Environmental Factors Influencing the Spread and Invasion Potential of Arundo donax in Central Texas
Date
2022-12
Authors
Herod, Megan
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Abstract
Invasive species are a global concern and a significant contributor to
anthropogenic global change. As invasive species continue to invade new regions, they
impact natural ecosystem function and displace native species. The success and impact of
invasive species can be tied to species biology and the attributes of the invaded
ecosystem. A two-step experimental approach using a greenhouse experiment and remote
sensing methodology was used to develop an understanding of the environmental
conditions where Arundo donax, a large-statured invasive wetland species, performs best
and how it may colonize new areas. I predicted that Arundo would exhibit higher values
of performance-related traits such as aboveground biomass (AGB), belowground biomass
(BGB), net photosynthesis, and total tiller length under high light, high soil moisture, and
high nutrient conditions because there would be fewer factors limiting growth for this
species. I also predicted that the spread of Arundo would be closely tied to major flood
events when the transportation of propagules downstream and the scouring of banks leads
to colonization opportunities. Eight of the eleven response variables analyzed, including
AGB, BGB, total tiller length, and net photosynthesis showed a significant interaction
between soil moisture and light with plants grown in saturated, high light conditions
having the highest values for performance related traits. Nutrients were found to
influence biomass allocation patterns, with plants grown with added nitrogen and
phosphorous exhibiting higher shoot:root and stem:leaf ratios; however nutrients were
not found to significantly influence performance related traits. Major flood events were shown to positively influence the rate of spread of Arundo in the studied stretches of the
Guadalupe and Medina rivers in Texas. Understanding how invasive species respond to
changes in abiotic factors and what influences their ability to colonize new areas is
necessary to make predictions about species expansion and prioritize management efforts
and can provide necessary information for the development of ecological models.
Description
Keywords
Invasive species, Arundo donax, Giant reed, Biomass allocation, Nutrient addition, Soil moisture, Light
Citation
Herod, M. (2022). <i>Environmental factors influencing the spread and invasion potential of Arundo donax in Central Texas</i> (Unpublished thesis). Texas State University, San Marcos, Texas.