Document: JOA-3-81-15

Consequences of road construction: The threat of increasing hybridization to a rare plant species.

BAGGS, J.E.* and J.MASCHINSKI

The Arboretum at Flagstaff Flagstaff AZ 86001 USA ¹

Abstract:
Existence of the endangered shrub Purshia subintegra is believed to be threatened by hybridization with the more common Purshia stansburiana. Using discriminant function analysis, we found the parents and hybrids had detectable morphological differences that we could use to classify individuals. We examined plant performance in a common garden experiment. To determine the performance of P.. subintegra and it hybrids across a soil gradient, we collected stem cuttings from P.. subintegra, P.. stansburiana, and hybrids and transplanted rooted cuttings to pots containing one of each of the three parent soils. After 9 months, all plants had the greatest growth in the hybrid soils when compared to P. subintegra and P. stansburiana soils. We next examined the habitat of both parents and their hybrids in the Verde Valley. We found a significant difference between disturbed and undisturbed habitats in the distribution of P. subintegra, P. stansburiana, and hybrids. Washes and roadsides contained a greater proportion of hybrids than undisturbed habitat. Undisturbed habitat contained a greater proportion of P. subintegra. Increased road construction and human disturbance in the rare P. subintegra habitat may increase the invasion of hybrids and have implications for the management of this rare species.

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This abstract is being presented at: 4:45 PM in session:
Oral Session #51: Disturbance Ecology: Harvesting, Grazing and Roads.