Answer:
Decreases.
Step-by-step explanation:
Biodiversity may be defined as the variety of the living organism found in the earth. The diversity of the species may get affected and do not have any constant number.
The natural or human made calamity can decrease the species diversity. The fire on a grassland causes the death of many species, have harmful effects on many species and reduces the species number as well. This decreases the species diversity of the grassland.
Thus, the answer is decreases.