J. D. Sauerländer's Verlag, Bad Orb

Silver birch (Betula pendula Roth, “birch”) establishes rapidly as the dominant pioneer tree species on wind-disturbed sites. The following study considers the potential of birch as a species for production of valuable timber. In total 514 trees of various ages from 41 temporary experimental birch plots under varying stand conditions in southwest Germany (Baden-Württemberg, Saarland; Fig. 1, Tab. 1) were measured. Measurements included crown diameter, height to live crown, stem height, and diameter at breast height (dbh, 1.3 m) as well as tree height and stem diameter development over time. Based on the results, the following general guidelines are suggested for successfull management of birch for timber production. Early hight growth is fast (Fig. 2, Tab. 4), but self-pruning of birch is poor: even though the branches die off early (Fig. 3, Tab. 5), shedding is slow. Thus, to minimize wood defects from branches, pruning is required early in the stand’s development. We suggest early intensive release of selected target crop trees pruned to a stem height of 5 m. It appears not advisable to manage for target dbh considerably larger than 45–50 cm. Two reasons apply: first, the diameter growth decreases rapidly with tree age (Fig. 4) and even heavy release thinning result only in marginally increased diameter growth at higher ages (> 25 yrs). As a consequence, production time should not exceed 50–55 years allowing 95–120 crop trees ha–1 to reach target dbh between 45–50 cm (Fig. 5, Tab. 6). Secondly, birch older than 50–55 years increasingly develop brown colored heartwood (Fig. 6, 7, Tab. 7a,b), which reduces the value of the produced timber.

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