We developed a method of measuring the turning moment for standing trees in natural wind. We used strain gauges attached to stems 1.3m in height to measure the strain to which they were exposed while swaying in the wind. The turning moment of the trees was obtained by multiplying the measured strain with coefficients determined by pulling tests of the trees.
We considered an adequate sampling frequency to detect the strain fluctuation peaks and pulling heights of tree stems to obtain coefficients in the pulling tests of trees. In our case, more than 10Hz of sampling frequency was needed to detect the peaks of the turning moment fluctuation. Pulling heights at the gravity center of wind were required to measure the coefficient due to the height dependency. We measured the turning moment for four trees in a coastal pine forest ( Pinus thunbergii ) in Aichi prefecture. The recorded maximum turning moment were estimated in 100Nm-600Nm for sample trees under strong wind conditions in 8 to 10m/s. Developed method is expected to use in evaluation of wind damage risk and ecological researches to clarify the effects of wind force to trees and forests.

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Characteristics of coastal forest damage in the Sendai Plain caused by the 2011 off the pacific coast of Tohoku Earthquake Tsunami is that a lot of tree uprooting damages were observed with a part them being washed away all together with the roots. Therefore, conditions that caused tree uprooting have been demonstrated by measuring the depth of ground water beneath the affected area where Pinus densiflora Sieb.et Zucc.and PinusThunbergii Parl grew. Relationship of trunk break and tree uprooting damage with tree size (diameter at breast height) was also examined. At a part with a ground water depth of less than about 1.0 m, trees were uprooted and flown out regardless of their sizes. In contrast, both trunk break and tree uprooting were observed in only smaller number of samples with a diameter at breast height of more than 20 cm. Therefore, we think that it was required to secure adequate depth of ground water by way of filling and regenerate forests filled with thick and robust trees in order to build up coastal forests with higher resistance against tsunami. In consideration of impacts of ground sinking and the like, it was believed the depth of ground water to be secured for filling was required at least 1.5 m.

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The purpose of this study was to clarify the salt-water tolerance of broadleaved trees on the basis of their damage and recovery in premises forests, shrine and temple groves. The superiority or inferiority of salt-water tolerance for each tree species was judged by the extent of flooding of trees due to a tsunami and by the growth condition based on the rate of leaves on the trees at each site, and the salt-water tolerance in the sites was ranked by collating the rankings at each site. As a result, it was inferred that Euonymus japonicus has a similar salt-water tolerance to Pinus thunbergii ; it is likely that such trees with high salt-water tolerance will be used in the replanting of coastal forests in the future. In addition, it was inferred that Zelkova serrata and Celtis sinensis have salt-water tolerance from the recovery of trees by progress of time. The superiority or inferiority of trees and the ranking of salt-water tolerance were performed using strict definitions with no logical inconsistencies, although few trees were investigated. Moreover, an objective conclusion without site-specific factors (i.e., microtopography and growth conditions) and with a limited influence at each site was reached by conducting an investigation of many sites.

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