Flooding and the decomposition of litter of four emergent plant species in a prairie wetland

Abstract

Changes in mass, N, and P for old and new litter of four emergent plant species (Scolochloa festucacea (Willdl.) Link,Phragmites australis (Cav.) Trin ex Steud.,Typha ×glauca Godr., andScirpus lacustris L. spp.glaucus (Sm.) Hartm.) were studied under two water-level regimes in a 10-cell experimental marsh complex in the Delta Marsh, Manitoba, Canada. In the normal regime, water levels were kept at the regulated water level for Lake Manitoba until the fall of 1981, while in the flooded or high-water regime, they were raised 1 m above the regulated level in the fall of 1980. In the spring of 1980, old litter (i.e., litter from the previous growing season) was placed in all ten cells of the complex, and in the fall of 1980, new litter (i.e., litter from the 1980 growing season) was placed in the same 10 cells. Litter ofS. festucacea had the highest mean decomposition rate (k=0.00171), followed byT. ×glauca (0.0131),S.l. glaucus (0.00126), andP. australis (0.00050). Mean decomposition rates were higher in the flooded treatment than in the normal treatment forP. australis andS. festucacea. Within water-level treatments, mass loss depended on initial litter age. The amount of N and P lost or gained by the end of 1981 varied with species, litter age, and water-level treatment.Scolochloa festucacea old and new litter had a lower percent N and P remaining in the flooded than in the normal water-level treatment. The percent N and P remaining in old litter ofP. australis andS.l. glaucus at the end of the study was higher than that in new litter regardless of water-level treatment. ForT. ×glauca, however, new litter had a higher percent of N and P remaining than old litter at the end of the study in both water-level treatments. Litter with lower initial N and P levels accumulated more N and P than did that with higher initial levels.