Pacfic Northwest: Even thinning forest near Spotted Owl Nests causes nest abandonment
Thinning trees near sites where threatened northern spotted owls are
nesting is causing the owls to abandon their nests, a trend that has
researchers with the U.S. Forest Service Pacific Northwest Research
Station concerned. Researcher Janice Reid, who has studied the owl for
twenty-four years, and her colleagues first noticed the disturbing
trend in 2004. The Bureau of Land Management, which manages some of
the acreage in an owl study area near Roseburg, Oregon, began
commercially thinning young forests near nest sites within the area’s
older forests. Although the 1994 Northwest Forest Plan prohibits
logging in sections of these forests that are older than eighty years,
it allows thinning in younger stands if doing so will create
old-growth forest conditions more rapidly.
However, the plan is clear
that thinning can occur only if it meets the over-arching objective of
protecting the owl. A biological assessment for the study area refers
to several instances of site abandonment by owls immediately following
thinning within a pair’s core area. Reid’s concerns were heightened by
data that showed a sharp decline in the spotted owl population since
2005. From 146 adult owls in 2005, the population dropped to 119
adults in two years. In the past two survey seasons, the number of
spotted owl nesting pairs dropped to the lowest levels since the study
began twenty years ago.
Reid oversees spotted owl research at the Tyee
study area, one of eight federal spotted owl demographic study areas
in the Pacific Northwest. Each year, scientists survey, capture, mark
and re-capture every spotted owl living within the 615-square-mile
area. Reid and her colleagues have documented 107 sites where spotted
owls have been known to nest. The biologists visit each site multiple
times during the year to determine if the owls are present, nesting or
producing young. The Tyee study area is a mix of BLM and private land,
much of it in a checkerboard of alternate square miles. Clear-cut
logging on the federal portions of the study area has declined
dramatically since the mid-1990s as a result of the Northwest Forest
Plan.
Logging on private land, however, has been largely unaffected by
the designation of the spotted owl as a threatened species in 1990.
The Tyee includes within its boundaries four of the Northwest Forest
Plan’s late-successional reserves—older forests, but not necessarily
old growth—totaling more than 40 percent of the study area. Designated
in 1994, the late-successional reserves are the backbone of the
government’s attempt to ensure that northern spotted owl populations
remain viable. The Northwest Forest Plan’s objective for protecting
owl habitat is clear. The plan’s intent is to “to protect and enhance”
late-successional reserves and old-growth forest ecosystems that serve
as habitat for certain species, including the owl.
The plan specifies
what kind of logging can take place in these reserves. Forests within
the reserves include recent clear-cuts in addition to old-growth
forests, with older forests accounting for about half the reserve’s
total acreage. The Northwest Forest Plan proposes that natural aging
of younger forests over a hundred or more years will compensate for
present-day logging of old-growth forests outside the reserves and
provide sufficient protection for the spotted owl. The plan is as
ambitious in its geographic scope as it is irreversible if it doesn’t
work. Reid knew from earlier studies that spotted owl nesting pairs
are especially vulnerable to logging within their “core area,” which
provides nesting and roosting sites and is where the owls are most apt
to forage. Core areas also moderate air temperatures around the nest
and roosting trees (spotted owls are sensitive to overheating).
Thinning a forest opens up the canopy, exposing the spotted owl to a
higher chance of predation and increasing air temperatures, which can
lead to nest site abandonment. BLM has been thinning within spotted
owl nesting areas. District-wide, sixteen thinning projects occurred
between 2002 and 2006 within the core areas of twenty-one pairs of
spotted owls. Forest Service Employees for Environmental Ethics will
continue to look into harvest practices that compromise remaining
spotted owl sites throughout western Oregon BLM lands. If the trend
continues and is ignored by BLM, there will be little recourse but to
list the species as endangered in the near future. Northwest
environmental groups have generally endorsed thinning as a source of
substitute timber for the old-growth logging that used to dominate the
region’s federal forests. Reid’s work shows that all thinning is not
alike: as with real estate, location matters. — Andy Stahl Forest
Magazine | FSEEE
http://www.fseee.org/index.html?page=http%3A//www.fseee.org/forestmag/index.shtml
— Posted to http://forestpolicyresearch.com via gmail to posterous and
also to forestpolicyresearch@yahoogroups.com
See and download the full gallery on posterous
Posted via email from Deane’s posterous