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Medientyp:
E-Artikel
Titel:
Defoliation by the common pine sawfly (Diprion pini) and subsequent growth reduction in Scots pine: a retrospective approach
Beteiligte:
Kurkela, Timo;
Aalto, Tarmo;
Varama, Martti;
Jalkanen, Risto
Erschienen:
Finnish Society of Forest Science, 2005
Erschienen in:Silva Fennica
Sprache:
Nicht zu entscheiden
DOI:
10.14214/sf.360
ISSN:
2242-4075
Entstehung:
Anmerkungen:
Beschreibung:
<ja:p>The foliage status in the main stem of Scots pines (Pinus sylvestris) was studied retrospectively using the needle trace method (NTM) on a stand, seriously defoliated by the pine sawfly (Diprion pini) in the 1980s. Needle density increased abruptly in the seasons following the defoliation. The strongest reduction in annual needle production occurred one year later. As a consequence of lower needle production, the annual number of attached needles decreased three to five years after the defoliation. Needle retention and the average age of attached needles tended to increase after defoliation. In analyses of covariance with the NTM variables, needle density (logarithmic transformed values) and average age of attached needles, had the highest, significant, negative relationship with radial and height increments both in the period prior to the defoliation and in the time when the trees were suffering from defoliation. The relationships between height increment and the number of needles and needle loss were positive and significant. Also radial increment had a positive relationship with the number of needles but not with needle loss. Interestingly, an abrupt increase in the needle density gave a good indication of the effects of a sudden defoliation in pines.</ja:p>