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首页> 外文期刊>Berichte des Meteorologischen Institutes der Universitat Freiburg >The development of a wind risk model for irregular stands
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The development of a wind risk model for irregular stands

机译：不规则看台的风向风险模型的开发

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Modelling wind risk to forests has concentrated to date on damage within uniform stands.However, as continuous cover forestry becomes more widely practised, models will be requiredthat can predict the risk of damage to individual trees within any stand structure. The key tobuilding such models is developing an understanding of the response to wind loading ofindividual trees of different sizes. In earlier work on nine trees in a mature Sitka spruce stand(Wellpott, 2008) a turning moment coefficient (Tc) was derived as a measure of the maximumturning moment experienced by a tree in response to a given wind speed. It was found thatsimple competition indices (CI), derived from the ,zoximity and relative size of neighbouringtrees, could be used to estimate Tc for individual trees. We have now analysed additional data collected within five different treatments in a Sitkaspruce spacing experiment (Gardiner et al., 1997) and from a 2-storey larch stand (Wellpott,2008). The wind loading, wind speeds and tree locations relative to their neighbours wereavailable from both sites and provided Tc and C/ for individual trees. Altogether 29 trees werecompared across the three experiments and due to the large differences in tree height (h) (8.7-31.9 m) the data were normalised by h3 (h = tree height) as suggested from earlier wind tunnelexperiments (Stacey et al., 1994). We found that the data collapsed onto a single curve giving astrong relationship between Tc/h3 and CI. Further field measurements are underway in order toobtain a more comprehensive data set to fully validate the relationship. The relationship between competition index and turning moment coefficient provides a methodfor calculating the response to individual trees to wind loading. This allows the calculation ofdifferences in risk of damage across a stand and to build risk models for complex standstructures.
机译：迄今为止，对森林风的风险建模主要集中在统一林分内的破坏。然而，随着连续覆盖森林的广泛应用，将需要模型来预测对任何林分结构内单个树木的破坏风险。建立这样的模型的关键是要了解不同大小的个体树木对风荷载的响应。在成熟的Sitka云杉林中对9棵树进行的早期工作中（Wellpott，2008年），得出了转弯矩系数（Tc）作为对树木在给定风速下所经历的最大转弯矩的度量。研究发现，从邻近树的近邻度和相对大小得出的简单竞争指数（CI）可用于估计每棵树的Tc。现在，我们已经分析了在Sitkaspruce间距实验（Gardiner等人，1997）和2层落叶松林架（Wellpott，2008）中在五种不同处理方式下收集的其他数据。可以从两个站点获得风荷载，风速和树木相对于其邻居的位置，并为单个树木提供了Tc和C /。在这三个实验中总共比较了29棵树，由于树高（h）（8.7-31.9 m）的巨大差异，数据根据h3（h =树高）进行了归一化，如早期风洞实验所建议（Stacey等， 1994）。我们发现，数据折叠到一条曲线上，从而在Tc / h3与CI之间建立了牢固的关系。为了获得更全面的数据集以充分验证这种关系，正在进行进一步的现场测量。竞争指数与弯矩系数之间的关系为计算单个树木对风荷载的响应提供了一种方法。这样可以计算整个展台受损风险的差异，并为复杂的展台结构建立风险模型。

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