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SEPARC Annual Meeting 2011 - Surasinghe and Baldwin 2011
- 1. Diversity and distribution of stream-dwelling Plethodontidsalong a land-use gradient in Piedmont & Blue Ridge ecoregions, USA ThilinaSurasinghe Robert Baldwin Dept of Forestry & Natural Resources, Clemson University, SC
- 2. Project Objectives How do different land-use activities in the riparian zone affect habitat association of stream-dwelling salamanders? Is there a correlation between species composition of stream salamanders and environmental variables?
- 3. Study Area – Upstate South Carolina
- 4. Methods & Materials Randomized block design Blocked across level IV ecoregions & river basins 40 sampling locations land-use types: forested areas, agricultural lands, residential areas, & urban areas Field transect survey 100 m stream transects Visual observation & active searching Random sampling : sequence/time among different sites
- 5. Active Searching Wet channel and stream banks Rectangle-framed kick nets, D-framed nets & dip nets Date, start / end time, weather & crew size are recorded Identification and specimen preservation
- 6. Methodology: Environmental variables Canopy cover Litter cover Litter depth Watershed size Canopy height Basal area
- 7. Results & Discussion Non-metric Multidimensional Scaling Bray-Curtis distance metric, 2 dimensions, the 1/4-power transformation Categorization of species assemblages reflecting species response to LU gradient Habitat Associations Forest assemblages: disturbance avoiders Forest/residential or agricultural assemblages: disturbance adapters Exclusively residential/urban assemblages: disturbance exploiters
- 8. EurL: Eurycea larvae Ecir:Euryceacirrigera Eglut: E. guttolineata Equad:E. quadridigitata Ewild: E. wilderae DesL: Desmognathuslarvae Dfus: D. fuscus Dmont: D. monticola Dmam: D. marmoratus Doco: D. ocoee Dcont: D. conanti Dquad: D. quadramaculatus Prub: Pseudotritonruber Pmon: P. montanus GprL:Gyrinophilus larvae Gpr: G. porphyriticus Doco Ecir Eglut Dcont Dfus GprGprL Pmon EurL Prub Dquad Dmam Dmont DesL Ewild Equad NMDSOrdination. The green, grey, and red dots indicate the LU type at sampling locations; black letters indicate species names.
- 10. EurL: Eurycea larvae Ecir:Euryceacirrigera Eglut: E. guttolineata Equad:E. quadridigitata Ewild: E. wilderae DesL: Desmognathuslarvae Dfus: D. fuscus Dmont: D. monticola Dmam: D. marmoratus Doco: D. ocoee Dcont: D. conanti Dquad: D. quadramaculatus Prub: Pseudotritonruber Pmon: P. montanus GprL:Gyrinophilus larvae Gpr: G. porphyriticus Doco Ecir Eglut Dcont Dfus GprGprL Pmon EurL Prub Dquad Dmam Dmont DesL Ewild Equad NMDS Ordination. The green, grey, and red dots indicate the LU type at sampling locations; black letters indicate species names.
- 13. Results & Discussion Partial Mantel test (95% confident level): Correlation between environmental variables and species composition Distance matrices Geographic location: Euclidean, Environmental variables: Euclidean, Species composition: Bray Curtis 10,000 permutations Test statistic: r = 0.1123, p = 0.00724 Significant correlation between the species composition matrix and the environmental variable matrix
- 14. EurL: Eurycea larvae Ecir:Euryceacirrigera Eglut: E. guttolineata Equad:E. quadridigitata Ewild: E. wilderae DesL: Desmognathuslarvae Dfus: D. fuscus Dmont: D. monticola Dmam: D. marmoratus Doco: D. ocoee Dcont: D. conanti Dquad: D. quadramaculatus Prub: Pseudotritonruber Pmon: P. montanus GprL:Gyrinophilus larvae Gpr: G. porphyriticus Equad Canonical Correspondence Analysis Effect of environmental variables on species occurrence
- 16. Historical land use…. (Ghost of the land-use past..!!!)
- 18. Competition
Editor's Notes
- Level III EPA ecoregion: Blue Ridge & PiedmontFour major river basins: Savannah, Saluda, Catawba, Broad
- The Jaccard index, also known as the Jaccard similarity coefficient (originally coined coefficient de communauté by Paul Jaccard), is a statistic used for comparing the similarity and diversity of sample sets.The Jaccard coefficient measures similarity between sample sets, and is defined as the size of the intersection divided by the size of the union of the sample sets:The Jaccard distance, which measures dissimilarity between sample sets, is complementary to the Jaccard coefficient and is obtained by subtracting the Jaccard coefficient from 1, or, equivalently, by dividing the difference of the sizes of the union and the intersection of two sets by the size of the union:
- In ecology and biology, the Bray Curtis dissimilarity is a statistic used to quantify the compositional dissimilarity between two different sites. It is equivalent to the total number of species that are unique to any one of the two sites divided by the total number of species over the two sites. In other words, it is the ratio between the turnover of species between the two sites and the total species richness over the two sites.The Bray Curtis dissimilarity is directly related to the Sørensen similarity indexBCij = 1 − QSij. The Bray Curtis dissimilarity is bound between 0 and 1, where 0 means the two sites have the same composition (that is they share all the species), and 1 means the two sites do not share any species.The Bray Curtis dissimilarity is often erroneously called a distance. The Bray Curtis dissimilarity is not a distance since it does not satisfy triangle inequality, and should always be called a dissimilarity to avoid confusion.