SPATIAL PATTERNS OF INORGANIC-N, P-AVAILABILITY, AND ORGANIC-C IN RELATION TO SOIL DISTURBANCE - A CHRONOSEQUENCE ANALYSIS

This study quantified intersite variation and spatial pattern in organ ic C content,total inorganic N and extractable inorganic P in soils am ong six sites constituting a post-disturbance chronosequence in southw estern Ohio, USA. The study sites included an agricultural field with a 25 + yr history of soybean cropping (chronic disturbance), a site wh ich had been stripped of its surface soil and reclaimed using post-min ing procedures (pseudo-stripmine, acute disturbance), 5 and 10 year ol d fields, a 25-30 year old prairie restoration, and an undisturbed, ma ture forest. All six sites were on soils with similar texture and clas sification. With the exception of the active soybean field, P and orga nic C increased with time since disturbance. Inorganic N was high in t he soybean field and mature forest and low in the other four sites, wi th no consistent temporal trend. Spatial dependence of inorganic N and organic C were high in most sites and decreased with time since distu rbance. Spatial dependence of P was lower than those of inorganic N an d organic C and did not exhibit any clear temporal trend. Each nutrien t exhibited its own unique spatial and temporal pattern of variation, and correlations among resources were weak. The results emphasize the need for quantifying and understanding spatial patterns as a prerequis ite for developing restoration planting protocols or operationalizing mechanistic models predicting vegetation change in specific study site s. (C) 1998 Elsevier Science B.V.