Refers to the process of dead moss and conifer leaves turning into peat. It occurs in regions where a wet climate inhibits frequent fires, and is a natural way of creating compost. It could be considered a shift from forest and grassland to areas of peat through this system.
Many species of trees depend on fires to control their population, whether it is to keep them alive, or to keep them eradicated. The Oregon White Oak is a species dependent on fire to keep the Douglas-firs from taking hold in the savanna habitat. An intermittent source of acorns, the Kalapuyan Native Americans used fires extensively to keep the habitat in check, much like a landscaper mows grass or trims bushes. (In the United States, this is the most popular practice due to many risks to our environment including smoke, risks to human lives, ecological risks, and economic impacts to the timber industry).
Certain species of pine utilize fire to catalyze seed germination, breaking open cones sealed with resin. Charring the soil also helps ensure the seedling will have access to nutrients and minerals for growth.
The fire cycle is a pattern of naturally occurring forest fires that occur in a frequency, dependent on the climate and amount of precipitation an area gets per year. Typical natural cycles can vary between 100 and 500 years, but modern forest management practices and the whole of humanity inhibit naturally- and unnaturally-occurring fires. There are many reasons for this, but the social stigma of forest fires that have been created over hundreds of years has inhibited reasonable discussion on manmade forest fires. As such, the thought of a community blanketed in smoke, or burning an area we might find ‘pristine’ is not natural to us because we have not been raised to accept this as normal. The early European settlers were the first to have difficulty with this idea, and might have set off the notion that we should not set fires manually.
Intolerance refers to regular invaders of freshly-charred land, mainly the larches, Douglas-firs, and pines, intolerant of shade. Tolerant species are able to withstand competition from other species than intolerant ones because of their shallower root systems, but this makes them susceptible to falling over in a storm. Trees that are intolerant don’t have the ability to take over an established forest, but need open land and full sunlight to grow.
Five benefits of fire
- Inhibit takeover of habitat by unwanted pests and diseases by disabling them from feeding on plants and removing diseased trees that could be a host.
- Prevent seral succession from decreasing nutrient capacity, enabling diverse species for future generations.
- Promote forest diversity. Changing the composition of the soil through fires adds more nutrients to support a more varied amount of life. Adds more nitrogen, calcium, potassium, and phosphorus to be uptaken by young plants.
- Specifically with nutrients, burning needles from conifers releases the minerals that are otherwise trapped for a longer time before they decompose.
- Keeps water table stable by controlling the amount of trees that draw water from it.
Types of fires
Surface fires are the most ideal (and most common). They burn dry flammable material on the floor, but full-grown trees aren’t affected as severely. Trees such as the Oregon oak and the Red and Ponderosa Pines, can withstand the effects of surface fires. They free the trees from low-lying competition, enabling them to reach their full height
Crown fires are when a forest fire only affects the tops of trees, or crowns. These can be the most impressive of the types of fires, and if combined with surface fires and large quantities of material, they can unleash devastation throughout the forest and take down everything in its path.
Ground fires comprise of the third type of fire, which occur with peat accumulation. This type of fire lays low underneath the forest floor, with the only sign of it occurring being the occasional sight of smoke. Things like partially extinguished fires can start this type of fire, and surprisingly they can burn for months undetected, using the forest floor as a roof over a large smoldering mass of peat.
Average fire cycles
Forests on western side of Oregon Cascades
- Forest fires prevailed throughout history and prehistory
- Low-intensity fire regime due to moist forest settings
- Around 400 years for a cycle
Lodgepole pine forests of Central Oregon
- Lodgepole pines tolerate poor soil really well
- Saplings and seedlings grow fastest, and cones wait for fires to open up
- Isolated stands of Ponderosas, living on 8.7: of precipitation per year.
- Therefore, average duration of forests is about 100 to 200 years, but this climate takes off about 25 years due to dryness.
What is a dog-hair stand? How do they develop?
A dog-hair stand is a massive regeneration of a tree, usually lodgepole pine, which is intolerant to shade and grows best in fire-charred soil. The dog-hair stands can have any density from 10,000-20,000 trees per acre. It has been noted that the lodgepole pine specifically might hold its seed for a long time, waiting for a fire to open it up and release future seedlings to the forest. This release and planting of seeds en masse are how dog-hair stands come to fruition.