Indices of grassland biodiversity in the Chihuahuan Desert ecoregion derived from remote sensing

Citation
Eh. Muldavin et al., Indices of grassland biodiversity in the Chihuahuan Desert ecoregion derived from remote sensing, CONSER BIOL, 15(4), 2001, pp. 844-855
Citations number
27
Categorie Soggetti
Environment/Ecology
Journal title
CONSERVATION BIOLOGY
ISSN journal
08888892 → ACNP
Volume
15
Issue
4
Year of publication
2001
Pages
844 - 855
Database
ISI
SICI code
0888-8892(200108)15:4<844:IOGBIT>2.0.ZU;2-9
Abstract
We used a relatively simple and direct remote-sensing approach to determine biodiversity values in arid ecosystems and thus identify potential conserv ation sites. We developed indices based on regression models between, grass , shrub, litter, exposed-soil groundcover components and Landsat thematic m apper satellite imagery reflectance values over a reference site in the nor thern Chihuahuan Desert in New Mexico. This site supports low-disturbance g rasslands that have been under a continuous grazing regime for over 100 yea rs. Greater richness and abundance of noninvasive and nonruderal plant spec ies were associated with the low-disturbance grasslands that had lower shru b abundance, increased litter and grass cover, and lower exposed soil. Usin g the thematic mapper indices, we computed an additive grassland biodiversi ty index such that, as exposed soil and shrub values go down, litter and gr ass values go up, as does the biodiversity index. When the biodiversity ind ex was applied to the reference-site landscape, grasslands previously ident ified for their high conservation value were detected. As a further test, w e applied the indices to a site in Chihuahua, Mexico, that supports similar grasslands but for which there are few other data on condition and conserv ation values. The soil, grass, and shrub indices were moderately effective in describing the range of variation at the Mexico site, but the litter equ ation was not. Still, higher biodiversity value in terms of nonruderal plan t diversity tended to correspond to higher grass cover and lower soil expos ure and a higher overall biodiversity index. Some localized calibration wit h geologic substrate may be required along with an assessment of the tempor al constraints, but generally the index shows promise for quickly and effic iently detecting desert grasslands of high biodiversity conservation value.