Amoebas with shells “told” about ancient fires in Siberia

Scientists and students of the Institute of Ecology and Geography of the Siberian Federal University conducted comprehensive research on the restoration of forest ecosystems in the northern taiga after fires. The results will help predict changes in the high-latitude ecosystems of the Northern Hemisphere in a changing climate. And helped the researchers in their work, oddly enough, amoeba with shells. The article was published in the journal “Forest Science”.

Siberian forest ecosystems, formed under permafrost conditions, are of particular ecological importance for biodiversity conservation and climate regulation. Fires in the northern taiga larch forests of Central Evenkia used to occur with an interval of 60-100 years, but the climate changes recorded recently make fires more intense and frequent. SibFU scientists analyze the recovery dynamics of northern taiga larch forests and assess the recovery potential of cryogenic forest ecosystems.

“The existence of northern taiga larch forests is supported by repeated fires. Gmelin’s larch is a typical pioneer species, intensively regenerating in burned areas in the first 2-3 years after the fire. In the future, the intensity of natural renewal sharply decreases, but depending on the edapho-cenotic conditions, it can last up to 7-8 and even up to 20 years. In the process of restoring the living ground cover on the burned areas, the species composition of the vegetation changes, and the pioneer plant species of the cover give way to species that can hold the territory for a long time, ”said Olga Shabalina, Associate Professor of the Department of Ecology and Nature Management.

It is noteworthy that testate amoeba, representatives of miniature soil nanofauna, helped scientists to analyze how larch forests are being restored in the permafrost zone.

“Restoration of vegetation cover, soils, complexes of soil invertebrates, changes in the microclimate and other components of the ecosystem in the burnt areas occur in close interaction. We studied the associated dynamics of vegetation and communities of testate amoebae on larch burnt areas of different ages that formed after strong, stable fires that led to the complete destruction of the vegetation cover, ”said Anna Grenaderova, Associate Professor of the Department of Ecology and Nature Management.

Scientists conducted a rhizopod analysis of testate amoebae. These creatures can be used as a bioindicator of the state of ecosystems – they are sensitive to changes in the moisture regime in the soil, and the shells are preserved for a long time and well after the death of amoebas. It was found that at the initial stages of colonization of post-fire sites, only small, easily wind-borne xerophilous species dominate. 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 litter on burnt areas, together with the improvement of the hydrothermal regime, causes obvious changes in the communities of testate amoeba – more moisture-loving forms appear. In old burnt areas, the mosaicity of the vegetation cover ensures the existence of a whole spectrum of morpho-ecological groups of amoebas – from small xerophilous to large moisture-loving forms.

According to scientists, the larch forest is considered to be completely restored 25 years after exposure to the pyrogenic factor: this is evidenced by a well-developed living ground cover and a high density of testate amoebae (8140 specimens per gram, the number of species reaches 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 impact of climate and the pyrogenic factor in permafrost conditions. It is also possible to identify factors that ensure 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 a changing climate,” summed up the head of the Department of Ecology and Nature Management, Doctor of Biology Irina Bezkorovainaya.

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