Structure and biodiversity changes affected by fires in larch forests at Khilok river (lake basin. Baikal) upstream flow

The study results of changes in the larch forests’ structure and biodiversity in the upper Khilok River basin (right tributary of the Selenga River) affected by the climate change and forest fires in the period from 1996 to 2018 are presented. It was found that the area of closed forests decreased by an average of 51 %, the burnt forest area and burnt timber increased by 46%, dwarf birches decreased by 12 %, the natural reforestation of the sample areas is 90 % poor and unsatisfactory. It was revealed that due to fires in forest communities, the total number of plant species and lichens decreases, indices of species wealth and biodiversity concentration decrease in plant communities, and the ratio of species of latitudinal geographical groups (forest, steppe and meadow) changes. It is shown that with further climate aridization, an increase in the area of dwarf birches communities after fires can lead to the replacement of forests with shrubby, and later grassy communities. It is recommended to continue research on changes in the structure and biological diversity of plant communities in the selected model areas due to an increase in the amount of spring-summer precipitation in the region.