The breakdown of macrophytes in a reservoir wetland

Weight losses from leaf laminae and petioles of Nelumbo lutea (Wild.) Pers., and from leaves of Ludwigia leptocarpa (Nutt.) Hara. and Typha angustifolia L., were measured by exposing air-dried leaf material in nylon mesh bags at upper (exposed 25 days, inundated 40 days) and lower (inundated 154 days) wetland sites in a Texas reservoir. No significant differences (P < 0.05) were found between sites, so data were combined to yield estimates of plant litter breakdown for the entire wetland. Breakdown rates (in percentage of ash free dry weight lost per day) for the 4 litter types were: Nelumbo leaves - 0.0108 ± 0.0016; Ludwigia - 0.0050 ± 0.0007; Typha - 0.0047 ± 0.0006; Nelumbo - petioles 0.003 ± 0.0010. Times required for a 95% loss of litter, based on an exponential model, are 278 days, 600 days, 638 days and 909 days for these 4 litter types, respectively. These rates are comparable to those reported for emergent aquatic macrophytes in other lakes and wetlands. Colonization of decaying wetland plants was dominated by the gatherers, Chironominii (54%) and Caenis sp. (26%).