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57,795,000 Yen
The decline of Sugi forest in the Kanto and Kansai plains was investigated in dynamics of acid deposition, tree ecophysiology and soil buffering capacity for elucidating the decline mechanism and to predict the influence of acid deposition to the forests.
More remarked declination was observed for the old tall trees,and trees which were isolated or grown in forest edges. The decline was displayed to be still continuing.
pH and chemical composition of precipitation, throughfall and stemflow were determined to characterize the acid deposition into forests in quantity and quality. Acidification of stemflow and soils near trunk of Sugi were clarified.
The methods for measuring emission of nitrogenous and sulfurous compounds from forest floor were established.
From the exposure experiment to artificial acid rain,Sugi was judged not to be damaged by the present precipitation. It was found that Sugi has small tolerance against water deficit because of its rapid transpitation rate and high resistance of water flow in plant body.This physiological characteristics of the tree were presumed to be associated with the decline. Air temperature in summer was related significantly with the decline.
The contents of Al and K in the needles of declined Sugi were high and low,respectively.
Buffering reaction pf soil was exhibited to consist of four different steps;i.e. carbonate at pH 6, salt adsorption at pH 6, cation exchange at pH 5 and aluminum at pH 4. Surface soil was weaker in buffering than subsoils in most forest soils.
Acid Deposition, Forest Decline, Cryptomeria japonica, Stemflow, Buffering Capacity