Data/hora: 12/06/2024 19:13:37

Provedor de dados: | 7
País: | Canada
Título: | Marsh Creation in a Northern Pacific Estuary: Is Thirteen Years of Monitoring Vegetation Dynamics Enough?
Autores: | Dawe, Neil K; Canadian Wildlife Service; Neil.Dawe@ec.gc.ca; Bradfield, Gary E; University of British Columbia; garyb@interchange.ubc.ca; Boyd, W. Sean; Canadian Wildlife Service; Sean.Boyd@ec.gc.ca; Trethewey, Donald E. C.; Canadian Wildlife Service;; Zolbrod, A. Nana; University of British Columbia; nzolbrod@hotmail.com.
Data: | 2000-12-15
Ano: | 2000
Palavras-chave: | Adaptive management of ecosystems; Carex lyngbyei; Deschampsia caespitosa; Eleocharis palustris; Estuarine marsh creation; Juncus balticus; Long-term vegetation dynamics; Mitigation cautions; Natural vs. constructed wetlands; Potentilla pacifica; Restoration ecology; Wetland creation.
Resumo: | Vegetation changes were monitored over a 13-yr period (1982-1994) in the Campbell River estuary following the development of marshes on four intertidal islands. The marshes were created to mitigate the loss of a natural estuarine marsh resulting from the construction of a dry land log-sorting facility. Plant species coverage was measured along 23 permanent transects in planted and unplanted blocks on the constructed islands, and in naturally occurring low-marsh and mid-to-high marsh reference communities on nearby Nunn&amp;#8217;s Island. Five dominant species, Carex lyngbyei, Juncus balticus, Potentilla pacifica, Deschampsia caespitosa, and Eleocharis palustris  established successfully and increased in cover in both planted and unplanted areas. The planted, unplanted, and Nunn&amp;#8217;s Island low-marsh sites had similar total plant cover and species richness by the 13th year. Principal components analysis of the transects through time indicated successful establishment of mid-to-low marsh communities on the constructed islands by the fourth year. Vegetation fluctuations on the constructed islands were greater than in the mid-to-high and low-marsh reference communities on Nunn&amp;#8217;s Island. Results showed that substrate elevation and island configuration were major influences on the successful establishment and subsequent dynamics of created marsh communities. Aboveground biomass estimates of marshes on the created islands attained those of the reference marshes on Nunn&amp;#8217;s Island between years 6 and 13. However, Carex lyngbyei biomass on the created islands had not reached that of the reference marshes by year 13. Despite the establishment of what appeared to be a productive marsh, with species composition and cover similar to those of the reference marshes on Nunn&amp;#8217;s Island, vegetation on the created islands was still undergoing changes that, in some cases, were cause for concern. On three of the islands, large areas devoid of vegetation formed between years 6 and 13, probably a result of water ponding. Adaptive management has allowed us to modify the island configuration through the creation of channels to drain these sites in an attempt to reverse the vegetation dieback. These changes, occurring even after 13 years, further underscore the need for caution when considering the trading of existing natural, healthy, productive wetlands for the promise of created marshes that may or may not prove to be equal to the natural systems. Where marsh creation is warranted, we recommend that management of created marshes be adaptive and flexible, including a long-term monitoring program that should continue at least until the annual variation in vegetation of the created marsh is similar to that of natural, nearby systems.
Tipo: | Peer-Reviewed Reports
Idioma: | Inglês
Identificador: | vol4/iss2/art12/
Editor: | Resilience Alliance
Formato: | text/html
Fonte: | Ecology and Society; Vol. 4, No. 2 (2000)