Answer:
E. all of the above
Step-by-step explanation:
The productivity of a forest is affected and defined by numerous factors. The soil fertility provides the nutrients for the growth of the plants, so the more fertile the soil is the more vegetation there will be, and vice versa. The water supply defines the type of vegetation in the forests, as well as how much that vegetation will produce. The higher amounts of water result in high productivity, while the smaller amounts of water in lower productivity. The climate is always a very important factor, as it can either have negative influence on the forest productivity if it is too harsh or be the basis for high productivity if it is more moderate. The human activities are the newest factor that influences the forest productivity. The humans, with their activities, are more often than not a serious threat to the forests, as most commonly it ends up with destruction of the forest.