Final answer:
Natural fires play a crucial role in maintaining temperate grassland ecosystems by preventing the growth of trees and shrubs, thereby preserving grasslands and promoting biodiversity. option a is correct.
Step-by-step explanation:
Natural fires in temperate grassland biomes serve as a crucial ecological process. These fires, often ignited by lightning strikes or occasionally by humans, play a key role in maintaining the prairie ecosystem by suppressing the growth of trees and shrubs. Without fire, temperate grasslands would eventually transition into scrubland or dense forests. Fires help to maintain these grasslands by allowing for the regular removal of invasive shrubs and preventing trees from overtaking the area, which would lead to a decrease in grassland diversity and biomass.
The natural fire regime maintains the dominance of grasses over woody plants, which is essential for the conservation of the grassland ecosystem. Moreover, the presence of fire maintains a balance within the biome by controlling invasive species and recycles nutrients back into the soil through the burning of dead material. This process is known as the grass-fire cycle, where fires enabled by grasses lead to a reduction in woody biomass and promote the growth of more invasive grasses, further perpetuating the cycle.
Additionally, controlled burns, also known as prescribed fires, are often used by conservationists to mimic the effects of natural fires and keep ecosystems healthy and diverse by preventing the encroachment of trees and shrubs and maintaining open grasslands that support a variety of wildlife.