Answer:
the one that you chose it the correct answer.
Explanation:
I believe this would be referred to as the biomass.
A biome is a group of ecosystems which shares the same characteristics. The world is split up into several biomes such as freshwater, marine, desert, forest, grassland, and tundra.
The grassland biomes are the regions which are dominated by grasses, often 3 to 6 feet tall at maturity. They may have an open shrub layer and the climate is temperate or tropical.
Answer: I haven't seen "wolves change rivers", whatever that is, but my best guess would be "carrying capacity"