Carbon isotopic ratios of wetland and terrace soil sequences in the Maya Lowlands of Belize and Guatemala (original) (raw)
Related papers
A long-term decrease in the persistence of soil carbon caused by ancient Maya land use
The long-term effects of deforestation on tropical forest soil carbon reservoirs are important for estimating the consequences of land use on the global carbon cycle, but are poorly understood. The Maya Lowlands of Mexico and Guatemala provide a unique opportunity to assess this question, given the widespread deforestation by the ancient Maya that began ~4,000 years ago. Here, we compare radiocarbon ages of plant waxes and macrofossils in sediment cores from three lakes in the Maya Lowlands to record past changes in the mean soil transit time of plant waxes (MTTwax). MTTwax indicates the average age of plant waxes that are transported from soils to lake sediments, and comparison of radiocarbon data from soils and lake sediments within the same catchment indicates that MTTwax reflects the age of carbon in deep soils. All three sediment cores showed a decrease in MTTwax, ranging from 2,300 to 800 years, over the past 3,500 years. This decrease in MTTwax, indicating shorter storage times for carbon in lake catchment soils, is associated with evidence for ancient Maya deforestation. MTTwax never recovered to pre-deforestation values, despite subsequent reforestation, implying that current tropical deforestation will have long-lasting effects on soil carbon sinks.
Geoarchaeology, 2007
The ancient Maya subsisted in an environment limited by shallow soils and unpredictable weather patterns until their collapse ~A.D. 800-900. Ancient subsistence can be a difficult subject, with little physical evidence of agricultural artifacts and structures. This study characterized soil profiles and utilized changes in stable carbon isotope ratios of soil organic matter (SOM) to locate and interpret areas of ancient C 4 plant growth and maize (Zea mays) cultivation among the Maya. The investigation indicated some of the challenges the Maya faced, including shallow and sloped soils in some areas. The C 4 plant signature was found in seasonal wetland soils on the opposite side of the Laguneta Aguateca from the ruins of Aguateca, but not in the perennial wetlands on the immediate side. No C 4 plant signature was detected in the shoulder and backslope soils. Based on these findings, the ancient Maya of Aguateca probably adapted to their environment by farming rich toeslope soils. It is possible that maize was also grown in the seasonal wetlands adjacent to the site. If the steep backslope soils around Aguateca were used in ancient agriculture, the evidence has probably eroded away.
Johnson_et_al_-_Ancient_soil_resources_of_the_Usumacinta_River_Region__Guatemala.pdf
In this study we present the results of a combination of methods used to identify possible agricultural activity of the ancient Maya in the Usumacinta River Basin in Guatemala. These methods included stable carbon isotope analysis of bulk soil organic matter, soil profile investigations and a spatial model of gentle slopes and well-drained soils to identify favorable agricultural conditions. Stable carbon isotope analysis of bulk soil organic matter in particular offers potentially direct evidence of agricultural activity. The d 13 C results suggest that there is a strong signature of C 4 plants, such as maize and tropical grasses, throughout the study area. Further, the current soil conditions and extent of relatively gently sloped areas are favorable to agriculture. Overall, the results are supportive of the hypothesis that the area, located between the polities of Piedras Negras and Yaxchilán, was agriculturally important to surrounding areas.
Quaternary International, 2014
The reconstruction of the Maya Lowlands vegetational history and its paleoecological implications during the Middle-Late Holocene was carried out using phytolith analysis and organic matter stable isotopic ratios. Three sections located in a terrace of the Usumacinta River were studied: Tierra Blanca I, Tierra Blanca II, and El Pochote. They consisted of a series of alluvial sediments alternating with paleosols that contained artifacts belonging to the Formative, Classic, and Postclassic periods according to the Mesoamerican chronology. Our results showed that the Middle Holocene paleosols had well developed vertic features with À16‰ d 13 C values, which evidence seasonal-semiarid conditions. However, phytolith content recorded a predominance of C3 plants, and paleosol micromorphology showed a set of features related to an alternation of humid and drier conditions. Therefore, stable isotope composition reflects the integral signal of the last period of soil formation. Phytoliths and soil micromorphology correspond to a more extensive record that represents the successive stages of pedogenetic and environmental changes.
Ancient Maya impacts on the earth's surface: an early anthropocene analog?
ABSTRACT: The measure of the “Mayacene,” a microcosm of the Early Anthropocene that occurred from c. 3000 to 1000 BP, comes from multiple Late Quaternary paleoenvironmental records. We synthesized the evidence for Maya impacts on climate, vegetation, hydrology and the lithosphere, from studies of soils, lakes, floodplains, wetlands and other ecosystems. Maya civilization had likely altered local to regional ecosystems and hydrology by the Preclassic Period (3000-1700 BP), but these impacts waned by 1000 BP. They altered ecosystems with vast urban and rural infrastructure that included thousands of reservoirs, wetland fields and canals, terraces, field ridges, and temples. Although there is abundant evidence that indicates the Maya altered their forests, even at the large urban complex of Tikal as much as 40% of the forest remained intact through the Classic period. Existing forests are still influenced by ancient Maya forest gardening, particularly by the large expanses of ancient stone structures, terraces, and wetland fields that form their substrates. A few studies suggest deforestation and other land uses probably also warmed and dried regional climate by the Classic Period (1700-1100 BP). A much larger body of research documents the Maya impacts on hydrology, in the form of dams, reservoirs, canals, eroded soils and urban design for runoff. Another metric of the “Mayacene” are paleosols, which contain chemical evidence for human occupation, revealed by high phosphorus concentrations and carbon isotope ratios of C4 species like maize in the C3–dominated tropical forest ecosystem. Paleosol sequences exhibit “Maya Clays,” a facies that reflects a glut of rapidly eroded sediments that overlie pre-Maya paleosols. This stratigraphy is conspicuous in many dated soil profiles and marks the large-scale Maya transformation of the landscape in the Preclassic and Classic periods. Some of these also have increased phosphorous and carbon isotope evidence of C4 species. We synthesize and provide new evidence of Maya-period soil strata that show elevated carbon isotope ratios (δ13C), indicating the presence of C4 species in typical agricultural sites. This is often the case in ancient Maya wetland systems, which also have abundant evidence for the presence of several other economic plant species. The “Mayacene” of c. 3000 to 1000 BP was thus a patchwork of cities, villages, roads, urban heat islands, intensive and extensive farmsteads, forests and orchards. Today, forests and wetlands cover much of the Maya area but like so many places, these are now under the onslaught of the deforestation, draining, and plowing of the present Anthropocene.
This paper uses stable isotopic research on faunal remains from archaeological sites in the Maya area to describe ancient environments through time in the region. Carbon isotope signatures of white-tailed deer remains recovered from the Petexbatún and Motul de San José polities in Guatemala are combined with other published data to provide a regional diachronic perspective on variations in availability of maize, a C4 plant, to herbivores. These data are used as a proxy for the extent of agricultural fields through time across the Maya world and the results indicate considerable temporal and spatial heterogeneity, likely linked to natural environmental heterogeneity and local land-use histories. The local nature of variations underscores the need for greater detail in paleoenvironmental studies at the drainage-basin or site level. Preliminary oxygen isotope research on white-tailed deer from the Motul de San José polity is also presented as the basis for discussion of the role of archaeologically linked oxygen isotope signatures in correlating large scale climate shifts with other site-specific evidence for environmental change over the period of Maya occupation. Together discussions of the two isotopic data sets emphasize the importance of paleoenvironmental and particularly isotopic research on materials from well-dated archaeological contexts.
Geoarchaeology and tropical forest soil catenas of northwestern Belize
Quaternary International, 2017
New research on soil catenas under old growth tropical forest in NW Belize aims to understand soil formation, long-term human impacts, and slope stability over time. We studied areas with intensive ancient Maya impacts from 3000 to 1000 years ago and those with little ancient impact to compare how ancient land-use influenced slopes after about 1000 years of stable tropical forest cover. We characterized the physical, chemical and chronological characteristics of soils at crest/shoulders, backslopes, footslopes, and depression locations, analyzing typical soil parameters and carbon isotopes (d 13 C) in dated and undated sequences. Several of the footslope and depressions sites preserved evidence of buried paleosols with increased d 13 C dating (by four new AMS dates and three others we reported earlier) from the Maya Classic period, with high amounts of soil organic matter from C 4 species in ecosystems where only a few C 4 species occur today. Most crest/shoulders and backslopes had no evidence for increased d 13 C, though some crests and mid-slope sinks preserved evidence of ancient Maya impacts. The observation that steep slopes preserved no evidence of C 4 species inputs may mean that ancient Maya land use maintained forest reserves here. Alternatively, ancient Maya land uses caused slope erosion, with the d 13 C signatures detected today resulting from more recent soil development under forest and soil reformation over the last millennium. Additional evidence that these soils are recent in age includes elevated CaCO 3 , Sr, and low soil magnetic susceptibility, showing less leaching compared with older soils in our study. Other human impacts on soils include increased concentrations of Fe and Mn, terracing, and further evidence of substantial topsoil erosion in antiquity.
Quaternary international, 2008
This paper uses stable isotopic research on faunal remains from archaeological sites in the Maya area to describe ancient environments through time in the region. Carbon isotope signatures of white-tailed deer remains recovered from the Petexbatu´n and Motul de San Joseṕ olities in Guatemala are combined with other published data to provide a regional diachronic perspective on variations in availability of maize, a C4 plant, to herbivores. These data are used as a proxy for the extent of agricultural fields through time across the Maya world and the results indicate considerable temporal and spatial heterogeneity, likely linked to natural environmental heterogeneity and local land-use histories. The local nature of variations underscores the need for greater detail in paleoenvironmental studies at the drainagebasin or site level. Preliminary oxygen isotope research on white-tailed deer from the Motul de San Jose´polity is also presented as the basis for discussion of the role of archaeologically linked oxygen isotope signatures in correlating large scale climate shifts with other sitespecific evidence for environmental change over the period of Maya occupation. Together discussions of the two isotopic data sets emphasize the importance of paleoenvironmental and particularly isotopic research on materials from well-dated archaeological contexts. r
The ancient agricultural landscape of the satellite settlement of Ramonal near Tikal, Guatemala
Quaternary International, 2012
Soil science methodologies often enrich archaeological reconstructions. In the Maya Lowlands of Mesoamerica, stable carbon (C) isotope ratio (δ13C) analysis of soil organic matter (SOM) from profiles near ancient archaeological sites has been used to interpret the vegetative histories related to ancient maize agriculture. Due to distinct photosynthetic processes, the decomposed organic matter from the cultivation of maize can be distinguished from SOM derived from native forest detritus. The recalcitrant nature of humic substances allows for this distinction to be preserved through time. This study evaluates SOM δ13C from 98 soil profiles near Tikal, Guatemala to identify areas of ancient Maya agriculture and the staple crops used. Ancillary physical and chemical properties of the soil profiles were examined to facilitate and to supplement the interpretation of the isotope data. Most of the soils analyzed in this study are shallow Haprendolls with limited C isotopic evidence of prehistoric vegetation changes. The deeper, well-developed Argiudolls and Hapludolls contained strong evidence of vegetation changes associated with ancient maize agriculture. Areas with strong δ13C signatures of ancient C4 vegetation corresponded with foot- and toeslope locations, high clay content and low phosphorus (P) levels. The shallow backslope soils lacked significant evidence of ancient agriculture. The connections between profile location, settlement, isotope data, and P levels enable the identification of both agriculture production zones and enhanced understanding of stable C isotope dynamics in soils within the unique physiographic and archaeological surroundings of the Maya Lowlands.