Salvage logging of mountain birch after geometrid outbreaks: Ecological context determines management outcomes
Permanent lenke
https://hdl.handle.net/10037/11765Dato
2017-12-01Type
Journal articleTidsskriftartikkel
Peer reviewed
Forfatter
Vindstad, Ole Petter Laksforsmo; Jepsen, Jane Uhd; Klinghardt, Moritz; Ek, Malin; Ims, Rolf AnkerSammendrag
Outbreaks of pest insects occasionally cause mortality of entire forest stands. Salvage logging of affected stands is
the most common management response to such events. Logging may aid stand recovery by increasing the
production and establishment of saplings, or stimulating the production of basal sprouts in sprouting tree species.
However, the outcome of logging may depend on the ecological context in which it is implemented, with
both herbivory and local growing conditions being potentially important factors. We conducted a field experiment
to assess how logging affects recovery by saplings and sprouts in stands of mountain birch that have been
damaged by outbreaks of geometrid moths. The study was conducted at the two locations Luftjok and Bugøyfjord
in subarctic Norway, where moth outbreaks have caused widespread mortality of mountain birch during the last
two decades. Logging generally caused a strong increase in the production of basal sprouts, and also improved
sprout growth in Luftjok, resulting in a substantial production of new stems in the logging plots at this location
within the six-year period of the study. In Bugøyfjord, sprout growth was retarded in logging plots compared to
controls, resulting in complete failure to produce new stems during the study period. This appears to have been
caused by ungulate browsing, possibly in interaction with regional, geologically determined, gradients in
growing conditions. The outcome of logging also depended on local site quality, with limited sprouting occuring
in rich meadow type stands, which traditionally have been assumed to have low capacity for sprout production.
Birch saplings were less abundant in logging plots than in controls by the end of the study, especially in
Bugøyfjord, suggesting that logging did not improve sapling production. We conclude that logging may stimulate
damaged mountain birch stands to recover by means of basal sprouting, but that the positive effects of logging
may be reduced by browsing in some areas. Logging should also be practiced with care in rich meadow type
stands, which have limited capacity for sprouting.
Basal sprout
Sapling
Herbivory
Stand recovery
Site quality
Field experiment