Fireweed: The Pink Pioneer


Fireweed, seen here in Glacier National Park in Montana, tends to be one of the first organisms to populate areas previously burned by forest fires. Hence, the name fireweed. Bernd Thaller/Used Under Creative Commons CC BY-ND 2.0

Wildfires, if left unchecked, might rage for days or weeks at a time. But even the brief ones can have long-term effects on the environment. Tree-devouring blazes often leave forest critters hungry and exposed. What's more, wildfires tend to open the door for future disasters.

Vegetation soaks up water and is thus a great line of defense against erosion. By stripping the ground of its plant matter, these fires invite rainwater to oversaturate the soil — which can result in landslides. Alternatively, the lack of foliage may cause flooding because shrubs, grasses and trees slow down runoff precipitation.

It's for these reasons that plants like fireweed (Chamaenerion angustifolium) are so important.

Sometimes called rosebay willowherb, fireweed grows in the northern hemisphere, typically in places with moderate climates above the 40th parallel. In North America, it's indigenous to every Canadian province and most U.S. states outside of the southeast. (Sorry, Florida...)

The fireweed is an attractive perennial. Like poison ivy, it's got stems that spread horizontally underground. Roots plunge deeper into the soil while vertical shoots rise through the surface. These shoots can stand up to 9 feet (2.7 meters) tall, though heights of 4 to 6 feet (1.2 to 1.8 meters) are more common. Between June and September, they're dotted with tiny, four-pedaled flowers, most of which adopt a pink or purplish hue. White ones are rarer, but not unheard of.

Fireweed has evolved to take advantage of wildfires and other forest-clearing calamities. In doing so, it provides a huge service to other life forms. A single fireweed plant makes around 80,000 seeds per year. Using delicate hairs, the seeds glide away on wind currents when they mature. This allows the species to spread itself out over considerable distances. So after a logging crew or forest fire wipes out the foliage somewhere, fireweed seeds can travel to the site from unaffected areas.

The hardy seeds do well in nutrient-poor, ashy soils. They also develop into adult plants rapidly. It is no wonder, then, that fireweeds were among the first organisms to bounce back after the eruption of Mount St. Helens on May 18, 1980. Over 200 square miles (517 square kilometers) of forested terrain were blanketed in ash that day and more than 100,000 tons (90,700 metric tons) of young trees and saplings perished. Yet within a month, fireweed sprouts were poking through the soot. A year after the incident, fireweeds represented 81 percent of all the new seedlings around the volcano.

Wherever this species establishes a colony, bees and other pollinizers exploit its flowers while herbivorous mammals come over to nibble on the shoots. Fireweeds also put nutrients back into the soil, allowing other plants — trees included — to eventually take root. And so the beautiful, inspiring process of revegetation beings. Life, like a phoenix, rises from the ashes.



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