Diverse elevational diversity gradients in Great Smoky Mountains National Park, U.S.A.: Chapter 10

We addressed whether ridges, which are ecologically distinct from slopes, harbor specialized plant assemblages with a high representation of endemic species. We surveyed pteridophytes in 28 plots each of 400 m2 in ridge and slope forests at 2,430-2,660 m at three different localities in southeastern Ecuador. Data analysis was based on those 147 species with reliable determinations and excluded 14 undetermined species. Range sizes were expressed as the latitudinal distance between the northernand southernmost collections, and species were then assigned to range-size quartiles, with the 1st quartile including the 25% most widespread species, etc. Differences in species richness per range-size quartile were determined using G-tests and differences in abundance using ANOVAs. The recorded 147 fern species were represented by 21,800 individuals, including 106 terrestrial (7,300 individuals) and 98 epiphytic species (14,500). Ridges had fewer species than slopes, and there was no higher representation of localized species on ridges. Overall, widespread species were weakly (R2 = 0.03) but significantly more abundant than localized species. Ridges had significantly higher abundances of terrestrial but not of epiphytic species compared to slopes, especially among the widespread species of the 1st range-size quartile. The contribution of ridge habitats to overall pteridophyte diversity and as habitats for endemics in our study region is low. Methodologically, the separation of species into range-size classes in an ecological study is novel and effective, as statistically significant patterns were found only for species belonging to the 1st or 4th quartiles. Are Ridge Habitats Special Sites for Endemic Plants in Tropical Montane Rain Forests? A Case Study of Pteridophytes in Ecuador Michael Kessler & Marcus Lehnert # Institute of Botany, Academy of Sciences of the Czech Republic 2009 Abstract We addressed whether ridges, which are ecologically distinct from slopes, harbor specialized plant assemblages with a high representation of endemic species. We surveyed pteridophytes in 28 plots each of 400 m in ridge and slope forests at 2,430–2,660 m at three different localities in southeastern Ecuador. Data analysis was based on those 147 species with reliable determinations and excluded 14 undetermined species. Range sizes were expressed as the latitudinal distance between the northernand southernmost collections, and species were then assigned to range-size quartiles, with the 1st quartile including the 25% most widespread species, etc. Differences in species richness per range-size quartile were determined using G-tests and differences in abundance using ANOVAs. The recorded 147 fern species were represented by 21,800 individuals, including 106 terrestrial (7,300 individuals) and 98 epiphytic species (14,500). Ridges had fewer species than slopes, and there was no higher representation of localized species on ridges. Overall, widespread species were weakly (R2=0.03) but significantly more abundant than localized species. Ridges had significantly higher abundances of terrestrial – but not of epiphytic – species compared to slopes, especially among the widespread species of the 1st range-size quartile. The contribution of ridge habitats to overall pteridophyte diversity and as habitats for endemics in our study region is low. Folia Geobot DOI 10.1007/s12224-009-9047-8We addressed whether ridges, which are ecologically distinct from slopes, harbor specialized plant assemblages with a high representation of endemic species. We surveyed pteridophytes in 28 plots each of 400 m in ridge and slope forests at 2,430–2,660 m at three different localities in southeastern Ecuador. Data analysis was based on those 147 species with reliable determinations and excluded 14 undetermined species. Range sizes were expressed as the latitudinal distance between the northernand southernmost collections, and species were then assigned to range-size quartiles, with the 1st quartile including the 25% most widespread species, etc. Differences in species richness per range-size quartile were determined using G-tests and differences in abundance using ANOVAs. The recorded 147 fern species were represented by 21,800 individuals, including 106 terrestrial (7,300 individuals) and 98 epiphytic species (14,500). Ridges had fewer species than slopes, and there was no higher representation of localized species on ridges. Overall, widespread species were weakly (R2=0.03) but significantly more abundant than localized species. Ridges had significantly higher abundances of terrestrial – but not of epiphytic – species compared to slopes, especially among the widespread species of the 1st range-size quartile. The contribution of ridge habitats to overall pteridophyte diversity and as habitats for endemics in our study region is low. Folia Geobot DOI 10.1007/s12224-009-9047-8 M. Kessler :M. Lehnert Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Abteilung Systematische Botanik, Untere Karspüle 2, 37073 Göttingen, Germany Present Address: M. Kessler Systematic Botany, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland Present Address: M. Lehnert (*) Staatliches Museum für Naturkunde Stuttgart, Am Löwentor, Rosenstein 1, 70191 Stuttgart, Germany e-mail: lehnert.smns@naturkundemuseum-bw.de Methodologically, the separation of species into range-size classes in an ecological study is novel and effective, as statistically significant patterns were found only for species belonging to the 1st or 4th quartiles.