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The monitoring studies carried out in the southern Romanian Carpathians (Retezat and Bucegi - Piatra Craiului Mts) provide a scientific support for long term ecosystem research (LTER). Their general objective is to characterize the air pollution and its potential effects upon forest ecosystems’ status and biodiversity in close connection with climatic changes. Two monitoring networks were placed in selected forest ecosystems for each LTER site (11 plots in Retezat and 22 plots in Bucegi - Piatra Craiului, respectively). Both in Retezat and Bucegi - Piatra Craiului Mts, the distribution of mean ozone (O3) concentrations are significantly correlated with altitude. The location (plot) has a significant influence on ozone concentration and in some cases the exposure period along the growing season has an influence. Ambient ozone (O3) and ammonia (NH3) concentrations were below toxicity levels for forest trees, their health status (crown condition) and volume growth being insignificantly affected. More than 45% of the rain events were acidic with pH≤5.5, thus contributing to an increased N deposition on forest stands. In Retezat Mts crown condition was relatively better than in Bucegi - Piatra Craiului Mts. As a consequence, in 2009 European beech (Fagus sylvatica) was the least affected species, with a percentage of damaged trees (crown defoliation higher than 25%) between 8.0% (Retezat) and 9.8% (Bucegi - Piatra Craiului), followed by Norway spruce (Picea abies) with 12.9% (Retezat) and 27.7% (Bucegi - Piatra Craiului). The most affected species was Silver fir (Abies alba) with 31.6% of damaged trees (Bucegi-Piatra Craiului). In the last period, both European beech and conifers (Norway spruce and Silver fir) with high defoliation (damaged trees) had lower annual relative increment than trees with low defoliation (healthy trees). A definite trend regarding rapid environmental modifications is not evident and no significant reduction of biodiversity occurred. In addition, all the vegetation biodiversity components of the forest ecosystems are specific to the stand type’s structures and local climate conditions, and no quantifiable consequences of specific air pollutants on ecosystems’ diversity occurred. more...

Dehydryn genes are involved in plant response to environmental stress and may be useful to examine functional diversity in relation to adaptive variation. Recently, a dehydrin gene (DHN3) was isolated in Quercus petraea and showed little differentiation between populations of the same species in an altitudinal transect. In the present study, inter- and intraspecific differentiation patterns in closely related and interfertile oaks were investigated for the first time at the DHN3 locus. A four-oak-species stand (Quercus frainetto Ten., Q. petraea (Matt.) Liebl., Q. pubescens Willd., Q. robur L.) and two populations for each of five white oak species (Q. frainetto Ten., Q. petraea (Matt.) Liebl., Q. pubescens Willd., Q. robur L. and Q. pedunculiflora K. Koch) were analyzed. Three alleles shared by all five oak species were observed. However, only two alleles were present in each population, but with different frequencies according to the species. At population level, all interspecific pairs of populations showed significant differentiation, except for pure Q. robur and Q. pedunculiflora populations. In contrast, no significant differentiation (p > 0.05) was found among conspecific populations. The DHN3 locus proved to be very useful to differentiate Q. frainetto and Q. pubescens from Q. pedunculiflora (FST = 0.914 and 0.660, respectively) and Q. robur (FST = 0.858 and 0.633, respectively). As expected, the lowest level of differentiation was detected between the most closely related species, Q. robur and Q. pedunculiflora (FST = 0.020). Our results suggest that DHN3 can be an important genetic marker for differentiating among European white oak species. more...

Little is known about genetic differences among Quercus frainetto and Q. pubescens, two species of section Dascia Kotschy (subgenus Lepidobalanus, white oaks) that reach in Romania the margins of their natural distribution range. A set of genomic SSRs (simple sequence repeats) and EST (expressed sequence tags)-SSRs was used to estimate the genetic differentiation among four natural populations of the two species. Q. pubescens had higher values of genetic diversity than Q. frainetto, although the differences were not significant. Two out of seven marker-loci, QrZAG112 and QpZAG110, displayed very high FST values. Averaged across loci, the genetic differentiation was high and significant (FST = 0.067). Genetic distances were much higher among species than among populations within species. A Bayesian analysis indicated that two is the most appropriate number of genetic clusters. Using a blind procedure (i.e. based on multilocus genotypes only) the vast majority of sampled individuals (90%) could be assigned to the cluster corresponding to their phenotypes. When information about sampling localities was introduced in the assignment test, all individual trees were correctly classified. The higher degree of admixture in Q. frainetto as compared to Q. pubescens may be explained by different rates of introgressive hybridization. more...