Effect of Climate Change on the Growth of Tree Species: Dendroclimatological Analysis

Tree ring analyses can assist in revealing the effect of gradual change in climatic variables on tree growth. Dendroclimatic analyses are of particular importance in evaluating the climate variables that affect growth significantly and in determining the relative strength of different climatic factors. In this study, we investigated the growth performance of Pinus sylvestris, Picea abies, and Pseudotsuga menziesii in northern Germany using standard dendrochronological methods. The study further analyzed tree growth responses to different climatic variables over a period of a hundred years. Both response function analysis and moving correlation analysis confirmed that the climate and growth relationship is species-specific and variable and inconsistent over time. Scots pine and Douglas fir growth were stimulated mainly by the increase in winter temperatures, particularly the January, February, and March temperatures of the current year. In contrast, Norway spruce growth was stimulated mainly by the increase in precipitation in May, June, and July and the increase in temperature in March of the current year. Climate projections for central Europe foresee an increase in temperature and a decrease in the amount of summer precipitation. In a future, warmer climate with drier summers, the growth of Norway spruce might be negatively affected

Effect of Climate Change on the Growth of Tree Species: Dendroclimatological Analysis

Tree ring analyses can assist in revealing the effect of gradual change in climatic variables on tree growth. Dendroclimatic analyses are of particular importance in evaluating the climate variables that affect growth significantly and in determining the relative strength of different climatic factors. In this study, we investigated the growth performance of Pinus sylvestris, Picea abies, and Pseudotsuga menziesii in northern Germany using standard dendrochronological methods. The study further analyzed tree growth responses to different climatic variables over a period of a hundred years. Both response function analysis and moving correlation analysis confirmed that the climate and growth relationship is species-specific and variable and inconsistent over time. Scots pine and Douglas fir growth were stimulated mainly by the increase in winter temperatures, particularly the January, February, and March temperatures of the current year. In contrast, Norway spruce growth was stimulated mainly by the increase in precipitation in May, June, and July and the increase in temperature in March of the current year. Climate projections for central Europe foresee an increase in temperature and a decrease in the amount of summer precipitation. In a future, warmer climate with drier summers, the growth of Norway spruce might be negatively affected

Genetic similarity of natural populations and plantations of Pinus roxburghii Sarg. in Nepal

•  Genetic structures of five population pairs each consisting of one natural population and one neighbouring plantation of Pinus roxburghii Sarg. in Nepal were assessed using nuclear (nSSRs) and chloroplast microsatellite loci (cpSSRs). • The mean number of alleles at nSSRs loci in natural populations was 5.0 compared to 4.93 in plantations while the average observed heterozygosities were the same in both groups ($H_{0}=0.50$). Most of the alleles were common to all the populations, indicating that the populations correspond to a single genetic entity. Similarly forty-seven haplotypes were observed in natural populations compared to fifty haplotypes in plantations. Mean haplotype diversities of natural populations (0.953) and plantations (0.955) were very similar. Genetic diversity of Pinus roxburghii was relatively high with low or no evidence of inbreeding while genetic differentiation among all populations was very low (about 1%). •  The very low differentiation among natural populations indicates efficient long- distance gene flow among populations resulting in homogeneous genetic structures at least at selectively neutral loci. Even though the harvest and production of seeds and seedlings was largely uncontrolled, genetic structures of most plantations show no signs of reduced variation, inbreeding or other negative effects compromising the adaptedness or adaptability of planted forests.Similitude génétique des populations naturelles et des plantations de Pinus roxburghii Sarg. au Népal. • Les structures génétique de cinq paires de populations composées chacune d'une population naturelle et d'une plantation voisine de Pinus roxburghii Sarg. au Népal ont été évalués à l'aide de loci nucléaires (nSSRs) et de loci microsatellites chloroplastiques (cpSSRs). • Le nombre moyen d'allèles à loci nSSRs dans les populations naturelles était de 5,0 comparé à 4,93 dans les plantations alors que la moyenne des hétérozygoties observées étaient les mêmes dans les deux groupes ($H_{0}=0{,}50$). La plupart des allèles étaient communs à toutes les populations, indiquant que les populations correspondent à une seule entité génétique. De même, quarante-sept haplotypes ont été observés dans les populations naturelles par rapport à cinquante haplotypes dans les plantations. La diversité moyenne des haplotypes des populations naturelles (0,953) et des plantations (0,955) étaient très similaires. La diversité génétique de Pinus roxburghii a été relativement importante, avec peu ou pas de preuve de consanguinité tandis que la différenciation génétique entre les populations était très faible (environ 1 %). •  Le très faible différenciation entre les populations naturelles indique des flux de gènes efficaces à longue distance entre les populations issues de structures génétiques homogènes avec au moins une sélectivité neutre des loci. Même si la récolte et la production de semences et de plants ont été largement incontrôlées, les structures génétiques de la plupart des plantations ne montrent aucun signe de réduction de la variation de la consanguinité ou d'autres effets négatifs compromettant la faculté d'adaptation des forêts plantées

Evidence for local climate adaptation in early-life traits of Tasmanian populations of Eucalyptus pauciflora

Understanding the genetic basis of adaptation to contemporary environments is fundamental to predicting the evolutionary responses of tree species to future climates. Using seedlings grown in a glasshouse from 275 open-pollinated families collected from 37 Tasmanian populations, we studied quantitative genetic variation and adaptation in Eucalyptus pauciflora, a species that is widespread in Tasmania and the alpine regions of mainland Australia. Most traits exhibited significant quantitative genetic variation both within and between populations. While there was little association of the trait-derived Mahalanobis distance among populations with geographic distance or divergence in putatively neutral markers (F ST ), there was strong evidence of climate adaptation for several genetically independent, functional traits associated with ontogenetic maturation, biomass allocation, and biotic interactions. This evidence comprised the following: (i) significantly more differentiation among populations (Q ST) than expected through drift (F ST ); (ii) little association of pairwise population divergence due to drift (F ST ) and trait divergence (Q ST); and (iii) strong correlations of functional traits with Q ST > F ST with potential environmental drivers of population divergence. Correlates with population divergence in quantitative traits include altitude and associated climatic factors, especially maximum temperature of the warmest period and moisture indices. It is argued that small changes in climate, such as a long-term 1 °C increase in the maximum temperature of the warmest period, are likely to affect the adaptation of local populations of the species. However, since there appears to be significant quantitative genetic variation within populations for many key adaptive traits, we argue that populations are likely to maintain significant evolutionary potential