The effects of site preparation equal those of seeding at a dryland restoration site: 6 years of plant community development

Abstract

Dryland ecosystems generally require active restoration to recover from severe land degradation caused by resource and energy extraction operations. While seeding remains one of the most used forms of active restoration, land managers in dryland systems have generally had difficulty re‐establishing desirable plant communities, due in part to alterations in supporting ecosystem processes and the episodic nature of resource availability. In this study, we examined the impacts of site preparation, seeding, and livestock grazing on developing plant communities after the construction of a buried natural gas pipeline corridor in the southwestern United States. We monitored plant species cover and composition beginning with the second season of growth through the sixth. Analysis of each individual year show that conclusions from the initial year of data collection did not well represent the findings in the following years. The site preparation and topsoil treatment had an ongoing positive effect on richness and cover compared to the nearby baseline conditions, while seeding only further increased cover and richness in the first year of monitoring (second season of growth). However, without seeding, the plant communities were driven by ruderal, annual species, whereas the seeded plant communities were driven by desirable seeded perennial grasses and forbs. Grazing and trampling effects were not significant overall, and the effects of livestock may have been confounded with effects of small mammals due to the exclosure configuration. We suggest that the site preparation, topsoil treatment, and configuration linearity of the disturbance corridor allowed for high levels of natural recruitment.