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.