Latitude, Elevation, and Mean Annual Temperature Predict Peat Organic Matter Chemistry at a Global Scale

Peatlands contain a significant fraction of global soil carbon, but how these reservoirs will respond to the changing climate is still relatively unknown. A global picture of the variations in peat organic matter chemistry will aid our ability to gauge peatland soil response to climate. The goal of this research is to test the hypotheses that (a) peat carbohydrate content, an indicator of soil organic matter reactivity, will increase with latitude and decrease with mean annual temperatures, (b) while peat aromatic content, an indicator of recalcitrance, will vary inversely, and (c) elevation will have a similar effect to latitude. We used Fourier Transform Infrared Spectroscopy to examine variations in the organic matter functional groups of 1034 peat samples collected from 10 to 20, 30–40, and 60–70 cm depths at 165 individual sites across a latitudinal gradient of 79°N–65°S and from elevations of 0–4,773 m. Carbohydrate contents of high latitude peat were significantly greater than peat originating near the equator, while aromatic content showed the opposite trend. For peat from similar latitudes but different elevations, the carbohydrate content was greater and aromatic content was lower at higher elevations. Higher carbohydrate content at higher latitudes indicates a greater potential for mineralization, whereas the chemical composition of low latitude peat is consistent with their apparent relative stability in the face of warmer temperatures. The combination of low carbohydrates and high aromatics at warmer locations near the equator suggests the mineralization of high latitude peat until reaching recalcitrance under a new temperature regime.Estación Experimental Agropecuaria BarilocheFil: Verbeke, Brittany A. Florida State University. Department of Earth, Ocean, and Atmospheric Science; Estados UnidosFil: Lamit, Louis J. Syracuse University. Department of Biology, Department of Environmental and Forest Biology; Estados UnidosFil: Lilleskov, Erik A. USDA Forest Service; Estados UnidosFil: Hodgkins, Suzanne B. Florida State University. Department of Chemistry and Biochemistry; Estados UnidosFil: Basiliko, Nathan. Laurentian University. Department of Biology and the Vale Living with Lakes Centre; CanadaFil: Kane, Evan S. USDA Forest Service; Estados UnidosFil: Andersen, Roxane. University of the Highlands and Islands. Environmental Research Institute; Reino UnidoFil: Artz, Rebekka R. E. Ecological Sciences, James Hutton Institute; Reino UnidoFil: Benavides, Juan Carlos. Pontificia Universidad Javeriana. Departmento de Ecología y Territorio; ColombiaFil: Enriquez, Andrea Soledad. Instituto Nacional de Tecnologia Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Área de Recursos Naturales; ArgentinaFil: Enriquez, Andrea Soledad. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; ArgentinaFil: Chanton, Jeffrey P. Florida State University. Department of Earth, Ocean, and Atmospheric Science; Estados Unido