Studies on the Circulation of Carbon and Nitrogen in Forest ecosystems

Abstract

本報告では各種の森林の物質現存量を求め, それらの蓄積を支配する要因についての考察を通して, 炭素とチッ素の循環のパターンを比較し, それぞれの特性とその相互関係について考察を加えた。生態系内に蓄積された炭素量およびチッ素量と温度との間にははっきりした関係はみとめられなかった。しかし, 両物質とも供給量および分解量は気温の高い地域など大きくなる傾向がみられた。すなわち, 炭素およびチッ素の循環速度は高温地域ほど大きくなると考えられた。林地の炭素とチッ素は量的に密接な関係にあり, その比 (C/N) は気候帯によって異なり, 熱帯林で10, 暖温帯林で15, 亜寒帯林で20となり, 高温地域ほど小さくなる傾向がみられた。気候帯によるC/Nの違いは炭素とチッ素とで供給量と温度との関係が異なるためであろう。林地のC/NとC_m/N_mとの間に C_m/N_m=16C/N/33-1.1C/N の関係があることが認められ, C/Nが大きくなるとC_m/N_mの値が大きくなり, チッ素の分解量に対し炭素の分解量の割合が大きくなる。この結果としてC/Nがしだいに小さくなると考えられた。

This paper deales with studies on comparing the carbon-cycle with the nitrogen-cycle from the studies of amounts stored in various forest ecosystems and on presuming the interaction of these materials. Amounts of carbon and nitrogen stored in forest ecosystems did not clearly related with temperature, but the rates of input and of output tended to increase with the increasing temperature, that is, the cycling rates of carbon and of nitrogen in forest ecosystems were presumed to be higher in higher temperature. Carbon and nitrogen were closely related quantitatively, and the ratios of C-N were about 10, 15 and 20, in tropical forests, warm-temperate forests and subarctic forests respectively. The difference of C/N between climatic zones would be attributed that the relationship between input and temperature was different between carbon and nitrogen. The relationship between C/N and Cm/Nm in soils was expressed by the formula; [Figure omitted] The larger was C/N ratio, the more was the propotional rate of mineralized carbon to mineralized nitrogen. So that the large value of C/N ratio in soils would become smaller gradually.