Fig. 1.

CH₄ production in amended sediments. Production over a 150-day growing season is orders of magnitude higher in sediments amended with 20% organic matter from emergent macrophyte (Typha latifolia; TYP) litter than deciduous (DEC) or coniferous (CON) forest litter. CH₄ production increases further with addition of methanogen-rich sediment (i.e., spiked-treatments) only in control (CTR) and TYP sediments. Different numbers (1–4) represent significant differences (p < 0.05) among amendments (ANOVA F₇, ₂₄ = 39.47), with n = 4 replicates per amendment type. Results are shown on a log scale because of large differences between TYP and the other amendments, and error bars represent standard errors in production estimates