Mounds of mires

Researchers from Tuvan and Tomsk universities wanted to understand the impact of climate change on palsa mires which are frozen mounds of peat bogs found in the highlands of southern Siberia. They are caused by permafrost and can be several metres high and up to several hundred km2 in area.

When reading existing research they found two types of ‘palsa mires’, large dome shaped or flat, commonly referred to as ‘mound bogs’ in Russian scientific articles. The flat mounds are found further north in the northern taiga and forest tundra, compared to large mound bogs. Existing research shows degradation or disappearance of these bogs during the last 100 – 200 years, affected by changes in permafrost on the landscape.

Figure 4. The surface of frozen mound with cracks (a), and micro-depressions (b). The palsa mire sites in Adyr-Khem river valley at Alash plateau; southern slope of the Western Sayan montane region, Republic of Tuva, Russia. The photos are by Kvasnikova dated: 30 July 2020, 15 July 2021.

However they also found evidence in existing research of local growth affected by changes in rivers beds, lakes, soil hydrology and even beaver activity. The researchers chose a study region in Tuva, southern Siberia – in the basin of the Ak-Sug river at the Alash highlands of the Western Sayan mountain range. The climate has precipitation varying between 300 – 1000mm of rain, shallow snow winters and affected by anti-cyclone systems. The temperature varied from approximately -5ºC in winter to 18ºC in the middle of 20th century with an average daily temperature around 0ºC.

They used geographical maps, satellite imagery, took their own photographs, plant samples. For the peat samples, they used Russian peat coring technology to help identify the distribution and impact of permafrost. They used GPS and geobotanical descriptions to identify vegetation. They also took water samples from Adyr-Khem river and thermokarst lakes, then measured dissolved oxygen, pH, electrical conductivity, and temperature at the sites. They used analysis in their laboratories to identify soil and peat composition.

There isn’t an existing meteorological station in the study area so they compared data from surrounding stations, up to 2019. They found the average annual temperature recorded at all stations increased by 1.7–2.1 °C; and +3.4ºC at Ust-Usa station, reflecting similar trends in global warming.

They identified over 200 thermokarst lakes, ‘pioneer’ shrubs of moss, grass, lichen in floodplains, cryophilic steppe meadows and open mires. The vegetation varied across the mires, described as ‘valley mires’, with more green mosses and lichen appearing where permafrost has degraded and lower peat levels. Overall they found a high diversity of natural ecosystems, environmental impacts with richer floral diversity in the large mounds. The thermokarst lake development affected by degrading permafrost also affects the plant species and variation across the study area.

They recommend an increase in environmental monitoring, including carbon dynamics. They have set up a meteorological station to measure air temperature, atmosphere pressure, air humidity, wind speed, direction, precipitation and solar radiation. They are installing soil moisture sensors and in 2023 will use the data collected to help identify short term trends for the region.

Kirpotin SN, Kvasnikova ZN, Potapova SA, Volkova II, Volkov IV, Pyak AI, Byzaakay AA, Kolesnichenko LG, Lushchaeva IV, Khovalyg AO, Kuzhevskaia IV, Chursin VV, Peregon AM. Pilot Studies of the Unique Highland Palsa Mire in Western Sayan (Tuva Republic, Russian Federation). Atmosphere. 2022; 13(1):32. https://doi.org/10.3390/atmos13010032

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