報告書番号

482024

タイトル（和文）

地熱発電所周辺における樹木活性度の推移－葛根田地熱発電所での調査－

タイトル（英文）

ON THE TIME-COURSE CHANGES OF TREE GROWTH VIGOR IN THE VICINITY OF THE GEOTHERMAL POWER STATION-AT KAKKONDA POWER STATION-

概要 （図表や脚注は「報告書全文」に掲載しております）

地熱発電所の稼働に伴う周辺の樹木の経年変化について，葛根田地熱発電所（５３年５月運開）周辺で５３，５４，５７年に樹木活性度を調べた。１．５７年の秋に，５地点で大きな樹木被害が観察された。その発生原因は自然噴気孔の発生・活性化などの自然環境の変化によるもの，発電所施設の影響によるものの２つが推定された。２．継続調査木における樹木活性度の経年推移には，年々活性度の低下するタイプ（１），年々活性度の上昇するタイプ（２），一定傾向を示さないタイプ（３）の３タイプが観察された。３．（１）のタイプは排出蒸気量の多い蒸気井基地周辺，比較的新しく掘削された蒸気井基地，冷却塔周辺で観察され，（２）のタイプは排出蒸気量の少ない蒸気井基地周辺，試掘井跡地周辺で観察され，（３）のタイプは発電付帯施設よりやや離れた地点で観察された。４．樹木活性度の低下・回復（上昇）過程には，明確に類別できる樹木被害形態がいくつ

概要 （英文）

IN ORDER TO CLALIFY THE IMPACTS OF THE GEOTHERMAL POWER STATION ON THE SURROUNDING TREES,THE TREE GROWTH VIGOR WAS STUDIED FOR TREES OF FAGUS CRENATA NEAR TO THE EQUIPMENTS OF KAKKONDA GEOTHERMAL POWER STATION IN 1978(THE OPERATION HAD STARTED),1979,AND 1982. 1.IN THE DISTRICT NEAR TO THE POWER STATION,SOME SEVERE TREE DAMAGESWERE OBSERVED AT 5 SMALL AREAS WHERE THE CAUSE OF THE DAMAGE AT 3 AREAS SHOULD BE THE CHANGE OF NATURAL ENVIRONMENTS SUCH AS A GAS ESCAPE,ANDTHE CAUSE OF THE DAMAGE OF RESIDUAL 2 AREAS WAS ESTIMATED TO BELONG THE EFFECTS OF THE POWER STATION. 2.THREE TYPES OF CHANGE PATTERN WERE OBSERVED FOR THE TIME-COURSE CHANGES OF THE TREES STUDIED.ONE TYPE WAS TODECREASE THE TREE GROWTH VIGOR WITH INCREASING YEAR,ONE TO INCREASE THE TREE GROWTH VIGOR,AND OTHER WAS TO FLUCTUATE. 3.THE FIRST TYPE WAS OBSERVED WHERE CLOSELY NEAR TO THE STEAM PRODUCTION WELL BASE WHICH EMITTED MUCH MORE STEAM,OR NEAR TO THE COOLING TOWER.THE SECOND TYPE WAS OBSERVED WHERE CLOSELY NEAR TO THE EXPERIMENTAL WELLS AND NEAR TO THE WELLBASE WHICH EMITTED MORE LITTLE STEAM.THE THIRD TYPE WAS OBSERVED WHEREAPART FROM THE EQUIPMENT OF THE POWER STATION. 4.SOME APPARENT MORPHOROGICAL DIFFERENCES WERE OBSERVED AMONG THE TREES AT DIFFERENT DAMAGE STAGES. 5.EPIPHYTIC BRYOPHYTA WERE OBSERVED MUCH MORE ON THE TRUNKS OF TREES WITH HIGHER TREE GROWTH VIGOR THAN THAT WITH LOWER TREE GROWTH VIGOR. 6.THE CONTENTS OF TOTAL SULPHUR IN LEAVES OF INVESTIGATED TREES WEREAT LOWER ENOUGH LEVELS(0.20-0.33%).

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