the causes and consequences of deforestation among the prehistoric maya

Human Ecology, Vol. 16, No. 4, 1988

The Causes and Consequences of Deforestation Among the Prehistoric Maya

Elliot M. Abrams t and David J. Rue 2

The collapse o f the Classic Maya state is investigated from an ecological perspective. Settlement and palynological data from the Maya center o f Copan, Honduras, are presented which indicate that substantial clearing o f the upland pine forest had occurred prior to and during the abandonment o f that urban center. A comparative use-rate analysis suggests that the increased clearing o f pine was primarily caused by demands for domestic fuel wood by an expanding urban population. This forest mismanagement is directly linked to accelerated erosion rates which are considered primary elements in the collapse o f the Maya state.

KEY WORDS: deforestation; palynology; Maya collapse.

INTRODUCTION

For over a century, archeological research has produced important data from which to reconstruct the historical and processual evolution of the southern Lowland Maya culture of Central America (Hammond, 1982; Sharer, 1983). Much of this research has been directed toward reconstruct- ing the collapse of the Lowland Maya from the height of their cultural complexity in the Late Classic period (650-900 AD). Early unilinear models of this collapse, invoking single variables such as earthquakes and foreign invasions, have since yielded to more multi-causal, polythetic models incorporating several interactive and diachronic variables (Willey and Shim- kin, 1973). One set of variables which is often recognized as having played a considerable role in the collapse is that of environmental deterioration caused

tOhio University. 2WAPORA, Inc.

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378 Abrams and Rue

by increasing population densities. The subsequent ecological mismanagement would have led to reduced productivity of the agricultural system, which in turn would have been largely responsible for the depopulation of relatively large urban centers. Although many diverse variables must be considered in any holistic model of this specific pattern of evolutionary change, several researchers have focused on the ecological relationship between population and natural resources, and this paper wilt add to this body of cultural ecological research by considering the role of deforestation in the collapse of the Late Classic Maya cultural system.

Specifically, settlement, pollen, and soil erosion data pertaining to the Maya center of Copan, Honduras (Fig. 1), will be presented, confirming the hypothesis that a condition of deforestation had developed during the Late and Terminal Classic periods. A comparative assessment of human needs for arboreal resources suggests that deforestation was the result of extensive clearing from the foothill zone for agricultural and habitational purposes and from the upland forest zone for domestic purposes of cooking and heating. This reconstructed condition of deforestation, leading to accelerated levels of soil and nutrient loss through erosion, is considered primary in stimulating political instability and encouraging the gradual abandonment of this major center. However, a brief discussion of the environmental set- ting of Copan and of previous research involving deforestation in Maya prehistory should be presented.

THE ENVIRONMENT OF COPAN

The Late Classic Copan polity occupied four geomorphologically-similar alluvial pockets of the Copan Valley, as well as several smaller valleys along tributaries of the Copan River. Since the westernmost alluvial pocket, the Copan pocket, witnessed the rise of the Main Center and experienced the highest Classic period population density, the description will focus on that pocket alone. Formed by a lessening of the constriction of the flanking mountains and transected by the westerly flow of the Copan River, the Copan pocket measures approximately 12.5 km long (E-W) and up to 4 km wide (N-S). The overall geologic form of this and many other similar pockets throughout Central America resulted from volcanic action during the Cretaceous Era and pedologically is a mixture of sedimentary and more recent igneous stone.

A cross-sectional description of the Copan pocket best reveals its basic ecological zonation (Fig. 1). Proceeding north from the river, a first terrace of alluvial floodplain of varying width is encountered, followed by a second, slightly higher terrace of alluvium, the two of which constitute the vega

Deforestation among the Prehistoric Maya 379

r i l

[ ] let Terrace

N2nd Terrace [ .'~." Foothills N Upland Pine

Fig. 1. Basic environmental zonation of the Copan pocket.

or bottomland zone of highest agricultural productivity. Today, corn and tobacco are the principal crops grown within this zone. The vega is followed by an upsloping foothill or piedmont zone covered with mixed tropical deciduous trees and brush (Turner, Johnson, Mahood, Wiseman, Turner, and Poole, 1983, Appendix IV). This zone is currently used largely for agricultural purposes. The foothill zone merges with the upland forest zone, which reaches an altitude of about 900 masl, about 300 m above the Copan River. This upland forest zone serves as a reservoir for a wide range of floral and faunal resources, but currently is not used for agriculture and, based on per- tinent settlement data, was not used for agriculture by the Classic Maya (Fash, 1983; Freter, 1988). Of the 42 plant species in this ecozone of the pocket, the dominant arboreal species is Pinus oocarpa Schiede (Turner et al., 1983, p. 137). The palynological evidence presented below further indicates that pine dominated this forest zone during the periods of Maya occupation. The domination of this species of pine within the forests of the Copan pocket

380 Abrams and Rue

is paralleled elsewhere in Honduras, comprising 70-90% (by volume) of the 27,000 km 2 of Honduran upland forests (FAO, 1968, p. 7).

DEFORESTATION AND THE LOWLAND MAYA

Deforestation is literally the long-term reduction in the areal extent of the arboreal forest through the removal of tree species, either for the trees themselves or for some other resource(s) associated with the forest (Oldfield, 1981, p. 280). Deforestation is not simply tree removal p e r se; the process of deforestation necessitates a greater rate of tree removal than that of tree regrowth, or reforestation. The simple felling of forest cover is not a pr ior i

deforestation unless there is a long-term and permanent reduction of the forest ecozone. The definition of deforestation generally implies, however, only a reduction in size of the forest and not in quality of trees. For example, if hardwoods are replaced by softwoods, thus reducing the BTU/vol of forest, the quantity remains constant while the quality has been significantly reduced.

Deforestation has been referred to as having had deleterious effects on the Late Classic Lowland Maya system in the contexts of physioenviron- mental degradation, relating to agricultural losses, and epidemiolog- ical increases, relating to demographic losses. With respect to environmental deterioration, perhaps Cooke (1931) was the first to present the basic model of deforestation and its consequences for the Maya:

The Mayas were an agricultural people and needed much cleared land to raise the great quantities of corn required to feed their large population. The rate o f erosion of the soil must have been enormously accelerated when the forest was cut and the cultivated soil was exposed to the full force of the torrential rains. (p. 286).

Initial support for this model came from Sanders (1962, 1963, 1973). Although solely inferential, Sanders (1973) provided the necessary agronomic and topographic data from the Peten which support this erosion model. These data indicated that over 40~ of the Peten soils are classified as having a high to very high susceptibility to erosion (p. 336), and that, of these soils, approximately 37% are of high fertility, and thus attractive within the context of an expanding agricultural system. Sanders added that these soils "... are found on well-drained slopes which, prior to cultivation, Were covered with tropical forests" (1973, p. 337). Thus, these data support the model which links deforestation to agricultural decline within the context of an expanding Late Classic Maya urban population.

The data presented by Sanders are considered important in providing the environmental context consistent with the model of deforestation and erosion. Direct data supporting this basic ecological model have come largely from palynological and limnological research conducted in the Peten,


Guatemala (Deevey, Rice, Rice, Yaughan, Brenner, and Flannery, 1979; Rice, Rice, and Deevey, 1985; Vaughan, Deevey, and Garrett-Jones, 1985; Wise- man, 1978, 1985). Although questions concerning the rate, absolute chronology, and specific causes of ecological deterioration remain, the data offered by this research clearly indicate that increased soil and nutrient loss, in conjunction with deforestation, had developed in the Peten during the Clas- sic period. The overall process of urban growth, involving agricultural clearing and construction, are cited as creating an ecological context conducive to long-term agricultural decline and subsequent population abandonment.

In addition, Wiseman (1978, 1983) specifically focuses on the need for fuel wood as a component of the Maya agroeconomy. By linking arboreal reduction with fuel wood consumption, he introduces into the total equa- tion of cultural ecological stress the potential conflict between land for agricultural produce and arboreal fuel. In essence, he has anticipated the results of the present analysis, which point directly to fuel wood as the primary cause of upland arboreal depletion.

Deforestation has complementarily been modeled as having had epidemi- ological consequences on the Late Classic population. Shimkin (1973, p. 277) has suggested that eventual shortages of fuel wood, necessary for heating and cooking, may have led to increased endemic respiratory and gastroin- testinal diseases, contributing to a higher mortality rate.

If these data and interpretations are accepted, then it is essential to determine whether the reconstructed condition of deforestation in the Peten was in any way experienced at other Maya sites and, specific to this paper, at the Maya center of Copan.

EVIDENCE FOR DEFORESTATION AT COPAN

A brief description of the settlement history and chronology of Copan for those centuries associated with the collapse will provide the framework for interpreting the ensuing palynological data. These settlement data are drawn from Freter (1988) and, although subject to modification, represent solid estimates of population growth and decline. Population size within the Copan pocket appears to have grown to about 5000 people from 550 AD to 700 AD. The bulk of this population would have resided in the vega. The population then dramatically increased up to perhaps 20,000 people from 700 AD to 850 AD, representing the peak population size. This population expanded onto the foothill zone such that virtually all areas except the upland forest were utilized for either agriculture or habitation. Between 850-1000 AD, the population was reduced by 50O7o within the pocket, with the ensuing 150-year period experiencing an additional 50~ reduction in size. By 1200 AD, only a small residual population of perhaps 2000 people, restricted to

382 Abrams and Rue

the vega, remained, and by 1250 AD, the entire pocket appears to be completely abandoned. It is not until the nineteenth century that significant settlement returned to the Copan pocket, increasing to its current size of about 20,000-25,000 people.

From this brief outline of settlement dynamics, two points of analytic significance emerge. First, the abandonment of Copan did not occur at 800 AD in a sudden act of depopulation, but rather was a gradual process span- ning several centuries. Second, the current population size and agricultural activities approximate that of the Late Classic period. In terms of the pollen profile from the pocket, we would then expect a decrease in arboreal species during the Late and Terminal Classic periods, a gradual reforestation period associated with an increasingly reduced population, and a second period of deforestation reflecting the arboreal conditions in the Copan pocket today (Fig. 2).

The palynological data were obtained from a core extracted from the Agua- da de Petapilla, a small bog located in an intermontane basin in the foothills just north of the Copan pocket alluvium (Rue, 1986, 1987). This locus is approximately 5 km east of the main center of Copan, within the zone of dense settlement that characterized this part of the pocket during the Late Classic period. A previously reported core analyzed by Wiseman (Turner et al., 1983) was not long enough to reach Maya occupation levels; the post-Maya zone in the present core, however, equates well with that analyzed by Wiseman. Another core sample, east of and beyond the Copan pocket, was analyzed and par- tially corroborates the conclusions presented below, although this core lacked stratigraphic integrity. Figure 3 presents percentage curves for the significant taxa from the Petapilla sequence. Organic material from between 125-130 cm of the 135-cm core yielded a radiocarbon date of AD 1010 • 60 (Beta-12789), while material from 65-70 cm yielded a date of AD 1355 • 70 (UGa-3579), The lowest levels of the core consequently reflect the end of the Terminal Classic period. Although specific pollen data from the heart of the Late Classic period would more directly test for deforestation, the data provide the empirical framework for drawing inferences concerning deforestation during that time period.

The arboreal pollen/non-arboreal pollen curve and Pinus percentages are based on total pollen, while percentages for all other taxa are based on a pollen sum including total pollen minus Pinus. Pinus was subtracted from the pollen sum because its very high percentages would obscure taxa which occur less frequently. Pinus includes all pine species, but P. oocarpa dominated all levels by over 90~ followed by Quercus (oak). "Meliaceae and Meliaceae-type" includes pollen of tropical forest deciduous trees in the ma- hogany family, as well as pollen of a type which is probably Meliaceae, but which also has affinities to genera in the Urticales. Gramineae (grass) and


Depth (cm)

C 14

A.D. 1,355_+70 L _ _ _

C 14

A.D. 1,010"~60 L . . . .

so 30 ~ ~ 10 5 20 2s a s 1'o 1'0 f5

Percent of Total Pollen - ~ ~ = Present, -<t% (Note different scales)

Fig. 2. Petapilla pollen profile.

Fig. 3. Foothill and upland zones of the Copan pocket, illustrating the extensive condition of deforestation.

384 Abrams and Rue

Zea (maize) are indicative of human disturbance. Finally, Azolla is an aquatic fern indicative of wet conditions.

Zonation is clearly evident in the pollen diagram. Levels from 100-135 cm mark the latest phases of Maya disturbance in the Copan Valley. Grass and fern pollen percentages are high, indicative of forest clearance. Zea is present in two levels. Tropical deciduous tree pollen is virtually non- existent, this forest having been presumably cleared from the alluvium and lower foothills for centuries. Between 130-135 cm, arboreal species continue to decline, reflecting ongoing activity by the thousands of people still resid- ing in the pocket. However, it appears that the pollen profile has captured the last stages of the gradual Copan pocket abandonment, at which time the most extensive clearing had already occurred.

Reforestation occurs above 100 cm, a level dated by extrapolation to the beginning of the thirteenth century, at which point nearly all population had abandoned the pocket (Freter, 1988). Reforestation is suggested by a decrease in grass pollen and the absence of Zea, increases in Pinus, and the resurgence of "Meliaceae and Meliaceae-type." AzoUa occurs only in this zone, directly correlated with the return of the deciduous forest. Its occurrence here most likely marks an expansion of the swamp concurrent with reforestation; forest cover held back runoff water in the Petapilla Basin, thus impeding drainage. Overall, the percentage of arboreal pollen is double that of the preceding period of deforestation.

Modern disturbance is discernible above 35 cm. It is extremely important to note that the scale of arboreal clearing represented in the upper end of the profile is very similar to that at the base of the profile. Since arboreal clearing today is extensive, necessary to meet various demands of a growing population, it is reasonably inferred that the similarly low percentages of arboreal species in the Terminal Classic period reflect the same condition of deforestation, the consequence of the increasing needs of the growing Clas- sic population.

Some of the disturbance period behavior of the Pinus curve may be due to percentage effects. If grass pollen increases drastically, other types would decrease correspondingly, even though their absolute frequencies remain stable. However, enough non-grass taxa increase in percentage along with pine in the reforestation zone, i.e., "Meliaceae and Meliacea-type" and Azolla, to dampen percentage effects on pine, and thus there remains considerable support for the hypothesis that decreased pine pollen production occurred within the Copan region during the Classic period, caused by human reduction of pine forests.

Additional support for the reconstructed condition of deforestation comes from soil erosion data. That is, if significant levels of soil erosion were determined, those data would support the reconstructed condition of deforestation, since soil and nutrient loss through erosion is typically one


of the ecological consequences of deforestation. The effects of soil erosion within the Copan pocket can only briefly be discussed since there currently are no data from this area with which to test this hypothesis. There are, however, data from adjacent areas in Honduras which bear upon this question of tree removal and soil erosion.

Controlled experiments conducted in central Honduras indicated that after the burning of pine from upland slopes, relative surface runoff and sediment loss were significantly increased (Hudson, Kellman, Sanmugadas, and Awarado, 1983a, p. 275). In addition, the rate of nutrient loss, particularly of potassium, phosphorus, and magnesium, was found to be highly correlated with sediment loss, again related to, if not directly caused by the removal of the tree cover (Hudson, Kellman, Sanmugadas, and Alvarado, 1983b, p. 297). Finally, surface vegetation and not the angle of slope was considered the primary factor affecting runoff and sediment loss (Hudson et al., 1983a, p. 279).

Based on pedologic analyses from the Naco Valley in N. W. Honduras and from the site of La Canteada in the easternmost pocket of the Copan Valley, Olson (1975) concluded that often severe soil erosion occurred on those slopes from which natural forest vegetation had been removed through human activity and ecological mismanagement. In addition, Olson recovered Mayan artifacts at La Canteada buried beneath 42 cm of sheet erosion, sug- gesting that soil erosion and flooding were accelerated through forest removal (1975, pp. 50, 68). This easternmost pocket of the Copan Valley appears to have been occupied at about 1200 AD, presumably by Maya emigrating from the Copan pocket. Interestingly, this condition of deforestation and soil erosion at La Canteada may then have been caused by the descendents of those who created the same ecological condition in the Copan pocket.

There are many other studies outside Honduras which correlate reduced agricultural productivity with exacerbated rates of soil loss (Brown and Wolf, 1984), but given the absence of specific agronomic data from the Copan pocket itself, further citations would add little to the thesis at hand. Nonetheless, the data collectively point toward a condition of increased population cou- pled with deforestation and soil erosion during the Late and Terminal Clas- sic periods in Maya prehistory.

C O M P A R A T I V E USE-RATES OF PINE

Characteristics of Pine

We can augment our understanding of this process by addressing the question of causality and extent of deforestation. A comparative analysis of use-rates of the dominant upland arboreal species, Pinus oocarpa Schiede, is considered effective toward answering this question. Two significant

386 Abrams and Rue

methodological qualifications must be made explicit prior to conducting such an analysis involving this species of pine (referred to in the vernacular as ocote). The first is that, despite an excellent environmental reconnaissance of the Copan pocket (Turner et al., 1983), as well as various studies of ocote conducted elsewhere (Denevan, 1961; FAO, 1968), generally only maximal figures of tree size are provided, thus overlooking the more dynamic charac- ter of the forest ecosystem. As a consequence, gaps exist in the data concerning the growth of this specific species. A second qualification is that the characteristics of pine are assumed to be estimates. We lack these specific data from the Copan forest, and P. oocarpa as a species demonstrates a wide variation of sizes within distinct microenvironmental settings (Mirov, 1967, p. 563). This analysis is of course meant as a general exercise. Our goal is to elicit a broad relationship between demographic and cultural change at Copan which can be effectively achieved through the use of average size and density estimates of ocote. A summary of these standard characteristics is presented in Table I.

Pinus oocarpa Schiede generally ranges from 600-1700 masl (FAO, 1968, p. 7; Molina, 1964, p. 11), although it has been found as low as 250 masl (Lamb, 1973, p. 20). Apparently, a variety of climatic factors, not simply those associated with elevation, are responsible for the vertical distribution of ocote (Johannessen, 1963, p. 22). Generally a five-needle pine, ocote grows in soils which are relatively poor with regard to agricultural productivity; at Copan, ocote is associated with Dystropepts, a series of shallow, low nutrient, high acidity soils (Turner et al., 1983, p. 75). Interestingly, the growth of the pine and the acidic quality of the parent soil are in a positive feedback relationship; by dropping its needles, the pine perpetuates the acidity of the soil matrix, thus enabling the pine to outcompete other tree species within the upland forests. These pine needles further perpetuate the life of the pine during instances of forest fire. In many cases, pine needles will ig- nite with contact to fire but extinguish that fire before it can reach the heart of the tree; for this reason, pines are considered relatively fire-resistant. This ability to withstand low-level fire, however, characterizes only more mature trees; those younger than 4-7 years generally cannot survive a major fire (Vogel, 1952, p. 6; Johannessen, 1963, p. 22).

Clewell (1972) recorded the diameters of 114 ocote which had been al- lowed a regrowth period of 1-2 years after having been burned. It was recorded that 40% of the ocote had a diameter of 1-18 cm, 30~ had a diameter of 19-24 cm, and the remaining 30% had a diameter of 25-38 cm (Clewell, 1972, p. 179), the average diameter at breast height (1.3 m) being 22 cm, or given slightly more time for regrowth, 25 cm. The maximal diameters for ocote have been recorded as 40-60 cm (Denevan, 1961, p. 275) and 50-80 cm (Molina, 1964, p. 13), figures consistent with the extrapolated average. From the figures of dynamic growth in diameter, the progressive height of


Table I. Standard Characteristics of P. Oocarpa

Height 20 m Diameter .25 m Volume/tree 1.0 m 3 Volume/ha 528 m 3 Trees/ha 528 Weight 620 kg/m 3 Regrowth 7 m3/ha/yr

ocote can be extrapolated. Again, a set of maximal heights for ocote have been provided: 17-23 m (Denevan, 1961, p. 275), 21 m (Din, 1958, p. 125), 25-30 m (FAO, 1968, p. 9), and 12-30 m (Molina, 1964, p. 13). Using a maximal height of 25 m, we can estimate that, in an actual forest, 40~ of the ocote would have had a height of 10 m, 30% had a height o f 15 m, and 30% and a height of 25 m, thus yielding an average height of 16 m. As was done with the average diameter, the average height of 16 m will be increased to 20 m, based on the assumption that a longer regrowth period would have yielded above average but not maximal tree sizes in the Copan forest. Since our goal is to retrodict general rates of pine usage, it is important that we avoid extremes in characterizing pine. Using an average height of 20 m and an average diameter at breast height o f .25 m, the average volume/tree is ca 1.0 m 3, using the Huber formula wherein volume = area at mid-cross- section x height (Bruce and Schumacher, 1942, p. 29).

Although an average volume of 62.2 m3/ha of ocote has been reported for Honduras (FAO, 1968, p. 7), this figure is considered too low, a consequence of pine bark beetle disease, logging activity, and forest fire. Clewell (1972, p. 179) notes that the average number of pine within the upland forests o f Honduras is 528/ha, and this number represents a useful estimate of pine density during the Classic period. The projected volume of pine, then, within the Copan upland forest would have been 528 m3/ha.

Although the rate Of forest regrowth is dependent on a variety of factors, annual pine regrowth in Honduras ranges f rom 2.5-11 m3/ha (FAO, 1968, p. 9). We will simply use the average of these two figures, roughly a regrowth rate of 7.0 m3/ha/yr . Although the average weight of P. oocarpa was not obtained, the weight/volume of generic pine is 620 k g / m 3 (USDA, 1974, p. 34).

Explanat ions for Defores ta t ion

It is likely that no single factor led to the reconstructed condition of deforestation, especially since two distinct ecozones, the foothills and the

388 Abrams and Rue

upland forest, offering different resources to the population, were deforested. For either ecological context, it is perhaps best to consider deforestation the cumulative result of both conscious and unconscious acts, i.e., the com- bined effect of human exploitation and accidental fires caused by people or fires occurring naturally. However, since deforestation necessitates the permanent removal of trees, it is likely that cultural factors were primary in producing this condition, perhaps only supplemented by stochastic natural acts.

Considering first the foOthill zone, it appears that the primary cause of deforestation was the need for cleared land either for habitation and/or cultivation. The settlement data from within the Copan pocket indicate that settlement was first concentrated on the vega land which then, during the Classic period, expanded onto the foothill zone (Fash, 1983; p. 166; Freter, 1988), thus initiating the significant felling of trees in this zone. The fact that this area was densely occupied by the Late Classic period suggests that this area was proportionately deforested for this purpose. The pollen data presented above clearly indicate the absence of broadleaf deciduous species which would have occupied this foothill zone. At present, it is uncertain to what extent this foothill zone was put into cultivation, even in terms of small infield garden plots; however, the presence of Zea maize in the Petapilla pollen profile suggests that this foothill zone was also used for agricultural purposes.

The upland forest zone, unlike the foothills, was neither cultivated nor settled to any significant degree (Fash, 1983; Freter, 1988); thus, the expla- nation for deforestation of this ecozone must focus on the uses of the pine itself. Pine was probably relied upon as a source of fuel needed for cooking and heating, especially given the absence of any equally viable substitute such as animal dung. "Industrial" fuel wood was needed for ceramic and lime production, and certainly this need would have increased as specialized production broadened and intensified. All structural components of rural houses in the Copan pocket today are made, although not exclusively of pine (Abrams, 1984), and it is probable that pine was used heavily in this context during the Late Classic period. An unknown number of wooden artifacts were certainly manufactured at Copan, as inferred from those found in caves along the Sibun River, Belize (Pendergast, 1974). Ocote, a very resinous tree, may have been tapped for its sap, used today as a fuel for torches (Denevan, 1961, p. 298), or more directly used as a pine torch or fire starter (Wisdom, 1940, p. 181). Finally, pine extract may have served various medicinal needs, as is the case today in the Copan Valley.

Although we do not accept the notion that any one cause was solely responsible for deforestation within the upland forest, we do not consider it particularly satisfying to simply state that all of the above needs for pine led to this condition. Therefore, we will evaluate some of those human needs


for wood which perhaps represented the higher levels of arboreal felling within this upland zone.

Domest ic Fuel W o o d

Procurement of domestic fuel, wood used in cooking and heating, was a basic, daily requirement which had to be met, directly or indirectly, by the entire population. Despite the critical importance of fuel wood and its diminishing availability on a world scale (Eckholm, 1976; Brown and Wolf, 1984), very few data concerning its use-rate, within the context of the house- hold as the basic economic unit have been collected. However, those data which are available are surprisingly consistent. Myers (1984, p. 117) noted that the use-rate of domestic fuel wood in pre-industrial societies ranges from .5-1.5 tons/person/year which, taking the average of 1 ton/person/year, equals 1.5 m 3 of ocote/person/year (910 kg/620 kg). FAO studies of domestic fuel wood consumption in Latin America also offered a use-rate of 1.5 m3/p/yr (deMontelembert and Clement, 1983, p. 85), as did a study of fuel wood consumption among households in rural tropical Kenya (Hosier, 1984, p. 31). Although many factors, such as cooking habits and family size and organization, can and do affect domestic fuel wood use-rates, it seems reasonable to project this rate of 1.5 m3/p/yr for the Late Classic Maya. It should be remembered that Copan is not a typical lowland center in terms of elevation, resting at 600 masl, which justifies the use of a highland-lowland average. It is clear, however, that further research needs to be conducted to ascertain more accurate and contextual rates of fuel wood consumption. Based on a Late Classic population peak of 20,000 people, the use-rate figure of 1.5 m3/p/yr suggests that 30,000 m 3 (1.5 x 20,000) of ocote had to be felled each year to meet domestic fuel wood requirements, and this volume of trees would have covered 57 ha or .57 km z (30,000/528).

Lime Plaster Production

As a result of survey and test-pitting conducted at Copan (Webster, 1985; Webster and Freter, 1985), there is some evidence that the lime needed for plaster production may have been calcined within enclosed kilns. Until further research is conducted, however, the amounts of fuel needed and lime produced remain unknown. We do have these data for the open-air method of lime production (Morris, Charlot, and Morris, 1931, Erasmus, 1965; Abrams, 1984), and it is this set of figures which will be used to determine the use-rate of fuel wood, providing perhaps a slightly exaggerated estimate relative to the more efficient kiln operation.

390 Abrams and Rue

Morris et al. (1931), based on observations of open-air lime processing, reported that 11 m a of wood were required in the production of approximately 10 m 3 of lime. Although admittedly crude, it is estimated that 3250 m a of lime plaster were required to cover the surfaces of the final phase of construction at Copan (main group = 1000 m 3, Sepultura = 1000 m a, Bosque = 1000 m 3, and additional outlying plastered structures = 250 m3). Thus, 3575 m 3 of wood were required to produce all of the necessary plaster. This is the equivalent of 6.7 ha of cleared forest (3575/528) which, if extended over a 50-year period, equals .13 ha of upland forest cleared each year for plaster production. It appears then that the impact of felling trees for lime processing was negligible, even multiplied several times to account for additional "industrial" processing yields a comparatively low use-rate figure.

Rural H o u s e Construct ion

All of the structural components of perishable houses, those with wat- tle and daub walls and thatched roofs, were wooden. A survey of households within the Copan Valley indicated that, of the minimal 17 species of trees used in house construction, ocote was the preferred species, owing to its availability, abundance, wide range of sizes and strengths, and relative ease of felling (Abrams, 1984). In addition, it was found that ocote was used in all structural components of the house, from thin rafters to supporting mainposts. However, of all the structural components, only the four mainposts were constructed from the trunks of mature trees, all others were der- ived from either samplings or branches (Wauchope, 1938). Paradoxically, the clearing of samplings may have actually enhanced the growth of matur- ing trees, thus countering the process of deforestation.

In quantifying the use of wood in rural house construction, we cannot simply equate the number of structural components with that of trees, since many components consist of saplings and branches (particularly the rafters). Nor can we equate the number of mainposts with felled trees since a 15-meter high tree can yield 4-6 mainposts. Having expressed these difficulties, we will use an admittedly rough estimate of five trees/house. As is evident in the ratio of fuel wood consumption presented below, even a significant adjust- ment of this figure fails to alter the essential conclusion of the analysis. Set- tlement data from the Copan pocket indicate that 3179 residential structures stood in the Late Classic period (Fash, 1983). If we assume that 85~ of these were built of perishable material, then approximately 2700 perishable structures existed during this period. Using the figure of five trees/house, 13,500 trees were felled for rural house construction, assuming for the sake of com- parability no reuse of trees (which undoubtedly did occur). At 528 trees/ha,


2.6 ha of forest had to be cleared which, over a 100-year period, translates into .026 ha/year.

In reviewing the results of this analysis, it should be recognized that only a few factors considered in isolation have been quantified and that some of the data are simplified and unfortunately rather crude. Nonetheless, the comparative results are provocative; the arboreal cover cleared by the Late Classic population was 57 ha /yr for domestic fue lwood, . 13 ha /yr for lime processing, and .026 ha /yr for house construction (roughly a 2192:5:1 ratio). In terms of order of magnitude, it is clear that the primary cause of deforestation of the upland forest zone was the continual procurement of domestic fuel wood.

As noted, only direct human activities have been considered in contributing toward deforestation. One other factor which likely exacerbated this process was accidental forest fire. In Honduras today, large tracts of forest are lost annually to fires (FAO, 1968, p. 3) and, although impossible to retrodict, it seems likely that uncontrolled fire, as a result of lightning, milpa clearing, or some other act, would have periodically destroyed tracts of valuable ocote in Late Classic Copan. The fact that young pine trees, in the context of regrowth after human clearing, are relatively vulnerable to fire would further inhibit the process of reforestation of the pine forest.

THE DEGREE OF D E F O R E S T A T I O N

Having estimated the rates of tree felling associated with various cultural needs, it is possible to extend this exercise by projecting the degree of upland pine deforestation. Like all previous calculations, this too is intend- ed to reconstruct a relative sense of this specific arboreal condition at Copan. Since the need for domestic fuel wood represented the overwhelming cost, only it will be considered.

If 57 ha were needed by 20,000 people at 800 AD and 28.5 ha were needed by 10,000 people at 600 AD, then a total of 8550 ha of trees had to be felled during this 200-year period (([57 + 28.5]/2) • 200). This as- sumes a linear growth in population, certainly an oversimplification. More importantly, however, the figure of 8550 ha does not account for forest regrowth. At a regrowth rate of 7 m3/ha/yr , one hectare, initially with 528 m 3 of timber, would actually yield an additional 1400 m 3 over the 200 years (7 m 3 • 200), for a total of 1928 m 3. The inclusion of regrowth suggests that 2341 ha, or 23.41 km 2, of the upland forest would have been completely denuded of pine by 800 AD. Hypothetically, at this time, no pine would have been standing for the entire 12-kin length of the Copan pocket for a distance of nearly 1.0 km away from any zone of settlement on either side

392 Abrams and Rue

of the Copan River. This projected scale of deforestation is likely a cautious underestimate since only domestic fuel wood needs are considered and des- truction by accidental fires is ignored.

IMPLICATIONS

If the above arguments are accepted, then several implications follow. First, the size of domestic fuel wood requirements suggests that no single segment of Maya society was "more responsible" for forest removal. Cer- tainly, the felling of trees for domestic fuel wood was an act in which, directly or indirectly, all Copanecos participated. Had the impact from, say, industrial uses of wood been particularly high, it could be argued that the elite were perhaps more instrumental in promoting deforestation. This, however, seems not to have been the case.

A second implication involves the possible direct ecological effects of deforestation, necessitating a brief discussion of where in the upland forest this reduction may have occurred. The forest surrounding the Copan pocket essentially continues in all directions from the population nucleus. It is reasonable to assume that these trees were cleared from the periphery in- ward, perhaps as suggested above, for a distance of 1.0 km. Peripheral clearing would be more efficient given the proximity to human settlement and the logistical ease of tree removal. This spatial aspect of deforestation is important since the increased scale and permanency of the felling would have exposed the adjacent agricultural foothills to the poorer upland soils through the accelerated process of soil erosion. The mixing of highly acidic soils with those from the foothill and vega would have lowered the productivity in those last ecozones, thus contributing to the diminished agricultural potential of the Copan pocket.

A third implication is that the process of deforestation is best considered a consequence of the broader process of urban growth, evidenced by increasing population size and density at Copan and other Late Classic centers. One inevitable consequence of rising population density is increased exploitation of a more restricted and localized resource zone, albeit per cap- ita consumption may remain constant. In other words, the once relatively dispersed catchment areas of pre-urban settlements now formed a larger single urban catchment area. This same process understandably is occurring in contemporary peasant societies, in part for the same need: "The impact of demand for fuel wood is felt most heavily around centers of population and processing, where demand is concentrated" (Arnold and Jongma, 1978, p. 6). The implication is that, unless checked, the consequences felt by the Maya will similarly be felt by contemporary populations.

Deforestation among the Prehistoric Maya

CONCLUSION

393

In this paper, the ecological relationship between growth of the Late Classic Maya urban population and the process of deforestation has been considered. Data have been presented which suggest a significant reduction of arboreal species, particularly that of the dominant pine, P i n u s o o c a r p a

Schiede, corresponding temporally to the Late and Terminal Classic periods. Explanations for this condition of deforestation were then considered.

It was suggested, based on settlement data and a comparative use-rate analysis, that the foothill ecozone of the Copan pocket was denuded of its tropical deciduous cover for the purposes of habitation and cultivation and that the upland forest ecozone was denuded primarily to meet domestic fuel wood requirements. It then was estimated that minimally 23 km 2 of the upland pine forest may have been completely cleared by the end of the Late Classic period. The overall conclusion is that the process of urban growth, generat-

i ng intensified exploitation of the local forest, may have exacerbated levels of soil and nutrient loss, thus contributing to the reduced productivity of the agricultural infrastructure at Copan. Thus, deforestation is linked directly to the reversal of urban growth or the collapse of the Copan Maya state system.

ACKNOWLEDGMENTS

We would like to thank the Instituto Hondurefio de Antropologia e Historia for extending the permission necessary to collect and present the data in this paper. We also would like to thank William Sanders and David Webster for intellectual and financial support during our research at Copan. Important information presented in this paper was offered by Ira Becker- man and AnnCorinne Freter, and Alfred Traverse generously made available the pollen laboratory facilities at the Pennsylvania State University. Added thanks are extended to the Graphic Arts facility at Ohio University for draft- ing the figures. Of course, the authors assume full responsibility for any er- rors contained within this paper.

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the causes and consequences of deforestation among the prehistoric maya

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