Windthrow probability as a function of stand characteristics and shelter

Lohmander, Peter; Helles, Finn

doi:10.1080/02827588709382460

Cited by 190 publications

(147 citation statements)

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“…Thinning operations are a major element of silviculture and an important factor with respect to wind as they temporarily reduce stand stability [1,11,30,51,57]. Our experimental installations were unable to provide information on the effect of time since the last thinning operations because the 20-yearold stand had not yet been thinned and the 51-year-old stand had been thinned 16 years before the storm in all the plots at the same date ( figure 3).…”

Section: Stand Density and The Damping Stand Effectmentioning

confidence: 95%

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: 95%

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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“…This study further extended former studies by pioneering the introduction of shrub biomass in a wildfire occurrence model and by using ignitions points. Previous studies used logistic methods to predict wind and snow damage probability as a function of stand variables (Jalkanen and Mattila, 2000;Lohmander and Helles, 1987) and also to predict fire ignition probabilities Vanconcelos et al, 2001), showing to be an appropriate technique to model events which occurrence is a binomial outcome Monserud and Sterba, 1999).…”

Section: Discussionmentioning

confidence: 99%

Assessing wildfire occurrence probability in Pinus pinaster Ait. stands in Portugal

Marques¹,

García-Gonzalo²,

Botequim³

et al. 2012

For. syst.

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Maritime pine (Pinus pinaster Ait.) is an important conifer from the western Mediterranean Basin extending over 22% of the forest area in Portugal. In the last three decades nearly 4% of Maritime pine area has been burned by wildfires. Yet no wildfire occurrence probability models are available and forest and fire management planning activities are thus carried out mostly independently of each other. This paper presents research to address this gap. Specifically, it presents a model to assess wildfire occurrence probability in regular and pure Maritime pine stands in Portugal. Emphasis was in developing a model based on easily available inventory data so that it might be useful to forest managers. For that purpose, data from the last two Portuguese National Forest Inventories (NFI) and data from wildfire perimeters in the years from 1998 to 2004 and from 2006 to 2007 were used. A binary logistic regression model was build using biometric data from the NFI. Biometric data included indicators that might be changed by operations prescribed in forest planning. Results showed that the probability of wildfire occurrence in a stand increases in stand located at steeper slopes and with high shrubs load while it decreases with precipitation and with stand basal area. These results are instrumental for assessing the impact of forest management options on wildfire probability thus helping forest managers to reduce the risk of wildfires.Key words: forest management; risk; fire occurrence model; Pinus pinaster Ait. Resumen Evaluación de la probabilidad de ocurrencia de fuegos en rodales de Pinus pinaster en PortugalEl articulo presenta un modelo para evaluar la probabilidad de ocurrencia de incendios en masas regulares y puras de Pinus pinaster en Portugal. Se desarrolla un modelo basado en datos de inventario fácilmente disponibles de tal forma que pueda ser una herramienta útil para los gestores forestales. Los datos proceden de los dos Inventarios Nacionales de Portugal (NFI) y de los datos de los parámetros de incendios forestales durante los años 1998-2004 y de 2006 a 2007. Se ha utilizado un modelo de regresión logística binarias utilizando datos biométricos del NFI. Los datos biométricos incluyen indicadores que puedan ser cambios en las operaciones prescritas en los planes forestales. Los resultados muestran que la probabilidad de ocurrencia de incendios en un rodal aumenta en rodales localizados en grandes pendientes y con una carga alta de matorrales, mientras que decrece con la precipitación y con el área basimétrica. Estos resultados son instrumentos para evaluar el impacto de las opciones de gestión forestal en la probabilidad de incendios ayudando por tanto a los gestores a reducir el riesgo de incendio.Palabras clave: gestion forestal, riesgo, modelo de ocurrencia de incendios, Pinus pinaster Ait.

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“…The highest risk of wind damage is most likely to be found where there are sudden changes in wind loading to which the trees are not acclimated, as in stands adjacent to recently clear-felled areas or in stands that have recently been thinned intensively (Neustein, 1965;Kolstock and Lockow, 1981;Laiho, 1987;Lohmander and Helles, 1987;Peltola, 1996a,b;Gardiner et al, 1997Peltola et al, 1999a). Therefore, the most basic questions in the planning of forest management are how new clear-cuttings and/or thinnings may affect the speed and direction of local airflow and how the wind hits the downwind forest (Peltola, 1996b;Peltola et al, 1999a;Talkkari et al, 2000).…”

Section: Introductionmentioning

confidence: 99%