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Loss rates of organic detritus in ecosystems can be determined by measuring rates of CO₂ release from decomposing organic substrates. We used an open system employing inverted boxes and an infrared gas analyzer (IRGA) to obtain continuous measurements of CO₂ evolution from the floor or a mixed mesophytic forest. Plexiglass sheets were used to partition respiratory activity of two litter horizons (01 and 02) and soil. Root respiration rates were determined with a differential respirometer. We compared the open system with a closed system in which KOH was used as the CO₂ absorber. Respiration measurements with KOH were 63% of IRGA values at 20 degrees C and 90% at 12 degrees. Flow rates (28 to 340 liters hr — 1) had no effect on rates of CO₂ evolution. Nighttime CO₂ evolution rates were generally higher day — 1. Preliminary data indicate annual CO₂ evolution of 3. 8 kg m — 2 (48% from litter, 17% from soil, and 35% from roots). This estimate is equivalent to 2. 3 kg m — 2 organic mass catabolized, assuming a carbohydrate substrate, which is 11% higher than independent estimates of the organic detritus annually available for catabolism.
Edwards et al. (Thu,) studied this question.