Profiles of cellulose mass loss were measured for sixSphagnumbogs in eastern North America as an index of decomposition rates. After 2 years, mass loss rates in the upper 5ensp;cm of the profiles averaged 49 in hummocks, 52 in hollows where the water table was more than 5ensp;cm below the surface, and 21 in hollows where the water table was within 5ensp;cm of the surface. Hummock profiles were of three types: (i) mass loss highest at the surface, gradually decreasing to very low rates below the water table; (ii) mass loss highest at the surface, decreasing for 10 ndash; 20ensp;cm, with a second peak in the region of the water table; and (iii) mass loss low at the surface with a subsurface peak. Mass loss rates for all profiles reached minimum values below the water table, averaging 3 in hummocks and 5 in hollows after 2 years. Cellulose mass loss was quite variable in upper portions of the profiles; within-site variance was almost as great as between-site variance, reflecting similarity among these bogs and heterogeneity within each site. Analysis of variance of mass loss at the hummock surface showed no significant effect of site; however, contrasts among means showed that mass loss rates at the surface of hummocks of the northern (Newfoundland) bogs were significantly lower (pensp;ensp;0.05) than those from the sites farthest south (in Nova Scotia and Maine).Key words: cellulose mass loss,Sphagnumbog, decomposition.
展开▼
