5. CONCLUSIONS
This study shows that 6 years after soil restoration with two different
organic amendments, homogeneously added over the plots, and pine-chips
as mulch, together with planting native species, the final plant
communities (planted, spontaneous and pines) remain markedly different
and enhance soil properties recovery.
Organic amendments favored spontaneous opportunistic species which
competed with those planted. Such species can delay succession with
regards what would occur if the first step had been only native alpha
grass and Anthyllis . Independently of the pace of plant
succession, spontaneous plants contribute to erosion control and to
pedogenesis.
In this context, this study shows that there are pioneer species which
may be used to accelerate secondary succession by facilitating the
establishment of such targeted higher-value native species on later
successional stages.
The strong interaction between substrates and amendments advises to look
closely at which amendments should be used at each site for economic
reasons and local availability. But special care should be taken on how
they’ll be used (characteristics, dose, depth) to avoid unexpected
negative results.
Despite we are aware of the need for further studies on other adverse
environmental factors such as nutrient limitation, our results indicate
the potential suitability of spontaneous species and pine chips mulch
for restoration of post-mining areas.