Siberian Federal University: Amoebas Shared about Ancient Fires in Siberia

Scientists and students of the School of Ecology and Geography of SibFU do a comprehensive research on the restoration of forest ecosystems of the northern taiga after fires. The results of their studies will help to predict changes in the high-latitude ecosystems of the Northern Hemisphere under the changing climate.

Siberian forest ecosystems formed in permafrost conditions are of particular ecological importance for biodiversity conservation and climate regulation. Fires in the Northern Taiga’s deciduous woods of Central Evenkia previously occurred at intervals of 60-100 years; however, recent climate changes make fires more intense and frequent. Now, SibFU scientists are analysing the recovered dynamic of Northern Taiga’s larch forests and evaluating the recovery potential of cryogenic forest ecosystems.

“The existence of Northern Taiga’s larch forests is supported by repeated fires. Gmelin larch is a typical pioneer species intensively renewed on the burning fields in the first 2-3 years after the fire. In the future, the intensity of natural restoration decreases sharply, but depending on edaphytocenotic conditions, it can last up to 7-8 or even up to 20 years. In the process of restoration of the live ground cover on the burning areas there is a change in the species composition of vegetation, and the pioneer plant species in the cover give its way to species capable of holding the territory for a long time,” said Olga Shabalina, associate professor of the Department of Ecology and Environmental Management.

It is remarkable that testate amoebas — representatives of miniature soil nanofauna — helped scientists to analyse how the restoration of larch trees in the permafrost zone is going on.

“The restoration of vegetation cover, soils, complexes of soil invertebrates, changes in the microclimate and other components of the ecosystem on the burning areas occurs within close cooperation. We have studied the conjugate dynamics of vegetation and communities of testate amoebas on larch fire areas of different ages formed after strong lasted fires that led to the complete destruction of vegetation cover,” said Anna Grenadyorova, Associate Professor of the Department of Ecology and Environmental Management.

The scientists conducted a rhizopod analysis by studying testate amoebas. These creatures can be used as a bioindicator of the state of ecosystems — they react sensitively to changes in the moisture regime in the soil, and their shells keep well and long after the death of the amoebas. It was found that the initial stages of settlement of post-fire places are dominated by exceptionally small, easily wind-blown xerophilic species. In the second year after the fire, the number of amoeba species doubled, and the density increased 20 times. The development of vegetation cover and bedding on the burnt areas, together with the improvement of the hydrothermal regime, causes obvious changes in the communities of testate amoebas — more moisture-loving forms appear. In old burning areas, the mosaic of vegetation cover provide the existence of a whole spectrum of morpho-ecological groups of amoebas — from small xerophilic to large moisture-loving forms.

According to the scientists, larch forest is considered to be fully restored in 25 years after the impact of the pyrogenic factor: this may be seen by a well-developed living ground cover and a high density of testate amoebas (8140 specimens per gram, the number of species reaches up to 21).

“Long-term monitoring of post-fire recovery processes allows us to give a comprehensive assessment of the response of vegetation and key groups of living creatures living in the soil to the combined effects of climate and pyrogenic factor in permafrost. It is also possible to identify factors that guarantee the stability of the biological potential of soils. Our research makes a significant contribution to predicting changes in the status of high-latitude ecosystems of the Northern Hemisphere in the changing climate,” — summarized Irina Bezkorovaynaya, head of the Department of Ecology and Nature Environmental, Doctor of Biological Sciences.