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Bidirectional flows in the layering branches between parent and daughter tree in a Norway spruce polycormon

Senfeldr, M., Urban, J., Madera, P., Kucera, J.
Acta horticulturae 2013 no.991 pp. 277-283
Picea abies, branches, heat, progeny, reproduction, root systems, rooting, sap flow, treeline, trees
Layering, in which clonal offsprings are formed by the rooting of lower branches of the parent tree, is an important way of vegetative tree reproduction at treelines. These rooting branches (termed “layering” branches) mediate connection between parent and clonal daughter tree. In this contribution, we aimed to investigate quantity and directions of sap flow in layering branch of Norway spruce clonal tree - polycormon, consisting of a 53-year-old parent tree and a 23-year-old daughter tree. Trunk heat balance method (sensors manufactured by EMS Brno) was used for the sap flow measurements. Based on the sap flow measurements we discovered bidirectional flow in layering branch. We found, that in the daughter tree 7% of the transpired water was supplied from the parent’s tree root system and, in some cases, up to 25% of the instantaneous daughter tree sap flow was supplied from the parent tree. On the other hand, water provided from the offspring’s root system to the parent tree comprised only a negligible amount of less than 1% of the parent’s whole tree sap flow. Our findings suggest that even after 23 years of development the new tree is still semi-dependent on the parent tree. Combination of water supply to the daughter from the parent tree and from its own root system helps to establish new individuals upon harsh conditions of the treeline.