plants
may invade the
site
Anne Eschtruth, UC Berkeley
salvage logging?
►3
silvicultural options following hemlock
mortality
 do nothing
 cut 20-50% dead hemlock
 cut >50% dead hemlock
Shaughnessy Forest Products, New
Hampshire
Haliburton Forest, Ontario, Canada
PURE HEMLOCK
ZERO 20-50 >50
HARDWOODS
+CHANGED
UNDERSTORY
SNAGS = HABITAT
HARDWOODS
+CHANGED
UNDERSTORY
HARDWOODS
+CHANGED
UNDERSTORY
PLANTED REGEN.
(ie PINE) CAN
COMPETE WITH
HARDWOODS
+WEEDY SPECIES
INVASIVES?
EROSION?
DAMAGE HEALTHY HEMLOCK SEEDLINGS?
► Salvage
logging may cause more
environmental damage than HWA alone.
 increased nitrification, soil pH, and nitrogen
leaching
► Pre-emptive
salvage is not recommended.
 eliminates possible HWA tolerant seed source.
Rehabilitation planting
► Replacement
conifers:
 native pine,
spruce, or fir
► Breeding
Single tree/group selection in Red spruce (Picea rubens),
Eastern Hemlock (Tsuga canadensis), Balsam fir (Abies
balsamea) stand on the Penobscot Experimental Forest. Photo:
Doug Maguire, Oregon State University
 HWA resistant Chinese hemlock has been
crossed to Carolina hemlock
► Hemlock
regeneration
site selection
 Factors that increase
tolerance to HWA:
►soil
moisture
►low nitrogen
►cold temperatures
Regeneration
Photo: Chris Evans,
University of Georgia
Regeneration cont.
► plant
hemlock in small gaps (<100 m2) to
reduce competition from hardwoods.
► expose mineral soil if seeding hemlock.
► vegetation control is needed in open areas.
Take home
► surviving
hemlocks can be regenerated on
cold, wet, low N sites.
► group selection cutting, soil prep., and weed
control help natural hemlock regeneration.
► protect unique seed sources for the future!
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