How do wildfires affect wildlife and forests?

Seeing a forest recently burned in a wildfire can be upsetting. Green is replaced by shades of gray. Earth is calm. The sun’s rays look hotter. However, it wasn’t long before the forest came back to life.

“Wildlife is incredibly resilient,” said Stephanie Ayes, chief wildlife biologist with the US Fish and Wildlife Service’s Bureau of Fish and Wildlife in Sacramento. “California has a long history with wildfires, and many species have adapted to tolerate them.”

Eyes has been assessing the effects of wildfires on wildlife for more than a decade. Prior to joining the service, she worked in Yosemite National Park, surveying the effects of fire on the California spotted owl. Today, data collected on wildfires is used to determine the impact on the habitat of endangered and endangered species that live in the Sierra Nevada.

Fires burn at different temperature levels, can be large or small, and cause varying impacts on land, wildlife, and neighboring communities. Topography, amount of dry vegetation present, weather factor in fire size and damage. Low-intensity fires burn close to the ground, ‘cleaning’ and mitigating the forest by removing thick, flammable vegetation from the forest floor. Highly dangerous fires burn in high heat, climb up and remove the canopy of trees, and can burn the soil and tree roots. On a large scale, extremely dangerous fires can be incredibly devastating to wildlife and the ecosystem. Mosaic fires are a mixture of mostly low intensity fires with patches of intense and medium intensity fires and some unburned forests. Wildlife can survive, and even thrive, in areas that experience mosaic fires.

When wildfires break out, animals do their best to stay out of the direct path of the flames while staying close to home if they can find a safe haven.

Eyes explained that “wildlife will move around their area of ​​origin, avoiding smoke and will actively burn areas until it is safe to return.”

Some animals, such as frogs and rodents, do not move far. They will retreat to deep underground burrows where they are protected from the heat. Fish and frogs will swim to the deepest parts of a stream or lake. If the fire burns only a few feet high, birds and animals that can climb will sometimes climb into the branches and canopy of trees to avoid the flames. Hunters may crawl into a tree hollow for protection. Other animals, such as deer and bears, will move around the forest until the flames subside.

“When I was working in Yosemite, there was a female spotted owl in California that survived many wildfires. We always worried about her, but she would still be there year after year,” said Oyoon.

But when a very dangerous fire burns across a large natural area, it moves quickly and climbs through the tree canopy. Wildlife is having a more difficult time finding refuge from these flames.

“Wildlife has adapted to deal with small fires, and unfortunately, sometimes they can’t escape these last big fires,” Eyes said.

The service listed the southern Sierra Nevada fish in 2019 and the Sierra Nevada red fox in 2021, both of which are endangered species. Highly dangerous wildfires have been identified among the major threats to the continued survival of both species due to habitat loss and the elimination of safe movement corridors. as such

Learn more about climate change prolonging droughts, and the forests and species that live there will continue to face the threat of large and very dangerous wildfires.

After burning

Over the past seven years, intense wildfires have burned thousands of acres across California. Unprecedented drought mixed with thunderstorms in the middle of summer fueled wildfires so large that they created their own weather systems. While many areas were severely burned, pockets of forests continued to thrive.

Nancy Kelly, a wildlife biologist in the Sequoia National Forest of the US Forest Service, has worked for more than 20 years surveying and studying wildlife habitats.

“The ability for wildlife to adapt continues to surprise me,” Kelly said. “They can be content with what is left after the fire.”

As a wildlife biologist, Kelly advises employees at Sequoia National Forest on ways to reduce the impact of management activities, such as prescribed burns and tree-thinning projects, on endangered and endangered species.

At first, fire is a big problem. Kelly said it’s been changing how species interact with their environment for a long time. “But fire is a tool that nature has been using for eons to keep ecosystems healthy.”

After the low-intensity fires, grasses and ferns are the first to return, with the help of freshly fertilized soil of leaf ash, burnt plants and woody debris, as well as sunlight that can now reach the forest floor. The trees are still alive and grow new leaves during the next growing season. Their healthy root systems prevent soil from eroding into nearby streams and lakes.

“We’ve seen groups of sensitive plants multiply after a fire because they love the open canopy,” Kelly said.

It doesn’t take long for wildlife to start using low-density burning areas. New grasses, ferns, and fallen branches provide enough coverage for mice and squirrels to feel safe searching for fallen seeds during a fire. Their presence attracts owls, hunters, foxes, and other animals that take advantage of the newly opened areas of the forest floor to spot prey. The delicate grass shoots provide food for herbivores such as deer and rabbits. Amphibians return to their waterfront homes to feed on insects that have also returned.

“We’ll see wildlife come back through the area as it cools down again,” Kelly said. “They are just as curious as we are. They take advantage of new growth and other food sources available after the burn.”

Regrowth after a large-scale, high-risk fire looks different. Some soil is so burned that tree roots below the surface burn, killing the tree. Ash from leaves and woody debris may take longer to break down and enrich the soil so that vegetation can sprout from the ground. Rain often erodes the soil in nearby waterways. Muddy water leads to less pure water sources for animals to drink from and can also bury amphibians and fish eggs before they hatch.

While these high-risk burn areas look like views of the moon, they are not entirely devoid of life. “It’s just a different life,” Kelly explained.

Woodland beetles begin to colonize freshly burned trees. Woodpeckers move to eat beetles. Dead trees fall off, and their ash provides much-needed nutrients to restore the soil.

“Unfortunately, in some of these large, very serious burns, we’re seeing more weeds and weeds grow because they can survive in less-than-ideal conditions,” Kelly said. “These species can outperform native herbs and plants for water and light.”

One native plant, white mountain thorn, grows on the ground when forest canopies are present. But after a very serious fire, the shrub can again grow to heights of more than 6 feet. Its growth then blocks sunlight from tree seedlings that sprout from the ground, and the landscape can transition from woodland to bushland.

Kelly explained that sometimes an animal’s life shifts after a fire, too.

“This year we’ve seen red-tailed hawks and other types of grassland birds because we have more open areas now,” she said. “Until the trees come back, I expect we’ll continue to see these types of grasslands and open areas in the mountains.”

stay or go

It can be more than 100 years before large trees return to the landscape after a high-risk fire, and some species cannot survive without a forest canopy, even if they try.

“California spotted owls can find places to sit, but they can’t find good places to nest,” Eyes said. “Just like us, if they don’t have a roof over their heads, they’ll leave.”

Hunters also avoid open landscapes, which make them vulnerable to predators as they move between their dens and scavenging grounds. Hunters often travel miles in search of food, mates, and good reproductive habitat, but intense wildfires can cut off these safe travel corridors, limiting them to smaller and smaller ranges and reducing their chances of finding an adequate mate and prey.

Fortunately, agencies like the US Forest Service, the National Park Service and the Bureau of Land Management are working to restore habitat after major fires like these.

“if it was

Learn more about burning described can be used to reduce the risk of a high-risk fire or vegetation can be planted immediately after a fire, and the wildlife usually returns,” Oyoun said.

Sequoia National Forest conducts a variety of activities aimed at reducing the risk of large-scale and high-risk fires, such as prescribed burns, brush management projects, and mitigating overgrown tree groves. Kelly is working with biologists with the US Fish and Wildlife Service to identify ways to reduce the impact on listed species in the area. While projects cause some minor disruptions during their implementation, the time period is usually short and much less disruptive and damaging than a high-risk fire.

Kelly and her team also support the restoration of burned landscapes by replanting native plants and trees on open slopes and near streams to reduce erosion and begin the process of bringing the area back to life.

“Forests provide food, water, and shelter for wildlife, but they are also important to humans,” Kelly said. “By taking care of forests, we also take care of the air, water sources, and communities.”

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