Pedological and Isotopic Relations of a Highland Tropical Peatland, Mountain Range of the Espinhaço Meridional (Brazil) Ingrid Horák, Pablo Vidal-Torrado, Alexandre Christófaro Silva, and Luiz Carlos Ruiz Pessenda Revista Brasil Ciencia Solo 35(1): Reviewed by: Paul Decker SWS 5716: Environmental Pedology April 20, 2015

Research Motivations Peatland soils dominated by organic matter illustrate paleo-conditions Climatic status of the past Atmospheric carbon levels and implications for climate change Vegetation trends over Earth’s history Reconstructing the past from preserved soil materials Ecological interactions Plant communities Hydrology Soil material and characteristics 2

Goal of Research Histosols of peatlands behave as a record of temporal and spatial dynamics of vegetation. What vegetation types grew back then? Where did they grow? Why did they grow? How can this information be tied into the Earth in the present? Interactions of soil properties and pedological principles Organic matter content Fibric material; O i, O e, O a Physical properties related to age and depth 3

Study Area Histic peatlands of Pau-de-Fruta Special Protection Area Southern Espinhaço Mountains of Coastal Brazil Depressional mountain peatlands 82 of total 1,700 ha (4.8%) 1,300 – 1,400 m ASL cm annual rainfall Cold, dry winters (June-Aug) Mild, wet summers (Oct-Apr) Mosaic of forest, grassland, and savanna 4

Methodology Soil core extracted using a vibro-corer Profile selected based on deepest available (505 cm) 43 subsamples of the profile were taken at 10 cm intervals Portions excluded due to water content (water table) Analytics include: Bulk density (g cm -3 ), gravimetric water content, OM content, OM density, mineralogy, Eh, pH, color, rubbed and unrubbed content 13 total horizons were described from profile 10 were found to be Histic O-C sequence, with OM underlain by sandy deposits. 5

Results Base of profile contains unstructured gravel and sand Water layer with high viscosity OM from cm Increased density and low hydraulic conductivity in lower layers; permanent anoxia Oldest material at bottom, younger with ascending depth Max sedimentation between 55 and 60 cm; 1.54 cm yr -1 Varying degrees of decomposition with depth 6

Results 7 Lighter colors (10 YR 4/4) near surface with darker colors (10YR 2/1) near base Sapric (O a ) near base ( cm) Hemic (O e ) from cm Fibric (O i ) with 30 cm of surface Decreased rubbed fiber content with depth Moisture content generally decreased towards base Related to density of soil and moisture holding capacity Evidence of soil profile collapse

Results 8 High C:N illustrate terrestrial plants Low C:N illustrate algae and phytoplankton C 4 plants (grasses) increase, field vegetation increases Iron Age (very cold, very dry), added to field vegetation type Moisture fluctuations yield fluctuating values of C:N  short, dry periods, charcoal and sandy material found

Implications and Conclusions 9 Degree of decomposition with depth Law of Superposition C:N illustrates proportion of woody versus grassy vegetation type Humidity and temperature of time period Indicates fluctuation of climate, temperature, and moisture of study site with time Evidence of interaction between soil genesis and soil forming factors Vegetation Climate Time

Pedological Principles 10 Soil forming factors Necessity of time for OM accumulation Parent material linked to vegetation type Topographic effects from Depressional position Vegetation effects on OM type, and consistence Climate variability and links to soil profile New example from organic soil type Variations of morphology assessment Principles surrounding Histosol soil order Taxonomic class of this study profile: Sandy, siliceous, dysic, isothermic, Hemic Haplosaprists 1 Courtesy: NRCS 1 USDA, NRCS Keys to Soil Taxonomy