The plots are quickly covered with vegetation within two years. This is due to backfilling by arable soil and the richness of this soil. The ratio (R) of woody species to total species increases with the age of the formations.
- R1 = 0 for the plot aged a few mouths (less than one year)
- R2 = 0,27 for the 1 year backfilled plot and not yet reforested
- R3 = 0,3 for the 2 year backfilled plot and not yet reforested
- R4 = 0,44 for the 2 year reforested backfilled plot.
The increase in the ratio shows a diversification of ligneous regeneration within recolonizing vegetation.
The increase in the ratio between R3 and R4 is due to the low density of herbaceous vegetation in the reforested plot.