CARBON FLOW AND STORAGE IN A FOREST ECOSYSTEM 353 



sively spiders) averaged 61 mg/m 2 . Using 45% as the mean analyzed carbon 

 content of insect tissue gives values for the carbon pools in herbivores and 

 predators of 101 and 27 mg C/m 2 , respectively. 



The majority of litter macroinvertebrates (77% by number and 88% by 

 weight) belong to 10 taxonomic groups: Araneae, Chilopoda, Coleoptera, 

 Collembola, Diplopoda, Diptera, Hymenoptera, Lepidoptera (larvae), Orthop- 

 tera, and Pulmonata. Densities ranged from a low of 690 individuals per square 

 meter in April to a high of 2700 individuals per square meter in July. Mean 

 annual biomass was 842 mg (dry weight)/m 2 (Moulder and Reichle, 1972). 

 Microinvertebrates in litter averaged 5.9 X 10 4 individuals per square meter with 

 a biomass of 342 mg/m 2 ; soil microinvertebrates numbered 3.9 X 10 individ- 

 uals per square meter and had a biomass of 220 mg/m (McBrayer and Reichle, 

 1971). Earthworms (14 g/m 2 ), primarily Octolashim, constituted the bulk of the 

 soil invertebrate biomass. Total aboveground biomass was 1.2 g/m ; below- 

 ground invertebrate biomass averaged 14.2 g/m . With an average carbon 

 content of 45%, the belowground carbon pool is 6.4 g C/m . The aboveground 

 carbon pool was calculated by using a 20% carbon value for heavily skeletonized 

 chilopods and snails that comprise about 20% (0.44 g/m 2 ) of the biomass and a 

 45% carbon content for the remainder of the fauna. The aboveground 

 invertebrate carbon pool is 0.52 g C/m . 



Microbial populations, determined from biweekly plate counts, varied 

 throughout the year with changes in temperature and moisture. Moisture is the 

 dominant limiting factor at temperatures > 10 C. Carbon content of total 

 microflora in litter was 1.45 mg C/m 2 , apportioned approximately 60% to fungi 

 and 40% to bacteria. The carbon pool in total soil microflora was 3.56 mg C/m , 

 with approximately 65% in fungi and 35% in bacteria (Ausmus, personal 

 communication). Densities per gram substrate for bacteria were 2.3 X 10 for 

 Oj litter, 2.5 X 10 8 for 2 litter, and 5.6 X 10 6 for Aj soil to 5 cm; fungal 

 densities were 2.7 X 10 6 for O x litter, 124 X 10 6 for 2 litter, and 0.3 X 10 6 

 for Ai soil to 5 cm (Edwards, 1972). 



Annual Carbon Increment and Changes in Pool Sizes 



Table 2 summarizes rates of annual accumulation in aboveground autotroph 

 components based on standing-crop differences between 1962 and 1970 (Sollins, 

 1972). Saplings unaccounted for in 1962, but present in 1970, were assumed to 

 have been added at a uniform annual rate over the 8-year period. Tree mortality 

 also was assumed to have occurred at a uniform rate. Net contribution to a 

 standing dead carbon pool of bole and branch material was calculated to be 

 50 gC m" 2 year -1 . A net total of 166 g C m" 2 year 1 accumulated in woody 

 structural components. Over the 8-year period, other overstory components 

 decreased, whereas understory trees showed a slight gain (Table 2). Stump 

 increment was assumed to be directly proportional to bole increment. 



