Wildfires alter delicate biodiversity of GSMNP

Two years after wildfires devastated the Great Smoky Mountains National Park, researchers are striving to understand the fire’s drastic and long-term effects on biodiversity.

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GSMNP is the most biologically diverse park in the National Park System, according to the Parks, with more than 19,000 documents species.

Now, biodiversity is shifting  from soil to salamanders, with some species proliferating, disappearing and maintaining. Researchers are trying to understand the species’ reactions after the fires to inform future fire events in the eastern U.S.

Creation of soil charcoal, pine tree fire scars

The soil is the first level of ecosystem regeneration, and geographer Sally Horn’s research could create a timeline between wildfires and environment regrowth.

Biologists say pine trees are record-keepers for fire history. In a wildfire, flames burn the tree trunks but do not kill it. New bark grows around the wound, trapping the charcoaled bark in a tree ring – called a fire scar. When trees later die and decay, the charcoal deposits are transferred to the soil. Analyzing soil cores and tree rings, researchers can construct fire histories going back thousands of years.

“We really want to understand the links between climate and vegetation and fire and historic human impacts that give character to the landscapes we see today. Understanding the fire history of the past can provide a long-term perspective for thinking about fire safety issues and things associated at the wild land/urban interface,” Horn said.

Table Mountain pine trees only exist in the Appalachian mountains. Serotinous cones release seeds when the environment is under stress. When the fires occurred, the heat melted resin in the cones and the pineapple-shaped armor of protection around the seeds transformed into thin layers of exposed empty seed pods.

High burn areas were blanketed by pine trees seedlings. Soil fungi developed around the roots of the pines, and the forest diversity changed in the burn area from the soil up.

Appearance of fire specific fungi

Mycologist Karen Hughes recorded fluctuations in soil fungal diversity over the past two years. The environmental controls on fungal growth in the Smokies has constituted Hughes’ 20 years of fungal research.

“The Smokies are exceptionally diverse in anything that ‘likes wet,’ which includes fungi. So there’s a lot of biodiversity and a lot of endemics, fungi that aren’t found anywhere else,” Hughes said.

Approximately 40 new species of fungi never previously recorded in the GSMNP were discovered as a result of the wildfires. These fire fungi can only grow where the soil has been burnt.

“Most of the fire fungi are tiny as the head of a pin, and when they blossom or fruit on burned soil its so prolific that it looks like the ground is all orange,” Hughes said.

 

Like a phoenix, the fire fungi Pholiota highlandensis blossoms from the ashes of burnt soil.

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Funaria hygrometrica, the bonfire moss, proliferates in burn sites.

Morels, edible fungi, appeared by the hundreds after the fires but lasted only two weeks. Others fungi persisted for two years and are only now beginning to decline.

Among the fungi there has formed a slick green streak of mosses like a primer for plant species to come, for regrowth of vegetation after the fire.

Invasion of non-native plants

Plants and low-level vegetation is exactly what ecologist Mali Hubert is examining.

Understory plants and vegetation below the tree line are some of the first large-scale life to regenerate after a fire. Examining what species exist and how abundant those species are in burn sites can provide insight to the levels and rates of succession after a fire.

Fires create more competition between native plants and invasive species. When a major disturbance like a wildfire occurs, space opens up for any species to occupy, and the resilience of invasive species makes them prime candidates.

 

“Luckily, so far, we haven’t seen this pattern of invasives,” Hubert said. “But the high burn would be the most susceptible.”

High burn areas like Chimney Tops have shown only slight improvements in the past two years. Medium burn areas are more likely to have spore, vegetation and tree remains, and these areas are performing rapid regrown. Changes in the diversity of species at the vegetation levels effects what other organisms can exist in the park, including other plants, trees and animals.

Resilience of salamanders

In Appalachia, salamanders are studied as examples for climate, competition and environment because of the specific ecological conditions in which they can survive.

“With respect to the fire, we would like to know if there are lasting impacts on diversity, especially because the Chimneys area is a hotspot of diversity in the Park. So far, it looks that there is not a difference in species in affected and unaffected streams, but there may have been a reduction in reproduction,” said herpetologist Benjamin Fitzpatrick.

Stream salamanders are born in water, travel across land for adolescence and then return to the water to reproduce. Any changes in land or water could effect their life cycle. Some salamanders’ can live around 20 years, and their long lifespan could make them resilient.

“With things like salamanders, which are very long lived and have a dual life of land and water, they may be pretty resilience to short term impacts in their breeding. Adults are starting to coming back, and in maybe two or three years, they will ramp up reproduction in these streams,” Fitzpatrick said.

 

GSMNP is known as salamander capital because it’s home to over 30 species of salamanders, more than any other single location in the world. Some species of salamanders live in Tennessee , like the cave salamander and Jordans red-cheek salamander.

The 2016 wildfires affected GSMNP at every level, but research can help set a standard for fire events in the future.

“Fire used to be part of the normal pattern, then it was suppressed with urbanization. Now with the climate changing so fast, the old normal is not true anymore,” Horn said.

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