Crossing borders - European forest reproductive material moving in trade.

Forest reproductive material (FRM) is constantly traded between European countries, but bilateral trade statistics on a European scale are limited. For the first time we analysed national datasets according Council Directiv 1999/105/EC for the tree species Picea abies, Pinus sylvestris, P. pinaster, Fagus sylvatica, Fraxinus excelsior, Quercus robur, Q. rubra, and Q. petraea. Based on the period 2004-2014 we (i) quantified the amount and identified European FRM trade and production routes, (ii) applied a gravity model of economic trade to examine the determinants of trade, (iii) discussed the putative genetic impact of transferred FRM on native tree populations, and (iv) considered legislation and documentation processes to their compliance, purpose, and benefit in producing data relevant to sustainable forest management. On average, 30 million plants and 400,000 kg seeds were annually traded. About 85% of traded seedlings were Norway spruce. Coniferous FRM trade is dominated by Scandinavian and Baltic countries, while broad-leaved species are extensively traded in Central Europe. FRM trade and production are interconnected on a multinational level, and besides domestic FRM, most countries are also trading with foreign material. The results of the gravity model indicate that among other significant factors the bilateral trade is driven by geographical distance, currency, and forestry contribution to the domestic gross product. As no detailed data on seed transfer were made available by most countries, the total FRM transfer is biased and probably underestimated.