Table 8. Mean residence time for organic matter and nutrients in the surface litter layer of contrasting forest types (*). Values are calculated by dividing the forest floor mass by the mean annual litterfall. Organic matter and nutrient turnover rates show a large increase with decreasing altitude, reflecting the temperature increase with decreasing latitude. Deciduous species have greater turnover rates than conifers due to better litter quality.
| Forest Type | n | Organic Matter | N | K | Ca | Mg | P |
|---|
| Mean residence time (yr) |
| Boreal coniferous | 3 | 353 | 230 | 94 | 149 | 455 | 324 |
|---|
| Boreal deciduous | 1 | 26 | 27.1 | 10.0 | 13.8 | 14.2 | 15.2 |
|---|
| Temperate coniferous | 13 | 17 | 17.9 | 2.2 | 5.9 | 12.9 | 15.3 |
|---|
| Temperate deciduous | 14 | 4.0 | 5.5 | 1.3 | 3.0 | 3.4 | 5.8 |
|---|
| mediterranean deciduous | 2 | 3.4 | 3.9 | 0.8 | 4.4 | 2.5 | 2.3 |
|---|
| Tropical rain forest | 4 | 0.4 | 2.0 | 0.7 | 1.5 | 1.1 | 1.6 |
|---|
(*) Data for boreal and temperate forests and one Mediterranean forest are from Cole and Rapp (1981); one from Mediterranean forest from gray and Schlesinger (1981); and tropical forests from Edwards and Grubb (1982).