The primary succession is a process that occurs on newly formed environments. In this case, we have a newly formed dune. The dune is consisted only of sand, and it has no vegetation on it. If a grass manages to grow on the dune, than it will be a pioneer species as there are no other species present, thus it will start the primary succession on the dune. As the grass spreads out, it will create more and more biomass, as well as releasing certain chemicals in the dune, thus starting to create a soil, which in turn will provide conditions for more species to move in and start the second succession.
Reforestation is a process of planting trees in an area so as to conserve the land as future forest. According to the given situation, reforestation is the practice which can be used by the biologists to grow nitrogen fixing plants in an area so as to increase the nutrient concentration of the soil which have been depleted.
