Deforestation, agroforestry, and sustainable land management practices among the Classic period Maya

Quaternary International 249 (2012) 19e30

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Deforestation, agroforestry, and sustainable land management practices among the Classic period Maya Cameron L. McNeil Department of Anthropology, Lehman College, CUNY, 421 Davis Hall, 250 Bedford Park Blvd. West, Bronx, NY 10468, USA

a r t i c l e i n f o

a b s t r a c t

Article history: Available online 23 July 2011

This article explores evidence of deforestation and forest management practices in the Maya lowlands during the pre-Columbian period. In the early twentieth century, scholars first began to examine the role of the environment in the rise and collapse of the great southern Maya polities of the Classic period, proposing that deforestation was an important factor in their political fragmentation and depopulation between the eighth and tenth centuries. In the last twenty-five years, this hypothesis has gained broad acceptance largely due to research at the ancient city of Copan, Honduras. At Copan, scholars claim to have demonstrated that the Maya failed to sustainably manage their forests in the face of rising populations, and that they consequently destroyed vital natural resources. In spite of the popularity of the deforestation hypothesis, evidence in support of it is scant. New research at Copan, described here, rejects deforestation as a cause of that polity’s collapse. Instead, it shows that human populations at that site, as in many parts of the lowland Maya region, adapted to diverse environmental contexts and produced food, building materials, and fuel without destroying the landscape’s potential to support large populations over the long term. Ó 2011 Elsevier Ltd and INQUA.

1. Introduction Motivated by speculation about the causes of societal collapse, archaeologists and paleoecologists have investigated the landscape management strategies of the pre-Columbian Maya extensively. As far back as the early twentieth century, some scholars conjectured that the forest cover of the southern lowland Maya region was devastated by its human inhabitants concurrently with the development of their chiefdoms into fledgling states. These scholars reasoned that complex polities require large surpluses to support both food producers and non-producers such as royals, courtiers, and craft specialists. They believed that tropical forest ecosystems inhibited the success of large population centers, assuming that adequate food surpluses could not be produced in an environment with soil fertility issues and high annual rainfall that ensured erosion on slopes unprotected by forest cover. Proposed as an inevitable outcome of rising populations around the great Maya cities, large-scale deforestation would initiate land degradation and ultimately result in the failure of polities. This deforestation has been promoted by many in academia and the popular press as an important factor in the political fragmentation of the southern lowland cities between A.D. 780 and 980. Nevertheless, recent

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research has shown that around many of the ancient lowland cities, the Maya found creative ways to manage their landscapes and preserve forested space. Perspectives on ancient Maya resource use have at times been shaped by conceptions of agriculture that fail to take into account the importance of arboreal resources for Mesoamerican populations. Recent research in the Maya area has provided insight into the history of land-use practices and has demonstrated that, in many areas, the landscape during the population apogee of the Late Classic period (zA.D. 600e900) was not significantly more deforested or degraded than that of the Early Classic period (zA.D. 250e600). Furthermore, it has shown that populations during the Preclassic period (z1800 B.C.eA.D. 250), despite being smaller, often had a more significant negative impact on the environment than has been widely acknowledged. That is, ignorance of the environmental limits of newly-settled regions would appear to have been a greater danger to environmental sustainability than the large populations of the Classic period cities. This article presents a review of research on the relationship between the ancient Maya and their environment. After summarizing theories of environmental over-exploitation by the preColumbian Maya, it discusses ecological research conducted in the Copan Valley, Honduras, the most commonly cited ‘type site’ for the deforestation hypothesis. Following this, it explores evidence for Preclassic and Classic period deforestation from elsewhere in

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the Maya world, and discusses evidence of sustainable agroforestry practices among the pre-Columbian Maya. 2. The Maya area This article focuses on the southern lowland and transitional areas occupied in pre-Columbian times by the Maya, but will also touch on the northern lowland communities of the Yucatán Peninsula, which outlasted their southern neighbors. The Maya area encompasses northwestern Honduras, Guatemala, northern El Salvador, Belize, and southeastern and southern Mexico (see Fig. 1). This area is geographically diverse, containing lowlands, highlands, and transitional zones, arid regions and tropical rainforests, areas with large lakes, and coastal regions. 2.1. The Maya area: environment and topography Ancient Maya communities, though united by many different cultural practices, occupied a wide variety of environments. For example, significant environmental and topographical differences are found between the ancient lowland communities of the north and those of the south. The northern Maya lands of the Yucatán Peninsula are characterized by karst rock formations with thin soils on a Paleogene limestone base (Curtis et al., 1996; Leyden et al., 1998). The topography is marked by cenotes (limestone sinkholes), underground streams, and subterranean depressions (Rice, 1993). The water table is relatively close to the surface and can be reached through cenotes or caverns (Rice, 1993; Brenner et al., 2003). In contrast, in the southern Yucatán Peninsula and south into the Petén (central lowland area), the topography becomes hilly, surface rivers become possible, and seasonal wetlands (also called bajos) are found more frequently (Voorhies, 1982; Rice, 1993). The total annual rainfall in the southeastern Maya lands is significantly higher than in the north, and is a result of the direction in which the trade winds blow. While the northernmost areas of the Yucatán Peninsula receive as little as 500 mm of rainfall per year, some anciently-occupied parts of Honduras receive up to 2000 mm, and coastal areas of Belize can be even higher at 4000 mm per year (Turner et al., 1983; Rice, 1993:19). In ideal years, the southern lowland Maya lands are fertile zones for agriculture. However, the water table in the south runs deep beneath the surface, and, during periods of drought, the inhabitants could not easily dig down to reach water prior to the invention of modern machinery (Dahlin, 1983; Brenner et al., 2003). The altitude of ancient polities also varies greatly: Copan, on the southeastern periphery of the Maya area, is 607 m above sea level, at least 305 m above most large “lowland” Classic Maya polities (Popenoe, 1919; Willey and Leventhal, 1979:78). Differences in soil, rainfall, and altitude naturally give rise to a range of forest types in the Maya area, including tropical lowland evergreen forests, tropical semi-deciduous forests, tropical semideciduous woodlands, palm communities, and mangrove forests, with grasslands and wetlands interspersed among them (Greller, 2000). 2.2. Theories of agriculture and forest clearance Until a little over thirty years ago, it was widely believed that the ancient Maya relied solely on swidden agricultural techniques, a method of food production whereby forest cover is burned and turned into the soil as a source of fertilizer. The newly-produced field (termed a milpa) is used until the nutritional quality of the soil becomes degraded. The field is then often transitioned into an orchard garden and eventually becomes wooded again (Nations and Nigh, 1980). Swidden cycles vary with the quality of soil and

the traditions of farmers. The Maya had no large domesticated animals whose dung could be used to augment soil fertility or that could be used with agricultural implements to turn over the soil, and they lacked the sturdy metal tools found in other parts of the ancient world to aid them in weeding their fields (Sanders, 1973:333). Modern analogues can be used to assess how pre-Columbian swidden farming could have functioned. Nations and Nigh (1980:8) note that today among the Lacandon Maya, farmers prefer to cycle between the same areas over time rather than clearing primary forest, since the latter involves more work. Fields are traditionally planted for two to five years and then tree crops are grown there for five to seven years, after which the vegetation is burned to replenish the soil and the cycle of planting begins again. However, milpas on land cleared from primary forest are significantly more productive than those on land cleared of secondary growth (Nations and Nigh, 1980). Various herb and tree species are dispersed throughout the milpa between patches of maize. Maize is frequently interplanted with beans and squash. This method of farming shades the ground, hindering water evaporation, and lessens erosion (Alcorn, 1984:51). Trees and root crops can also help to reduce the erosion that would occur in a field planted solely in maize (Nations and Nigh, 1980). The planting of tree and root crops and lower-story herbs with variable maturation points means that the Lacandon make use of the maximum amount of space in their fields and provide food along an annual continuum (Nations and Nigh, 1980:11). In this system, failure to observe fallow periods would result in soil without the nutrients required for successful milpa growth. Analysis over the last several decades has found evidence for a more complex system of pre-Columbian land management strategies than initially believed: these will be discussed in the latter half of this paper. In addition, analysis of traditional Maya diets has demonstrated that the food triad of maize, beans, and squash, which has often been stressed as a central focus of Maya subsistence, is only one component of a larger range of foods from both fields and forest that are collected and consumed today. It can be assumed that pre-Columbian diets were at least as complex as modern ones, if not more so (Nations and Nigh, 1980; Atran, 1993). 3. Political fragmentation and population decline in the Terminal Classic (A.D. 780e980) The “Classic period” (zA.D. 250e900) of the Maya civilization was a time when the lowland Maya constructed many cities throughout southern Mexico and the Yucatán Peninsula, Belize, the Petén region of Guatemala, and western Honduras. Scholars have traced the transition from chiefdoms to states in many of the polity centers. The royal families of these communities intermarried, most commonly with royal women sent to marry lords of distant lands (Martin and Grube, 2008). The elites documented their lineages and battle successes on stone stelae, and in other, more perishable media, in a refined system of hieroglyphic writing. Dates were carefully recorded, frequently in the “long count” system that fixed the existence and activities of divine kings and queens into a calendar system calibrated to a Gregorian calendar starting point of August 11, 3114 B.C. The city centers contained palaces and pyramidal platforms capped by temples, and served as focal points for trade and commerce. 3.1. Collapse Between approximately A.D. 780 and 980 the southern lowland Maya polities suffered steep population declines and many of these centers were nearly or entirely deserted (Culbert, 1973a; Demarest

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Fig. 1. Map of the Maya Area. (Drawn by K. Landau).

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et al., 2004). The dramatic fragmentation of political power is highlighted by the vandalism of palaces and temples found at some of these sites (Fash et al., 2004). The careful keepers of Maya history ceased their already ancient tradition of carving the long count into Maya inscriptions. The cessation of elite activities at the lowland Maya sites was formerly referred to as a “collapse” of the Maya civilization, although it was at most a collapse only of the southern lowland polities. Some Classic period Maya cities to the north continued to thrive through the 12th century; later Postclassic period Maya polities were found in the Yucatán Peninsula, the southern Guatemalan highlands, and the area of Lake Petén Itzá; and Maya people continue to maintain their vibrant culture today (Demarest et al., 2004; Martin and Grube, 2008). Theories of the political breakdown of the southern lowland cities and the disappearance of their inhabitants include internal warfare (between elites, or between commoners and elites), warfare between polities, natural disasters (particularly drought), and environmental devastation due to population pressure on natural resources, particularly deforestation and soil depletion (Culbert, 1973a, 1988; Demarest et al., 2004). This breakdown of Maya polities was neither the first nor the last political decline found in Mesoamerica. The prehistory of this area from the Early Preclassic period (z1800e850 B.C.) on witnessed the rise and fall of many chiefdoms and states. The failure of those whose power waned between the eighth and tenth centuries has been given more attention than any other documented breakdown because it left behind the remains of so many large cities with written inscriptions, elaborate palaces, and well-provisioned royal tombs. 3.2. Hypotheses of deforestation and land degradation As far back as the 1930s, scholars drawn to the splendor of the ruins of these cities speculated that deforestation and environmental over-exploitation may have been an important factor in their decline and abandonment. C. Wythe Cooke (1931:286), in his 1931 journey through the Petén, envisioned a past landscape of cleared maize fields, and commented on the “accelerated” erosion of soil that must have resulted from the deforesting of the dense tropical stands of trees in the face of a large hungry population. The deforestation and over-exploitation hypothesis gained ground with the publication of the landmark volume The Classic Maya Collapse (Culbert 1973a), in which three chapters supported the idea that environmental degradation had a role in the political fragmentation of the ancient cities e though each of these chapters stressed that no single factor was responsible for the collapse (Sanders, 1973; Shimkin, 1973; Willey and Shimkin, 1973). Sanders (1973:351) considered it inevitable that rising populations would have forced the lowland Maya to resort to swidden processes that did not allow a full re-growth of forests between cycles. Instead, they would have relied on what he termed “grass swiddening and permanent orchard cropping,” in which the land would slowly be taken over with grasses that had a low fertility contribution to the soil and were difficult for the farmers to manage. In addition, such practices would have deprived the Maya of valuable forest foods on which they had formerly depended. Shimkin (1973) argued that the fuel needs of ancient Maya cities would have contributed to the loss of forests, creating logistical problems for these societies as remaining wood resources became more distant from city centers. Moreover, the loss of underbrush and protective forests would have meant that the Maya had access to less animal protein, as many species lost their habitats. Willey and Shimkin (1973:486e487), in their synthesis of collapse theories, suggest that as populations increased around city centers, the swidden agriculturalists would not have observed traditional practices of allowing forest re-growth

to re-fertilize the land. In addition, agriculture would have been extended into marginal zones in an effort to expand production, and this would have contributed to a rise in agricultural pests and an increase in weeds, which may have undermined the adequate production of maize. Nonetheless, they note that Maya polities may never have reached the limits of food production of their respective lands, but that a subsistence program extended so close to the environmental limits could easily have reached the breaking point with the advent of a natural disaster. By the 1980s, many scholars accepted environmental mismanagement, particularly deforestation coupled with erosion, as a factor in the failure of the Maya polities (Wiseman, 1985; Santley et al., 1986; Abrams and Rue, 1988; Culbert, 1988). Culbert (1988:100), who mentioned this possibility in his analysis of Tikal’s political collapse and near abandonment (Culbert, 1973b), embraced it much more strongly in his later work, stating that he preferred “to emphasize long-term environmental degradation as a critical factor” in the polity’s decline. In a 1974 publication Culbert (1974) referred to this as “overshoot,” a term now commonly applied to cultures whose populations exceed their carrying capacity, or whose environmental practices exceed the ability of natural recovery. In the last two decades, the deforestation hypothesis has entered the canon of Maya studies as one of the leading contributors to the “collapse,” and is widely taught to students of Mesoamerican pre-Columbian history (Islebe et al., 1996; Redman, 1999; Webster, 2002; Diamond, 2005; Evans, 2008). Some researchers have struggled to reconcile this hypothesis with the sustainable forms of agriculture used by modern Maya. Pyburn (1996), for example, resisted the idea that Maya farmers of the Classic period could have willingly wreaked such havoc on the land. She speculated instead that this ecological failure may have occurred because elites were ignorant of the requirements and limits of farming around their cities and, by pushing commoners too hard for tradable food resources, forced them to ignore sustainable practices. Work in the last decade supporting the occurrence of a drought or series of droughts during the Late Classic period (Folan et al., 1983; Gill, 2000; Haug et al., 2003; Hodell et al., 2005) has also been adopted into the deforestation hypothesis (Shaw, 2003). In light of this and earlier data, Shaw (2003) proposed that the impact of the Terminal Classic period drought was compounded in the southern lowland area by wide-scale deforestation, as cleared land is less effective in absorbing water than forested land.

4. Copan: a type site for the deforestation hypothesis The archaeological site of Copan, located along the southern Maya periphery in Honduras, has been held up as the “type site” for the deforestation hypothesis since the mid-1980s (Rue, 1987; Abrams and Rue, 1988; Abrams et al., 1996; Redman, 1999; Webster et al., 2000; Webster, 2002; Diamond, 2003, 2005) (Fig. 1). Research on this site arguing that the Late Classic Maya destroyed their environment through deforestation was until recently accepted so broadly that some scholars used this data to analyze the possibility of collapse due to environmental constraints in contexts related to other cultures (Kuznar and Frederick, 2003; Bologna and Flores, 2008). The idea that Copan was a city destroyed by human ignorance of e or inattentiveness to e environmental limits is popularly accepted as fact and has been used as a warning to modern populations (Redman, 1999; Diamond, 2005). In his influential volume, Collapse: How Societies Choose to Fail or Succeed (2005), Jared Diamond cited Copan as an example of a state that destroyed itself because it failed to observe sustainable environmental practices.

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4.1. Copan, an ancient Maya city Copan is one of the most excavated of the great Classic period polities. The huge corpus of data produced by scholars working at the site has made it ideal for testing hypotheses regarding its rise and later abandonment. Beginning around A.D. 400, the Maya inhabitants of Copan carved hieroglyphic inscriptions into stelae, stairs, and smaller artifacts at the site, providing archaeologists with a relatively detailed outline of the dynastic history of the city (Stuart, 2000; Fash, 2001; Martin and Grube, 2008). Multiple excavations have also provided information on the first people to have settled in the valley, who are believed to have been closely related to the Lenca, an ethnic group whose population today lives along the Honduran-El Salvadoran border (Fash, 2001; Metz et al., 2009). Sharer (2009) has proposed that evidence for Maya interlopers can first be found in the second century A.D. According to inscriptions, a Maya individual named K’inich Yax K’uk’ Mo’ arrived in the valley in A.D. 427 and assumed rulership over the area currently at the city’s center. This new leader initiated the construction of the earliest levels of the Acropolis, a great mound composed of many layers of superimposed architecture capped by the remains of the final phase of the Late Classic city. The platforms, royal tombs, and important ceremonial structures contained within the Acropolis encapsulate hundreds of years of history at Copan (Stuart, 2000; Bell et al., 2004). The date recorded in the text of the latest inscribed monument found at the site, Altar L, correlates to A.D. 822 (Martin and Grube, 2008). There are signs that the city was burned and vandalized in the ninth century, and a dramatic demographic drop occurred around this time (Fash et al., 2004). 4.2. Hypotheses concerning deforestation and land degradation of the city Scholars working at Copan in the 1980s and 1990s on a project called Proyecto Arqueologico Copan II (PAC II) argued that environmental over-exploitation was one important cause of the ancient city’s collapse. PAC II was first directed by William Sanders, an early proponent of the hypothesis that severe environmental degradation was inevitable with the rise of ancient Maya cities (Sanders, 1973). Following some of the ideas published in The Classic Maya Collapse (Culbert, 1973a), these scholars proposed that the Classic

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period population exploited the local environment past its shortterm resiliency (Rue, 1987; Abrams and Rue, 1988; Abrams et al., 1996; Webster et al., 2000; Webster, 2002). The scenario generally advanced held that, as population increased, people began to deforest the hills surrounding the valley, both for the purpose of producing food, and for fulfilling construction and fuel needs. The ever-increasing population caused Copan’s inhabitants to shorten fallow periods beyond levels that would allow the re-growth of forests, and thus undermined fertility. In addition, the topsoil of the deforested hillsides eroded into the fertile bottomlands, negatively impacting both the upland and lowland fields. Determinations of the quantity of wood used by the community for fuel and construction, and estimates of soil erosion levels in response to deforestation, were largely based on mathematical calculations and computer modeling: these determinations depend heavily, of course, on the data selected for calculations. One line of evidence for deforestation, however, consisted of the analysis of a sediment core dating to A.D. 1000. While this is a Postclassic period (zA.D. 900e1519) sediment core and thus records a time after the Late Classic population apogee of Copan, it was proposed by members of PAC II that the collapse of the polity was not a sudden one, but rather a gradual process that spanned centuries and encompassed the basal sediments of the core. Rue (1987) proposed that the sediments revealed the continuous and catastrophic overexploitation of the environment long past the ninth century A.D. (Rue, 1987; Abrams and Rue, 1988; Abrams et al., 1996). Abrams and Rue (1988:391) determined deforestation levels by combining analyses of Postclassic pollen levels with calculations of the firewood and construction needs of the growing population. Pinus (pine) trees were a focus of their investigations, since Pinus is the genus most favored by the Maya for cooking and ritual activities. Their analysis suggested to them that by A.D. 800 there would have been no pine trees left in “the entire 12 km length of the Copan pocket for a distance of nearly 1.0 km away from any zone of settlement on either side of the Copan River” (Abrams and Rue, 1988:391) (Fig. 2). 4.3. Upsetting the paradigm: new data from Copan Recent analysis of the pollen in a sediment core taken from the same pond studied by Rue (1987) does not support dramatic

Fig. 2. Map of the Copan Valley showing its five agricultural pockets (Copan, Santa Rita, El Jaral, Río Amarillo West, and Río Amarillo East). (Drawn by T. Pugh after Turner et al., 1983 and Webster, 2002).

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deforestation in the Late Classic period (McNeil, 2006, 2009; McNeil et al., 2010). The core encompasses nearly 3000 years of environmental information with its oldest sediments dating to 2670  40 14C B.P. (900e790 cal B.C. at 2s) (be158480). While the analysis of pollen in the sediments preserved in the core does show two periods of heightened deforestation, these are found in the Middle Preclassic and the Late Preclassic/Early Classic period (Fig. 3). Surprisingly, and contrary to many predictions, the landscape near the city center was more forested during the Late Classic period than during the Early Classic period. The methodology used for this analysis is reported in McNeil et al. (2010), and raw and analyzed supplementary data can be found online associated with that article. By identifying the species found at selected intervals in a sediment core, changes in the environment can be documented. Pollen grains and spores are identified to family, genus, or species and then grouped based on whether they are aquatics, terrestrial herbs, or trees. Insect- or animal-pollinated (zoophilous) species generally occur in significantly smaller amounts in sediment cores than wind-pollinated (anemophilous) species. Many tropical tree species are dependent on insects or bats for pollination and may be under-represented in aquatic sediments. This can complicate the analysis of pre-Columbian deforestation around polities whose dominant forest cover was composed of tropical hardwoods. Copan’s location at a higher elevation than most other “lowland” Classic period polities means that only the floor of the Copán Valley is conducive to the growth of tropical hardwoods and that its hillsides are more commonly dominated by pine (Pinus) and oak (Quercus), arboreal species whose pollen is anemophilous. Analyzing deforestation levels at Copan is therefore less

problematic than in areas where the majority of species composing forest cover may be under-represented in the pollen profile. From the earliest levels of the sediment core until those corresponding to the era of the apparent political fragmentation of the city and concomitant population decline, the core records significant human disturbance embodied in the percentages of herb pollen present. The earliest levels of the sediment core, from 515 to 487 cm, are dominated by Asteraceae (daisy family) and Poaceae (grass family) pollen (Fig. 3). An abundance of microscopic charcoal combined with the presence of Zea sp. pollen in these levels implies that the deforested landscape is a product of human clearance and agriculture, and not a product of natural grasslands. The most dramatic level of deforestation in the entire core occurs 512 cm down into the sediments where 89.0% of the pollen profile is composed of herb pollen (McNeil et al., 2010). Following this period of heightened deforestation, the forests recovered briefly at the 443 cm mark with arboreal pollen composing 75.2% of the terrestrial pollen (Fig. 3). Of the terrestrial pollen in this level, 63.5% is pine. A sample of peat from 443 to 442 cm has been dated to 2190  40 14C B.P. (380e160 cal B.C. at 2s). The rise in pine pollen is brief: pollen from herbs increases again between levels 423e359 cm. These latter sediments contain a more balanced ratio of herbs indicting open space, and arboreal grains indicating forested space, than had been found in the earliest levels of the core. A second period of heightened forest clearance begins at 344 cm as herb pollen changes from 33.6 to 54.0% of the pollen profile. This episode reaches its peak around 324 cm when herb pollen comprises 65.3% of the terrestrial pollen sum (Fig. 3). The inception of this second episode is marked by the presence of pollen from the

Fig. 3. Graph of pollen percentages from the Petapilla pond sediment core. Arboreal (shrub and tree) and herb percentages are of the sum of shrub, tree, and terrestrial herb pollen. Aquatic species percentages are of the sum of aquatic grains and all terrestrial pollen. AMS dates are found along the left of the graph. A dotted line runs horizontally through the graph marking the presence of the Tierra Blanca Joven Tephra layer. Levels where statistical significance of pollen could not be attained are marked with dots in the second to last column on the right. The presence of Zea spp. and Acrocomiaaculeata pollen is marked with dots.

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coyol palm (Acrocomia aculeata (Jacq.) Lodd. ex Mart.), and is likely a signature of Maya agroforestry practices. Coyol palms first appear in trash middens in the Copán Valley at around the same time that Maya-associated Acbi ceramics are first found (Lentz, 1991). This evidence has led Lentz (1991:186) to suggest that the Maya introduced the palm to the valley. The coyol heart, sap, young inflorescences, nuts, and oil are all edible and continue to be consumed in the Copán Valley today. Pollen samples scraped from floors inside buried pre-Columbian temples at Copan indicate that coyol flowers adorned these spaces, implying that demand for ritual use may be another aspect of the economic importance of this tree for the local population (McNeil, 2006). While AMS 14C dates on Copan sediments or organic materials of the Preclassic and Classic period span approximately 200 years, level 344 cm is unlikely to align with the second century date when Sharer (2009) notes that evidence for Maya incursion first appears. The proximity of level 344 cm to a well-dated volcanic ash layer (tephra) in the sediment core makes it more likely that the appearance of coyol dates to at least a hundred years later than the first sign of ethnic Maya in the valley (Fig. 3). The volcanic ash layer is found at 321.1e320.75 cm in the sediment core. A tephra sample was sent to Andrei Sarna-Wojcicki at the USGS Tephrochronology Laboratory who identified it as the Tierra Blanca Joven eruption of El Salvador’s Ilopango Volcano. This ash layer has been dated nine times by various scholars, providing an overlapping range of A.D. 408e536, with the eruption most likely to have occurred around A.D. 430 (Dull et al., 2001). The presence of this chronological marker in the sediment core allows the environmental history around this important Maya site to be closely tied to the well-dated history inscribed on stone monuments there. It is uncommon to have this level of temporal resolution when analyzing data from a sediment core. The peak of the second elevated period of deforestation occurs just before the eruption layer (Fig. 3). Inscriptions at Copan tell us that the founder of the Copan dynasty, K’inich Yax K’uk’ Mo’, an interloper possibly from the Belizean Maya center of Caracol, arrived in Copan in A.D. 427 (Stuart, 2007; Price et al., 2010). Archaeological excavations in Copan’s Acropolis have demonstrated that more construction occurred in the heart of the community in the seventy-five years immediately after the arrival of this king than in the following three hundred years of the city’s occupation (Fash, 2001; Bell and Canuto, 2004). The reduced percentage of arboreal pollen found in the Early Classic period levels may be partially attributable to forest clearance for building materials and the acquisition of timber for stucco production. Construction of the early Acropolis would have required substantial amounts of wood to produce stucco floors and plaza surfaces, and the large stucco masks on building facades. Data from the sediment core discussed here reveal that Late Classic period Copan was not characterized by overwhelming environmental devastation, despite its increasingly large human population. The ratio of pollen representing open space to that representing forested space indicates that the area near the Acropolis was more forested in the Late Classic than during the Early Classic period (McNeil et al., 2010). Although it was predicted that there would be no pine trees left in the section of the valley where the city center is found, pollen from the Pinus genus increases steadily during the latter half of the Classic period (approx. A.D. 600e850) (Fig. 3). This evidence suggests strongly that the Maya employed forest conservation methods and sustainable practices. The inhabitants of the Copán Valley may have developed methods of sustainable forest management in response to the negative consequences of deforestation during the Early to Middle Preclassic periods (z900 B.Ce350 B.C.), and then again in the Early Classic period. A good example of this kind of

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environmental alertness can be found in the construction of stucco masks in the ritual center, where Late Classic period builders of elite structures used thinner layers of plaster than during the Early Classic period (Fash and Fash, 1996). The collapse of the great Maya city is marked in the sediment core by a relatively rapid reforestation, suggesting that the gradual collapse scenario that underlies the interpretation of Rue’s sediment core is untenable. Between level 270.5 cm and 260.5 cm the arboreal pollen changes from comprising 59.8 to comprising 71.0% of all terrestrial pollen, and then from level 255.5e250.5 cm, rises from 70.3 to 89.8%. A peat sample from 262.5 to 261.5 cm in the sediment core was dated to 1160  40 14C B.P. (Cal A.D. 780 to 980 at 2s) (McNeil et al., 2010) (Fig. 3). The last date recorded at the site correlates to A.D. 822. A rapid collapse is also suggested by archaeological data showing that the city center was vandalized and burned at the end of the Classic period and largely abandoned (Fash et al., 2004). In the period following the collapse, signs of coyol cultivation disappear and evidence of maize cultivation is found in only one additional pre-Columbian level (220.5 cm). In level 250.5 terrestrial herb pollen (predominantly Asteraceae and Poaceae), makes up only 10.2% of the terrestrial pollen total, the inverse of level 512 cm, which reflects the most highly deforested period in the sediment core (Fig. 3) (McNeil et al., 2010). 5. Other evidence for pre-Columbian forest clearance within the Maya area Evidence from Copan does not support the deforestation hypothesis, but Copan is only one of the great Maya cities whose political structure and population suffered a dramatic collapse. In order to understand the interactions between the Maya and their environment, it is crucial to look at land-use patterns throughout the lowland areas. To what degree were other regions deforested? And what evidence is there for land management strategies? The forests of today’s Maya area were predominantly formed in the early Holocene by a gradually warmer and moister climate, which was introduced by rising sea levels (Leyden, 2002). The wide-scale growth of tropical forests in the Maya lowlands was not possible until the moisture content in the air increased. Islebe et al. (1996:269) found that a developed tropical forest first appeared around 8600 B.P. in the area around Lake Petén Itzá. Jones (1991:77e8) has documented a similar pattern in Belize, where savannas prevailed until eight thousand years ago. Thus the tropical forest habitats of Mesoamerica’s lowlands developed relatively recently in an area occupied by humans who, prior to domesticating plants in this region, hunted megafauna (de Anda, 1956). 5.1. Limitations of comparing data from different sites and time periods Comparing analyses of past environments near lowland Maya archaeological sites is complicated by specialists’ use of different techniques for acquiring dates, by differences in methods, and even by issues in the presentation of data. This is particularly true for palynology. 14C AMS dating was not commercially available until 1984, and earlier analyses had to contend with issues related to the hard-water lake effect (Deevey et al., 1979). Without accurate dating methods, scholars were left to analyze correlations between the environmental record and archaeological remains based on patterns in vegetation change, the delineation of which can be speculative (Deevey et al., 1979; Wiseman, 1985). Dates acquired from organic material originating outside of the body of water, such as leaves, wood, and seeds, are more likely to return reliable dates than those from bulk sediments or from organisms that lived within the bodies

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of water, such as the shells of various types of ostracods. However, even wood can produce misleading dates if the sample comes from the heartwood of a very old tree: in that case, the sample would date the initial formation of the tree rather than its demise. In addition, individual palynologists have used diverse standards for determining how many pollen grains must be counted to achieve a statistically significant representation of the pollen spectrum per level in a sediment core. For example, McNeil et al. (2010) used a standard of 200 arboreal pollen (AP) grains per level (or 1500 grains of herb pollen in one level where arboreal grain numbers were particularly low), but some other scholars employ much smaller AP counts, or count a standard sum of all pollen instead of using AP grains as a guide. Since weedy herbs and aquatics can appear in much larger numbers in sediments than arboreal grains, counting to sums of only 300 grains total or less may limit a detailed understanding of the ratio of pollen from trees to that of pollen from herbs, and will most certainly impede the identification of rare pollen types in the sediments. For example, had the standard for the analysis of the Petapilla sediment core been limited to 300 grains total per level, the pattern of coyol pollen distribution during the Classic period would not likely have been discovered. As Faegri et al. (1989:150) note, in contexts where “minor constituents” such as maize and coyol are important, counts limited to as little as 150 AP grains will certainly curtail the information that could be acquired from the sediments. Another complication arising from the comparison of data from different palynologists is that results are commonly represented in silhouette form, instead of as histograms (as seen in Fig. 3). Silhouettes may be appropriate for the analysis of extremely long sediment cores, but the smoothing of data points that characterizes silhouettes prevents other researchers from clearly assessing how many levels were analyzed, what percentages of each individual species, genus, or family group were found in those levels, and which levels did not have pollen counts meeting the standard of statistical significance. If silhouettes are used in the presentation of data (and they can be useful), then they should be accompanied by additional information that clearly delineates the levels that were counted (assuming that each of these had enough pollen grains to meet the established standard of statistical significance), and lists the pollen data for these levels. The following review of paleoecological analysis in the Maya area is undertaken with these caveats. 5.2. Landscape transformation during the Preclassic period (z1800 B.C.eA.D. 250) Scholars working in the Maya area have sometimes assumed that rates of deforestation would be directly related to rising populations (Sanders, 1973; Abrams and Rue, 1988; Abrams et al., 1996). In the case of the pre-Columbian period, however, ignorance of environmental limits may have posed an equal or greater threat to the landscape and its forests than the size of the population (McNeil, 2006; McNeil et al., 2010). In fact, while deforestation is found during the Classic period (A.D. 250e900), and found continuously during periods in which humans are practicing agriculture, heightened levels of deforestation are common during the Early to Middle Preclassic period in many parts of Mesoamerica, including in Copan. Pollen cores from both the northern and southern Maya lowlands contain signs of large-scale forest clearance between 3000 and 4600 years (Leyden, 1984; Rue, 1987; Hansen, 1990; Jones, 1991; Islebe et al., 1996; Pohl et al., 1996; Leyden et al., 1998; Rosenmeier et al., 2002; Brenner et al., 2003; McNeil, 2006; Wahl et al., 2006). This pattern is undoubtedly a product of the transition from a subsistence system based heavily on hunting and gathering to one dominated by agriculture. Data from sediment cores have allowed scholars to document the rise of

agriculturalists in the Maya area and to show that the period of initial deforestation, as currently understood, spans at least 1600 years. Nevertheless, work by Pohl et al. (1996) indicates that the earliest experiments in plant cultivation do not register significant forest clearance in pollen profiles. 5.3. Erosion as a product of forest clearance Deposits referred to as “Maya clay” have been found in a number of bodies of water in the Maya area (Brenner et al., 2003; Beach et al., 2006; Anselmetti et al., 2007). These layers of “silty, montmorillonitic clay” were first reported by Deevey et al. (1979:301). Such layers are a product of deforestation episodes thatremoved the roots and plants that anchor soil, causing large-scale erosion (Brenner et al., 2003; Beach et al., 2006). When first recorded by Deevey et al. (1979:301), the authors assumed that the Maya clay layers began in the Early Classic period, although the “hard-water lake effect” led to such large errors in dates that they were rendered useless. In the last decade, analysis of sediments from Lake Salpetén, Guatemala relied on 14C AMS to date small organic samples. This method assigned most of the erosion deposits there to the beginning of the Early Preclassic period (2000e700 B.C.) and showed that erosion continued to be a significant problem into the Late Preclassic period (250 B.C.eA.D.250) (Anselmetti et al., 2007:916e917). Islebe et al. (1996), working in Lake Petén Itzá, Guatemala, used14C AMS to date the beginning of the most significant period of forest clearance to 1880 B.P. and postulated that this period extended until approximately 950 B.P. They further noted that the Maya clay layers in Lake Petén Itzá aligned with this forest clearance, but unfortunately they did not specify the depths at which these layers were found within the span of significant forest clearance. Hopefully, at some time in the future, new methods of dating will be applied to some of the earlier analyzed lake sediments in order to determine the breadth of the pattern of association of Maya clay layers with evidence for deforestation. Research at Copan has produced results similar to those attained by Anselmetti et al. (2007): that is, they document a more significant problem with erosion in the Preclassic period than in the Classic period. Seven predominantly clay layers (464e463 cm, 459e458 cm, 454e453 cm, 419e418 cm, 414.4e413.4 cm, 399e398 cm, 350e349 cm) in the Petapilla sediment core analyzed by the author contained statistically insignificant amounts of pollen, indicating that they were laid down rapidly and are likely to be the product of erosion events (McNeil et al., 2010) (Fig. 3). Three of these layers are found following the earliest period of heightened deforestation, and all occur prior to the deposition of the Tierra Blanca Joven ash layer, which, as noted above, is believed to have occurred around A.D. 430. Two peat levels also contained low amounts of pollen: levels 434e433 cm, and 340e339 cm. 5.4. Deforestation during the Classic period (zA.D. 250e900) While a substantial number of sediment cores have been analyzed from the Petén lakes, many were sampled prior to the availability of 14C AMS dates. The human impact recorded in their sediments cannot, therefore, be clearly tied to the history documented by archaeologists (Deevey et al., 1979). Nonetheless, an interesting array of Classic period human environmental interactions can be documented. Dunning et al. (1997:257) found in their analysis of the Petexbatún region of Guatemala that while forest clearance did occur in the Late Classic period, substantial forest cover remained. Significantly, the forest cover at this time is lacking some arboreal species common to primary forests, leading the authors to suggest that the forests were actively managed. A local sediment core from Lake Tamarindito produced no evidence of

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significant erosion during the Late Classic period. Dunning et al. (1997) suggest that, in this area, steep slopes were probably left forested, and that footslope terraces were used at their bases to form small agricultural fields. Analysis by Wahl et al. (2006) of Lago Puerto Arturo in northern Petén documented forest clearance beginning approximately 3400 cal B.P. with a return to a heavily forested landscape after approximately A.D. 840. While the beginning of the period of disturbance contains a higher percentage of Poaceae (grass family) and the later a higher percentage of Asteraceae (daisy family), there does not appear to be a substantial increase in deforestation between the Middle Preclassic period and the Late Classic period. To the north in the Yucatán Peninsula, an area that did not suffer a dramatic decline at the same time as the southern polities, a similar pattern is found. Leyden et al. (1998) analyzed a sediment core from Lake Cobá, near the northern lowland site of Coba in Mexico. They found elevated deforestation beginning just after 850 B.C. and lasting until A.D. 720, after which deforestation dropped off significantly e although disturbance continued until A.D. 1240 when Coba was abandoned. However, levels of herb pollen do not increase significantly between the Middle Preclassic and Late Classic period, and therefore the data does not support an increasing level of environmental degradation at the end of the Classic period (Leyden, 2002). Following the political breakdown and population collapses of the southern Maya lowland polities, the forests grew once again, as shown by pollen profiles across this area (Leyden, 2002; McNeil, 2006; Wahl et al., 2006). There is debate as to precisely when forests returned after the failure of the lowland polities, and whether the timing of re-growth was affected by climate (Brenner et al., 2002; Leyden, 2002). In addition, in some sections of the Petén, particularly around Lake Petén Itzá, there were substantial populations during some of the Postclassic period, which would certainly have affected a return to full forest. 5.5. The role of climate in pre-Columbian deforestation While there is debate concerning the role of climate change in the rise and fall of Mesoamerica’s city states, there is also debate about the impact of climate fluctuations on the relative abundance of different botanical species. There is ample evidence that Holocene vegetation in Central America has been strongly affected by and is expressive of changing equilibria between climate, humans, and the environment. As noted above, climatic changes created an environment in which lowland forests could thrive, but was it also climate that contributed to the destruction of these forests? Some scholars have suggested that this might be the case (Brenner et al., 2001). Over periods of time, fluctuations in temperature may influence which species thrive. However, deforestation for the majority of the Holocene appears to be more closely tied to human influences. Links between reforestation and climate may be stronger. In recent years, scientists have found increasing evidence that a large drought or a series of smaller droughts occurred during the Terminal Classic in the Maya area (Folan et al., 1983; Gill, 2000; Hodell et al., 2001, 2005; Haug et al., 2003). Drought, by reducing food production, could have been one factor in the political fragmentation of the lowland polities. If this occurred, then droughts would ultimately contribute to the re-growth of forest cover as human populations starved or migrated elsewhere. 6. Evidence of Maya land management strategies Evidence from several regions of the ancient Maya world suggests that deforestation and erosion were not critical problems

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for most Maya communities at the end of the Classic period, and that in some areas, like Copan, forest cover actually increased in the Late Classic period. How then did the Maya manage their resources and organize their landscape to maximize subsistence outputs for their cities’ growing populations? From their first attempts at domestication, the people of Mesoamerica were learning how to manipulate botanical resources. In addition, the early agriculturalists undoubtedly acquired important information on resource management from the repercussions of large-scale deforestation in the Early to Middle Preclassic periods. This misstep, which led to significant erosion events and the loss of valuable fertile topsoil, was a mistake that humans still live with in many areas of modern Mesoamerica where the soil quality has not recovered, particularly on deforested slopes. While incipient Mesoamerican farmers undoubtedly practiced swidden agriculture, by the Classic period, the Maya had developed a myriad of more sustainable subsistence strategies (Puleston, 1978; Turner, 1978; Dunning, 1996; Fedick, 1996; Chase and Chase, 1998; Sheets and Woodward, 2002). Scholars have increasingly found evidence of agricultural intensification around ancient Maya cities. In the face of rising populations, these practices would have been necessary to preserve the landscape and the forests while still feeding the populace. As numerous scholars have discussed, a purely swidden-based agricultural system seems unlikely to have produced sufficient foodstuffs to feed the great Classic Maya polities (Bronson, 1966; Siemens and Puleston, 1972; Sanders, 1973; Willey and Shimkin, 1973; Turner, 1974, 1978; Puleston, 1978; Culbert, 1988). 6.1. Fields, terraces, dams, and wetlands Scholars working in Maya lands have documented diverse farming techniques in the remains of ancient settlements and in practices that survive among modern Maya farmers, providing clues to how large ancient cities were fed without wiping out their natural resources (Gómez-Pompa et al., 1987; Dunning, 1996; Gunn et al., 2002). The Maya augmented swidden agriculture with creatively managed plant systems, such as raised wetland fields (Puleston, 1978); kitchen gardens (Zier, 1992; Sheets and Woodward, 2002); managed forests (Gómez-Pompa et al., 1987); terracing (Healy et al., 1983; Dunning, 1996; Chase and Chase, 1998; Wyatt, 2008); and damming of the landscape (Dunning, 1996). Dunning (1996) has cautioned that not all forms of intensive agriculture could have been implemented throughout Maya lands. The adoption of certain practices was dependent on the type of vegetation zone, the type of soil, annual rainfall, and the elevation of a given area. Although they are rare, ridged fields have been found preserved in Mexico and El Salvador (Siemens and Puleston, 1972; Zier, 1992). Siemens and Puleston (1972:233) identified pre-Columbian ridged fields along the “higher and drier” margins of the bottomlands in the Candelaria region of the Yucatán Peninsula, the homeland of the Acalan Maya. The sixth century A.D. site of Ceren in El Salvador provides the most detailed view of Classic period farming practices, because the entire site was preserved in the ash of a volcanic eruption (Sheets, 2002). At Ceren, maize was grown on ridges, which in one field rose 10 cm above the field surface and were 38e42 cm apart (Zier, 1992:224). Raised fields can simplify weeding, help to aerate the soil, concentrate fertile topsoil, and focus greater amounts of moisture around plants (Zier, 1992:218). Agricultural terraces and dams have been found in many parts of the lowland Maya area (Turner, 1974; Puleston, 1978; Healy et al., 1983; Turner et al., 1983; Dunning, 1996; Chase and Chase, 1998; Wyatt, 2008). Dunning proposes that terraces were a natural outgrowth of farming on hillsides. As humans first farmed sloped

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surfaces, they moved rocks to one side, producing long rows of stone that aided in soil preservation (Dunning, 1996:62). In the Petexbatún region of Guatemala, Dunning determined that the Maya used three forms of terraces. One method involved excavating a level surface into bedrock and shoring up the edge with rocks, creating an area that preserved soil; a second method involved building terraces at the bottom of hills to catch soils that washed off from above; and a third method constructed dams across arroyos or seasonal streams (Dunning, 1996:62e3). Dunning (1996), however, also notes that not all communities employed terraces. For example, his research around Puuc Maya sites in the Yucatán Peninsula located none, despite the hilly terrain. Wyatt (2008) has found evidence suggesting that at the site of Chan in Belize wood ash, likely from household hearths, was added to terraced soils to augment their fertility. Scholars working in the Maya lowlands have identified wetland agricultural fields developed by the Maya to maximize the use of land and water (Pohl et al., 1990). Culbert (1988) noted that in some parts of the Maya lowlands, bajos constituted 50% of the land and thus their use would greatly increase potential agricultural zones. However, while wetland agricultural systems facilitated increased production of foodstuffs, only a fraction of wetlands were suitable for agricultural modification (Dunning, 1996). Wetland areas ideal for modification are those that rest on karstic formations with low annual water fluctuation (Dunning, 1996:55). Work by Dunning (1996) determined, for example, that despite the presence of wetlands in the Petexbatún region, large fluctuations in water levels did not allow for their use for agriculture. 6.2. From wild forests to managed forests Forests and trees were integral to Maya lifeways. Within forests a diversity of food was found, both vegetal and animal, as well as important trade goods, medicines, fuel, and building materials. Insight into pre-Columbian forest management strategies can be achieved by studying the role of forests in modern Maya communities together with the sparse evidence found by archaeobotanists and paleoecologists. The modern Maya create and manage forests in which favored arboreal species are selected for and encouraged (Nations and Nigh, 1980; Alcorn, 1983; Gómez-Pompa et al., 1987; Atran, 1993). Such forests were first reported in the Colonial period by Landa (1941 [1566]) in the Yucatán Peninsula, where cacao was grown along with other arboreal and herb species in cenotes. While little is known about pre-Columbian arboriculture, scholars have long conjectured that it served an important role in ancient subsistence patterns. Dennis Puleston (1968, 1982) argued that the ramon or breadnut tree (Brosimumalicastrum Sw.) was an important source of food during the Classic period, although other scholars have disputed this (Lambert and Arnasson, 1982). The remains of forest products are frequently found in archaeological household middens, which is evidence of their importance in everyday Maya life. Joyce (2007) has suggested that the longer a people lived in an area, the more they may have invested in tree crops, which require years to mature, but may produce for decades or even generations. Modern managed forests (or “orchard gardens”) generally contain a diversity of useful species (Nations and Nigh, 1980; Alcorn, 1983; Gómez-Pompa et al., 1987; Atran, 1993). The Lacandon produce small managed orchards, which they call pakchekol (“planted tree milpa”) on the depleted soils of their agricultural fields, as do the Itza (Nations and Nigh, 1980; Atran, 1993). Coyol trees, like those found around the Petapilla pond in Copan, Honduras during the Late Preclassic and Classic periods, particularly favor disturbed areas such as former milpas. Forests that grow out of the depleted soils of milpas occupy an ecotone between

primary forest and open field, and attract wildlife that also serve as a valuable protein food source (Nations and Nigh, 1980:15e17). Deer, preferred by Maya elites for meat consumption, favor such ecotones for browsing (Pohl, 1981). Trees such as cacao, which grow best in shaded environments, are cultivated today by Ladinos in some modern managed forests in the Copán Valley (McNeil et al., 2006). Pre-Columbian managed forests were vital for producing a range of important trade goods, including cacao, copal, and rubber (Gomez-Pompa, 1987; Lentz, 1991, 2000; McKillop, 1994; Crane, 1996). Many forest products played critical roles in the accumulation and maintenance of elite power and in the construction of elite identities. The jaguar pelts and bird feathers that signaled high elite status, as well as cacao and deer meat for feasting, valued woods, and medicines frequently came from forested areas or their margins, and were fundamental components of the elite prestige economy. Ancient Maya elites therefore had a vested interest in the sustainable use of forests. Trees were also important sources of fuel and construction materials. A recent analysis of timbers used to support structures at the ancient city of Tikal determined that the Classic Maya there used two types of wood for lintels, namely Manilkara zapota (L.) P. Royen and Haematoxylon campechianum L. The most commonly used of these two, M. zapota, grows in moist tropical forests (Lentz and Hockaday, 2009). The second is found in forested wetlands. The authors propose that one lintel from Temple IV could have been produced from a tree as old as 280 years. Since this temple dates to A.D. 747, and the lintels appear to have been carved from freshly cut wood rather than from reused timbers, the authors infer that tropical forests remained close to the city during the Late Classic period and that at least some older trees were preserved (Harrison, 1999; Lentz and Hockaday, 2009). However, by A.D. 766 the builders of Tikal moved towards using H. campechianum L., which may have been less favored and more difficult to extract. Tikal’s builders only reverted to the use of M. zapota after approximately four decades, at which time they employed smaller lintels. Lentz and Hockaday (2009) propose that the use of H. campechianum was due to the depletion of old growth M. zapota. If true, then it would appear that the Maya allowed forest stocks of M. zapota to recover before returning to use that species again. A forty year period of abstention from the use of M. zapota displays impressive agroforestry control on the part of the ancient Maya. 7. Conclusions A substantial body of research in recent decades has demonstrated that human populations in Mesoamerica in the Early to Middle Preclassic periods (z1800e350 B.C.) heavily deforested the landscape, producing the most significant episodes of preColumbian erosion in many areas. Nevertheless, scholars and public alike continue to focus on the Late Classic Maya as purveyors of environmental devastation. Despite the common emphasis on rising population as a cause of land clearance in pre-Columbian times, evidence from paleoecological analyses clearly indicates that small Preclassic populations were capable of causing, and did cause, significant environmental damage throughout the Maya lowlands as they first experimented with agriculture. In later periods, with greater populations, the Maya were forced to produce food and fuel more sustainably, and did so successfully for several hundred years prior to the collapse of the southern lowland polities. Patrick Culbert (1988) predicted that in most of the Maya area, swidden agriculture would have ceased to support the population towards the end of the Late Preclassic period. Evidence indicates that by the Classic period, and perhaps earlier, the Maya developed

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more sustainable forms of agriculture and agroforestry such as terraces, raised fields, dams, and orchard gardens. In most sediment cores from the Maya area, pollen evidence from Late Classic levels does not indicate that deforestation was significantly elevated during this time, and at some sites, such as Copan, the inhabitants of Maya cities were apparently able to develop subsistence practices that actually increased forest cover during the Late Classic period.

Acknowledgements I would like to thank Eric Hilt, Shannon Plank, Joel Gunn, and an anonymous reviewer for comments on this article, and Kristin Landau, Marc Wolf, and Timothy Pugh for assistance with figures. This work was supported by a Fulbright Fellowship through the Institute for International Exchange, and grants from the Foundation the Advancement of Mesoamerican Studies, Inc. and Sigma Xi, The Scientific Research Society. This research would not have been possible without support from the Instituto Hondureño de Antropología e Historia. Workspace for laboratory analysis was provided by the Plant Research Laboratory of the New York Botanical Garden.

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