title: Geographic variation in plant community structure of salt marshes: species, functional and phylogenetic perspectives.
abstract: 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.
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America.
authors.forename: Hongyu
authors.initials: H
authors.lastname: Guo
authors.affiliation: Department of Ecology and Evolutionary Biology, Rice University, Houston, Texas, United States of America.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Chamberlain
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America.
authors.forename: Eran
authors.initials: E
authors.lastname: Elhaik
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America.
authors.forename: Inder
authors.initials: I
authors.lastname: Jalli
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America.
authors.forename: Alana-Rose
authors.initials: AR
authors.lastname: Lynes
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America.
authors.forename: Laurie
authors.initials: L
authors.lastname: Marczak
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America.
authors.forename: Niv
authors.initials: N
authors.lastname: Sabath
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America.
authors.forename: Amy
authors.initials: A
authors.lastname: Vargas
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America.
authors.forename: Kazimierz
authors.initials: K
authors.lastname: Więski
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America.
authors.forename: Emily M
authors.initials: EM
authors.lastname: Zelig
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America.
authors.forename: Steven C
authors.initials: SC
authors.lastname: Pennings
mesh_terms: D005843:Geography; D005845:Georgia; D016014:Linear Models; D010802:Phylogeny; D010944:Plants; D054712:Salinity; D013045:Species Specificity; D013781:Texas; D053833:Wetlands