ARS | Publication request: The effect of heterogeneous landscape dynamics on ecotone types at two convergent semi-arid biomes

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: August 15, 2009
Publication Date: September 11, 2009
Citation: Klass, J., Peters, D.C. 2009. The effect of heterogeneous landscape dynamics on ecotone types at two convergent semi-arid biomes [abstract]. 2009 All Scientists Meeting, September 12-16, 2009, Estes Park, Coloradop. p. 102.

Technical Abstract: Landscapes in biome transition zones consist of a mosaic of patches dominated or codominated by species from adjacent biomes. Shifts in the vegetation composition and dynamics of a biome transition zone depend upon the underlying patch dynamics of the ecotones between these dominant species. Landscapes can consist of a number of different types of ecotones (directional, shifting, stationary) hypothesized to differ in the strength of three major factors: abiotic drivers, biotic feedbacks, and abiotic feedbacks. In this poster, our objective was to test the hypothesis that vegetation patterns across stationary ecotones are strongly related to abiotic factors that influence water availability (soil texture, microtopography) where weak correlations were expected for shifting ecotones. We tested this hypothesis for landscapes at the Sevilleta LTER site in central New Mexico, USA. Landscapes at the Sevilleta consist of a mosaic of patches dominated or codominated by three species: two perennial C4 grasses, Bouteloua gracilis (blue grama) and Bouteloua eriopoda (black grama), and one C3 shrub, Larrea tridentata (creosotebush). We estimated cover by species, analyzed soil samples (0-20cm), and obtained elevation using a Total Positioning Station every 5-10m along multiple transects for 10 ecotones. Our results show that stationary ecotones occur on finer-textured soils at slightly lower elevations (cms) compared with shifting ecotones. Soils and elevation were not good predictors of the location of shifting ecotones. Our results suggest that landscape dynamics at a biome transition zone depend on the factors controlling different types of ecotones. Even though the same species may be involved, the underlying processes determining ecotone dynamics may vary for different parts of the landscape.