DECOMPOSITION AND NUTRIENT RELEASE FROM LOGGING RESIDUE FOLLOWING CONVENTIONAL HARVEST OF SITKA SPRUCE IN NORTH WALES

Decomposition and macronutrient release of woody logging residue was examined for a clearfelled Sitka spruce plantation at Beddgelert Forest in North Wales. Weight loss from branches was low and branches lying on the ground decayed much more rapidly than those suspended in the air. Woody roots decayed at rates comparable to branches on the ground, and weight loss of both branches and roots was much more rapid for smaller than larger diameter classes. Nutrient release from woody residue generally followed the order: K > Ca = P > N, and net nitrogen accumulation was observed through 10 yr of decay except in the smallest size class (< 0.5 cm); however, the magnitude of N release from this smallest size class greatly exceeded the accumulation in all other classes combined. Leaching from logging residue helps to explain differences in macronutrient leaching between conventional and whole-tree harvest plots at Beddgelert Forest, thereby balancing to a limited extent the much lower nutrient removal in wood products associated with conventional harvest practices.