Poplars and willows in Germany: Report of the national poplar commission 2012-2015

The most recent National Forest Inventory (Thünen Institute of Forest Ecosystems, National Forest Inventory) subdivides the areas not devoted to short rotation coppice (SRC) as follows: Aspen 81,000 ha, black poplar & hybrid varieties 38,500 ha, grey poplar 5,500 ha, white poplar 2,600 ha, balsam poplar 19,200 ha, in total 147,000 ha. During the period under review, the area cultivated by poplars and willows as SRC has hardly extended. Several factors are responsible for this: attractive alternative crops, in particular maize production for biogas, combined with the far-reaching ban on converting grassland and a lack of incentives from the Regulation on Greening decided at EU level in 2014. With regard to the cultivation of poplars and willows greening stipulates that their cultivation as SRC or agro-forestry-system may be counted as ecological focus area, yet only with a factor of 0.3. The total SRC surface in Germany has hence only increased to some 7,000 hectares and is currently almost stagnating. The woody biomass of approx. 50,000 t that is annually produced in SRCs is insignificant as compared to the quantities of fuel wood used in private households of 34 million m3 and the imported wood pellets, which amount to several million tonnes. Efforts have been continued to preserve the remaining pure black poplar occurrences, consisting mostly of relict stands with over-mature trees through in situ and ex situ measures and to approve black poplar stands for harvesting reproductive material for conservation purposes in accordance with the Act on Forest Reproductive Material (Forstvermehrungsgutgesetz - FoVG). Using molecular-genetic methods the species purity of the reproductive material is safeguarded. For 11 of the 14 poplar species, species-specific SNPs/InDels in the chloroplast genome and for identification of poplar cultivars sets of genetic markers have also been developed. For the identification of cultivars of the Section Populus 24 nuclear SSRs and for the identification of willow cultivars 12 nuclear SSRs were established, which are developed further continually. These markers also facilitate the unequivocal identification of multiple hybrid varieties and the resolution of the genealogy of hybrids up to the parental generation. Under the provisions of the Act on Forest Reproductive Material three poplar clones, Matrix 11, 24, and 49 from the Northwest German Forest Research Station (NW-FVA) and four hybrid aspen cultivars and two hybrid aspen families (in each case P. tremula × P. tremuloides) by the Thünen Institute for Forest Genetics, Grosshansdorf, were approved for the production of forest reproductive material in the category "Tested". Over 50 research projects, carried out at 26 institutions on genetics and breeding, cultivation, physiology, resistance of poplar and willows as well as wood utilisation were funded by third parties and have been included in the report. Also, over 180 scientific publications and seven book titles are listed in the report.