The layer of dead and dying vegetation found on the surface of the soil (some soil classifications assign the litter layer to the A horizon, shown as A00). Cellulose, hemicellulose, and lignin make up 20–30, 30–40, and 15–40% of the total litter mass, respectively; the exact values are governed by plant type and age, onsite conditions, and yearly environmental variations (Yadav and Malenson (2007) PPG 31, 2).