The purpose of this study was to use soil physical and chemical analyses to better understand the ancient agricultural landscape around the ancient Maya cities of Rio Amarillo and Piedras Negras, two tributary sites to Copan, Honduras. Our primary objective was to determine whether a mass erosion event around 800 A.D. occurred which could have caused crop failure and famine or if stable soil conditions persisted during the collapse of these city-states. Stable carbon isotope analysis of the humin fraction of the soils showed that much of this valley was used anciently for agriculture, including hillslopes and hilltops; however, there is no evidence of mass erosion in the soil profiles. Soil horizon development and texture is consistent with stable soil conditions in this area. The demise of these city-states was likely caused by a variety of factors including warfare and political unrest, and not solely by environmental degradation as postulated in previous studies of the valley.

Stable carbon isotope analyses of the humin fraction of the soil organic matter were conducted on more than 160 soil profiles from Tikal, Guatemala. The profiles were collected from near areas associated with the earthworks of Tikal; an ancient ditch and parapet construction hypothesized to have formed ancient boundaries of the polity. In addition to the isotope analyses, the physical and chemical characteristics of the horizons were determined. Maize, a C4 plant, formed an integral part of the ancient Maya diet and is the only known C4 plant cultivated by the Maya. Prior to and subsequent to the ancient Maya occupation of Tikal, the landscape was dominated by C3 forest vegetation. Over the centuries C4 plant biomass including rhizodeposition decomposed to form soil organic matter that contains a distinct C4 signature reflecting the vegetation history of the area. Forested areas anciently cleared for agriculture were identified through interpretation of significant isotopic shifts that signaled past vegetation changes. Buried horizons were encountered in the upland depressions and bajo wetlands. The aggraded soil deposits were likely the result of increased human activity related to settlement and agriculture. The buried horizons and the overlying sediments exhibited stable carbon isotope shifts associated with forest clearance and maize agriculture. Geospatial analysis of the stable carbon isotope ratios indicated that ancient Maya agriculture was focused on deeper footslope and toeslope soils in both bajos and upland depressions. Some evidence of infield agriculture or food processing was also encountered in connection with ancient settlement at upland locations. The soil data provide insight into ancient land use and sustainability that could potentially contribute to subsistence and population reconstruction models.

abstract: Irrigation agriculture has been heralded as the solution to feeding the world's growing population. To this end, irrigation agriculture is both extensifying and intensifying in arid regions across the world in an effort to create highly productive agricultural systems. Over one third of modern irrigated fields, however, show signs of serious soil degradation, including salinization and waterlogging, which threaten the productivity of these fields and the world's food supply. Surprisingly, little ecological data on agricultural soils have been collected to understand and address these problems. How, then, can expanding and intensifying modern irrigation systems remain agriculturally productive for the long-term? Archaeological case studies can provide critical insight into how irrigated agricultural systems may be sustainable for hundreds, if not thousands, of years. Irrigation systems in Mesopotamia, for example, have been cited consistently as a cautionary tale of the relationship between mismanaged irrigation systems and the collapse of civilizations, but little data expressly link how and why irrigation failed in the past. This dissertation presents much needed ecological data from two different regions of the world - the Phoenix Basin in southern Arizona and the Pampa de Chaparrí on the north coast of Peru - to explore how agricultural soils were affected by long-term irrigation in a variety of social and economic contexts, including the longevity and intensification of irrigation agriculture. Data from soils in prehispanic and historic agricultural fields indicate that despite long-lived and intensive irrigation farming, farmers in both regions created strategies to sustain large populations with irrigation agriculture for hundreds of years. In the Phoenix Basin, Hohokam and O'odham farmers relied on sedimentation from irrigation water to add necessary fine sediments and nutrients to otherwise poor desert soils. Similarly, on the Pampa, farmers relied on sedimentation in localized contexts, but also constructed fields with ridges and furrows to draw detrimental salts away from planting surfaces in the furrows on onto the ridges. These case studies are then compared to failing modern and ancient irrigated systems across the world to understand how the centralization of management may affect the long-term sustainability of irrigation agriculture. / Dissertation/Thesis / Ph.D. Anthropology 2013

The objective of this study was to use soil chemical properties, particularly carbon isotopes to describe the agricultural landscape in the Blue Creek region on the Rio Bravo Escarpment in northwestern Belize. The primary question associated with this study focused on the comparative agricultural potential of the soils between the upland karst environment and the lowland coastal plains using the distribution and frequency of ancient Maya maize production. Soil physical features, such as clay concentrations throughout profiles in conjunction with soil chemical properties were used to aid in determining the level of ancient maize production. Isotopic evidence suggests that anciently, lowland soils were used for maize production more so than upland soils. In addition, profiles at Crocodile Lake indicate the potential for transport of soil δ13C signatures as a result of mass movement events.

The ancient inhabitants of the Maya Lowlands enjoyed a long and fruitful period of growth which climaxed at around AD 800. At that time, millions of people successfully subsisted in a challenging environment that today only supports a population a fraction of that size. These facts, and the subsequent "Maya Collapse", are the impetus of many recent studies that utilize environmental data, in addition to conventional archaeology, to investigate this Maya mystery. Pedological studies and stable carbon isotope analysis of soil organic matter, combined with Geographic Information Systems (GIS) are three tools that can be used to answer crucial questions as to how the Maya managed their soil resources. GIS maps that indicated areas of best agricultural potential based on slope and soil type were used as a guide to opportunistically sample soils in an area south of Piedras Negras Guatemala – an area that was densely vegetated and unexplored. Soils that represented the different soil resources of the area were sampled with a bucket auger at 15 cm intervals. The samples were then tested in a laboratory for physical and chemical characteristics and δ-13C values were determined for soil organic matter. Soil taxonomical descriptions indicated that overall the soil resources of the area were very good as almost all the soils were classified as Mollisols - the most fertile of all the soil orders. The suite of great groups found was Haprendolls, Argiudolls, Argiaquolls and Udorthents. The characteristics which distinguish these great groups were used to further investigate relative agricultural productivity from an ancient soil resources point of view. Haprendolls were better drained and probably made for good agricultural soils given soil depth and rainfall were adequate. The Argiudolls and especially the Argiaquolls were probably less favored because of very high clay contents that made them more difficult to work with and poor drainage. Stable carbon isotope analyses revealed strong evidence for maize agriculture in some environments of the study area. δ-13C values as high as -16.6‰ (76% C4—Carbon) were observed in areas of significant soil accumulation in well drained and moderately drained soils. Minimal evidence of maize agriculture was found in more marginal environments such as those with little soil accumulation or poorly drained areas. Also, the pattern of the graph of δ-13C values versus depth indicated that ancient agriculture occurred continuously in some areas, but in other areas as distinguishable events. Finally, when the strength of the C4 signal was represented graphically and overlaid with a modified GIS agricultural potential map, a visual representation of the extent and degree of ancient agriculture was achieved. Our findings suggest that upland agriculture was favored by the ancient Maya of Piedras Negras and that the region between Piedras Negras and Yaxchilan was an agriculturally important breadbasket. The methods and results of this study provide foundational information for the investigation of ancient Maya agriculture. In future studies, it may be possible to more systematically map ancient agricultural fields and estimate the carrying capacity of a region based on its soil resources.

The objective of this study was to use pedological evidence in conjunction with Geographic Information Systems, and soil physical and chemical analyses as means to better understand the agricultural landscape surrounding the ancient Maya city of Uci. Specifically, the query of this thesis is to determine whether there is an association between settlement density and soil resources, and what relationship if any there is between the ancient sacbe of Uci and its surrounding agricultural potential. Stable carbon isotope analysis of the humin fraction of the soil organic matter was conducted on several profiles from karst depressions known as rejolladas near the site center, and from a select number of sufficiently deep profiles along and surrounding the ancient sacbe, and from beneath ancient structures. A strong C isotopic signature of ancient C4 crops was found in a limited number of profiles while a majority of the profiles showed no evidence, or little to inconclusive evidence due to a mixture of C3 and C4 plants in the natural landscape. A majority of the soils surrounding Uci are shallow to extremely shallow and many profiles sampled and studied did not allow for C isotopic analysis. Isotopic evidence along with other soil chemical and physical characteristics suggests that settlement density was linked to soil resources, specifically in the case of the rejolladas proximity to the Uci site center. However, it does not appear that the construction and location of the sacbe was linked to its surrounding soil resources or agricultural potential even though ancient maize crops may have been cultivated sporadically close to the sacbe and nearby structures. The soil resources of Uci are not conducive to the production of large maize crops and the ancient Maya of this area likely utilized maize along with alternative crops, arboriculture, wild game and trade to sustain its population.

Human land use legacies have significant and long lasting impacts across landscapes. However, investigating the impacts of ancient land use legacies ( > 400 years) remains problematic due to the difficulty in detecting ancient land uses, especially those beneath dense canopies. The city of Caracol, one of the most important Maya archaeological sites in Belize, was abandoned after the collapse of the Maya civilization (ca. A.D. 900), leaving behind numerous structures, causeways, and agricultural terraces that persist beneath the dense tropical forest of western Belize. LiDAR (Light Detection and Ranging) technology enables detection of below canopy Maya archaeological features, providing an ideal opportunity to study the effects of ancient land use legacies on contemporary tropical forest composition. LiDAR also provided us with a detailed record of the 3-dimensional forest structure over the 200 km2 study area. This allowed the investigation how ancient land uses continue to impact both forest composition, in terms of tree species, and forest structure. I recorded tree species over four land use categories: 1) structures, 2) causeways, 3) terraced, and 4) non-terraced land. Using non-metric multidimensional scaling (NMS) and multiresponse permutation procedures (MRPP) to test for differences between the classes, I found significantly distinct tree communities associated with the presence of terraces and the underlying topography. Terraced slopes appear to function as micro-valleys on the side of a hill, creating an environmental "bridge" between slope and valley tree communities. Tree species composition over causeways and structures was also found to be significantly different from terraced and non-terraced plots. Forest structure was assessed by extracting LiDAR points for terraced (n=150) and nonterraced (n=150) 0.25 ha plots. I calculated average canopy height, canopy closure, and vertical diversity from the height bins of the LiDAR points, using slope, elevation, and aspect as covariates. Using PerMANOVA I determined that forest structure over terraces was significantly different from non-terraced land. Terraces appear to mediate the effect of slope, resulting in less structural variation between slope and non-sloped land. These results led to the conclusion that human land uses abandoned >1000 years ago continue to impact the contemporary forests.

This thesis addresses the question of whether Roman military garrisons on the frontiers of the Empire could sustain their annual supplies of grain from the local countryside; and if they could, to what extent. The paper examines first the general diet of a Roman soldier and the administrative and logistical system by which the military was supplied with its required foodstuffs. Three case studies of specific forts: Hauarra in present-day Jordan, Vindolanda in present-day Britain, and Vindonissa in present-day Switzerland, based on the surviving granary structures of the forts and on the theoretical grain yields of the area, show that it was possible for these forts to supply themselves with their annual requirements of grain from the local area, without recourse to costly importation. / Graduate

Agricultural yields in Northwest Yucatán are constrained by climate, thin soils, and low fertility. Despite this, the ancient Maya city of Chunchucmil Yucatán, Mexico, boasted an immense, dense, and wealthy population during the Middle Classic period (ca A.D. 400-700). Soil physical and chemical properties were explored to determine how the ancient Maya of Chunchucmil fed themselves. Soil profiles were collected from various locations within ancient Chunchucmil's suspected sustaining area. The physical and chemical properties, carbon isotopes, black carbon, and coprostanols of soil profiles sampled were compared to ancient rural settlement and remotely sensed images, such as AIRSAR (airborne synthetic aperture radar). Our objectives were to geographically determine the areas of agricultural importance and determine whether evidence of ancient agricultural intensification could be observed in the surrounding soil resources of Chunchucmil. Indigenous Maya of the area identify three major soil classes, boxlu'um, saklu'um, and kancab. The ancient Maya likely preferred kancab because it provided some security with higher soil moisture, greater soil depth, and improved nutrient availability. The land use capability is severely limited in the swamp/estuary and tzekel. The lack of rural settlement within these zones suggests that they were not used for cultivation in ancient times; however, the wood resources likely provided Chunchucmil with vital raw materials. The carbon isotopic signature of ancient C4 crops was not detected suggesting that either maize was not extensively produced or that the mix of native C3 and C4 plants in the savanna hid the signature. There were no soil chemical or biomarker evidences of ancient agricultural intensification, suggesting that ancient agriculture was mainly based on shifting cultivation at Chunchucmil. Concentrations of black carbon, calcium, phosphorus, potassium (Olsen Method), magnesium, and organic carbon within urban and rural settlements were enhanced by incidental human activities. We determined that the land requirement would have been extensive to sustain the population of Chunchucmil during the Middle Classic based on traditional agricultural methods. The ancient Maya of Chunchucmil likely traded marine and estuary products from the Gulf coast and other high value trade items for agricultural products from the nearby Puuc Hills.

Tropical forests provide important habitat for a tremendous diversity of plant and animal species. However, limitations in measuring and monitoring the structure and function of tropical forests has caused these systems to remain poorly understood. Remote-sensing technology has provided a powerful tool for quantification of structural patterns and associating these with resource use. Satellite and aerial platforms can be used to collect remotely sensed images of tropical forests that can be applied to ecological research and management. Chapter 1 of this article highlights the resources available for tropical forest remote sensing and presents a case-study that demonstrates its application to a neotropical forest located in the Petén region of northern Guatemala. The ancient polity of Tikal has been extensively studied by archaeologists and soil scientists, but little is known about the subsistence and ancient farming techniques that sustained its inhabitants. The objective of chapter 2 was to create predictive models for ancient maize (Zea mays L.) agriculture in the Tikal National Park, Petén, Guatemala, improving our understanding of settlement patterns and the ecological potentials surrounding the site in a cost effective manner. Ancient maize agriculture was described in this study as carbon (C) isotopic signatures left in the soil humin fraction. Probability models predicting C isotopic enrichment and carbonate C were used to outline areas of potential long term maize agriculture. It was found that the Tikal area not only supports a great variety of potential food production systems but the models suggest multiple maize agricultural practices were used.