Answer:
Rabbits and snakes increase in number but grasses decrease in number.
Step-by-step explanation:
If the population of hawk is decreases to half then the population of rabbits and snakes increases because hawk feeds on rabbits and snakes. The amount of grasses also decreases due to increase in the population of rabbits which feeds on these grasses. Hawks controls the population of rabbits and snakes when these hawks are decrease in number then the ecosystem will destabilize by increasing number of rabbits and as a result vegetative cover decreases quickly.