Geographic variation in plant community structure of salt marshes: species, functional and phylogenetic perspectives.

In general, community similarity is thought to decay with distance; however, this view may be complicated by the relative roles of different ecological processes at different geographical scales, and by the compositional perspective (e.g. species, functional group and phylogenetic lineage) used. Coastal salt marshes are widely distributed worldwide, but no studies have explicitly examined variation in salt marsh plant community composition across geographical scales, and from species, functional and phylogenetic perspectives. Based on studies in other ecosystems, we hypothesized that, in coastal salt marshes, community turnover would be more rapid at local versus larger geographical scales; and that community turnover patterns would diverge among compositional perspectives, with a greater distance decay at the species level than at the functional or phylogenetic levels. We tested these hypotheses in salt marshes of two regions: The southern Atlantic and Gulf Coasts of the United States. We examined the characteristics of plant community composition at each salt marsh site, how community similarity decayed with distance within individual salt marshes versus among sites in each region, and how community similarity differed among regions, using species, functional and phylogenetic perspectives. We found that results from the three compositional perspectives generally showed similar patterns: there was strong variation in community composition within individual salt marsh sites across elevation; in contrast, community similarity decayed with distance four to five orders of magnitude more slowly across sites within each region. Overall, community dissimilarity of salt marshes was lowest on the southern Atlantic Coast, intermediate on the Gulf Coast, and highest between the two regions. Our results indicated that local gradients are relatively more important than regional processes in structuring coastal salt marsh communities. Our results also suggested that in ecosystems with low species diversity, functional and phylogenetic approaches may not provide additional insight over a species-based approach

Thematische Kartierung und Sensitivitaetsraster im deutschen Wattenmeer Juni 1987 - Juni 1993. Abschlussbericht

Das Vorhaben 'Thematische Kartierung und Sensitivitaetsraster des Deutschen Wattenmeeres' beinhaltet eine methodisch einheitliche Inventur des gesamten deutschen Wattenmeeres zwischen 1987 und 1992. Sie basiert auf quantitativen und beschreibenden Daten und enthaelt eine Dokumentation temporaerer Aspekte. Das Vorhaben war Ausgangspunkt fuer das synchron erstellte Wattenmeerinformationssystem WATiS. Es liefert weiterhin eine Grundlage fuer direkte Anwendungen bei Naturschutz- und Oelbekaempfungsmassnahmen sowie eine Vorgehensweise zur Abgrenzung repraesentativer Areale im Rahmen flaechendeckender Monitoring-Untersuchungen, wie sie zum Beispiel im 'Trilateral Monitoring and Assessment Program' vorgesehen sind. Mit einer Kopplung an das im Aufbau befindliche rechnergestuetzte maritime Umwelt-Managementsystem 'REMUS' werden Voraussetzungen geschaffen, die Planung von Vorsorge- und Bekaempfungsmassnahmen im Verbund von logistischen, technischen und wissenschaftlichen Massnahmen zu optimieren. (orig.)The project 'Thematische Kartierung und Sensitivitaetsraster des Deutschen Wattenmeeres' includes a methodically uniform inventory of the whole German Wadden Sea performed between 1987 and 1992. The inventory is based on quantitative and descriptive data and contains a documentation of temporary aspects. The project acts as a nucleus for the development of the Wadden Sea information System WATiS. The project forms the basis for direct applications for nature protection and oil-spill measures; in addition, a procedure to deliminate representative areals is demonstrated which can be used for example in the 'Trilateral Monitoring and Assessment Program' for the Wadden Sea. With the coupling to the computerbased maritime environmental management system 'REMUS' (presently developed) the prerequisites are generated to combine logistical, technical and scientific techniques for provision and combat measures. (orig.)SIGLEAvailable from TIB Hannover: RA 3251(94/E/10) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekUmweltbundesamt, Berlin (Germany)DEGerman