Abstract Detail



Ecology

Barfknecht, David [1], Gibson, David [2].

Species composition, diversity, and environmental differences in acid seeps.

Acid seeps are valued ecosystems within southern Illinois and harbor unique floral communities. Since 2008, Microstegium vimineum (an exotic grass) has invaded several acid seeps of Pope County, IL. These acid seeps have experienced steam down-cutting. The objective of this research was to collect species abundance and environmental data that would allow us to suggest restoration protocols for land managers.
Plots were randomly established along transects within ten acid seeps in southern IL. Vascular plant species abundance was recorded in July 2017. Soil samples were collected to assess soil acidity and conductivity. Overhead tree canopy cover was measured for each seep, along with slope and aspect. Photosynthetically active radiation was recorded above the herbaceous layer within each acid seep. Soil moisture was recorded in summer months. Environmental variables and 12 indices diversity and evenness were calculated for each seep including Shannon-Weiner diversity, Pielou’s J, Hill’s numbers, and nearest taxonomic index (NTI). A non-metric multidimensional scaling ordination (NMDS) was conducted based on Bray-Curtis dissimilarities. Vector analysis allowed fitting of environmental data and diversity indices to the NMDS. A permutational test of homogeneity of dispersion (PERMDISP) was used to investigate differences in dispersion of plots between acid seeps. A permutational analysis of variance (PERMANOVA) was used to investigate differences among individual seeps.                
The two-dimensional NMDS displayed that only NTI had a significant relationship with species composition among seeps as a diversity index (r2=0.6611; p=0.026). Soil moisture in June (r2=0.8074; p=0.005), July (r2=0.759; p=0.01), and August (r2=0.7008; p=0.018) and canopy cover (r2=0.5847; p=0.049) were environmental variables significant as vectors. There was significantly different dispersion of plots within seeps (F9=2.0244, p=0.39) and among individual seeps (F9=4.8465, p=0.01). Acid seeps with more shade had lower soil moisture.  NTI values separated species composition of acid seeps along a vector nearly perpendicular to canopy cover and the soil moisture vectors. This gradient in NTI values indicates phylogenetic clustering differences that result often from variations in environmental filtering. Mircostegium vimineum was central in NMDS, confirming its presence in all acid seeps.  Microstegium dominance does not explain acid seep community compositional differences. Species associated with shady, dry springs were Boehmeria cylindrica and Polystichum acrostichoides. while ones associated with open wet springs included Osmunda cimmamomea and Apios Americana. Species associated with high NTI values were Rubus allegheniensis and Osmunda regalis.


1 - 7672 Giant City Rd., Carbondale, IL, 62902, United States
2 - Southern Illinois University Carbondale, 1263 Lincoln Drive, Carbondale, IL, 62901, USA

Keywords:
Ecology
biodiversity
invasives
acid
seeps
Microstegium
NTI.

Presentation Type: Poster
Number: PEC003
Abstract ID:97
Candidate for Awards:Ecological Section Best Graduate Student Poster


Copyright © 2000-2018, Botanical Society of America. All rights reserved