A case study on the effect of Japanese larch (Larix kaempferi Carr.) arable land windbreaks on the reduction of wind damage in Kamioribe District, Shihoro Town, eastern Hokkaido, Japan, is reported. Wind damage occurred on May 8, 2016. Buds of larches were supposed to be just opened, and the leaves on short shoots were still extending at that time. The percentage of severe damage was high on arable lands outside sheltered areas. In contrast, it was low on lands within areas 15 to 20 times the heights of windbreaks leeward to Japanese larch arable land windbreaks. These differences were statistically significant. The results of this study indicate that Japanese larch arable land windbreaks are effective for the reduction of wind damage during the early spring cultivation season, regardless of if its buds are closed or its leaves are not fully extended.
The "preserved tree system" and "preserved forest system" aim to preserve trees and forests in cities in Japan, and are operated by local governments. We conducted a questionnaire of the operators of the preserved tree system to examine their awareness of the systems in Nagoya (215 operators) and Shizuoka (60 operators), and clarified the relationships among operators, local governments, and community residents not involved in tree management. Questionnaires were returned by 117 (Nagoya) and 30 (Shizuoka) operators. The results were as follows: 1) Although local governments and operators agreed on the goals of the system (green preservation, improving aesthetic appeal, and preservation of trees with historical and cultural value), there were concerns over the associated costs and economic burden faced by the management; 2) There was a risk of conflict between the operators and community residents because calls for preservation by neighboring residents increased when operators stopped tree management. For sustainable preservation of designated trees in the local environment, promotion of cooperation between community residents and operators is crucial.
This study proposes a way to apply stem analysis to pollarded trees and to show the relationship between the growth of a pollarded tree and topping the main trunk. As an example, we examined a pollarded wild sugi (Cryptomeria japonica) tree. The study tree was in a sugi plantation with scattered wild sugi trees in Tsunagi hamlet, Aga Town, Niigata Prefecture, Japan. The main trunk was thought to have been broken by heavy snow. The part of a coppiced tree that differs most from a single-stemmed tree is the area that connects the remaining trunk and the pollard shoots. Examining disks taken by slicing through part of the tree allows the budding location and timing of the formation of the shoots to be determined from the distribution of annual rings. This study showed that losing the upper part of the trunk had a great effect on the secondary growth of the remaining trunk, suggesting that topping a main trunk also affects the secondary growth of the remaining trunk. Competition between the shoots was found, suggesting that in order to obtain large, high quality logs from the remaining trunks, shoots that are likely to die are pruned before they put on much growth.