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TWENTY‐FIVE YEARS OF ECOSYSTEM DEVELOPMENT OF CONSTRUCTED SPARTINA ALTERNIFLORA (LOISEL) MARSHES
Author(s) -
Craft Christopher,
Reader Judy,
Sacco John N.,
Broome Stephen W.
Publication year - 1999
Publication title -
ecological applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.864
H-Index - 213
eISSN - 1939-5582
pISSN - 1051-0761
DOI - 10.1890/1051-0761(1999)009[1405:tfyoed]2.0.co;2
Subject(s) - marsh , spartina alterniflora , wetland , environmental science , salt marsh , ecology , spartina , biomass (ecology) , ecosystem , brackish marsh , macrophyte , species richness , biology
Wetland creation and restoration are frequently used to replace ecological functions and values lost when natural wetlands are degraded or destroyed. On many sites, restoration of ecological attributes such as secondary production, habitat/species diversity, and wetland soil characteristics do not occur within the first decade, and no long‐term studies exist to document the length of time required to achieve complete restoration of wetland dependent functions and values. Characteristics of community structure (macrophyte aboveground biomass, macro‐organic matter [MOM], benthic invertebrates) and ecosystem processes (soil development, organic C, N, and P accumulation) of two constructed Spartina alterniflora (Loisel) marshes (established 1971 and 1974) and paired natural S. alterniflora marshes in North Carolina were periodically measured during the past 25 yr. On constructed marshes, the macrophyte community developed quickly, and within 5 to 10 yr, aboveground biomass and MOM were equivalent to or exceeded corresponding values in natural marshes. After 15–25 yr, benthic infauna density and species richness were greater than in the natural marshes. Soil bulk density decreased, and organic C and total N increased over time in constructed marshes, but after 25 yr, soil organic C and N reservoirs were much smaller than in a 2000‐yr‐old natural marsh. Organic C accumulation was similar in constructed and natural marshes with 12–24% of the net primary production buried annually. Nitrogen accumulation was much higher in constructed marshes (7–12 g·m −2 ·yr −1 ) than in natural marshes (2–5 g·m −2 ·yr −1 ), reflecting the open biogeochemical cycles and paucity of N in these young ecosystems. Different ecological attributes develop at different rates, with primary producers achieving equivalence during the first 5 yr, followed by the benthic infauna community 5–10 yr later. Accumulation of soil nutrients to levels similar to those of reference marshes may require more time.