Location

USU Eccles Conference Center

Event Website

http://www.restoringthewest.org/

Streaming Media

Abstract

Energy development on the Colorado Plateau has led to increased fragmentation of open space by roads with negative consequences for native plant species. Roads reduce available habitat, spread exotic species, and create barriers to dispersal. In addition, unpaved roads also increase dust loads on leaves and floral structures, which may significantly reduce the growth and reproduction of nearby plants. We studied the effects of an unpaved road on the successful reproduction of the endangered Utah endemic shrub Hesperidanthus suffrutescens (shrubby reed-mustard). We measured the size and reproductive output of 156 plants and dust deposition at increasing distances from the road. We hand outcrossed 240 flowers on 80 plants to determine whether reduced reproduction, if any, is due to pre or post-pollination mechanisms. Additionally, we experimentally dusted 3 leaves on 30 plants (n=90) and measured stomatal conductance pre-dust, post-dust, and after washing. We

also dusted 3 flowers on 10 plants (n=30) prior to hand pollination and measured fruit set. Differences were analyzed using generalized linear mixed models to determine significant correlations between reproduction, proximity to the road, and dust. When controlling for plant size and distance, fruit set decreased with increasing proximity to the road and was negatively correlated with increasing levels of dust deposition (ƒ1,15 = 5.26, p

= 0.0366). The number of seeds per plant, the mean plant seed weight, and the proportion of hand-pollinated flowers that set fruit were also negatively correlated with dust, although not significantly. Although correlated with dust, the observed pattern of reduced reproduction could be due to other factors. Roads have been shown to interrupt complex plant-pollinator interactions, resulting in reduced reproduction. Stomatal conductance was significantly reduced (ƒ1, 58 = 87.56, p < 0.001) by the application of road dust. Eighty percent (24/30) of hand pollinated flowers set fruit after dusting, suggesting that dust did not prevent pollination. However, the process of applying pollen by hand could have removed any dust on the stigma. Overall, these results suggest that dust may impact fruit set through reduced physiological processes. The results also highlight the need for further research into the effects that roads and dust have on nearby plants while suggesting negative consequences for the conservation of an endangered shrub in Utah’s Uinta Basin.

Matthew Lewis, Graduate Research Assistant, Utah State University Department of Wildland Resources, 5230 Old Main HIll, Logan, Utah, 84322, ma.le@aggiemail.usu.edu

Matthew Lewis is a Graduate Research Assistant working towards his Master’s degree in Ecology through the Department of Wildland Resources and the Ecology Center at Utah State University. He completed his Bachelor’s Degree in Conservation and Restoration Ecology at Utah State University.

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Oct 31st, 1:20 PM Oct 31st, 1:30 PM

Dust Deposition from Unpaved Roads is Correlated with Decreased Reproduction of an Endangered Utah Endemic Shrub

USU Eccles Conference Center

Energy development on the Colorado Plateau has led to increased fragmentation of open space by roads with negative consequences for native plant species. Roads reduce available habitat, spread exotic species, and create barriers to dispersal. In addition, unpaved roads also increase dust loads on leaves and floral structures, which may significantly reduce the growth and reproduction of nearby plants. We studied the effects of an unpaved road on the successful reproduction of the endangered Utah endemic shrub Hesperidanthus suffrutescens (shrubby reed-mustard). We measured the size and reproductive output of 156 plants and dust deposition at increasing distances from the road. We hand outcrossed 240 flowers on 80 plants to determine whether reduced reproduction, if any, is due to pre or post-pollination mechanisms. Additionally, we experimentally dusted 3 leaves on 30 plants (n=90) and measured stomatal conductance pre-dust, post-dust, and after washing. We

also dusted 3 flowers on 10 plants (n=30) prior to hand pollination and measured fruit set. Differences were analyzed using generalized linear mixed models to determine significant correlations between reproduction, proximity to the road, and dust. When controlling for plant size and distance, fruit set decreased with increasing proximity to the road and was negatively correlated with increasing levels of dust deposition (ƒ1,15 = 5.26, p

= 0.0366). The number of seeds per plant, the mean plant seed weight, and the proportion of hand-pollinated flowers that set fruit were also negatively correlated with dust, although not significantly. Although correlated with dust, the observed pattern of reduced reproduction could be due to other factors. Roads have been shown to interrupt complex plant-pollinator interactions, resulting in reduced reproduction. Stomatal conductance was significantly reduced (ƒ1, 58 = 87.56, p < 0.001) by the application of road dust. Eighty percent (24/30) of hand pollinated flowers set fruit after dusting, suggesting that dust did not prevent pollination. However, the process of applying pollen by hand could have removed any dust on the stigma. Overall, these results suggest that dust may impact fruit set through reduced physiological processes. The results also highlight the need for further research into the effects that roads and dust have on nearby plants while suggesting negative consequences for the conservation of an endangered shrub in Utah’s Uinta Basin.

Matthew Lewis, Graduate Research Assistant, Utah State University Department of Wildland Resources, 5230 Old Main HIll, Logan, Utah, 84322, ma.le@aggiemail.usu.edu

Matthew Lewis is a Graduate Research Assistant working towards his Master’s degree in Ecology through the Department of Wildland Resources and the Ecology Center at Utah State University. He completed his Bachelor’s Degree in Conservation and Restoration Ecology at Utah State University.

http://digitalcommons.usu.edu/rtw/2012/october31/8