Vegetative reproduction of Picea abies by artificial layering at the ecotone of the alpine timberline in the Giant (Krkonoše) Mountains, Czech Republic

No information is currently available as to whether highly damaged Picea abies stands with no generative reproduction at the ecotone of the alpine timberline can be effectively restored by an artificial layering. We asked how much vitality of the mother tree, the forest habitat type and the dominant understory plant species affect the long-term mortality and layering success of artificially buried branches.A total of 1300 branches of P. abies were artificially buried in the Giant Mountains in 1989, 1990 and 1991 and monitored during the subsequent 5 years for their mortality and rooting. Part of the buried branches was then checked for the mortality again after 20 years, in 2010.The cumulative mortality of the buried branches was 3.5%, 3.8%, 6%, 7.6%, 8.8% and 36% in the first, second, third, fourth, fifth and twentieth year, respectively. The mortality was the highest for very weak mother trees, forest habitat types affected by the high water table (Deschampsia cespitosa and Sphagnum sp. in the understory), the windward (western) position of buried branches in relation to the mother tree and for stands with dominant Athyrium distentifolium, where high infection by Herpotrichia nigra (black snow mould) was recorded. Roots developed on 3–5 year old parts of buried branches during 2 years, therefore the burial of young, rather than old, parts of branches is recommended for the practical use.We concluded that artificial layering can be successfully used for the reproduction of P. abies at the ecotone of the alpine timberline.

► Artificial layering can be used for the reproduction of Picea abies at the alpine timberline.
► The layering is highly successful in stands unaffected by a high water table.
► Roots developed on 3–5-year-old branches buried for more than 2 years.