Assessing the Risk of Snow and Wind Damage from Tree Physical Characteristics

Valinger, Erik; Lundqvist, Lars; Bondesson, Lennart

doi:10.1093/forestry/66.3.249

Cited by 69 publications

(40 citation statements)

References 9 publications

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“…Previous studies on cultivated stands indicate either an increased risk of damage as the density increases, e.g. in Pinus radiata [11], Pinus sylvestris [56] and Picea abies [1], attributed to the increase of H/D ratio, or a reduced risk as in Picea sitchensis on a peaty gley soil [9]. However, Gardiner et al [21] argue that theses studies did not consider that the wind loading on trees at wider spacing is higher and leads the trees to overturn rather than to break.…”

Section: Stand Density and The Damping Stand Effectmentioning

confidence: 99%

Wind-firmness in Pinus pinaster A�t. stands in Southwest France: influence of stand density, fertilisation and breeding in two experimental stands damaged during the 1999 storm

Cucchi

Bert

2003

Ann. For. Sci.

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-Maritime pine (Pinus pinaster) stands in the Aquitaine region are of great economic importance but subject to Atlantic storms. In the Bordeaux region, two experimental sites located near each other, aged 20 and 51 years, made it possible to study the effects of different types of silviculture on wind-firmness during the 1999 storm. Stand density has a major influence on tree growth. When density increases, height increases and circumference decreases appreciably. In the dense stands, windthrown trees were less abundant and there were more leaning pines. With respect to other silvicultural factors in stands planted at typical densities: (i) genetic breeding did not increase damage intensity at the 20-year-old experimental site and phosphorus fertilisation decreased the windthrow at the 51-year-old experimental site; (ii) compared to the undamaged trees, the circumference of windthrown trees was 3.6 cm smaller, the relative crown length was 10% shorter and the stem taper coefficient was higher. This research has shown that wind-firmness is better in stands where the height, circumference and crown length are homogeneous. A more closed canopy seems to improve wind resistance by increasing the damping effect of swaying as a result of the crowns being in contact with each other and provides a more favourable ratio between the aerial parts and the roots.windthrow / silviculture / Pinus pinaster / stability / storm Résumé -Résistance au vent de peuplements de pin maritime dans le sud-ouest de la France. Influence de la densité, de la fertilisation et de l'amélioration génétique sur deux dispositifs endommagés lors de la tempête du 27 décembre 1999. Les peuplements de Pinus pinaster en Aquitaine sont économiquement très importants mais exposés aux tempêtes océaniques. Dans la région de Bordeaux, deux dispositifs de 20 et 51 ans peu éloignés ont permis d'étudier l'influence de la sylviculture sur la résistance au vent lors de la tempête de 1999. La densité est le facteur sylvicole le plus influent sur les caractéristiques des peuplements. Quand la densité augmente, la circonférence moyenne diminue notablement et la hauteur moyenne a tendance à augmenter. Les chablis étaient moins abondants et les pins penchés plus nombreux dans les peuplements denses. Pour les densités pratiquées en forêt de production : (i) l'amélioration génétique n'a pas augmenté l'intensité des dégâts dans l'essai de 20 ans, et la fertilisation au phosphore a réduit le taux de chablis sur l'essai de 51 ans ; (ii) par rapport aux pins intacts, les chablis ont une circonférence inférieure de 3,6 cm, une longueur relative de houppier plus courte de 10 % et un coefficient d'élancement du tronc plus fort. Ces caractéristiques peuvent traduire la diminution des capacités d'amortissement du balancement des arbres lors des bourrasques. Ces recherches ont montré que la résistance au vent est meilleure dans les peuplements homogènes en hauteur, circonférence ou longueur de houppier. Un couvert plus fermé semble améliorer la résistance au vent en augm...

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Section: Stand Density and The Damping Stand Effectmentioning

confidence: 99%

Wind-firmness in Pinus pinaster A�t. stands in Southwest France: influence of stand density, fertilisation and breeding in two experimental stands damaged during the 1999 storm

Cucchi

Bert

2003

Ann. For. Sci.

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“…Tree and stand characteristics (e.g., crown type, stem taper and strength and stand density) control the resistance of trees to snow, and some tree species are thus more vulnerable to snow damage than others (Valinger et al 1993;Nykänen et al 1997;Peltola et al 1997Peltola et al , 1999Fridman 1997, 1999;Päätalo 2000). For example, Norway spruce (Picea abies (L.) Karst.)…”

Section: Introductionmentioning

confidence: 99%

Modelling crown snow loads in Finland: a comparison of two methods

Lehtonen¹,

Hoppula²,

Pirinen³

et al. 2014

Silva Fenn.

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Modelling crown snow loads in Finland: a comparison of two methodsLehtonen I., Hoppula P., Pirinen P., Gregow H. (2014). Modelling crown snow loads in Finland: a comparison of two methods. Silva Fennica vol. 48 no. 3 article id 1120. 30 p. Highlights• A new method to model crown snow loads is presented and compared with a previously published simpler method.• The heaviest crown snow loads in Finland are found to typically occur in the eastern parts of the country.• The relative importance of different snow load types varies between different regions of Finland. AbstractThe spatial occurrence of heavy crown snow loads in Finland between 1961 and 2010 is studied by using for the first time a model that classifies the snow load into four different types: rime, dry snow, wet snow and frozen snow. In producing this climatology, we used meteorological observations made at 29 locations across Finland. The model performance is evaluated against classified daily images of canopy snow cover and with the help of two short case studies. The results are further compared to those achieved with a simpler method used in previous studies. The heaviest crown snow loads are found to occur typically in eastern Finland. The new method reveals that this holds not only for the total snow loads but also for the different snow load types, although there are certain differences in their geographical occurrence. The greatest benefit achieved with the new method is the inclusion of rime accretion. The forests most prone to heavy riming are those located on tree-covered hills in northern Finland, but as the terrain elevation affects riming efficiency greatly, these small-scale variations in the snow load amounts could not be described in this study in great detail. Moreover, the results are more inaccurate in northern Finland where variations in the terrain elevation are greater than elsewhere. Otherwise, the largest uncertainties in this study are related to wind speed measurements and possibly partly because of that, we were not able to detect any significant trends in the crown snow-load amounts over the study period.

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“…Interpretation keys, largely based on such information, have been proposed for some parts of Canada but they either are not adapted for balsam fir or do not take into account the whole set of influential factors (Meades and Moore 1989, Racey et al 1989, Zelazny et al 1989, Stathers et al 1994, Mitchell 1995. Empirical models based on observed damage have been developed elsewhere but are not calibrated for balsam fir (Valinger et al 1993, Valinger andFridman 1997).…”

Section: Introductionmentioning

confidence: 99%

Estimating windthrow risk in balsam fir stands with the ForestGales model

Ruel¹,

Meunier²,

Quine³

et al. 2000

The Forestry Chronicle

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Balsam fir (Abies balsamea (L.) Mill.) forests are inherently vulnerable to windthrow, especially when silvicultural treatments are applied. During recent years, it has become possible to model windthrow risk based on a good understanding of windthrow mechanics. In the present paper, the British ForestGales model has been adapted for balsam fir with data from a winching study in Quebec, Canada. This model calculates the threshold wind speed required to break or overturn the average tree in a stand and then calculates the probability of exceeding the threshold value. Modifications of the equations predicting crown characteristics and overturning resistance were introduced. The effects of age, site quality, wind exposure, thinning and the creation of new edges were assessed. The estimated critical wind speed for overturning and breakage decreases with age but the probability of damage remains low on sheltered sites. The creation of a new edge leads to an increased probability of damage, especially on exposed, highly productive sites. Thinning alone also increases the probability of damage and the magnitude of the increase varies with age and thinning intensity. On highly productive sheltered sites, the effect of thinning becomes especially important when thinning exceeds 35% of the number of stems or when stand age is greater than 70 years for a 35% thinning intensity. Thinning of new edges was also found to further increase the risk of windthrow on the most sheltered, high quality sites.Les peupements de sapin baumier (Abies balsamea (L.) Mill.) sont, de f a~o n inhkente, vulnCrables au chablis, en particulier lorsque des traitements sylvicoles y sont appliques. Au cours des dernicres annCes, il est devenu possible de modCliser le risque de chablis sur la base d'une saine comprChension de la mCcanique du chablis. Dans le prCsent article, le modkle Britannique ForestGales a Ct C adaptC pour le sapin baumier h partir d'une Ctude de treuillage rCalisCe au QuCbec. Ce modkle calcule la vitesse nkcessaire la rupture ou au deracinement de la tige moyenne d'un peuplement puis estime la probabilite que cette valeur soit dCpasde. Des modifications ont Ct C apportCes aux Cquations prkdisant les caracttristiques de la cime et la rksistance au renversement. La simulation a port6 sur l'effet de l'bge, de la qualit6 de station, de l'exposition au vent, de l'tclaircie et de la crkation de nouvelles lisikres. Selon les simulations, la vitesse critique pour le bris ou le dkracinement diminue avec l'bge mais la probabilitt demeure faible pour les sites abritCs.

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Assessing the Risk of Snow and Wind Damage from Tree Physical Characteristics

Cited by 69 publications

References 9 publications

Wind-firmness in Pinus pinaster A�t. stands in Southwest France: influence of stand density, fertilisation and breeding in two experimental stands damaged during the 1999 storm

Wind-firmness in Pinus pinaster A�t. stands in Southwest France: influence of stand density, fertilisation and breeding in two experimental stands damaged during the 1999 storm

Modelling crown snow loads in Finland: a comparison of two methods

Estimating windthrow risk in balsam fir stands with the ForestGales model

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