Are irregular stands more windfirm?

Mason, W. L.

doi:10.1093/forestry/75.4.347

Cited by 93 publications

(82 citation statements)

References 21 publications

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“…However, many authors expect greater stability of unevenaged systems due to overstorey trees becoming acclimated to the wind (Cameron, 2002;Mason, 2002). Selection forests would be more wind resistant mainly due to higher individual tree stability resulting from better shape (lever arm and bole taper) and better acclimation to wind (Dhôte, 2005).…”

Section: Regeneration Methodsmentioning

confidence: 99%

The influences of forest stand management on biotic and abiotic risks of damage

Jactel

Nicoll

Branco³

et al. 2009

Ann. For. Sci.

232

167

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Abstract• This article synthesizes and reviews the available information on the effects of forestry practices on the occurrence of biotic and abiotic hazards, as well as on stand susceptibility to these damaging agents, concentrating on mammal herbivores, pest insects, pathogenic fungi, wind and fire.• The management operations examined are site selection, site preparation, stand composition, regeneration method, cleaning and weed control, thinning and pruning, and harvesting. For each of these operations we have examined how they influence the occurrence of biotic and abiotic damaging agents, the susceptibility of European forests, and describe the ecological processes that may explain these influences.• Overall, we find that the silvicultural operations that have the largest influence on both biotic and abiotic risks to European forest stands are closely related to species composition and the structure of the overstorey. Four main processes that drive the causal relationships between stand management and susceptibility have been identified: effect on local microclimate, provision of fuel and resources to biotic and abiotic hazards, enhancement of biological control by natural enemies and changes in individual tree physiology and development.• The review demonstrates an opportunity to develop silvicultural methods that achieve forest management objectives at the same time as minimising biotic and abiotic risks. Mots-clés :sylviculture / peuplement / occurrence / sensibilité / Résumé -Influences de la sylviculture sur le risque de dégâts biotiques et abiotiques dans les peuplements forestiers.• Cette revue bibliographique s'intéresse aux effets de la sylviculture sur la sensibilité des peuplements forestiers aux principaux agents de dégâts biotiques et abiotiques que sont les mammifères herbivores, les insectes ravageurs, les champignons pathogènes, le feu et les vents forts. * Corresponding author: herve.jactel@pierroton.inra.frArticle published by EDP Sciences Ann. For. Sci. 66 (2009) 701 H. Jactel et al.• Les pratiques forestières analysées sont la sélection et la préparation des sites de reboisement, la définition de la composition en essences et le choix du matériel génétique, les méthodes de régé-nération et d'entretien, les modalités d'éclaircie et d'élagage, le mode de récolte finale. L'influence de chacune de ces opérations sur l'occurrence des agents de dégâts biotiques et abiotiques et sur la sensibilité des peuplements est examinée ainsi que les processus écologiques sous-jacents.• Les opérations sylvicoles qui se révèlent les plus déterminantes pour la sensibilité des forêts en Europe sont celles qui affectent la composition et la structure de la strate arborée. Quatre principaux processus écologiques semblent expliquer la relation entre sylviculture et sensibilité des peuplements : la modification du micro-climat, l'apport de ressources ou de combustible aux agents de dégâts, l'amélioration du contrôle biologique par les ennemis naturels et l'altération de la physiologie et du développement des arb...

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Section: Regeneration Methodsmentioning

confidence: 99%

The influences of forest stand management on biotic and abiotic risks of damage

Jactel

Nicoll

Branco³

et al. 2009

Ann. For. Sci.

232

167

View full text Add to dashboard Cite

show abstract

“…The initial recommendation was that CCF was best confined to sheltered sites on deep rooting soils where thinning at regular intervals could be used to gradually open up stands and provide a favourable regeneration environment [9]. A review of evidence about the stability of irregular stands [66] suggested that this recommendation might be pessimistic, since it overlooked the likelihood that dominant trees in irregular stands would be better adapted to withstand the forces of the wind, evidenced in more favourable (lower) height: diameter ratios, greater root mass, and stronger buttressing. Some preliminary modelling using the wind risk model ForestGALES [67] supported this suggestion, indicating that irregular structures could be more stable than regularly thinned even-aged stands on sites of intermediate wind exposure and that heavy early thinning might be used to develop stable dominants as part of the transformation process [66,68].…”

Section: Wind Stability Of Irregular Standsmentioning

confidence: 99%

“…A review of evidence about the stability of irregular stands [66] suggested that this recommendation might be pessimistic, since it overlooked the likelihood that dominant trees in irregular stands would be better adapted to withstand the forces of the wind, evidenced in more favourable (lower) height: diameter ratios, greater root mass, and stronger buttressing. Some preliminary modelling using the wind risk model ForestGALES [67] supported this suggestion, indicating that irregular structures could be more stable than regularly thinned even-aged stands on sites of intermediate wind exposure and that heavy early thinning might be used to develop stable dominants as part of the transformation process [66,68]. A wind tunnel examination of the effect of different stand structures (even-aged, shelterwood, selection) upon the incidence of damaging gusts found similar wind and turbulence characteristics over the different types.…”

Section: Wind Stability Of Irregular Standsmentioning

confidence: 99%

Implementing Continuous Cover Forestry in Planted Forests: Experience with Sitka Spruce (Picea Sitchensis) in the British Isles

Mason

2015

Forests

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Planted forests of Sitka spruce, a non-native species from north-west America, are the major forest type in Great Britain and Ireland. Standard management involves even-aged stands, rotations of 40-50 years and a patch clear-felling system with artificial regeneration. However, forest policies support managing these forests for multifunctional objectives with increased diversity of species composition and stand structure. Continuous cover forestry (CCF) is an alternative silvicultural approach used to provide such diversity, but the amount of CCF forest is under 10% of the forest area, and less in Sitka spruce forests; This paper reviews research carried out in the last two decades to support the implementation of CCF in Sitka spruce planted forests; Stand structures and microclimate favouring natural regeneration are understood. Harvesting systems have been adapted for use in CCF stands, a single-tree growth model has been calibrated, comparative costs and revenues have been determined, and operational trials established. The interaction between thinning and wind stability in irregular stands is problematic, together with the lack of suitable species for growing in mixture with Sitka spruce; Introduction of an alternative silvicultural approach may take decades and must overcome technical challenges and cultural resistance.

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“…Even if site conditions are assumed to be such that endemic windthrow is minimal, the threat of catastrophic windthrow remains [2]. However, it appears that there is little difference in windthrow risk between regular and irregular Sitka spruce stands on relatively sheltered sites [48]. Guidance on the selection of sites suitable for continuous cover forestry is generally to avoid areas of high wind risk [6].…”

Section: Risk and Stochastic Eventsmentioning

confidence: 99%

Comparing the Costs and Revenues of Transformation to Continuous Cover Forestry for Sitka Spruce in Great Britain

Davies

Kerr

2015

Forests

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Abstract:Recently continuous cover forestry (CCF) has become an accepted approach to forest management in Britain, but uncertainty about its economic consequences may be a barrier to its wider use. A study was carried out to examine the costs and revenues of transforming a stand of Sitka spruce (Picea sitchensis (Bong.) Carr.) to CCF. The main conclusion is that transformation to CCF need not be more costly than clearfelling and replanting if natural regeneration is successful and the aim is to produce a simple canopy structure. The long-term value of transformation to a more complex canopy structure, with three or more strata, is lower and the extra costs need to be justified in terms of management objectives. The main output from the study is an analysis spreadsheet that empowers practitioners and policy makers to investigate the effects of costs, revenues and discount rates on estimates of net present value over 20 years, 100 years and in perpetuity, to suit local conditions. This paper summarises the method and results of the study in a British context, sets these in a wider international context, and considers the merits, applications and possible further developments of the approach.

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Are irregular stands more windfirm?

Cited by 93 publications

References 21 publications

The influences of forest stand management on biotic and abiotic risks of damage

The influences of forest stand management on biotic and abiotic risks of damage

Implementing Continuous Cover Forestry in Planted Forests: Experience with Sitka Spruce (Picea Sitchensis) in the British Isles

Comparing the Costs and Revenues of Transformation to Continuous Cover Forestry for Sitka Spruce in Great Britain

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