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Continuous observations and environmental analysis of forest decline in sub-arctic coniferous forest

亚北极针叶林森林衰退的连续观测与环境分析

基本信息

批准号：
04404011
负责人：
OHSATO Shoichi
金额：
$ 11.84万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1994
项目状态：
已结题

项目摘要

1) Recently, decline of yezo spruce and todo fir in boreal forests in Hokkaido has been widely observed. In order to clarify the mechanism of the decline, water status of ezo spruce and todo fir trees were investigated at Tokyo University Forest in Hokkaido.The decline is occurring mainly in stands damaged by Typhoon XV in 1981 (D-stands), and not observed in undamaged stands (H-stands). Severity of decline in the sample trees was evaluated in the stands, and water relation parameters such as diurnal water potentials, water potential at turgor-loss point (PSIw (tlp)), osmotic potential at saturation point (PSIs (sat)), and cell wall elasticity (epsilon) were estimated by pressure chamber technique.The diurnal trends of the water potentials in sample trees were clearly different between D-stands and H-stands, that means water stress in trees was more severe in D-stands than in H-stands. An yezo spruce tree which died during the observation in a D-stand showed the most severe water stress of PSIw below -2.0MPa. PSIw (tlp) and PSIs (sat) of the declined trees were lower in D-stands than in H-stands.From these results, the major factor which cause decline of yezo spruce and todo fir is thought to be micro climate change in stand level by the typhoon damage, which resulted in water stress in the conifer trees. The measurement of water relation parameters should be useful for prediction of the decline.2) GPS positioning tests were conducted in the Tokyo University Forest in Hokkaido, to evaluate differential GPS (DGPS) accuracy in forested areas. The results indicate that the mean error was less than 1m by the carrier phase positioning method, and less than 10m by the translocation method, although operation efficiency reduced to 1/3 to 2/3 compared with point positioning.

1)近年来，北海道北方森林中的野藏云杉和东花旗松的衰退已被广泛观察。为了阐明这种衰退的机理，在北海道的东京大学森林对云杉和冷杉的水分状况进行了调查，结果表明，衰退主要发生在1981年第15号台风破坏的林分（D-林分），而未破坏的林分（H-林分）则没有观察到。在林分中测定了样木衰退的严重程度，并测定了日水势、蒸腾失点水势、蒸腾失点水势等水分关系参数（PSIw（tlp）），饱和点的渗透势（PSIs（sat））和细胞壁弹性（ψ）的日变化趋势在D林和H林有明显差异，说明D林分林木的水分胁迫比H林分严重。在D-林分观测过程中死亡的一株云杉表现出最严重的PSIw，低于-2.0MPa。结果表明，台风灾害引起的林分层次的小气候变化，导致针叶树的水分胁迫，是引起云杉和冷杉衰退的主要原因。在北海道的东京大学森林进行了GPS定位试验，以评估差分GPS（DGPS）在森林地区的精度。结果表明，载波相位定位法的平均误差小于1 m，移位定位法的平均误差小于10 m，但作业效率仅为单点定位的1/3 ~ 2/3。