WATER-RETAINING CAPACITY OF NEEDLES IN POPULATIONS OF THE MAIN FOREST-FORMING CONIFEROUS SPECIES IN THE FORESTS OF THE TAIGA ZONE OF SIBERIA

The limits of individual variation of trees by the water-retaining capacity of needles in populations of forest-forming coniferous species (Scots pine, Siberian pine, Siberian spruce and Siberian fir) growing in the conditions of the mountainous, middle and northern taiga of Central and Eastern Siberia were studied. It is found that among the compared evergreen species, Scots pine and Siberian pine are characterized by the highest intrapopulation variation in the rate of needles dehydration; Siberian spruce and Siberian fir are characterized by greater variability in the ability of needles to water absorption. However, in samples of the last two species, the share of trees with a low rate of water loss is quite large, even in wet habitats. In more drought-resistant pine species there is a smaller part of trees, which quickly evaporate moisture and have a high water capacity of needles. While a smaller part of trees of Siberian spruce and Siberian fir are less resistant to dehydration and differ by low water capacity of needles. While in Siberian spruce and Siberian fir a smaller part are trees less resistant to dehydration with low water capacity of needles. We revealed the significant differences between species in mixed stands and between geographic populations of species by water-retaining capacity of needles. The highest values of this indicator were obtained for Scots pine and Siberian spruce from Yakutia, as well as for old-growth trees of Siberian pine from the Western Sayan. The necessity of preserving old-growth stands and trees, characterized by the greatest drought resistance of needles, especially hygrophilous dark coniferous species in a changing climate is emphasized.The obtained data and correlations between the used features allow us to estimate one of the components of drought resistance of taiga populations of coniferous species and their intrapopulation diversity.