Conservation Biology Blue River Preserve in southern Oklahoma. Trials showed that failure of seedlings to establish was not due to seeds experiencing lethal cold temperatures in the soil nor absence of disturbance. There was an impact on establishment due to competitors. However, results unexpectedly found that the root microbiome, which is commonly associated with successful establishment in alders, may be an excessive carbon sink that hinders seedling survival 1
University Of Oklahoma, Microbiology And Plant Biology, 770 Van Vleet Oval, Norman, OK, 73019, USA2University Of Oklahoma, Department Of Zoology, University Of Oklahoma, Norman, OK, 73019, USA
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RYBICKI, NANCY* 1, STRIANO, ELIZABETH 2 and THUM, RYAN 3
An investigation of a cryptic introduction of Water Chestnut (Trapa sp.) in the Potomac River Watershed, Virginia
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he Eurasian Water Chestnut (genus Trapa) is a nonindigenous species of floating aquatic plant in North America that impedes growth of native submerged aquatic vegetation through shading. A key characteristic in differentiating species in this genus is the number of barbed horns (0, 2, 3 or 4) projecting from the fruit and its width. Populations of a Trapa sp. with a fourhorn fruit (Trapa natans L.) have been established in the Northeast United States since the 1800s. No other Trapa taxa have been reported in the US. In 2014, Trapa sp. was found growing in the tidal Potomac River in Virginia for the first time since the costly eradication of T. natans from this river in the 1940s. We compared the two-horn Trapa sp. characteristics with existing colonies of T. natans in Maryland and with the worldwide literature on Trapa spp. and we investigated its local distribution and mode of dispersal. This Trapa sp. has a medium size, 2-horned fruit that differs significantly from the historically reported large, 4-horned fruit of T. natans. In a comparison of the ITS DNA sequences of two- versus four-horned Trapa collected in 2014 we found that the two morphotypes exhibited a fixed difference for a single nucleotide indel, further suggesting these as closely-related but distinct taxa. Genetic characteristics did not differ at the chloroplast trnLf region. A literature review of Trapa species showed that the fruit morphology of Virginia Trapa sp. was not different from the 30 to 50 mm wide, two-horned species, T. japonica, described in Japan, Korea, and Taiwan. However, T. japonica appears to be synonymous with about six other names by which the species may be known and that differed depending on the country and taxonomic reference used. A survey of local waterways and investigation of earlier reports of T. natans in Virginia showed that Trapa sp. with two horns was spreading between 2000 and 2015 among ponds and a reservoir on four separate tributaries in the Potomac River watershed and into tidal water. Local seed dispersal has likely occurred by hydrologic transport and epizoochary on geese as evidenced by observations and photographs. Natural resource managers in North America should become
familiar with this previously unreported taxon. More work is needed to understand distinctions among Trapa spp. and to determine if ecosystem response and best management practices may differ between taxa. 1
US Geological Survey, 12201 Sunrise Valley Dr, Reston, VA, N/A, 20192, USA2A Green Footprint LLC, Fairfax Station, VA, 22039, USA 3Montana State University's Plant Sciences Department Bozeman, MT 59717
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WALDER, MORGAN* , BOROWICZ, VICTORIA A. and ARMSTRONG, JOSEPH
Takeover on the Tallgrass Prairie: How Lespedeza cuneata Establishes Dominance
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arwin’s naturalization hypothesis posits that an exotic species is less likely to establish in communities with closely related species because similarity in morphology and function among taxonomically related species would promote intense competition for resources. At fine scales this hypothesis predicts a negative correlation between abundance of an exotic species and the number of related species, and predicts that cooccurring species should differ in life history, morphology, and function in the community. We examined this hypothesis as it applies to Lespedeza cuneata, an exotic legume rapidly spreading through open, relatively infertile sites in the Midwest. Lespedeza cuneata has a greater biomass allocation to leaves resulting in a higher total leaf area as well as allelopathic leaf litter compared to its native congener, Lespedeza capitata. In addition, L. cuneata grows tall, coarse single stems that form large stands. Timing of flowering, height of vegetative and flowering structures, total number of flowering stems of L. cuneata and all other species were recorded in 96, 1 m2 plots on a reconstructed tallgrass prairie in central Illinois, USA. Photosynthetically active radiation (PAR) was measured at ground level in June in each of the experimental plots, and biomass of grasses, forbs, L. cuneata, and other legumes were recorded from a 0.25 m2 subsample in each plot. These plots, established in 2006, had received annual treatments that were combinations of fertilizer (granular 10-10-10 N-P-K added/not added) and hemiparasite (Pedicularis canadensis removed/not removed). Principal components analysis was used to produce uncorrelated variables describing the composition of the plant community in the 1 m2 plots. Three factors explained approximately 71% of the variance in the data. These were included with fertilizer treatment, hemiparasite removal, and their interaction in analysis of variance of the dry mass of L. cuneata in the plots. Consistent with predictions of the naturalization hypothesis, L. cuneata biomass was negatively correlated with the number of other species of legumes present and also PAR. Other factors, which expressed the numbers of C3 and C4 grasses, forbs, weedy species, and exotic species in the community, were not associated with L. cuneata mass. Overall, fertilizer reduced L. cuneata biomass and hemiparasite removal had no effect. Lespedeza cuneata is the second-to-last species to flower on the study site and exhibits a growth form distinct from
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