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| Photo: Erkki Oksanen |
Sap collection from a hole drilled into a birch causes a clear vertical colour defect in the stem. Hence, sap collection should be focused on trees that have a stem of weaker quality to save the best birch logs from defects. Sap collection did not reduce the radial growth of birches nor the foliar nutrition content.
Collection of new spruce shoots does not reduce the height growth of the spruce as long as the main apex is left untouched. Removal of new annual shoots on branches does, however, have a strong affect on the appearance of spruces and additionally, the results indicated retardation of the radial growth. During the two years, no weakening in the health status was observed. It is recommended that collecting new shoots be limited to trees likely to be removed and to the lower branches of larger trees. Metla conducted the study project coordinated by Foodwest Ltd.
Project 7129: Utilization of birch sap and of spruce shoots for small- and medium-sized food production – effects of collecting on tree growth and health.
Back to the list of the reported finished projects in 2005
