Nitrogen and Carbon accretion on Ohio coal minesoils: Influence of soil-forming factors

Abstract

Plantations of white pine ( Pinus strobus L.), tuliptree ( Liriodendron tulipifera L.), white ash ( Fraxinus americana L.) and black locust ( Robinia pseudoacacia L.), established in 1946 on ungraded calcareous, neutral or acid coal spoils, were sampled in 1976 for weight, carbon and nitrogen content of the forest floor, and for total N concentration in 4 depth increments of the underlying mineral soil. Minesoil characteristics were related to the following soil-forming factors: parent material (overburden), organisms (tree species) and relief (aspect and slope position). Forest floor weight was high under white pine on all parent materials and under black locust on acid parent material. Nitrogen content of the forest floor was highest on acid minesoil, as was total weight of N in the forest floor under all species except tuliptree. Although concentration of N in the forest floor was highest under black locust, total weight of forest floor N under pine exceeded that under locust on calcareous and neutral minesoils because of the much greater weight of forest floor under pine. C/N ration of forest floor was lowest under locust and on the acid minesoil. Total N concentration was highest at all depths in soils that formed under black locust: rate of decrease in total N concentration between the 0–5 and 5–15 cm depth increments was also greatest under black locust. Soils formed on calcareous parent material had higher total N concentrations at all depths than those formed on neutral or acid parent materials. We estimate that concentration of total N in the 0–5 cm horizon of calcareous minesoils has increased from 0.04 to 0.23% in the 30 years since tree establishment. The corresponding increase in the acid minesoils has been from 0.03 to 0.18%. Our results show that accretion of carbon and nitrogen on minesoils will be influenced both by overburden strata placed at the surface as parent material of the new soil and by tree species chosen for planting.