Distinctive Patterns of Carbon and Nitrogen Fractions in a Deforested and Converted Tropical Peat Dome

English Abstract:

A deforested, drained and converted peat is recently common in Indonesia. This study aims at assessing patterns of Carbon and Nitrogen densities in disturbed peat dome in the equatorial Borneo of West Kalimantan Province, Indonesia. We investigated 160 peat cores samples from community oil palm (LU1); open peat dominated by ferns (LU2); and degraded forest (LU3). Research variables include Carbon, Nitrogen, bulk density, C:N ratio, and Carbon and Nitrogen densities. We categorized the samples into upper depth section (D1 = 0-50 cm); mid section (D2=50-100 cm); and bottom section (D3>100 cm). All data do not have normal distribution and unequal variances. We employed traditional single factor and Brown Forsythe Anovas prior to Welch-t comparisons. Carbon concentration distinctively decreases in the upper depth section and in oil palm. Nitrogen concentration substantially increases in the upper depth section but is lower in oil palm (Elaeis guineensis) than in open peats and degraded forest. C:N ratio is substantially lower in the upper depth section than in mid and bottom sections, and is slightly higher in oil palm than in other two land uses. Due to anthropogenic influence, bulk density is high in the upper depth section and in oil palm, leading to an increase of bulk, Carbon and Nitrogen densities. Results of statistical analyses indicate non-significant difference on Carbon fraction according to these depth clusters, and land uses, and significant difference on Nitrogen concentration according to depth sections only. Decline of C:N ratio in surface peats suggests rapid peat decomposition. A high C:N ratio in oil palm due to loss of Nitrogen and rapid absorption by this plant. High bulk density leads to an increase of Nitrogen availability, which enhances the breakdown of selected organic matters. We assume Carbon stock in this peat is unstable.

Keywords: disturbance, tropical peat properties