ARS | Publication request: Hierarchical Spatial Processes in Grassland-shrubland Transitions in the Southwestern U.S.

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: January 15, 2010
Publication Date: February 7, 2010
Citation: Goolsby, D., Bestelmeyer, B.T., Archer, S. 2010. Hierarchical Spatial Processes in Grassland-shrubland Transisitons in the Southwestern U.S. [abstract]. 63rd Society for Range Management annual Meeting, February 7-11, 2010, Denver, Colorado. PC-94.

Technical Abstract: Grassland to shrubland transitions have been widely reported in drylands across the world, but remain poorly understood beyond local-scale drivers. Knowledge of ecosystem spatial properties and the environmental constraints underlying landscape pattern is crucial to determining why shrublands have replaced grasslands in some areas and not others as well as predicting where such transitions may be most likely to occur in the future. Managers need to anticipate which landscapes are most susceptible to shrub encroachment. Information currently available from traditional point-based inventory and monitoring programs and small-scale or short-term field experiments is not sufficient to make these predictions. We describe how a landscape perspective that acknowledges the role of heterogeneity in land history, soil-geomorphic patterns and processes, and other broad-scale interactions can be used to interpret and predict local state-transitions. Specifically, we use historical aerial photography, high resolution satellite data, land-use maps, soil maps, and soil-vegetation inventory to produce a spatial state-and-transition model for a relict basin floor landscape in south-central New Mexico. We illustrate how variation in soil development, land-use decisions in the early 20th century, and contagious processes related to shrub spread and erosion that have shaped the pattern of transition in this landscape. We also note the implications of these patterns for management responses at different points in time and in different parts of the landscape.