Abstract Detail


Motley, M'Kayla [1], McKain, Michael [2].

Identifying changes in environmental limits of Johnsongrass (Sorghum halepense) over the last fifty years in the continental United States.

Invasive species can have detrimental impacts both economically and environmentally, which leads to major changes that affect both humans and the natural environment. Invasive plant species have several characteristics that contribute to their successful invasion of novel habitats including copious seed production, efficient seed dispersal, production of allelochemicals, and robust spreading rhizomes. Despite these adaptions, such weeds have natural limitations that inhibit them from invading all novel habitats; these limitations include climatic factors, such as precipitation and temperature. However, rapid adaptation to new environments, repeated introductions, and long-distance dispersal by humans may allow invasive species to overcome their environmental limits. By looking at how the range of Johnsongrass (Sorghum halepense) has shifted within the US over the last 50 years, we can better understand what environmental factors limit the species spread and, where the species has overcome historical barriers and identify populations with unique adaptive characters. Using data from herbaria and online resources, such as observations from iNaturalist and bioclimatic variables from WorldClim, we collected location and environmental variables for thousands of accessions spanning from 1970 to 2020. We describe the current limitations of Johnsongrass within the US and identify the factors that appear to be limiting the species’ spread by comparing to multi-year windows of both observational data and bioclimatic data gleaned from herbaria. By comparing the range of Johnsongrass present-day and 50 years ago, we can recognize how patterns are shifting in environmental tolerances. Massive observational datasets provided by online herbarium records, iNaturalist, and WorldClim, allow us to look at changes in invasive species population range. We recognize the limitation with a bias for sampling and observations that accompany these platforms. Tools, such as iNaturalist may aid in the elimination of some bias, credited to its ease of use when compared to herbarium specimen preparation and storage. The use of these online datasets could be beneficial in the context of many other invasive species and could allow for surveillance of real-time spread into novel habitats.

1 - 2301 Veterans Memorial Pkwy, Unit 202, Tuscaloosa, AL, 35405, United States
2 - University Of Alabama, 411 Mary Harmon Bryant Hall, Tuscaloosa, AL, 35487, United States


Presentation Type: Poster
Session: P, Biogeography Posters
Location: Virtual/Virtual
Date: Monday, July 27th, 2020
Time: 5:00 PM Time and date to be determined
Number: PBG009
Abstract ID:657
Candidate for Awards:None

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