Soil properties and stable carbon isotope analysis of landscape features in the Petexbatún region of Guatemala

Abstract

Soil properties and stable carbon isotope ratios contained in the soil organic matter (SOM) were used to investigate the change in vegetative history of land cleared anciently for maize (Zea mays L.) agriculture in the Petexbatún region of Guatemala. Maize and other C 4 plants associated with land clearance leave a carbon isotopic signature in the SOM different from the C 3 plants of native forest vegetation. Soil profiles were collected from various landscape features around the Classic Maya site of Aguateca: control locations (areas likely not used in ancient agriculture), defensible locations (areas near defensive walls), rejolladas (natural karst depressions), upland locations (well-drained soils atop the Aguateca escarpment), and bajos (seasonal and perennial wetlands). The chemical and physical properties of the profiles were examined and the soils were taxonomically classified to the great group level. The changes in d 13C with soil depth were determined and compared statistically. The 13 C enrichment of the SOM in bajo and rejollada profiles were similar and were significantly ( p Ͻ 0.05) greater than the control, defensible, and upland soils. This isotopic signature of sustained C 4 vegetation was likely associated with forest clearance and ancient Maya agriculture. Both the bajo and rejollada landscape features appear to have been valuable agricultural resources for ancient Maya.

Ancient Maya impacts on the Earth's surface: An Early Anthropocene analog?

“…Next, to remove calcium and magnesium carbonates, the lab immersed the samples in a water bath heated to 70 C for at least 2 h. Next, we removed humic and fulvic acid fractions of the soil organic matter (SOM) by the alkaline pyrophosphate extraction method (Webb et al, 2004(Webb et al, , 2007. The stable carbon isotope ratio (d 13 C) of the remaining soil humin was measured with a Finnigan Delta Plus isotope-ratio mass spectrometer, connected to a Costech elemental analyzer (EAIRMS) (Wright et al, 2009). Recent articles discuss these laboratory methods in detail (Webb et al, 2004(Webb et al, , 2007Johnson et al, 2007a, b;Fig.…”

Holocene climate variability and anthropogenic impacts from Lago Paixban, a perennial wetland in Peten, Guatemala

“…3). Carbon isotope values from lacustrine sediment organic matter are often interpreted to represent input from local vegetation, with heavier values representing C 4 tropical grasses and other weedy taxa which are usually, but not necessarily, associated with agricultural activity (Lane et al, 2004(Lane et al, , 2008Wright et al, 2009). The Lago Paixban pollen diagram shows little change in grass pollen abundance at this time, though an increase in C 4 grasses would not necessarily be associated with a change in grass abundance.…”

Ancient Maya Commerce : Multidisciplinary Research at Chunchucmil

“…One way to delineate probable areas of ancient agriculture is through carbon isotopic ratios ( 13 C/ 12 C), and several studies have used these at other sites in the Maya lowlands Beach, Luzzadder-Beach, Cook, et al 2015;Beach, Luzzadder-Beach, guderjan, and Krause 2015;Burnett et al 2012aBurnett et al , 2012bFernández et al 2002;Fernández et al 2005;Lane et al 2008;Webb et al 2004Webb et al , 2007Wright et al 2009). Ancient long-term maize cultivation leaves a distinct isotopic signature in the SOM.…”