YAKUTSK, May 11. /TASS/. Longer droughts and irregular precipitation in the changing climate cause more intensive and bigger wildfires in the Far East and in the Arctic, said Alexander Ivanov, an expert of the Institute of Geology and Environmental Resource Management (the Russian Academy of Sciences' Far Eastern Branch).
The fire season has begun in the Far East. The most dramatic situations are in the Khabarovsk, Primorsky, Trans-Baikal and Buryatia Regions. According to the forestry aviation service, Avialesookhrana, as of the morning of May 9, the wildfires took an area of more than 6,100 hectares. Yakutia, where the snow layer has not melted away completely, is about to face a similar disaster. Experts fear the current dry weather may exacerbate the situation in the region.
"The climate change's negative consequences mean that precipitation is uneven and drought periods are getting longer. How that affects the fires? The strength and areas of fires depend on combustible materials - dry forest litter and a lot of dry wood. Naturally, the warming makes these combustible materials even drier, thus intensifying the fires," the expert told TASS.
Fires in Yakutia
Forecasts say the fire season in Yakutia will begin in last two weeks of May. Experts explain the forecast by the significant amount of snow that has remained since late winter.
According to Alexander Ivanov, Yakutia's forests are more vulnerable to fires. "Forest fires in Yakutia differ, firstly, because the region is an area with less precipitation. For example, while in Vladivostok the annual precipitation is about 850 mm, in Yakutsk it is only 200 mm. In other words, the Lena (River) territory is four times drier than the Amur (River) territory. Another factor is that 90% of forests in Yakutia are larch forests." he said.
Given the severe weather conditions, no different plant species are able to survive in Yakutia's forests, which explains the extremely low biological diversity there. "As we all know, the lower it is, the less is the resistance to whatever violations and, in particular, to fires. Thus we can say that Yakutia's forests are more vulnerable to more frequent fires than forests in other regions," he added.
"Zombie" fires
It is probably impossible to give an accurate forecast of fires for the upcoming season, he continued. Random factors may play a certain role. Those may be dry thunderstorms, or negligent fire handling. "As for global trends, we can see an increase in the average air temperature in Russia. This growth in central Yakutia is 0.4 - 0.6 degrees over 10 years, and twice quicker in the Arctic part - by 1 degree over 10 years. Noteworthy, there is no unified change in the precipitation amount. In some Siberian regions, we have noticed a slight increase in annual precipitation in recent years," he added.
The primary feature of fires in northern latitudes is the time of their mass occurrence: while forest fires occur mainly in spring or in early summer, the tundra fires happen between July and September.
Another feature is the dependence on swamps and peat bogs. Arctic fires are dubbed "zombie fires" because very often they "continue" under the ground. Even when there is snow and severe frost on the surface, peat continues to smolder and this process may go on for a few months, and consequently, in spring, dry grass, shrubs and trees start burning actively.
"We also know that the tundra and the Arctic desert zone are the areas where fires are never extinguished. This approach is called the "control zone". That is, using remote methods, it is possible to determine the locations of fires, then to calculate the areas of those fires. But as for extinguishing - there are no such opportunities - the infrastructure is not developed, and there are no roads," he said.
Ecosystem recovery
The North is known for much slower processes of plants' biomass accumulation - in comparison with, say, the south of Russia. Hence, the ecosystem's restoration in the North is slower, the expert continued. Moreover, the tundra vegetation is very poor in the species composition.
"This means, there are no opportunities for changing plant communities like in a warmer climate (for example, the replacement of larch trees by birch trees in the south of Yakutia). A more dangerous and irreversible process is the permafrost degradation. Fires, no doubt, accelerate this process and all the consequences - the thermokarst, erosion, solifluction. We must understand those are irreversible processes. In a place, where for thousands of years used to be the specific tundra vegetation, develops a thermokarst lake, and - most importantly - a reverse scenario is impossible," the expert said.
However, the tundra ecosystem degradation is not the biggest problem, as the main global-level fire threat is burning forests in Siberia and in the Far East, including in the Arctic zone. Not more than 1-2% of all fires in northern Eurasia are the damage to the tundra ecosystems. This may be explained also by the shorter snowless periods.