Utskrift
Etter en hogst skal ny skog etableres. For at foryngelsen skal bli biologisk og økonomisk optimal, må både planting og naturlig foryngelse gjennomføres på riktig måte. Markberedning er noen steder nødvendig for å sikre gode plante- eller spireplasser.
Kjersti Holt Hanssen
Forsker
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Divisjon for skog og utmark
(+47) 996 44 123 kjersti.hanssen@nibio.no Kontorsted: Ås - Bygg H8
Skog kan forynges både med planting, såing og naturlig foryngelse fra frø. I Norge er planting mest vanlig i granskog, mens det meste av furuskogen forynges naturlig.
Markberedning gir mange fordeler ved foryngelse av skog, men er ikke mulig å gjennomføre over alt. Les mer om markberedning her.
Gransnutebiller gnager barken av småplantene, og kan være et stort problem for foryngelsen. Les mer om gransnutebiller og mottiltak her.
Picea abies seedlings were given three different fertilization treatments in the nutrient solution by varying the potassium:nitrogen (K:N) ratios (2.5, 3.0 or 3.9 g g–1). All fertilization treatments were combined with short-day (SD) treatment or no such treatment (control). Above- and belowground growth responses in the seedlings were analyzed. The SD treatment resulted in significantly reduced shoot height, compared to untreated control, irrespective of K:N ratio. No combination of photoperiod treatment or fertilization treatment affected the root collar diameter. In the current year root fraction with diameter < 0.5 mm, the highest K:N ratio led to significantly increased root length in control plants. In each 0.1 mm root diameter class up to 0.5 mm, the highest K:N ratio significantly stimulated root growth in control plants, while the effect was less evident for SD plants. SD treatment stimulated length growth in some fine root diameter classes. We conclude that SD treatment is a good and sufficient measure to reduce height growth without compromising fine root growth of P. abies seedlings. Fertilization treatment did not significantly improve aboveground growth in SD treated seedlings, and only limited effects on root growth was seen on control plants.
Le gel printanier peut etre dommageable pour les semis de Picea abies (L.) Karst. nouvellement plantes si leur rythme de croissance n'est pas suffisamment adapte aux conditions climatiques de la station forestiere. Les objectifs de cette etude consistaient a determiner de quelle facon le debourrement et la resistance au gel printanier sont influences par un traitement de jours courts (JC) appliques a differents moments et avec differents regimes de temperature durant la periode de formation des bourgeons. A la suite d'un entreposage hivernal, la resistance au gel a ete evaluee apres une, trois et cinq semaines dans des conditions de forcage. Le traitement JC a avance le debourrement comparativement aux semis temoins. Par comparaison, le moment du traitement et les differentes temperatures ont eu peu d'effet sur le debourrement. Le traitement JC a augmente la resistance au gel des aiguilles d'un an pendant la periode de desendurcissement. Applique tot, le traitement JC a augmente la resistance au gel des aiguilles d'un an et le diametre au collet comparativement a une application plus tardive. Il est important que la periode de noirceur atteigne une duree critique lorsque le traitement JC prend fin pour eviter une deuxieme eclosion des bourgeons. Des temperatures basses a la suite du traitement JC ont augmente la resistance au gel des aiguilles et diminue celle de la tige. Les effets contraires de la temperature sur differents tissus vegetaux demontrent l'importance d'examiner differents tissus apres des essais de gel-degel. Spring frost may result in detrimental damage in newly planted Picea abies (L.) Karst. seedlings if their growth rhythm is not sufficiently adapted to the climatic conditions on the forest site. The aims of this study were to evaluate how bud break and spring frost hardiness were influenced by short-day (SD) treatments with different timing and different temperature regimes during bud formation. Following winter storage, frost hardiness was tested after 1, 3 and 5 weeks in forcing conditions. The SD treatment advanced bud break compared with the control seedlings. In comparison, the effects of timing and the different temperatures on bud break were small. The SD treatment improved frost hardiness in first-year needles during dehardening. The early SD treatment resulted in improved frost hardiness in first-year needles and greater root collar diameter compared with later SD treatment. To avoid a second bud flush, it is important that a critical night length is attained when the SD treatment terminates. Low temperatures following the SD treatment resulted in increased hardiness of the needles and decreased hardiness of the stems. The contrasting effect of temperature in different plant tissues demonstrates the importance of examining different tissues following freezing tests.
Manipulation of the canopy cover and site preparation are the most important silvicultural measures to enhance the conditions for natural regeneration of Norway spruce (Picea abies (L.) Karst.). During the early regeneration phase however, seedling mortality may be high, so it is important to study how different combinations of stand-level treatments and site preparation methods affect seedling establishment. We studied emergence, 1st winter and 2nd summer mortality for naturally regenerated spruce seedlings in a field experiment that combined four harvest treatments (shelterwoods of high (SH), medium (SM) and low (SL) residual basal area, and a 50 x 50 m clear-cut (CC)) and two site preparation methods (patch scarification and inverting). The CC had significantly fewer seedlings the 1st fall than the SL and SH (p = 0.0377), and in all harvest treatments, fewer seedlings emerged in inverted than in patch scarified spots (p = 0.0351). Mortality was also lower with patch scarification than inverting (1st winter: p = 0.0565, 2nd summer: p = 0.0377), but was not affected by harvest treatment (1st winter: p = 0.9211, 2nd summer: p = 0.1896). On average, mortality from 1st to 2nd fall reached 38% and 27% after inverting and patch scarification, respectively. First winter mortality accounted for approximately two thirds of the accumulated mortality, regardless of the harvest treatment and site preparation method.
