Evaluation of Percent Cover Requirements for Revegetation of Disturbed Sites on Alaska's North Slope
Keywords:Alaska, Arctic, North Slope, oil fields, percent cover, performance standards, rehabilitation, restoration, revegetation, tundra
On the North Slope of Alaska, attempts have been made to revegetate areas damaged by development. Some revegetation projects strive to achieve specific performance standards based on percent vegetation cover. This study uses data collected from 60 sites over 16 years to compare revegetating sites and natural reference sites. Results demonstrate that percent cover in most revegetation settings has the potential to reach levels comparable to those of reference sites, depending on how cover is defined. Linear models that explain between 48% and 84% of the variability in data show that planting cultivar seeds and fertilizing can increase cover (p < 0.05 for all models) and that cover continues to increase over time (p < 0.05 for all models), provided that cover is defined to include all live plants and plant litter. Ordination analysis separates reference sites from most revegetating sites along two significant axes (Monte Carlo tests, p < 0.01 with 100 randomizations). Comparison of ordination results with plots of change in plant cover over time shows that plant cover offers only limited insight into plant community development. If percent cover is to be used as a performance standard, it should be clearly defined, and the link between percent cover and restoration objectives should be carefully considered. Although this paper focuses on North Slope revegetation projects, the issues that are addressed have implications for all projects with performance standards calling for specific percent cover by vegetation.