Bush Encroachment of Forest-steppe Landscapes in the Mongolian Part of the Lake Baikal Basin

The character of competitive relationships between woody and shrub vegetation in the southern (Mongolian) part of the Lake Baikal basin was studied via model polygons. Depending on the environmental conditions, native forests are being replaced by different types of shrubs. The main factors contributing to these changesare the aridization of the climate and human activity. It is shown that the current state of shrub communities and their progressive dynamics along the southern border of boreal forests in Mongolia allow us to consider them stable cenoses, which prevent a natural renewal of coniferous (pine, larch) forests in this region. However, some shrub species may be considered indicators of ecotopes’ suitability for natural or artificial reforestation because their ecological requirements are similar to those of forest trees. Keywords: Lake Baikal basin, ecotone area, destruction of forests, bush encroachmen

Diverging climate trends in Mongolian taiga forests influence growth and regeneration of Larix sibirica

Central and semiarid north-eastern Asia was subject to twentieth century warming far above the global average. Since forests of this region occur at their drought limit, they are particularly vulnerable to climate change. We studied the regional variations of temperature and precipitation trends and their effects on tree growth and forest regeneration in Mongolia. Tree-ring series from more than 2,300 trees of Siberian larch (Larix sibirica) collected in four regions of Mongolia’s forest zone were analyzed and related to available weather data. Climate trends underlie a remarkable regional variation leading to contrasting responses of tree growth in taiga forests even within the same mountain system. Within a distance of a few hundred kilometers (140–490 km), areas with recently reduced growth and regeneration of larch alternated with regions where these parameters remained constant or even increased. Reduced productivity could be correlated with increasing summer temperatures and decreasing precipitation; improved growth conditions were found at increasing precipitation, but constant summer temperatures. An effect of increasing winter temperatures on tree-ring width or forest regeneration was not detectable. Since declines of productivity and regeneration are more widespread in the Mongolian taiga than the opposite trend, a net loss of forests is likely to occur in the future, as strong increases in temperature and regionally differing changes in precipitation are predicted for the twenty-first century

The nature of steppe fires in Siberia and Mongolia

The nature of catastrophic steppe fires in Siberia, which in recent decades have been spread over thousands of hectares each year, leading to economic losses, and losses of lives and livestock, is being considered. The paper follows spring (March–May) steppe and forest-steppe fires using satellite monitoring data. In the 10-year time interval of 2008–2017 a positive logarithmic trend in annual burned area of steppe fires has been identified. The trend in the number of fires is characterized by periodic variations in relation to the average values, which do not seem to increase. It has been shown that in today’s context the occurrence and spread of catastrophic steppe fires in Siberia are determined by the anomalies of hydrometeorological conditions. Also, natural and anthropogenic factors that cause the occurrence and spread of steppe fires are analyzed. A system of prevention is discussed, as well as technological solutions for the protection of settlements and facilities. It is proposed to focus attention not only on the immediate control of fires and the elimination of their effects, but also on the implementation of comprehensive preventive measures to aim at specific economic targets. As an example a technology is proposed to construct fire control barriers that would prevent the spread of steppe fires and scattering of burning particles to residential and structural settlements. These measures should have a positive effect on the national economy by significantly reducing the cost of rebuilding settlements after fires, saving lives, livestock and infrastructure