What is the term for the partly decomposed organic material on a forest floor?

The term for the partly decomposed organic material found on a forest floor is ground duff. Ground duff consists of leaves, twigs, and other organic matter that has fallen from trees and plants, which partially decomposes over time. This layer plays a critical role in the forest ecosystem, contributing to soil health by enriching it with nutrients as the organic material breaks down. Duff is also vital for retaining moisture within the soil, providing a habitat for various organisms, and influencing the forest's fire behavior due to its accumulation and state of decomposition. The understanding of ground duff is essential for both ecological studies and effective forest management practices.