Waldsieversdorf, Germany
Waldsieversdorf, Germany

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Eusemann P.,Thunen lnstitut fur Forstgenetik | Preuss A.,Niedersachsische Landesforsteri | Liesebach M.,Thunen lnstitut fur Forstgenetik | Liesebach H.,Thunen lnstitut fur Forstgenetik
Forstarchiv | Year: 2017

Quality demands on forest reproductive material are high. In addition to suitability for the geographical area where it is planted, it is expected to produce high-quality plants and to offer adaptability to changing climatic conditions. To meet these expectations, forest reproductive material is produced in seed orchards or certified seed production stands. To maximize genetic crop quality in such seed production stands, it is possible to selectively target high-quality trees for seed harvest. Using a stand of European beech, we studied to which degree it is possible to obtain seed from selected single trees under closed canopy conditions and whether isolation of high-quality seed trees through stand thinning improves the proportion of target seeds. Targeted seed harvesting by placing nets under target trees showed that, on average and showing a large variance, 45% of the crop originate from the target tree. 55% of the crop originate from other trees. 12% of the crop originate from the next-neighbouring low-quality tree. Thinning strongly increases the yield of target seeds. 74% of the crop originate from the target tree in the thinned stand. The mean distance between trees in the study stand is 11.3 m in the closed-canopy stand and 21.6 m in the thinned stand. Our results show that such distances are regularly covered by the relatively heavy beechnuts. Therefore, a targeted single-tree seed harvest can hardly be realized in a closed-canopy stand. In such stands, the crop will always contain seed from low-quality trees, possibly even exceeding the proportion of seed from the actual target tree. Therefore, thinning seems a promising strategy to increase crop quality in seed production stands. Building on these results, additional analyses will reconstruct seed and pollen dispersal in more detail within closed-canopy and thinned stands.


Grimrath A.,Thunen lnstitut fur Forstgenetik | Muller-Navarra A.,Thunen lnstitut fur Forstgenetik | Schneck V.,Thunen lnstitut fur Forstgenetik | Liesebach M.,Thunen lnstitut fur Forstgenetik
Forstarchiv | Year: 2015

In short rotation forestry, rust fungi of the Melampsora genus mean a significant hazard to poplars. They have therefore been subject of intensive research, focusing on Melampsora species harmful to poplars of the Populus sections Aigeiros and Tacamahaca. However, considerably less is known about the virulence and distribution of Melampsora species concentrating on poplars of the section Populus (aspen and white poplars). In context with the joint research project FastWOOD, aspen and grey poplar were monitored for resistance against rust on test sites and clone archives in Northern and Eastern Germany. Results show that hybrid aspen (progenies of crossings between European and American aspen) are more resistant against rust than mere European aspen. Additionally, rust samples were collected of infected leaves, from which rust-species were identified using DNA-barcoding. Two different rust-species were identified: Melampsora pinitorqua and M. magnusiana. M. pinitorqua showed a distinct preference for aspen and was altogether more prevalent than M. magnusiana, which preferred grey poplar as host. © DLV GmbH.


Liesebach H.,Thunen lnstitut fur Forstgenetik | Eusemann P.,Thunen lnstitut fur Forstgenetik | Liesebach M.,Thunen lnstitut fur Forstgenetik
Forstarchiv | Year: 2015

Provenance trials are very important to answer questions in practical forestry as well in forest science, i. e., to estimate the adaptive capacity of tree species to climate change. Experimental plots in field trials have to correspond to the characteristic variation of phenotypical traits under the given environmental conditions and should be representative of the respective seed origin. For that reason, seed lots for provenance trials should represent the genetic variation of the particular populations. Six offspring samples derived from a beech (Fagus sylvatica L.) provenance trial were genotyped by 14 highly variable nuclear microsatellite markers. The within-population genetic diversity (based on mean values of single loci) shows high levels in the Austrian, in the Romanian, and in the Czech samples, medium levels in the two German samples and low levels in the Spain sample. Besides common variation parameters, additional information was derived from the reconstruction of sibships and of parental generation from offspring multilocus genotypes by an efficient likelihood approach. The software package COLONY was executed on experimental data to estimate effective population sizes and the number of inferred parents. The ranking of the six populations was highly reproducible in replicated runs and independent from parameter settings. Also, the discovered halfsib families were highly concordant. Maximum halfsib family sizes range from 5 to 15 in sample sizes from 50 to 55 per provenance offspring. For some offspring samples, the mean variation parameters from single marker loci do not fit together with the inferred parameters from multilocus genotypes. Small effective population sizes could be derived from a high number of sibships among offspring individuals, whereas large effective population sizes are derived from a small number of sibships in offspring samples. Several causes could explain these differences, among others a biased seed collection and a reduced representativeness in parental populations. © DLV GmbH.

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