The reactions of Scots pine trees from different genetic groups comprising the population to the effect of meteorology and air pollutants at different stages of their development

Abstract

Genetic diversity of tree populations is a key factor of their sustainability. The knowledge gaps are mainly related to differences in reactions of trees from different genetic groups to environmental stress.Therefore in the present study we attempted to detect variation in tree reaction from the genetic group characterised by number of allele and their frequencies to climatic factors and regional pollution level. We hypothesized that in each population there existed most tolerant or most sensitive tree genetic groups,which could be the genetic basis of further sustainable forest development. From 200 to 400 sample trees with highly polymorphic nuclear SSR markers multiplexed with EST SSRs in each stand were chosen to be genotyped. 12 nuclear microsatellite loci were investigated.DNA was extracted from wood using the ATMAB-method. The genetic groups were distinguished based on allele frequencies using Bayesian clustering approach with STRUCTURE software.Tree reaction to the unfavourable environmental factors was established by applying long-term data set on tree crown defoliation and stem increment dendrochronology. The findings revealed that most productive and healthy trees, which demonstrated the highest tree growth rate and the highest sensitivity to environmental changes (meteorological parameters and pollutants) comprise one genetic group with the highest number of alleles and their frequencies.Meteorological parameters explained more than 70% variation in their stem ring width,meanwhile regional pollution load,mainly by N compounds, additionally increased this explanation rate up to 10%. Pine genetic group which characterised by lowest dendrometric parameters and worst crown condition had no possibility to survive environmental stress,why their existence in natural over-mature pine stand was not detected. The study is based on the results from national project supported by Lithuanian Council of Research "FOREstRESS" (SIT-3/2015).