Spatial patterns of inorganic N, P availability, and organic C in relation to soil disturbance: a chronosequence analysis

Abstract

This study quantified intersite variation and spatial pattern in organic C content, total inorganic N and extractable inorganic P in soils among six sites constituting a post-disturbance chronosequence in southwestern Ohio, USA. The study sites included an agricultural field with a 25 + yr history of soybean cropping (chronic disturbance), a site which had been stripped of its surface soil and reclaimed using post-mining procedures (pseudo-stripmine, acute disturbance), 5 and 10 year old fields, a 25–30 year old prairie restoration, and an undisturbed, mature forest. All six sites were on soils with similar texture and classification. With the exception of the active soybean field, P and organic C increased with time since disturbance. Inorganic N was high in the soybean field and mature forest and low in the other four sites, with no consistent temporal trend. Spatial dependence of inorganic N and organic C were high in most sites and decreased with time since disturbance. Spatial dependence of P was lower than those of inorganic N and organic C and did not exhibit any clear temporal trend. Each nutrient 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 prerequisite for developing restoration planting protocols or operationalizing mechanistic models predicting vegetation change in specific study sites.