Tropical peat soil variability along landscape and depth gradient using mid-infrared spectroscopy

BACKGROUND AND OBJECTIVES: Tropical peatlands, recognized as vital carbon sinks, remain vulnerable to drainage, canal and road construction, as well as frequent seasonal fires. These disturbances modify peat hydrodynamics and stimulate organic matter decay. Understanding chemical peat soil properties such as degree of decomposition provides support for landscape-based peatland management. The goals of this study were to analyze soil organic matter and its fluctuations with depth and location concerning hydrological features in a disturbed tropical peatland.METHODS: Peat samples were collected every ۵۰۰ meters along two transects representing different landscape and depth gradients. At every sampling location, samples were collected at every ۵۰ centimeters section, starting from the surface and continuing downwards until the mineral layer. Fourier transform infrared spectroscopy was used to characterize chemical functional groups of peat soil and to quantify the indices of humification, hydrophobicity, aromaticity, and decomposition. To analyze the trends between landscape and depths, principal component analysis was utilized. FINDINGS: Spectral analysis showed variation of functional groups between landscape and depth. The upper layer of peat exhibited a comparatively greater amount of aliphatic and oxidized substances than the lower layers, whereas the concentration of aromatic and humified structures generally rose with depth. Areas near the river or canal tended to have a lower hydrophobicity and higher decomposition pattern, which suggests a more active aerobic breakdown. Principal component analysis revealed that depth is the main variable that controls the pattern of functional group composition of the soil organic matter, while disturbance and hydrology contribute additional dimensions of spatial variability. CONCLUSION: Fourier transform infrared spectroscopy is useful for characterizing chemical properties of tropical peat soil. It demonstrates how drainage, hydrological matrix, and fire affect the composition of soil organic matter throughout different landscape and depth. The technique is useful and effective as a diagnostic tool for peat degradation detection to support peatland restoration efforts.

کلیدواژه ها:

Fourier transform infrared (FTIR) ، Landscape hydrology ، Peatland restoration ، Soil organic matter (SOM).