報告書番号

U89016

タイトル（和文）

スギの樹幹流，樹冠雨特性の解析－孤立木の樹幹流，樹冠雨のｐＨとＥＣ－

タイトル（英文）

CHARACTERISTICS OF STEMFLOW AND THROUGHFALL UNDER JAPANESE CEDAR (CRYPTOMERIA JAPONICA):PH AND EC OF STEMFLOW AND THROUGHFALL UNDER ISOLATED TREES

概要 （図表や脚注は「報告書全文」に掲載しております）

スギの衰退原因を解明する一環として，千葉県我孫子市において１９８７年夏季の８降雨を対象に，スギ孤立木の樹冠雨・樹幹流の雨量，ｐＨ，ＥＣの特性と気象条件，樹形との関係について検討した。樹冠雨量，樹幹流量は気象条件，樹形と関係した。ｐＨは樹幹流＜樹冠雨＜＝林外雨，ＥＣは林外雨＜樹冠雨＜樹幹流の傾向を示し，樹冠雨のｐＨ，ＥＣは樹冠下の位置によっても異なった。また，初期水と後続水でｐＨ，ＥＣの異なることが明らかとなった。これらのことから，樹幹流，樹冠雨は枝葉に付着している物質を洗い流していると推測され，初期の段階では枝葉に付着したほこりなどのｐＨを低下させない物質の割合が大きく，後続水では酸性の付着物質の占める割合が大きいと推測された。以上の結果から，スギ樹雨の測定に際しては分取が重要であり，樹冠雨の採取位置についても注意する必要のあることが示唆された。

概要 （英文）

THIS STUDY WAS TO CLARIFY THE CHARACTERISTICS OF STEMFLOW AND THROUGHFALL UNDER TWO ISOLATED SUGI (JAPANESE CEDARS:CRYPTOMERIA JAPONICA) IN ABIKO,CHIBA PREFECTURE. SAMPLES OF STEMFLOW AND THROUGHFALL UNDER SUGI IN EIGHT EVENTS WERE COLLECTED IN THE PERIOD OF JULY TO AUGUST,1987. THE INITIAL 100 ML OF RAINFALL IN EACH EVENT WASCOLLECTED SEPARATELY FROM THE REMAINING RAINFALL. AMOUNT,PH AND ELECTRIC CONDUCTIVITY (EC) OF STEMFLOW AND THROUGHFALL WERE DETERMINED AND WERE COMPARED WITH THOSE OF RAINFALL SAMPLE IN AN OPEN SPACE. 1)AMOUNT OFRAINFALL LESS THAN 5 MM IN EACH EVENT DID NOT PRODUCE STEMFLOW,HOWEVER,THAT MORE THAN 10 MM PRODUCED SIGNIFICANT AMOUNT OF STEMFLOW. THROUGHFALL WAS COLLECTED IN EVERY SURVEYED RAIN,HOWEVERE,ITS AMOUNT VARIED WITH THE SITE UNDER THE CANOPY. THE LEAST AMOUNTS OF THROUGHFALL DISTRIBUTED CLOSE TO THE TRUNK IN EVENT EXCEPT FOR THAT AT A STRONG RAIN INTENSITY. THROUGHFALL COLLECTED UNDER THE EDGE OF THE CANOPY WERE AFFECTED THE PREVAILING WIND DIRECTIONS. 2)THE PH OF WATER SAMPLES WAS : STEMFLOW < THROUGHFALL <= AMBIENT RAIN. THE EC WAS : AMBIENT RAIN < THROUGHFALL < STEMFLOW. ESPECIALLY,STEMFLOW WAS MARKEDLY LOWER WITH HIGHER EC THAN THOSE OF THE RAINS IN AN OPEN SPACE. THE PH AND EC OF THROUGHFALL VARIED WITH THE DISTANCE FROM THE TRUNK. THE LOWEST PH AND THE HIGHEST EC DISTRIBUTED CLOSE TO THE TRUNK. VALUES OF PH INCREASED RADIALLY OUTWARDS IN EVERY DIRECTION UNDER THE CANOPY,HOWEVER,THOSE OF EC DECREASED. LOW PHS AND HIGH ECS OF STEMFLOW AND THROUGHFALL CLOSE TO THE TRUNK SUGGESTED THAT CAPTURED ACIDIC DEPOSITIONS BY FILTERING EFFECT OF THE TREE CANOPIES WERE WASHED OUT BY THE RAIN AND FLOWED DOWN TO THE SURFACE SOIL.

報告者

キーワード