Final answer:
Forest fire suppression efforts over many years have led to a buildup of dead biomass that can fuel larger, more catastrophic fires, impacting both forest health and biodiversity. Therefore, the correct option is D.
Step-by-step explanation:
The decades-long policy of suppressing forest fires to protect life and property has led not only to some positive outcomes, such as the preservation of certain habitats, but it has also resulted in significant ecological challenges. One such outcome is (D) a buildup of dead biomass that can fuel larger, more destructive forest fires.
Without natural fire cycles to clear out undergrowth and dead materials, forests can accumulate large amounts of combustible material. Additionally, forest suppression policies can exacerbate issues by causing soil erosion on steep slopes, impacting forest biodiversity, and creating conditions that can make ecosystems more prone to catastrophic fires. Such policies may also hinder the processes that help maintain forested landscapes and the biodiversity they support, which rely on periodic fires to clear out older vegetation and make room for new growth.