報告書番号

U89017

タイトル（和文）

スギ衰退とオキシダント降雨量の分布に関する一考察

タイトル（英文）

DECLINE OF JAPANESE CEDAR(CRYPTOMERIA JAPONICA)AND POTENTIAL CORRELATION OF OXIDANTS AND PRECIPITATION

概要 （図表や脚注は「報告書全文」に掲載しております）

関東・甲信地方におけるスギの衰退分布とオキシダント，降雨量の関連性について検討するとともに，関東・甲信地方のスギ衰退地域と類似する地域を全国レベルで検討した。関東・甲信地方におけるスギの衰退地域は，オキシダント指数（５～９月の昼間の１時間値が０．０６ｐｐｍを越えた時間数の合計）が高い地域と重なり，スギの激害・中害地は長距離輸送に伴う内陸型大気汚染地域と海陸風の循環に伴う沿岸型汚染地域と重なった。ただし，降雨量が多いと衰退程度が軽減し，スギの激害・中害地はオキシダント指数が１５０以上の地域でかつ暖候期の降雨量が８００ｍｍ以下の地域に分布していた。また，オキシダント指数と暖候期の降雨量の分布について，全国レベル（北海道，沖縄を除く）で検討した結果，関東・甲信地方のスギ衰退地域の特徴と類似する地域が認められた。

概要 （英文）

THE DECLINE OF SUGI (JAPANESE CEDA ; CRYPTOMERIA JAPONICA) HAS BEEN RECOGNIZED AND STUDIED IN SUBURBAN AREAS IN JAPAN,SINCE THE LATE 1960 S. HOWEVER,THE CAUSAL FACTORS OF SUGI DECLINE HAVE NOT BEEN IDENTIFIED. IN THIS REPORT,RELATIONSHIPS BETWEEN THE DECLINE OF SUGI AND ITS POTENTIAL CAUSAL FACTORS IN THE KANTO-KOSHIN DISTRICTWERE DISCUSSED. 1)TYPICAL SYMPTOMS OF DECLINING TREES WERE DIEBACK FROM THE TOPS AND A GRADUAL DECREASE IN THE NUMBER OF NEEDLES. THE DISTRIBUTION OF DECLINED SUGI EXTENDED A LARGE REGION IN AN ELEVATION LESS THAN 150 M AND WERE NARROWER IN THE NORTHERN AND WESTERN PARTS OF THE KANTO DISTRICT RATHER THAN IN THE EASTERN PART. 2)DISTRIBUTION OF 01(OXIDANTS INDEX : AVERAGE OF TOTAL HOURS EXCEEDING 0.06 PPM/HR FROM MAY TO SEPTEMBER) MORE THAN 150 AND ATP(AVERAGE OF TOTAL PRECIPITATION FROM MAY TO SEPTEMBER) BELOW 800 MM COINCIDED WITH THE DISTRIBUTION OF SUGI DECLINE IN THE KANTO-KOSHIN DISTRICT. THUS,OXIDANTS AND/OR PRECIPITATION DURING THE GROWING SEASON OF SUGI ARE A POSSIBLE CONTRIBUTING FACTORS OF SUGI DECLINE. 3)TO STUDY THE POSSIBLE LINKAGE OF OXIDANT AND PRECIPITATION WITH SUGI DECLINE,NATIONWIDE ANALYSIS OF 01 AND ATP WERE CONDUCTED. THE AREAS WITH THE CHARACTERISTICS OF 01 AND ATP SIMILAR TO THOSE IN THE AREA WHICH SUGI DECLINED OF THE KANTO-KOSHIN DISTRICT WERE THE NARA BASIN,THE OSAKA AND WAKAYAMA PLAINS AND THE SETOUCHI DISTRICT. SUCH AREAS MAY ALSO EXPERIENCE THE DECLINE OF SUGI.

報告者

キーワード