The history of fire on the Kenai Peninsula is a major part
of the story of how moose populations likely increased on the Kenai after 1900.
Fire disturbance is one of the main drivers of ecological succession and change
on northern forests. Fire frequency appears to have accelerated greatly with
the arrival of European and American settlers in the mid-19th century. Prior to
this past century, major fires of unknown origin took place in 1871, 1883,
1891, and 1910, burning much of the Tustumena Benchlands, generating large
thick willow stands. Many black spruce burns north of the Kenai River date from
1835 to 1900 (DeVolder 1999). Large burns in 1926 in both Kasilof and the
Slikok area further set the stage for increased early successional habitat in
the 1930’s and 1940’s. A huge burn in 1947, just after the establishment of the
Kenai National Moose Range in 1941, burned from June to August, mainly in black
spruce lowlands. The normal temperatures and precipitation level that summer is
likely responsible for the patchiness of this fire, which left residual patches
of mixed hardwoods (birch, aspen, and cottonwood), white spruce, and grass,
mainly on moraine hills. These patches are still visible from the air today as
yellow patches in a sea of dark green black spruce in the fall.
The first Moose Range (precursor to the Kenai NWR) biologists
understood the importance of early successional vegetation stages for moose
winter survival. In 1950, nine permanent plots were set up to monitor
vegetation succession following the big 1947 burn. John Hakala was a graduate
student who later became the Refuge manager, and the plots became known
internally as the Hakala Plots. The plots, each 6.6’ by 66’ (0.010 acres or 10
milacres), are located along what is now Skilak Loop Road, on the old Sterling
Highway. Plots were selected to represent a wide range of stand types and
degrees of burn severity.
Each plot was carefully measured and photographed by Hakala
and his coworkers in 1950, 1955, 1961, and 1965. Every single tree stem of
every size was counted within the plots, with numbers running into the
thousands on some plots. Initially every stem was also mapped, with subsequent
surveys simplifying the mapping to list the dominant and minor species within
cells of a 10’x10’ grid.
In 1969, another massive burn occurred during a summer of
drought and high temperatures, leaving few unburned patches as in the 1947
burn. This severe fire burned off all the duff and litter layers of the forest,
leaving bare mineral soil ideal for hardwood regeneration. The hardwood stands
that developed after this fire have been an important source of winter browse
for decades for both moose and hares.
The Hakala plots have been resurveyed in 1955, 1961, 1965,
1995, 2000, 2005, and 2010. In 1976, 7 of the 9 original plots were revisited
by John Oldemeyer and his coworkers. They also added a survey of the
surrounding tree stands around each of the 9 plots using a method developed by
Daubenmire (1959) to study hardwood regeneration after disturbance, surveying a
total of 294 plots through 1981 (Oldemeyer and Regelin 1984). Dr. Ed Berg began
resurveys of the plots in 1995, following the original protocols, and repeated
the Daubenmire surveys of the surrounding stands (Berg 2000).
Successional pathway development, as the long-term
progression from bare soil to lichens and moss to sapling to hardwood trees to
softwood trees is known, is influenced by many factors, including pre-burn
vegetation, burn severity, topography, climate, and more. Pre-burn vegetation
determines what can grow back, either by seeds or by sprouting vegetation. Burn
severity determines the ground condition for tree regeneration. A lightly
burned stand may be able to regrow trees from root suckers (aspen trees) or by
stump sprouts (birch and alder). Or, a stand may have a thick clod of bluejoint
reedgrass left on it but no living trees – the grass survives and thrives,
preventing germination of tree seedlings. A severely burned stand may only have
sterilized bare soil left, which can lead to a flush of nutrients from burned
organic matter, and re-seeding by birch seeds blowing across the winter snow.
The age of the fire at the Hakala plots may allow one more
round of data collection to maintain a record of post-fire change with a known
date and fire severity level. However, as more fires occur around the Refuge,
we have the opportunity to install new fire successional plots in newly burned
areas to better understand fire ecology and successional in the context of our
currently changing climate.
Berg, E. E. 2000. Post-fire Regeneration on the Western
Kenai Peninsula, Alaska; a forty-eight year record from nine permanent plots.
USFWS, Kenai National Wildlife Refuge. Soldotna, AK. http://www.fws.gov/uploadedFiles/Berg_EE_2000b.pdf
Daubenmire, R. 1959. A canopy-cover method of estimating
vegetational analysis. Northwest Science 33(1):34-64. http://www.vetmed.wsu.edu/org_nws/NWSci%20journal%20articles/1950-1959/1959%20vol%2033/33-1/v33%20p43%20Daubenmire.PDF
Oldemeyer, J. L. and Regelin, W. R. 1984. Forest succession,
habitat management, and moose on the Kenai National Wildlife Refuge. Final
Report. USFWS, Denver Wildlife Research Center. Denver, CO.
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