Clear-Cutting Eucalyptus Trees in Hāmākua and Kaʻū Will Exacerbate Wildfire Problems
From wildland fire expert and Hāmākua resident, Pablo Akira Beimler: Clear-cutting eucalyptus forests will not eliminate Hāmākua and Kaʻū’s wildfire situation...it can actually make it much worse. This is something I have heard over and over again from foresters that I work with -- I have been in the wildland fire management and outreach field in Hawaii for 5 years (and 3 years in California). By clearing trees without immediately replacing the canopy cover, we would be allowing much more flammable and quick-spreading grasses and shrubs/small trees to grow and create a greater wildfire threat to Hāmākua and Kaʻū. Currently, the eucalyptus forests in Hāmākua are unique in that the trees are grown so closely together that they shade each other's lower branches and leaves out, creating space between the lowest tree branches and the cane and guinea grass underneath.
The trees also provide enough moisture and shade to rapidly break down fallen debris. I spoke to firefighters on the scene of the moderately-sized Paʻauilo fire in 2017 (see above) who described the fire actually slowing down once it got into the eucalyptus forest because there was more moisture and the flame heights of the burning grass were not enough to ignite the tree branches. Grass fires spread quickly but are considered flashy in that they don't create enough sustained heat to burn these trees compared to a downed log, shrubbier tree or conifer, or piles of debris. This situation is much different than in Kōkeʻe on Kauaʻi, where the eucalyptus trees burn VERY well. The structure is different: trees are spaced further away (see below). The understory is different: more shrubby and more downed logs and debris that aren't breaking down quickly. It's also quite dry during long periods of the year.
Which is not to say Hāmākua is not at risk of wildfire. It is a very important concern. Back in 1901, the largest wildfire in the State's recorded history occurred along the Hāmākua Coast from Oʻokala to Honokaʻa on the mauka side. It burned 30,000 acres and was the reason the State forestry department was created. The fire was a cane fire that went awry and spread quickly because cane and the other grasses/shrubs burn very well under windy conditions. More info here: http://www.pacificfireexchange.org/research-publications/category/hawaiis-big-burn-the-1901-hamakua-fire
The other concern would be the slash created by the logging. On November 10, highly-respected and renowned wildland fire expert, Stephen J. Pyne's explained how logging can actually be part of the wildfire problem:
"For members of the Trump administration, this reasoning leads to “forest management,” which they seem to equate with chainsaws. They argue that big-tree logging can be a benign (and profitable) surrogate for fire. But while all fuel is biomass, not all biomass is available as fuel. What fire wants is particles with a lot of surfaces relative to mass; it wants what a campfire or hearth fire wants. If you wish a fire to flash and roar, put in pine needles, dry grass, and kindling. Add a freshly cut green log and the fire will go out.
Which is to say, logging and burning do different things. Logging physically removes biomass; fire chemically changes it. Logging takes the big stuff and leaves the little; fire burns the little stuff and leaves the big. After a crown fire—a fire that flashes through a forest canopy—what remains are the tree trunks that logging would have hauled off. Removing them earlier would have lathered the land with post-cut debris called slash—exactly the kind of volatile fuel that fire favors. Slash disposal, in turn, typically means burning it, which has its own hazards for escape fires and which fills the sky with noxious smoke. Up until recent decades, the great conflagrations of American history have, with almost preternatural cunning, trailed logging and land-clearing. This is a country that is good at startups, not so great at cleaning up after itself. But that doesn’t mean some kinds of active management can’t work."
More here: http://www.hawaiiwildfire.org/news-center/fueling-the-fire-trump-thinks-logging-will-stop-the-burning-in-california