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The objective of this study was to estimate the effect of pre-commercial tending and commercial thinning on the genetic diversity parameters, especially rare allele loss and diameter-heterozygosity associations, in Scots pine stands by retrospectively modelling the removal of inferior/superior trees. Modelling was based on empirical data of DNA polymorphism in (a) a 60-year-old natural stand and (b) a 20-year-old young stand planted with seeds collected in a seed orchard. Within each of these stands, approximately 400 trees were systematically sampled within 1-ha plots (800 trees in total) and genotyped at 5 neutral and 7 EST-derived nuclear microsatellite markers. There was no significant association between heterozygosity, common allele number and tree diameter in either stand. Even at a high intensity, both simulated tending and commercial thinning had minor effects on the heterozygosity and allelic diversity but caused a significant loss of rare alleles. However, there was a nonlinear relationship between the loss of rare alleles and the thinning intensity in the young stand, such that below 30 % thinning intensity, the rare alleles were lost at a markedly lower rate. In conclusion, the association between commercial value and genetic diversity is weak in Scots pine. Thinning causes loss of rare alleles; however, for specific cases, it could be possible to identify the margins for a slow rate of rare allele loss. [ABSTRACT FROM AUTHOR]

Sloe ( Prunus spinosa L.) is a shrub native to Europe. In Germany, 50-80 % of all planted sloe is imported. Little is known about the genetic diversity patterns within and between German sloe populations. Thus, a debate arose how to avoid risks for nature and landscape by planting potentially maladapted material. The main objectives of our study are to analyse the genetic differentiation pattern of sloe populations in Germany, to identify geographic/genetic structures and to evaluate their potential for tracing reproductive material. 17 natural populations from Germany and 1 from Italy and Hungary were investigated by Amplified Fragment Length Polymorphisms (AFLP) and PCR-RFLP techniques. The AMOVA analyses based on AFLPs for all populations and for the German populations only result in equally high differentiation values of Φ = 15 % of molecular variance between populations. The analysis of cpDNA PCR-RFLPs resulted in 24 haplotypes with 30 % showing genetic variation between populations. Overall values of genetic variability over all loci and populations are: Na = 0.832, Ne = 1.114 and He = 0.072. Mantel tests for AFLPs and cpDNA haplotypes reveal no association between geographic and genetic distances between populations as a result of a lack of differentiation between German populations and those from southern and southeastern Europe. Weak geographic/genetic patterns were observed on a large scale. However, these concern the German populations only. Our results indicate that vegetative regeneration in combination with founder effects may influence the level of differentiation between populations. Populations with a large amount of vegetative propagation are more differentiated from other populations than those populations which exhibit less vegetative regeneration. The assignment of reproductive material (i.e. plant material) to potential source populations resulted in high values of correct allocations. Hence, such methods can be applied to trace reproductive material of unknown origin. [ABSTRACT FROM AUTHOR]

Seedlings of ten provenances of Scots pine ( Pinus sylvestris L.) from the southwestern to the central part of the species distribution range were investigated in a greenhouse experiment under dry conditions compared to a well-watered control. We conducted an isozyme study and recorded phenology as well as growth traits during the first year of growth. Genetic variability and genetic diversity increased from the westernmost provenances to those central to the distribution. Provenances from the Apennines and Spain revealed the strongest genetic differentiation compared to all others, whereas populations from Germany, Poland and Bulgaria were found to belong to the same gene pool. Seedling development and bud set were faster in northern populations. Shoot length was highest for Polish and German provenances within both regimes, populations from France and Spain had the longest roots. Reduced soil moisture slowed later development stages and delayed bud set for all provenances by about 5 days. Shoot growth decreased considerably under the dry regime for all provenances. German provenances were the most sensitive to drought, whereas Spanish provenances showed adaptation to drought conditions indicated by the lowest reduction in shoot growth relative to optimum conditions. The results of this pilot study show that under more pronounced drought conditions with repeated drought events, the so far established superiority of northeastern provenances compared to southwestern ones could diminish in the future. [ABSTRACT FROM AUTHOR]