I sure hope you’re sitting down when you visit the website today, because the findings of this new study on fires in the west are going to knock you off your feet entirely. Chalk this up to the “I told you so” category.

Researchers investigate combined effect of drought, fire on stream communities, highlighting importance of headwaters

Despite the importance of these waterways, scientists still don’t fully understand how they respond to fires. That’s why a team at UC Santa Barbara and the National Forest Service have studied wildfire impacts on streams over the past five years in parts of the Los Padres National Forest. The scientists’ new findings appear as the cover story in the December issue of Freshwater Science.

The results of this study also highlighted the significance of stream headwaters as refuges for sensitive aquatic species during fire and drought. After favorable conditions return, fish, amphibians and invertebrates can repopulate suitable downstream areas. This insight reinforced the importance of protecting these areas to ensure the resilience and biodiversity of watersheds as a whole.

What? Are you saying that headwaters matter to sensitive species like frogs and steelhead? Gee if ONLY there were some kind of animal that could protect them every day for free, I’m wracking my brain to think of what it could be,

A flurry of research activity followed the Zaca Fire in 2007 and Jesusita Fire in 2009. “That work showed that the riparian zone—the area of streamside vegetation—is really important in determining stream responses because if the riparian zone burns, it opens up the canopy,” said lead author Scott Cooper, a research professor in the Department of Ecology, Evolution, and Marine Biology. The added sunshine increases water temperatures and promotes algal growth, which in turn fosters a different community of algae-eating aquatic invertebrates. The reduced vegetation also results in increased runoff, erosion and sediment inputs that can change stream flow patterns, water quality and ultimately the community of animals in the stream.

In the short term, fires and landslides can increase creek flows because there are fewer plants drawing water from the soils and channels, Cooper explained. Increased flows during storms can scour streams and displace their flora and fauna, reducing their populations. Algae and certain invertebrates can quickly recolonize streams after flows recede, particularly if fire has opened up the riparian canopy. Streams often recover to pre-fire conditions within one to two years, he added, because vegetation quickly re-establishes in Mediterranean climates with their year-round growing seasons.

Gee that vegetation returning sure matters to streams. I guess it’s important that the roots reach the water and that mean’s it’s important the water table is as high as possible. It really would be great if there was something that helped these plants recover.

It’s still an open question whether drought hastens or delays an ecosystem’s reaction to fire. Fires often occur during droughts, when fuel is dry and temperatures are high. If these conditions continue, then the lack of water can slow the recovery of plants and delay a stream’s responses to later rain. On the other hand, heavy rains after a fire can cause floods, choke stream beds with sediment and, in extreme cases, lead to debris that remove most of the riparian vegetation. That said, rain can also promote the growth, which stabilizes soils and reduces erosion. “Over different timeframes, you can get very complicated results because rain can both stimulate plant growth while increasing stream disturbance,” Cooper said.

One thing consistently held true, though: Pools in stream headwaters were critical to the ecosystem’s recovery. “They’re refuges, through drought and wildfire, for fish and other aquatic animals,” Cooper said. “This is where sensitive species survive during inclement times, then recolonize downstream reaches when conditions become more amenable.” As a consequence, populations contract and expand through droughts, wildfires and favorable conditions, preventing the disappearance of species from creeks.

Wait, pools matter THAT much? They’re the game changer? You mean IF there are pools wildlife survive after a fire and if there aren’t they don’t? Gosh these pools sound really important. Have you thought about what might make them? Like some kind of pool-creating creature that just goes around building spots where water piles up?

Oh right! That kind of creature!