Portail documentaire

Conservatoire botanique national des Pyrénées et de Midi-Pyrénées

Dépouillements

Patterns of vegetation change and the recovery potential of degraded areas in a coastal marsh system of the Hudson Bay lowlands / I. T. Handa in Journal of ecology, 90 (1) (2002) 

Public Citation [article]  inJournal of ecology > 90 (1) (2002) . - 86-99 Titre : Patterns of vegetation change and the recovery potential of degraded areas in a coastal marsh system of the Hudson Bay lowlands Type de document : Imprimé Auteurs : I. T. Handa ; R. Harmsen ; R.L. Jefferies Année de publication : 2002 Article en page(s) : 86-99 Langues : Anglais (eng) Note de contenu : 1 In recent decades, foraging by increasing numbers of lesser snow geese has led to loss of vegetation and changes in soil conditions in marshes on the Hudson Bay coast. 2 Changes in species composition were recorded in areas unprotected from goose foraging and in exclosures of varying age (5–15 years) erected in intact swards and on bare sediments where foraging had occurred at La Pérouse Bay, Manitoba. 3 In the supratidal marsh, plants failed to establish naturally in either open or exclosed (15 years) plots in bare areas. In moist intertidal soils, vegetative fragments of the asexual species Puccinellia phryganodes readily established and formed a mat in exclosures (5 years). 4 Changes in species assemblages occurred over 11 years in exclosed and adjacent open plots in intertidal and supratidal marshes. Loss of vegetation cover and species richness, particularly dicotyledonous species, and the reversion of later successional plant assemblages to earlier successional assemblages occurred in open plots. In the absence of foraging, late successional graminoids and willow species replaced early successional graminoids. 5 Late successional grasses of the upper intertidal marsh died when transplanted into degraded soils but still survived after one season in control plots, suggesting that an early successional template is needed for establishment. 6 In the absence of goose foraging, natural re-vegetation by clonal propagation can occur only where edaphic conditions are suitable. Within exclosures, vegetation changes resemble those in undamaged areas where goose foraging pressure is still moderate. We propose a state and transition model for vegetation change in the system based on succession patterns, alternative vegetation states and geomorphological events. Identifiant : DOI : 10.1046/j.0022-0477.2001.00635.x Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=148689 Handa, I.T., Harmsen, R., Jefferies, R.L., 2002 . Patterns of vegetation change and the recovery potential of degraded areas in a coastal marsh system of the Hudson Bay lowlands. Journal of ecology, 90(1): 86-99.

Documents numériques

Article (2002) URL

The regulation of ecosystem functions by ecotypic variation in the dominant plant : a Spartina alterniflora salt-marsh case study / Denise M. Seliskar in Journal of ecology, 90 (1) (2002) 

Public Citation [article]  inJournal of ecology > 90 (1) (2002) . - 1-11 Titre : The regulation of ecosystem functions by ecotypic variation in the dominant plant : a Spartina alterniflora salt-marsh case study Type de document : Numérique Auteurs : Denise M. Seliskar ; John L. Gallagher ; David M. Burdick ; Laurie A. Mutz Année de publication : 2002 Article en page(s) : 1-11 Langues : Anglais (eng) Mots-clés : Spartina alterniflora Loisel. Résumé : 1 Genetic differences among populations of a keystone species may affect ecosystem functional properties. We tested this by planting Spartina alterniflora from different geographical regions in a newly created salt marsh in Delaware, USA. 2 Spartina alterniflora plants from morphologically distinct short-form (back marsh) populations were originally collected from Massachusetts (41°34′ N), Delaware (38°47′ N), and Georgia (31°25′ N) in the USA and vegetatively propagated for 6 years in a salt water-irrigated common garden in Delaware before transfer to a newly created salt marsh. 3 The magnitude of the expression of marsh functions in the created marsh, measured over 5 years, remained distinct in patches of each ecotype. End of season aerial biomass, below-ground biomass, root and rhizome distribution, canopy height, stem density, and carbohydrate reserves were closer to values reported for the plants’ native sites than to those typical of Delaware. Thus, many of the plant features characteristic of particular latitudes appear to be under genetic control. Such ecotypic differentiation influences ecosystem function through keystone resource and keystone modifier activities. 4 Respiration of the microbial community associated with either dead shoots or the soil varied with plant ecotype in the created wetland and the patterns reflected those reported for their native sites. High edaphic respiration under the Massachusetts ecotype was correlated with the high percentage of sugar in the rhizomes. Edaphic chlorophyll was greater under the canopies of the Massachusetts and Delaware ecotypes than under the Georgia canopy and exhibited a relationship similar to that of algal production rates reported for the native sites. Larval fish were most abundant in pit traps in the Massachusetts ecotype. Identifiant : DOI : 10.1046/j.0022-0477.2001.00632.x Permalink : https://biblio.cbnpmp.fr/index.php?lvl=notice_display&id=156367 Seliskar, D.M., Gallagher, J.L., Burdick, D.M., Mutz, L.A., 2002 . The regulation of ecosystem functions by ecotypic variation in the dominant plant : a Spartina alterniflora salt-marsh case study. Journal of ecology, 90(1): 1-11.

Documents numériques

Article (2002) URL