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Hakala Post-Fire Plots

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. 

Daubenmire, R. 1959. A canopy-cover method of estimating vegetational analysis. Northwest Science 33(1):34-64.

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.

Last Updated: Dec 19, 2012
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