Skógræktarritið - 15.05.2005, Síða 43

Heimildaskrá
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Summary
Effects of preculture of Nootka lupin (Lupinus
nootkatensis) for survival and growth of deciduous
tree cuttings.
The introduced Nootka lupin (Lupinus nootkatensis)
has been much used for land reclamation of barren
areas ín lceland the past few decades. Dense plant
cover and soil fertility is normally gained within a
relatively short time in the lupin patches. A growing
interest has been in using the lupin as a preculture
before planting trees. The present study evaluated
the possibilities for such forest establishment with
woody cuttings of three deciduous tree species, the
native tea-leaved willow (Salix phylicifolia) and two
much used introduced species, black cottonwood
(Populus trichocarpa) and feltleaf willow (Salix alaxensis).
ln total, 1800 cuttings of three lengths, 20, 50 and
80 cm, were prepared and planted into five blocks at
Hofsnes, Öræfasveit in SE-Iceland that each
contained a dense lupin patch and a barren eroded
area. ln each block, half of the cuttings were
inserted 1/3 into the soil and the other half was put
deeper, or 2/3 (Figure 3).
The lupin was on average 79 cm high and its
annual maximum LAI was 4.5 (Table 1). Hence,
only ca. 10% of the available light was reaching the
soil surface in the lupin patches. Three growing
seasons after establishment, the experimental
treatments were evaluated in terms of tree
survival, height and leader dieback. The results
showed that woody cuttings can be used to
establish deciduous forest in lupin patches
(Figures 5-7). Black cottonwood yielded the best
results, both in survival and growth, but the native
willow came second. The key for successful
establishment was to use long cuttings that were
inserted relatively deep into the soil (Tables 2 and
3). it is speculated that for optimal results, a little
longer cuttings (100-120 cm) should be used. The
lupin significantly enhanced the growth and
reduced leader dieback of those trees that
survived the first years (Figures 6 and 7). Outside
the lupin patches, the relative depth to which the
cuttings were inserted was critical. Inside the lupin
patches this was also apparent, but the effect was
not significant across all species (Table 3).
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