A Temporal Sequence (Chronosequence) of Soil Carbon and Nitrogen Development after Phosphate Mining on Nauru Island

Abstract

Ten composite soil samples (0-15 cm depth) were collected from
\nabandoned phosphate-mined sites on Nauru Island (Central Pacific) and
\nanalyzed for % organic C and % N. The samples represent a temporal sequence
\n(chronosequence) of soil development spanning < 55 yr. The increase of% C and
\n% N was fairly rapid. In recently mined sites « 1 yr) the values of % C
\nwere between 0.41 and 0.48, and those for % N were between 0.03 and 0.04.
\nFifty-five years after mining, the values of % C and % N were 4.56 and
\n0.33, respectively, and comparable to the amounts found in undisturbed
\nLithic Haplustolls, Typic Haplustolls, and Lithic Ustorthents epipedons. These
\nchanges in soil properties are considered to be a function of time and the
\naccompanying seral development of vegetation (particularly the fern cover of
\nNephrolepis biserrata and Polypodium scolopendria) , because parent materials,
\nclimate, and other factors of soil formation are considered to be constant. Rate
\nof soil development is faster in the unconsolidated sands and limestone rubble
\nof the pit bottoms and slower on the dolomitic limestone pinnacle surfaces.