Which type of decay primarily affects the lignin within and between the cell walls in the wood, reducing the tree's compressive strength?

The correct response focuses on white rot, which is a specific type of fungal decay that targets both lignin and cellulose found in wood. Lignin is a complex organic polymer that provides structural support and rigidity to trees. When white rot fungi invade wood, they break down lignin, leading to a significant reduction in compressive strength. This results in a weakened structure, making the wood more susceptible to collapse under pressure or load.

White rot not only affects the lignin but also leaves behind a bleached appearance and a soft, spongy texture due to the breakdown of the cell walls. This decay process is particularly concerning in structural timber and living trees, as it fundamentally compromises the tree's integrity.

Understanding the mechanisms of how different types of decay affect tree health and stability is crucial for effective tree management and arborist practices. Other forms of decay do not primarily target lignin in the same manner, which is what sets white rot apart in terms of its impact on compressive strength in wood.