Changes in Tuva ecosystems do not fit the global trends

In recent years, ecosystem changes in Tuva do not fit the global trends. While in most countries there is a tendency toward desertification, Tuva is increasingly covered with vegetation. Larch forests are replacing the steppes. This can lead to a decrease in native animal populations and the emergence of new fauna. The reasons for such changes are being investigated by a large interdisciplinary group of TSU scientists.

- Five years ago, during expeditions to the Eastern Sayan, we noted that Tuva vegetation is changing -says Oleg Merzlyakov, associate professor in the Department of Soil Science and Soil Ecology at the TSU Biological Institute. - For several years this trend has not only been observed, it has been intensifying. One of the most noticeable factors is the advance of larch forests into steppe areas. This phenomenon can be both natural and anthropogenic in nature - due to the decline in hayfields, there is a transition of arable land to fallow land. We assembled an interdisciplinary group to find out the true reasons for such a transformation: soil scientists, botanists, zoologists from the Biological Institute and hydrologists and specialists of the Department of Meteorology and Climatology of the TSU Faculty of Geology and Geography.

Presumably, one of the influential factors is fires that burn out old larch forests. The microclimate that formed from them is changing. As a result, the permafrost horizon, which is located at a depth of several tens of centimeters, begins to melt rapidly. Moisture migrates to the valleys and the steppe, which gives life to plants that are not typical for these areas.

- The processing of meteorological data over the past decades shows that noticeable warming has occurred in Tuva since 1998, - says Irina Kuzhevskaya, Associate Professor of the TSU Department of Meteorology and Climatology. - The average annual temperature has increased, and winters have become milder, thanks to which the plants tolerate this period better. Spring comes much earlier, April is quite warm. Usually, this period in Tuva is rather dry, but the analysis showed that in recent years the precipitation in April-May has almost doubled. All this together creates very favorable conditions for plants.

- What is happening in Tuva now contradicts world models and forecasts,- says Sergei Kirpotin, director of the TSU Center of Excellence Bio-Clim-Land. - While in different parts of the planet there is a tendency towards climate desiccation (decrease in precipitation, decrease in the productivity of biological ecosystems) and even desertification, in Tuva we observe a steady tendency towards humidification capability (increase in temperature and humidity). This transforms the vegetation - the steppe turns green and begins to be covered not only with shrubs but also with trees.

In particular, the scientists intend to find out whether the advance of the forest on the steppe is a cyclical phenomenon that was repeated in different geological periods of time, or it is a completely new feature caused by the human factor or global warming.

During a recent expedition, scientists took soil samples, and in the south of the region, where the Tannu-Ola mountain system is located, they installed equipment that helps to track the number of important parameters. At each site of the research transect, not only standard meteorological complexes were installed, but also thermo-braids enabling real-time readings in the soil from the surface to a depth of 140 cm, and soil moisture sensors. The indicators will be sent to one of the TSU servers via the mobile network. The new information will help scientists assess the intensity of the greening of the steppe and make a prediction of how the flora and fauna will change in this area.

The importance of new data is not only fundamental but also practical. The life of the local population and their methods of managing it depend largely on the climate and weather conditions. So, for example, due to the advance of forests on the steppe, the area of pastures may decrease, and due to the general instability of the climate, the number of catastrophic floods, landslides in the mountains, and forest fires may sharply increase.