A blood forest is a specific term used to identify the forests in the continent. They don't have any special traits apart from the blood trees that have red leaves. The harsh environment of the continent and its lack of sunlight made these trees evolve and now almost all the forest area is covered with them.
The grains and vegetables grown by the humans are planted inside the settlements and they only make a small portion of the greenery. The natural habitat is different for the blood forest. Generally, these trees are much better with life essence than regular plants.
So the beasts that eat the plants and trees with red leaves get more life essence. As it developed for millions of years, the beasts here became way stronger and rivaled even vampires.