Petrified Forest National Park Invasive Plant Survey and Mapping

A four year study of invasive plant distribution was conducted in select areas (approximately 2000 hectares) of Petrified Forest National Park.  The study conducted from 2002 to 2005 and utilized a novel grid sampling method.

This study will provide resource managers for Petrified Forest National Park baseline information on invasive plants in highly trafficked areas and their environs.  Occurrences collected on the grid sampling method will allow evaluation of the efficacy of different survey subsampling designs.

The findings show high yearly variability in invasive plant occurrence, which is highly correlated with seasonal and yearly rainfall patterns. The findings also demonstrated high invasive plant richness and cover near infrastructure and roads.  What was unexpected was the documentation of extensive infestations of Salsola spp. (tumbleweeds) throughout the Park study area.

Funding is being sought to examine the impacts of Salsola spp. on native biota in the park and the influence of this invasive forb on sand sheet and dune stability.  Unstabilized sand dunes have been correlated with the presence of Salsola on adjacent Navajo tribal lands.

	Contact: Kathryn Thomas USGS Southwest Biological Science Center Sonoran Desert Research Station, 125 Biological Sciences East University of Arizona Tucson, Arizona 85716 Kathryn_a_thomas@usgs.gov