Tracking environmental changes in restored Mediterranean dune slacks.

Restoration is an ecological tool that aims to recover the prior conditions and functioning of a degraded habitat. Three restoration projects targeted a dune slack system in the Eastern Iberian Peninsula and created a mosaic of ponds restored over three different periods: 1998, 2003 and 2007, the latter coinciding with the start of our study. Restoration works consisted of digging out the pond basin to its original morphometry. We monitored 12 restored ponds (six recent, three intermediate and three older ones) monthly, over four consecutive hydrological years (from 2007 until 2011) characterizing the most important limnological factors in order to disentangle the effects of man-made restoration over time. A multivariate statistical approach was used to detect the environmental trends of these ponds related to their restoration ages. Recently restored ponds tended to converge with older ones by decreasing values of conductivity, pH, oxygen and depth and increasing vegetation cover over time. Detected differences seem to address age-specific processes which increase over time after restoration: silting, salt leaching or an increase in organic matter decomposition. These processes could strongly influence the community build-up and biodiversity therein.