Ane Zubizarreta-Gerendiain, Petri Pellikka, Jordi Garcia-Gonzalo, Veli-Pekka Ikonen, Heli Peltola. (2012). Factors affecting wind and snow damage of individual trees in a small management unit in Finland: assessment based on inventoried damage and mechanistic modelling. Silva Fennica vol. 46 no. 2 article id 441. https://doi.org/10.14214/sf.441

Keywords: Pinus sylvestris; Picea abies; Betula spp.; critical wind speed; snow loading; damage risk

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In this work, we assessed the factors affecting wind and snow damage of individual trees in a small management unit in western Finland. This was done based on inventoried damage and observed wind speeds and snow loading in storms Pyry and Janika in 2001 and Mielikki in 2002 together with mechanistic model. First, we studied which factors explain the observed damage in individual trees. Secondly, we studied how well the mechanistic model (HWIND) could predict the wind speed needed to uproot individual trees at the margins of permanent upwind edges. We found that Pyry storm caused 70% and Janika and Mielikki 18 and 12% of observed damage. In Janika storm, all trees uprooted. In other storms, both uprooting and stem breakage occurred. Scots pine suffered the most damage. Recently thinned stands on the upwind edges of open areas suffered the most damage. But, damage occurred also on soils with relatively shallow anchorage. HWIND predicted correctly damage for 69% of all uprooted trees. No-uprooting was correctly predicted for 45 and 19% of standing trees (all Scots pines), which were measured within and at the immediate upwind edge of same stands. HWIND model needs further validation at the permanent edges and/or on soils with shallow rooting to improve its prediction accuracy in such conditions.

Zubizarreta-Gerendiain, Technical University of Lisbon, School of Agriculture, Forest Research Centre, Lisbon, Portugal E-mail: azg@nn.po
Pellikka, University of Helsinki, Dept. of Geosciences and Geography, Helsinki, Finland E-mail: pp@nn.fi
Garcia-Gonzalo, Technical University of Lisbon, School of Agriculture, Forest Research Centre, Lisbon, Portugal E-mail: jgg@nn.po
Ikonen, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland E-mail: vpi@nn.fi
Peltola, University of Eastern Finland, School of Forest Sciences, Joensuu, Finland E-mail: heli.peltola@uef.fi

article id 501, category Research article

Jiaojun Zhu, Yutaka Gonda, Takeshi Matsuzaki, Masashi Yamamoto. (2003). Modeling relative wind speed by optical stratification porosity within the canopy of a coastal protective forest at different stem densities. Silva Fennica vol. 37 no. 2 article id 501. https://doi.org/10.14214/sf.501

Keywords: coastal protective forest; optical porosity; Pinus thunbergii; vertical forest structure; wind speed

Abstract | View details | Full text in PDF | Author Info

Wind speed and optical stratification porosity (OSP) were measured at various heights inside a coastal protective forest thinned to different stem densities to assess whether any characteristics of the wind profile in the coastal protective forest could be predicted from OSP. OSP was defined as vertical distribution of the proportion of sky hemisphere not obscured by tree elements inside a forest stand, and was determined for various heights using hemispherical photographic silhouettes on a computer processing system. The distribution of OSP in the coastal forest follows the Lambert-Beer’s law with an extinction coefficient (v). The relative wind speed within the canopy can be described using an exponential form with an attenuation coefficient (a). Variation in relative wind speed was very closely correlated with the distribution of OSP within the canopy. While below the canopy, i.e., in the trunk space, relative wind speed was little correlated with the distribution of OSP because the distribution of OSP was relatively constant there. Therefore, the linear relationships between relative wind speed and OSP and between the two coefficients v and a were established within the canopy. The results suggest that OSP can be used to predict the wind profile in case of the application within the canopy of the coastal forest.

Zhu, Qingyuan Station of Forest Ecology, Institute of Applied Ecology, the Chinese Academy of Sciences, No. 72 Wenhua Road, Shenyang 110016, P.R. China; Faculty of Agriculture, Niigata University, Niigata 950-2181, Japan E-mail: jiaojunzhu@iae.ac.cn
Gonda, Faculty of Agriculture, Niigata University, Niigata 950-2181, Japan E-mail: yg@nn.jp
Matsuzaki, Faculty of Agriculture, Niigata University, Niigata 950-2181, Japan E-mail: tm@nn.jp
Yamamoto, Faculty of Agriculture, Niigata University, Niigata 950-2181, Japan E-mail: my@nn.jp

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