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Abstract Detail



Ecology

HUEBNER, CYNTHIA [1], Nilsen, Erik [2], Bao, Zhe [2].

Using Soil Seed Banks to Define Historic and Future Vegetation Composition of Paired Invaded and Uninvaded Forest Stands.

Soil seed banks provide a history of colonization of a site, and such colonization is the product of several disturbance events over time. Seed banks also enable us to predict the future vegetation composition of a site. Years of overbrowsing by deer and non-sustainable forest harvesting in some eastern forests have resulted in species-depauperate understories incapable of regeneration. Deer browse also reduces sexual reproduction of many understory plants, eventually leading to a depleted seed bank. Many studies show a lack of correspondence between the existing vegetation and the seed bank. Though several species are recalcitrant and not likely to be found in a seed bank, many non-weedy often shade-tolerant species should be present and have been documented in more pristine forests.
We compared the soil seed bank composition of sites that were (1) disturbed within the past 45 years and invaded by an exotic tree (Ailanthus altissima -- AA), (2) disturbed within the past 45 years and dominated by a native tree (Robinia pseudoacia -- RP), (3) disturbed within the past 45 years and containing both AA and RP, and (4) not disturbed in the past 90 years and composed of a mixture of native trees. Two WV locations where these four forest types were found in close proximity to each other were selected. We sampled soil under 10 AA trees at each AA site, 10 RP trees at each RP site, 5 AA and 5 RP trees at the sites dominated by both species, and 10 mixed native trees at the control sites. Significant differences among the different seed bank species compositions were determined using nonmetric multidimensional scaling and one and two-way permutation-based non-parametric multivariate analysis of variance.
We found that the sites with both AA and RP had seed banks with the most species and the control seed banks had the fewest species. The sites with both AA and RP seed banks had the highest density of individuals, while the control sites had the lowest density. The AA-dominated sites had the highest exotic:native species ratio, while the RP-dominated sites had the lowest. Rather disconcerting, however, is the fact that none of the seed banks differed significantly compositionally. Indeed, the mature forest seed banks contained about the same number of AA individuals as the AA-dominated sites. If ever cut, these forests appear likely to follow a successional trajectory similar to that of the AA sites.


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1 - Northern Research Station , USDA Forest Service, 180 Canfield St, Morgantown, WV, 26505, USA
2 - Virginia Tech, Department Of Biology, 2119 Derring Hall, Blacksburg, VA, 24061, USA

Keywords:
seed bank
invaded
species composition
nonmetric multidimensional scaling
Ailanthus altissima
Robinia pseudoacacia.

Presentation Type: Oral Paper
Session: 8, Ecology Section - Invasive Species
Location: Sundance 5/Omni Hotel
Date: Monday, June 26th, 2017
Time: 11:45 AM
Number: 8007
Abstract ID:231
Candidate for Awards:None


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