[Genetic diversity and differentiation of Gmelin larch Larix gmelinii populations from Evenkia (Central Siberia)]. / Geneticheskoe raznoobrazie i differentsiatsiia populiatsii listvennitsy gmelina v évenkii ( Sredniaia Sibir').

Within- and among-population diversity of Gmelin larch Larix gmelinii (Rupr.) Rupr. from Evenkia was inferred from data on 17 genes determining allozyme diversity of ten enzymes. More than 50% of the genes proved to be polymorphic. On average, each tree was heterozygous at 9.2% genes. Heterozygosity expected from the Hardy-Weinberg proportions was higher, 12.5%. A deficit of heterozygous genotypes was observed in all populations under study and attributed to inbreeding. With Wright's F statistics, average individual inbreeding was estimated at 26.6% relative to the population (F(IS)) and at 27.8% relative to the species (F(IT)). The greatest deficit of heterozygosity was observed for the youngest population. Within-population variation accounted for more than 98% of the total variation, while the contribution of among-population variation was 1.66%. Genetic distance between populations varied from 0.0025 to 0.0042, averaging 0.0035.

Growth and annual ring structure of Larix sibirica grown at different carbon dioxide concentrations and nutrient supply rates.

We compared effects of ambient (360 vpm) and elevated (720 vpm) carbon dioxide concentration ([CO2]) and high and low nutrient supply rates on stem growth, annual ring structure and tracheid anatomy of Siberian larch (Larix sibirica Ledeb.) seedlings over two growing seasons. Elevated [CO2] had no significant effect on either stem height or diameter growth; however, both stem height and diameter growth were enhanced by the high nutrient supply rate, and these increases were stimulated by elevated [CO2]. Elevated [CO2] tended to increase the width of the annual xylem ring, the number of cells in a radial file spanning the ring, and tracheid lumen diameter, whereas it tended to reduce cell wall thickness, although there were no statistically significant CO2 effects on tracheid anatomy. Changes in tracheid cell morphology seemed to be dependent on changes in shoot elongation rates.