Population and phenetic structure of laurel poplar Populus laurifolia Ledeb. in the Tom river basin

Abstract

In the basin of Tom River (Russia) the distribution of laurel poplar Populus laurifolia Ledeb. populations is fragmentary due to its ecological requirements and to the anthropogenic transformation of the territory. Adaptability of P. laurifolia to well-aerated gravel-boulder alluvium results in its narrow ecological niche, confining it to grow mostly in the multi-stream areas of mountain rivers. Current distribution of poplar stands in the Tom River basin, their primary location near islands and tributary mouths are largely determined by human economic activity in the 20th century. At present the relative sustainability of these poplar stands under anthropogenic transformations in the region is ensured by their low accessibility. The natural dynamics of poplar stands is influenced by massive invasion of alien plant species into the indigenous floodplain plant communities. Spatial differentiation of P. laurifolia populations according to their composition takes place in the area. The grey-bark form with rounded wedge-shaped leaf blade base is common in the up-stream areas, while in the tributary basin and mid-stream areas the white-bark form with a heart-shaped leaf blade base is common as well. Combined analyses of quantitative and qualitative traits and phenotype frequencies also confirmed population differentiation according to their composition. The mid-stream laurel poplar stands display greater phenotype diversity and a higher proportion of inter-population differences in phenotype composition. The latter trait did not differ significantly among the up-stream populations with low differentiation. It was suggested that the current population structure in the Tom River basin area developed as a result of the original populations’ fragmentation due to the combined effect of neotectonics, valley glaciation in the Kuznetsk Alatau Mountains and anthropogenic influence.

Keywords

• Populus
• populations
• morphological attributes
• phenotypes
• glaciation
• refugium
• Kemerovo Oblast
• Russia