Do you have a budget for fencing? The New Zealanders have done a lot of work on 'superfences' for keeping unwanted mammals out of specific areas. I agree with Vincent Raphael Nyirenda on bio-repellents as an option. Bear scat might work well for keeping boar away, and if you form a good relationship with a zoo, you could get it for free.
There are wolf urine sprays that can be used. They are available in hunting shops in Europe and reasonably effective, at least in the short term so maybe useful in terms of the short vulnerable period during reforestation activities. Once established it maybe okay. On a personal level our hunter used to spray regularly with this but also kept a regular check for damage. The combination worked well on our property.
However, wild boar do tend to adapt to deterrents after awhile and so I would want to know Vincent Raphael Nyirenda if any follow up was done to ensure that wild boar are staying out of the areas under investigation or whether they returned after the study period.
From the research I did a few years ago, the only effective deterrent was routine hunting. The most effective method being the shooting of a piglet, which encouraged the matriarch of the herd to move the whole herd away into the forest. This persuaded the animals to stay away from an area. If populations were not too high it was important not to shoot the matriarch, as that encouraged the the piglets to scatter leading to further trouble later. In Europe the lack of large predators meant that wild boar numbers were high.