Page Banner

United States Department of Agriculture

Agricultural Research Service

Title: Using GIS to guide spatial sampling of atriplex canescens in the northern Chihuahuan Desert

item Steele, Caiti
item Lucero, Mary
item Silva, Andre

Submitted to: Journal of Essential Oil Research
Publication Type: Abstract Only
Publication Acceptance Date: 2/27/2009
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: We intend to use comparative phylogeographic analyses between the widely distributed halophytic shrub species, Atriplex canescens and associated endophytes to expand understanding of endophyte interactions that influence vegetation dynamics at fine and broad scales. To optimize field sampling for this research, we require a prior knowledge of the spatial distribution of A. canescens. Specifically, for our sampling procedure, A. canescens must be stratified by soil salinity and samples must be well-distributed through the northern Chihuahuan Desert. Our sampling framework is based on an approach that divides the landscape according to homogeneous tracts or units of land. We defined these land units using the ecological site concept developed by the Natural Resources Conservation Service (NRCS). To represent these land units geographically, we compiled spatial data from the NRCS Soil Survey Geographic (SSURGO) Database into a geographic information system (GIS). These spatial data have limited attributes, but they are supplied with non-spatial data tables that contain more detailed information regarding the physical, chemical and ecological characteristics of each soil map unit. We used simple queries to extract ecological site, soil salinity and A. canescens presence/absence attributes from the tabular data. These attributes were then joined to the spatial data and used to create a map of areas of interest for the comparative phylogeographic analyses. In this poster, we provide a description of the steps taken to (i) create the geodatabase and the map, (ii) refine the spatial units and (iii) create sampling points within the area of interest. We also describe several caveats that must be observed when using this approach.

Last Modified: 10/17/2017
Footer Content Back to Top of Page