Woody Litter Decomposition Following Clear‐Cutting

Abstract

Unconfined Quercus prinus woody litter of three size classes (0—1, 1—3, and 3—5 cm diameter) was placed on forest floors of a control hardwood watershed and on mesic and xeric sites of a clear—cut watershed at Coweeta Hydrologic Laboratory, North Carolina. Exponential decay coefficients for mass loss on the control were .1524, .1728, and .0912 yr—1 for 0—1, 1—3, and 3—5 cm branches, respectively. Coefficients for 0—1, 1—3, and 3—5 cm branches were. 1752, .0756, and .1644 yr—1 on the mesic and site and .0456, .0948, and .0377 yr—1 on the xeric site. The effect of site differences on decomposition rate was greater than the effect of diameter, although an inverse relationship between diameter and decay coefficient is suggested. Time in the field, temperature, moisture, and microarthropod abundance also appeared to influence decomposition rate. Microarthropods dominated the animal community on decaying wood with oribatid mites and collembolans the most numerous. Microarthropod densities were highest on 0—1 cm twigs and lowest on 3—5 cm branches. Microarthropod densities were generally highest on the control, slightly depressed on the mesic site, and greatly depressed on the xeric site. Time in the field and state of decomposition both positively correlated with microarthropod abundance. Calcium concentration and total calcium exhibited transitory increases but little net change at the end of 1 yr in experimental branches. Total potassium decreased on all sites for 6 mo and for 12 mo on the control and xeric sites, with °60% remaining after 1 yr. Total potassium increased rapidly on the mesic site over the last 6 mo and reached 110% of the initial amount. Temperature, moisture, microbes, and microarthropods appeared to control nutrient dynamics. Wood litter dynamics were more important in terms of nutrient conservation on the clear—cut watershed than on the control and contributed to the resilience of the system. Removal or destruction of woody debris after clear—cutting would decrease the nutrient conservation properties of decaying wood and would probably contribute to watershed output of nutrients.