Multivariate analysis of impacts of environmental variables on the temporal change in species abundances Table 3 gives the mean change in cover percentage per species for those species where this change was at least weakly significant ( p < .1).
( 2012 ) found a significant overall increase in Ellenberg's ( 1991 ) nutrient availability indicator ( N ), a marginally significant decrease in Ellenberg's light indicator ( L ) but no significant change in species number.
The pH of the organic layer appears to be the most important explanatory variable, followed by tree species and other soil chemical variables, and there is a small, but highly significant effect of NO 3 deposition.
The significant effect of deposition on the floristic change in spite of a decreasing trend in deposition indicates that there is a considerable lag in the response of the vegetation to deposition.