Fig 7. Total vegetation cover in 2011 and 2012.

Differences among oiling/treatment classes, years, and the interaction of oiling/treatment class and year were observed (all p < 0.01). Specific oiling/treatment class differences were observed for reference versus all other classes, and manual treatment versus mechanical treatment and no treatment (all p < 0.01). Data are means ± 1 SE. N = 9 for the heavily oiled plots with no treatment; n = 5 for all other oiling/treatment classes including reference.