The data given in this illustration were collected in an oak forest close to the Brookhaven National Laboratory at the East Coast of the United States of America. 2,100 grams of the annual gross production of 2,650 grams of dry matter per square meter are lost in respiration. The remaining 550 grams are stored as new plant growth, litter, and humus. The oak forest belongs to the 'late successional' forests in which only 20 % of the total production are used as new material while 80% of the production is expended in respiration (according to G. M. WOODWELL, 1970).