Final answer:
The chaparral is diverse because of adaptations to periodic fires and a climate with limited rainfall; these result in a unique set of plants and animals, promoting biodiversity.
Step-by-step explanation:
The chaparral, also known as the scrub forest, is one of the more diverse terrestrial systems in California due to its unique adaptations to the climate and periodic fires.
The chaparral is characterized by shrub vegetation that has adapted to survive with limited annual rainfall, which mostly occurs in the winter, and long, dry summers with many plants remaining dormant.
The biodiversity of this biome is also greatly influenced by fire; some plants have evolved to produce seeds that only germinate after a hot fire. These adaptations, along with nutrient-rich ashes from fires, contribute to a cycle of regeneration and diversity. The tough conditions result in a specialized set of plants and animals that create a moderately biodiverse ecosystem.