Takuro Masuda

Impact of land use and land cover changes on the ambient temperature in a middle scale city, Takamatsu, in Southwest Japan.

There is a lack of information on urban heat island impact on the thermal environment due to low populated urban sprawl, although densely populated urban sprawl impact has been identified by several researchers. The Takamatsu area has recently developed in a low populated urban sprawl style without any increase in population. This paper examined the impact of a low populated urban sprawl on the thermal environment through an analysis of the last 30 years data set and investigated the contribution of vegetation fraction and population density to the temperature trend. As a consequence, it was shown that one of the most significant causative factors of temperature increase is an expansion of non-vegetated area even without population growth. This result implied that vegetated zones should be maintained in urban areas in order to realize sustainable urbanization.

Effects of radical water stress on Cinnamomum camphora and Quercus glauca.

野外に生育している大型の樹木 (クスノキとアラカシ) で飽和光合成速度の季節的変化を調べたところ, 夏の乾燥期に明らかな低下を示す個体が認められた。そこで, ポット植栽のクスノキ, アラカシの苗木を用いて水ストレスが光合成速度などに与える影響を調べた。土壌の水分張力が初期萎凋点を越えると, クスノキは日中の気孔開度が低下し, まず蒸散速度が低くくなり, その後, 光合成速度が徐々に低下した。一方, アラカシは, 水分張力が永久萎凋点を超えるまでは, 蒸散, 光合成活動は土壌の水分ストレスの影響をほとんど受けないで, 十分に水分のある状態と変わらない値を維持した。さらに, アラカシとクスノキでは吸水が完全に起こらなくなる土壌の水分張力に明らかな違いが認められた。

Wildfire damage evaluation by merging remote sensing with a fire area simulation model in Naoshima, Kagawa, Japan

Not only wildfire damage, but the failure of post-fire forest restoration is also one of the major threats for the conservation of forest ecosystems. Therefore, it is required to estimate wildfire damaged potential and recovery capacity to orientate the management of a post-fire community. The aim of our research is to estimate the resistibility against wildfire and the post-fire regeneration capacity by merging field observation data with Terra/ASTER Level1B satellite data and a fire area simulation model (FARSITE). As a result, the resistibility against wildfire and the post-fire regeneration capacity were high in the high prior-fire normalized differential vegetation index (NDVI) areas, where the trees had been thriving. Also, after the fire, the well developed surface soil (the A horizon) provided a good environment for resprouting from unburned stumps and the rhizome. It is suggested that the thriving forests have a strong resistance against wildfire and have large regeneration capacity.

Soil water Conditions and The Root Distribution of Salix matsudana in The Mu Us Desert, China

中国の毛烏素沙地において, 土壌水分条件および主要な緑化樹である旱柳の根系分布を調査した。旱柳は低地から砂丘の上まで植栽されているが, 地下水位80-100cmの低地では根系発達が極めて悪く, 枯死木もみられた。地下水位1.5m程度の半固定砂地で最も良い生育を示した。砂丘上の砂は有効水分が少なく, 早柳の根系分布密度は疎になり, 分布範囲か広くなっていた。高さ5m以上の砂丘では, 水分不足のため, 早柳の生育は困難であった。