YAKUTSK, March 6. /TASS/. The diversity of local communities in Yakutia's north dropped by about 30% after wildfires in the Kytalyk National Park, the park's expert and a chief scientist at the Institute for Biological Problems of Cryolithozone (the Russian Academy of Sciences' Siberian Branch) Elena Troyeva told TASS.

Five wildfires ranging from a few hundred to a few thousand hectares roared across the Kytalyk National Park in 2019-2021. After the disasters, scientists conducted the flora's studies. They analyzed the communities, typical for the local sub-Arctic tundra.

"The fire has destroyed almost the entire ground cover - the mosses and lichens that are like a blanket protecting the permafrost from the sunlight. <...> Similar to how it happens in forests after fires, within the first years on the moist soil grows a pioneer species of Marchantia liverwort, together with other moss species of the corresponding ecology, and on the second year it grew to cover up to 70%. Generally speaking, the community's species richness has decreased by about 30%," the expert said, pointing to the changed floral contents and dominants.

Among the pioneer plants that were the first to appear on the wildfire sites, also was narrowleaf willow, and marsh ashtray, which appeared there in the second year. "Reed grass has undertaken the main role in the post-pyrogenic community (formed after wildfires - TASS), and thus it can be called a successional explorer - a plant that gives an outbreak in disturbed habitats in the absence of competition from other species," she continued, adding in the second year, the plant's abundance increased from 10 to 50%.

Preliminary analyses of the insect fauna also have shown noticeable changes in the quality and quantity, which is expected in the changed habitat. "We believe, the species composition and abundance indicators in insects and arachnids can serve as an indicator of the tundra bio-geo-cenoses' disturbance. On the fire sites, we have noted nests and broods of three bird species from sparrow-like and plover-like groups, which were attracted by high numbers of insects. We also have noted that the juicy grass attracts to those sites musk oxen, which also contribute to the tundra's transformation after wildfires," she said.

By analyzing preliminary data, scientists can rate changes in the Arctic ecosystem. They plan to continue research and to study the recovery processes. They will analyze various indicators, including space surveys and surveys by drones. Experts will monitor the dynamics of moss cover restoration, since it is a determining factor in the permafrost soils stabilization and in the soil respiration. Scientists plan to assess the impact of the ungulates. Obtained data can be used in global climate change models and in planning the regional social, economic and environmental development.

Impact on permafrost

Another important aspect the scientists study in the Arctic is how wildfires influence the permafrost. Landscape fires trigger soil erosion processes: the tundra's upper cover, being left without plant protection, warms up faster and deeper, which leads to a significant degradation of the permafrost.

"As for soils, in the second year after a wildfire, the season thawing depth increased by 2.8 times compared to the untouched tundra areas. This is significantly higher than respective indicators for permafrost forest soils in central Yakutia, where this indicator increases by 1.5-2 times," said Alexander Chevychelov, the Institute's chief researcher.

Scientists explain the recorded thawing degree by at least two factors: the presence of long-term icy permafrost, and a relative surface elevation against the surrounding lowland plain.

The thawing process was accompanied by automatically increasing soil moisture due to the moisture from the thawing processes. "We have noted in the first year already the cryogenic processes and changes in the relief due to the permafrost thawing. We have pointed to developed cracks, soil subsidence, and the sinkholes filled with water," he added.

Permafrost thawing

Recent studies show that the melting of perennially frozen soils in the Arctic zone due to the climate warming leads to huge releases of methane and carbon dioxide, which exacerbate the global climate change. These processes are dramatically accelerated in wildfires.

Scientists forecast - an increase in the temperature of the cryolithozone upper horizons, which occupy 65% of the country's territory, will cause a loss of stability in foundations of buildings and engineering structures. These processes are taking place intensively: the number of deformed buildings has approached 40%.

Cryogenic factors cause 23% of failures in technical systems of the oil and gas industry and 29% of lost hydrocarbon production. The potential damage to buildings and structures from the permafrost melting in the Russian Federation's Arctic zone is estimated at 5-7 trillion rubles ($65-92 billion) to 2050, including 700 billion rubles ($9 billion) - to the housing stock.

Results of the studies, where Siberian scientists observed the temperature dynamics of frozen soils in post-pyrogenic landscapes in the sub-Arctic tundra, point to thermal anomalies in the permafrost that have persisted for many years.