In order to consider the state of the future of urban greening in China (especially in the Xinjiang Uygur Autonomous Region), we conducted fundamental research to examine differences in the conception and evaluation of natural landscapes and green tracts of land between the students in China and Japan. For this aim, we carried out questionnaire surveys among the students at Xinjiang Agricultural University (China) and Iwate University (Japan). The investigation included a question paper comprising the following: 1) A drawing investigation of natural scenery. 2) Use of the SD method for assessing photographs of natural and green tracts of land. 3) A description investigation asking about impressions created from the photographs. 4) Use of the AHP method to choose the most desirable photographic image. The results indicated that the Xinjiang students 1) considered the Japanese satoyama to be one of the most desirable landscapes, 2) did not think that roadside trees in farming villages were artificial, and 3) included many artificial objects (people, roads, etc.) in their pictures in comparison with the Iwate students. From the above results, we concluded that the Xinjiang students may have a greater sense of “togetherness of humans and nature” than the Iwate students.

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Using a hierarchical Bayesian model, we analyzed effects of suppression by woody vegetation and release after improvement cutting on growth (tree height and basal diameter) of Cryptomeria japonica clones. The model was constructed based on the differential of the Gompertz equation. The response variable was annual growth and the explanatory variables were annual initial size, suppression indices with coefficients, and growth decrease ratio after release for both traits. Each factor included a fixed effect represented by the average and a random effect of the clone. The suppression indices for evergreen and deciduous trees were the sum of the angles to the top of the competitors within a constant radius (R) from a fixed proportion (β) of the height of the target tree. The values of R and β used were 1.5 m and 0.75, respectively based on the Deviance Information Criterion. The estimated fixed effects indicated that basal diameter growth was more susceptible to suppression but recovered faster after release than height growth. The random effects of the clone suggest that the parameters of the initial growth rate and the maximum size were different among clones with respect to both traits. Clone differences were also observed in the response to deciduous-tree suppression and the recovery in height, but not basal diameter, growth after release. A weak positive correlation was found between the initial growth rate and the recovery after release of each clone. The characteristics of clones that were adapted to Cryptomeria japonica forestry with reduced weeding were discussed.

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We developed a new method to catch adults of the oak borer Platypus quercivorus, the vector of the Japanese oak wilt disease, by covering the entry holes bored on the trunk surface with a wetted face towel. We set towels on the base of three trees attacked by the borer from October to December and caught 13.3 adults per square meter of towel per day per tree. We observed that adults bored new tunnels into the towels extending from their entry holes and were trapped. The sex ratio was extremely biased to males and the rate of the male parents to all male adults captured in December was 24.0%. These results suggest that the reproductive success of P. quercivorus can be reduced by extracting male parents before winter with towels.

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The objective of this study is to quantify the changes in the coefficients of peak discharge (f_p) with reference to the long-term natural recovery of forests on denuded hills. The Ananomiya experimental watershed at the Ecohydrology Research Institute (the University of Tokyo Forests) was selected for this study. We compared the relationship between f_p and discharge when the discharge trend changed from decreasing to increasing (Q_i), and from the onset of precipitation to the time when peak precipitation (P_i) was attained. This was done in order to estimate peak discharge during an early 11-year period and a late 22-year period. Regardless of whether measurements were taken during early or late periods, the f_p increased when the P_i increased. Conversely, the relationship between f_p and Q_i, an indicator of the wetness condition of the watershed, was not clear. The maximum f_p values during the late period, when P_i was 0, 25, and 50, represented a decrease of 53, 45, and 42%, respectively, with respect to the corresponding figures from the early period. This study showed that f_p of a heavy precipitation event referred to as the Tokai Heavy Rain event (total precipitation of 401.5 mm), was 0.58, far below 1.0.

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Recently, securing water resources has become one of the major purposes of forest management in Japan; this is done by thinning in coniferous plantations, replacing coniferous plantations with broadleaved forests, and conducting clearing or thinning operations in bamboo forests to reduce water loss to evapotranspiration. However, the effects of forest management practices on water resources have not been fully clarified because of a lack of evapotranspiration data from Japanese forests. Transpiration is a primary component of evapotranspiration in forested areas. We presented an overview of transpiration measurements based on the sap flow technique, a typical method used for measuring transpiration, to contribute to the accumulation of transpiration data for Japanese forests. Firstly, we compared the sap flow technique with other transpiration measurement methods and showed the usefulness of the sap flow technique for examining the effect of forest management practices on transpiration. Secondly, we explained the scaling-up procedures needed to up-scale from measures of sap flux densities to individual tree-scale transpiration and from individual tree-scale transpiration to stand-scale transpiration. Finally, we summarized stand-scale transpiration measurements based on the sap flow techniques as used in Japan, and recommend the types of forests which should be measured to help land and water managers have an informed discussion related to modifying forest management with the goal of securing water resources by forest practices. Measurements of transpiration are needed from larch plantations, broadleaved forests, and bamboo forests in Japan. Transpiration data measured in Japanese cedar and Japanese cypress plantations at ages of more than 60 years and less than 20 years would also be useful for the discussion.

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Based on a literature review, opinion on the effects of the invasive tree Robinia pseudoacacia was formulated and argued from the viewpoint of social psychology. The current literature claims that soils will be eutrophied by symbiotic nitrogen fixation of R. pseudoacacia, leading to the exclusion of native plant species due to the increased success of nitrophilous invasive plants. However, these case studies failed to demonstrate the ecological effect of this species because of the fatal ‘correlation does not imply causation’ problem in the design of the investigations. Instead, the results of these studies should be considered illusory correlations because some researchers have reported little difference in understory plant diversity between native and R. pseudoacacia stands. Selective cognition based on confirmation bias in information processing should be noted for motivating the acceptance of biased explanations. A case of misrepresentation was also found in a review. Land use in floodplains and the termination of vegetation management in coastal black pine forests have allowed the invasion of R. pseudoacacia. Information about the toxicity of R. pseudoacacia to humans and other animals is limited, and some data are fragmented. Accidental overestimation and the concealing of evidence are suspected concerning the toxicity of this species. R. pseudoacacia contributes to the pollination of crops via apiculture. It is necessary to build a social consensus based on accurate information for the control of R. pseudoacacia.

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