Part A
The construction of roads, in general, tends to have negative effects on the flora and fauna. The construction itself means that lot of vegetation has to be cleared, thus destroyed, in order for the road to be constructed. If additional objects are set along the road, that will mean even more destroyed vegetation. The animals suffer mostly by being hit by vehicles as they do not know how to react to them. Their movement is stopped as they can not cross the roads, and the noise often drives them further away from it, meaning that the have to change their habits, or become exposed to predation. The humans also have much easier access in the interior of the forests, so there's always the big danger of destroying the forests by logging, and destroying the animal communist by poaching.
Part B
The roads can have positive effects on the forest ecosystems too, not just negative ones, but in order for that to be the case, the roads have to be planned and managed carefully. If the roads are planned carefully, by taking the forest ecosystem in consideration, then the roads can actually be very beneficial. The benefit can come in a way that the roads can be constructed in the areas of the forests that are not in danger and are not very sensitive, while in meantime being further away from the areas that are actually sensitive and very vulnerable, thus protecting them. Also, a carefully planned road, will have lot of places through which the animals can move from one side to another side of it, without having to cross the road, thus not influencing their movement and migratory patterns.