Ecological effects of low-level phosphorus additions on two plant communities in a neotropical freshwater wetland ecosystem

Robert J. Daoust, Daniel Childers

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

We conducted a low-level phosphorus (P) enrichment study in two oligotrophic freshwater wetland communities (wet prairies [WP] and sawgrass marsh [SAW]) of the neotropical Florida Everglades. The experiment included three P addition levels (0, 3.33, and 33.3 mg P m-2 month -1), added over 2 years, and used in situ mesocosms located in northeastern Everglades National Park, Fla., USA. The calcareous periphyton mat in both communities degraded quickly and was replaced by green algae. In the WP community, we observed significant increases in net aboveground primary production (NAPP) and belowground biomass. Aboveground live standing crop (ALSC) did not show a treatment effect, though, because stem turnover rates of Eleocharis spp., the dominant emergent macrophyte in this community, increased significantly. Eleocharis spp. leaf tissue P content decreased with P additions, causing higher C:P and N:P ratios in enriched versus unenriched plots. In the SAW community, NAPP, ALSC, and belowground biomass all increased significantly in response to P additions. Cladium jamaicense leaf turnover rates and tissue nutrient content did not show treatment effects. The two oligotrophic communities responded differentially to P enrichment. Periphyton which was more abundant in the WP community, appeared to act as a P buffer that delayed the response of other ecosystem components until after the periphyton mat had disappeared. Periphyton played a smaller role in controlling ecosystem dynamics and community structure in the SAW community. Our data suggested a reduced reliance on internal stores of P by emergent macrophytes in the WP that were exposed to P enrichment. Eleocharis spp. rapidly recycled P through more rapid aboveground turnover. In contrast, C. jamaicense stored added P by initially investing in belowground biomass, then shifting growth allocation to aboveground tissue without increasing leaf turnover rates. Our results suggest that calcareous wetland systems throughout the Caribbean, and oligotrophic ecosystems in general, respond rapidly to low-level additions of their limiting nutrient.

Original languageEnglish (US)
Pages (from-to)672-686
Number of pages15
JournalOecologia
Volume141
Issue number4
DOIs
StatePublished - Dec 2004
Externally publishedYes

Fingerprint

periphyton
Eleocharis
prairies
prairie
belowground biomass
plant community
plant communities
turnover
wetlands
Cladium mariscus subsp. jamaicense
phosphorus
marshes
marsh
ecosystems
primary production
primary productivity
wetland
leaves
ecosystem dynamics
ecosystem

Keywords

  • Everglades
  • Freshwater wetlands
  • Nutrient enrichment
  • Oligotrophic ecosystems
  • Phosphorus

ASJC Scopus subject areas

  • Ecology

Cite this

Ecological effects of low-level phosphorus additions on two plant communities in a neotropical freshwater wetland ecosystem. / Daoust, Robert J.; Childers, Daniel.

In: Oecologia, Vol. 141, No. 4, 12.2004, p. 672-686.

Research output: Contribution to journalArticle

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