Climate drives dryland plant response to disturbance: A lesson from natural gas pipeline corridors

Tyson J. Terry, Wildland Resources, Utah State University, Logan, UT and Peter Adler, Department of Wildland Resources and the Ecology Center, Utah State University, Logan, UT

Background/Question/Methods
Independent lines of research have examined effects of climate or disturbance on vegetation, but we lack a general understanding of how climate and disturbance interact over large climate gradients and long time periods. We used natural gas pipeline corridors as an opportunity to study the interactive effects of climate and disturbance on net primary production (NPP) and shrub cover following a near-uniform disturbance across regional-scale climate gradients in hot and cold deserts of the western US. We asked, how does the rate of recovery of NPP and shrub cover following disturbance depend on mean annual precipitation? We used remotely sensed data to compare NPP and shrub cover on disturbed pixels within the pipeline corridor with undisturbed neighboring pixels. This paired pixel approach allowed us to describe recovery up to 74 years post-disturbance, while controlling for variation in climate, soils, and topography.
Results/Conclusions
We found that disturbance impacts on NPP depend on precipitation, with disturbed vegetation returning to undisturbed levels 45 years post-disturbance in dry areas, and incomplete recovery in wet areas 74 years post-disturbance. In contrast, shrub recovery was more complete, occurring 60-70 years post-disturbance, and was not related to precipitation. Despite full recovery of shrub cover, wetter areas continue to show incomplete recovery of NPP, perhaps indicating shifts in species composition or new stable states.