Nutrient Cycling and Nutrient Use Efficiency

Forest ecosystems systematically produce more litterfall dry mass per unit of nitrogen in sites with less aboveground nitrogen circulation. This pattern is observed both within and among tropical, temperate deciduous, coniferous, Mediterranean, and fertilized ecosystems. The differences among sites are probably related to differences in soil nitrogen availability. Patterns of nitrogen use for root and wood production probably reinforce the litterfall results. An examination of phosphorus and calcium use efficiency for litterfall production yields more ambiguous results. The pattern for nitrogen circulation and nitrogen use efficiency in forests has important implications for ecosystem-level properties, including the development of low nitrogen availability in soil.