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Abstract Detail


Hull, Julia [1], Hultine, Kevin [2], Gehring, Catherine [3].

Native cottonwoods confront resource allocation tradeoffs in the face of invasive tamarisk and climate change.

Most ecosystems are simultaneously facing the ecological threats of climate change and invasive species. The southwestern United States is disproportionately affected by climate change and has been invaded by tamarisk (or saltcedar; Tamarix spp.), which is one of the most aggressive invasive species in the US. Tamarisk increases soil salinity and reduces the abundance and diversity of beneficial root-associated microbes upon which cottonwoods rely. These effects can remain for years following tamarisk removal. For the native foundation species Fremont cottonwood (Populus fremontii) to survive these two stressors, they must be both good competitors and drought tolerant. Functional traits associated with competitiveness and drought tolerance are opposite ends of the plant economic spectrum. Cottonwoods from sites with tamarisk (hereafter “experienced”) grown in tamarisk legacy soils have higher fitness, as measured by survival and growth, than cottonwoods from sites without tamarisk (hereafter “naïve”). However, functional traits that explain these differences remain unknown. Therefore, this study investigates functional traits of experienced and naïve cottonwoods grown in two types of soil legacies under simulated climate scenarios. We used a fully factorial greenhouse experimental design to identify traits that allow experienced cottonwoods to outperform naïve cottonwoods in tamarisk legacy soil and to determine the effects of experimental heating on resource allocation patterns. We quantified fourteen functional traits to test three predictions. First, experienced cottonwoods will have higher fitness, as measured by survival and growth, than naive cottonwoods when grown in tamarisk legacy soil. Second, compared to naive cottonwoods, experienced cottonwoods show resource allocation strategy associated with competitiveness. Third, cottonwoods grown in increased temperature will show resource allocation strategy associated with drought tolerance. We identified three major patterns. 1) Cottonwoods, no matter their source, were nearly twice as likely to die in tamarisk legacy soil compared to agricultural legacy soil. 2) Experienced cottonwoods allocated more resources to roots than naive cottonwoods. 3) Cottonwoods grown in experimentally heated conditions showed the resource allocation patterns associated with drought tolerance. We showed that experienced cottonwoods have resource allocation patterns that better equip them for growing in tamarisk legacy soil. These results suggest that following tamarisk removal, the use of experienced cottonwoods as vegetation stock would likely lead to better restoration outcomes.

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1 - Northern Arizona University, 617 S Beaver Street, Flagstaff , Arizona, 86011, USA
2 - 1201 N Galvin Parkway, Phoenix, AZ, 85008, United States
3 - Northern Arizona University, Department Of Biological Sciences, 617 S Beaver Street, Flagstaff, AZ, 86011, United States

climate change
invasive plants
resource use strategies.

Presentation Type: Oral Paper
Session: ECO2, Ecology 2: Invasive Plant Species
Location: Tucson A/Starr Pass
Date: Tuesday, July 30th, 2019
Time: 8:30 AM
Number: ECO2002
Abstract ID:897
Candidate for Awards:None

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