Wetland plant decomposition under different nutrient conditions: what is more important, litter quality or site quality?

• Published in: Biogeochemistry Vol. 80; no. 3; pp. 245 - 262
• Main Authors: REJMANKOVA, Eliska, HOUDKOVA, Katerina
• Format: Journal Article
• Language: English
• Published: Heidelberg Kluwer Academic Publishers 01.09.2006; Springer; Springer Nature B.V
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Aquatic plants; Belize; Biogeochemistry; Biological activity; Biological and medical sciences; Brackish; Cellulose; Decomposers; Decomposition; Earth sciences; Earth, ocean, space; Eleocharis; Enrichment; Exact sciences and technology; Forest soils; Freshwater plants; Fundamental and applied biological sciences. Psychology; Litter; Macrophytes; Marshes; Microbial activity; microbial biomass; Microorganisms; Mineral nutrients; Nutrient content; Nutrient loading; Nutrient resorption; nutrient resorption (physiology); Nutrients; Plant litter; pollution load; prediction; Primary production; primary productivity; Quality; Salinity; Salinity effects; Salinity gradients; Sedimentary soils; Sediments; Soils; Surficial geology; Synecology; Terrestrial ecosystems; wetland plants; Wetland soils; Wetlands; Belize; experimental studies; Central America; models; biomass; fatty acids; accumulation; nitrogen; vegetation; Northern Belize; nutrients; enrichment; wetlands; PLFA; conductivity; cellulose; organic materials; prediction; soils; Litter bags; Eleocharis cellulosa; phosphorus
• ISSN: 0168-2563; 1573-515X
• DOI: 10.1007/s10533-006-9021-y

Plants in nutrient poor environments are often characterized by high nutrient resorption resulting in poor litter quality and, consequently, slow decomposition. We used oligotrophic, P-limited herbaceous wetlands of northern Belize as a model system, on which to document and explain how changes in nutrient content along a salinity gradient affect decomposition rates of macrophytes. In 2001 we established a nutrient addition experiment (P, N, and N&P) in 15 marshes of a wide range of water conductivities (200-6000 μS), dominated by Eleocharis spp. To determine what is more important for decomposition, the initial litter quality, or site differences, we used reciprocal litter placement and cellulose decomposition assay in a combined “site quality” and “litter quality” experiment. Our prediction of the positive effects of P-enrichment on decomposition rate due to both the quality of litter and the site was confirmed. The site effect was stronger than the litter quality although both were highly significant. Strong site quality effect was apparently the result of more active decomposer community in P-enriched plots as supported by finding of higher microbial biomass in litter decomposing there. The strong effect of site quality on decomposition was further confirmed by the cellulose assay. The cellulose decomposition was significantly slower at high salinity sites indicating lower decomposer microbial activity. Litter nutrient N and P content and nutrient ratios were well correlated with decomposition with the best fit found for log C/P. At C/P mass ratio of >4000 decomposition processes were extremely slow. We hypothesize that in a long run, the increased decomposition will compensate the increase in primary production resulting from increased nutrient loading and there will be no differences in accumulation of organic material between the controls and nutrient enriched plots.