#ThesisThursday: Deforestation and the Collapse of Easter Island & the Classic Maya

thesisthurs2-16-17-01The collapse of the Easter Island (also known as Rapa Nui) and the Classic Maya population has remained a mystery since their discoveries. Despite substantial research, anthropologists still debate over what caused the fall of these ancient societies. The Easter Island and Classic Maya collapse, although different, were caused by one significant factor, deforestation. This catastrophic change held a close relation with ecocide, climate, and other contributing elements that occurred within each of these societies. In his book, Collapse: How Societies Choose to Fail or Succeed, Jared Diamond defines collapse as a decrease in political, social, economic, or cultural complexity (3). A decrease in complexity is evident in both of these ancient societal collapses with deforestation acting as an ultimate cause. Easter Island’s deforestation was expedited by three major elements: ecocide, the local climate, and Pacific rats (Rattus exulans).

There are many disagreements among researchers regarding the approximate date of Easter Island’s settlement. Issues regarding radiocarbon dating are the underlying cause for these disputes. The Long Chronology, based on the analysis of pottery, estimates that settlement on Easter Island occurred approximately between 300-400 A.D. However, the Medium Chronology, based on analysis of wood charcoal and porpoise bones, believes settlement occurred approximately between 800-900 A.D. Today, several archaeologists agree with the Short Chronology, which estimates that Easter Island was approximately settled around 1200 A.D. Most dating estimations from archaeological evidence, such as artifacts, charcoal, and the erection of moai, are focused around this chronology (McAnany and Yoffee, 28).

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Jubaea chilensis (Image provided by Palmpedia)

Before deforestation occurred, Easter Island’s ancient population relied on the Jubaea palm as a primary biotic resource. The people relied heavily on this tree because it provided an abundance of stem wood, palm nuts, palm sap and palm leaves. The Jubaea chilensis, was a palm species on Easter Island that once dominated the woodlands. The palm woodland, based on a reconstruction study of the spatial and temporal distribution of the last generation of palm woodland, is believed to have been very dense during early settlement. This study concluded that the average growing distance between trees was estimated at 2.6 m. These results suggest that Easter Island once grew approximately 16 million palm trees, which demonstrates that it was the dominate vegetation structure on the island. The Jubaea palm was not only a primary resource for Easter Island, but is also believed to have been significant to its unique megalithic culture. Some researchers argue that logs from the palm were possibly used for the transportation and erection of moai and for constructing ahu by placing the heavy stone on rolling logs. At many sites, moai and ahu were also established directly on top of burned surfaces. These may hold cremated remains of significant ancestors and charcoaled timber for the fire (Mieth and Bork, 418-423). Although deforestation may be related to some cultural needs on Easter Island, the main reasoning behind this environmental degradation is due to the demand of the Jubaea palm as a vital resource.

According to Mieth and Bork, several scholars suggest that ecocide enacted by the ancient population was the primary cause of deforestation on Easter Island (418). Ecocide is the process in which societies damage their environments and as a result, they damage the society itself (Diamond, 6). Researchers argue that ecocide on Easter Island was due to a rapid growth in population, a high demand for open land to build homes and grow crops, and the increasing need for firewood and timber. Degradation of Easter Island’s woodland began around 1000 A.D. and reached its height around 1800 A.D. (Mieth and Bork, 418). Hunt and Lipo state that, “Within the period when deforestation progressed, about 1200 A.D. and 1700 A.D., the population appears to have continued to rise. Thus, based on at least obsidian hydration date analysis, it is apparent that as the forest disappeared, the populations grew” (608). Other indications of ecocide are the clean cuts found on burned palm stumps discovered in situ that were efficiently cut a few centimeters above the soil surface. Further evidence also includes Mann’s analysis of sediment cores of Lake Rano Raraku. He found that the sediment stratigraphy contained signs of rapidly increasing amounts of charcoal and a decrease in palm pollen numbers, which all dated at the beginning of colonization around 1700 A.D. Mann’s results indicate a significant human impact on Easter Island’s woodland. Evidence of fires and prehistoric garden soils are found in the charcoal layers of soil profiles within the former palm woodland. Burned nutshells of the Jubaea palm are frequently found in these charcoal layers. The analysis of these soil profiles suggests that widespread fires within Easter Island’s forests were used for intensive slash and burn, which was introduced due to issue of soil erosion. Charcoal obtained from a burned nutshell in these soil profiles are dated with a 2-sigma cal age of 1244-1254 A.D.  and 1256-1299 A.D. (Mieth and Bork, 418-422). It is evident that Easter Island’s existing vegetation cover was severely disrupted by the population’s need for timber, firewood, and slash and burn agriculture.

Easter Island’s deforestation was not only caused by ecocide, but also by the local climate and its effects on the soil. The loss of sheltering palm woodland and the constant wind combined with cool temperatures discouraged the growth of tropical plants vital for the ancient population (Mann et al, 18). Mieth and Bork’s research found that:

The oldest cultural layers found are in garden soils that were preserved between the undisturbed casts of palm roots and underneath later cultural horizons. Early crop cultivation was an integrated part of the palm woodland with the advantage that the palms protected the gardens from drying, from harsh winds, runoff, and soil erosion by water and wind (422).

Deforestation, however, did not ultimately turn fertile soils into poor soils, but rather made moderately poor soils even worse. At many locations between 1200 A.D. and 1650 A.D., the depositions of colluvium imply a widespread erosion of Easter Island’s primeval soil cover (Mann et al, 24). Some researchers believe that stone mulching was a response to deforestation. However, recent evidence demonstrates that this agricultural adaptation appears approximately 300 years before the palm woodland vanishes. Stone mulching was used to optimize crop cultivation on Easter Island’s nutrient-poor soils damaged by windswept and variable rainfall conditions (Hunt and Lipo, 605-606). The climatic trigger responsible for Easter Island’s radical changes in moisture, particularly rainfall, is due to the latitudinal shifts in the subtropical storm track. These invariable changes in climate could have created periods of drought on the island, which may have been a factor in deforestation and also soil erosion. Soil cores collected from Rano Raraku, which date approximately at ca AD 1180-1290, show signs of the end of a warm, dry climate period. This evidence also coincides with similar results in both northern Patagonia and Tasmania dated at a similar time (Mann et al, 26).

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Rattus exulans (Image provided by Mammals’ Planet)

The Pacific rat, Rattus exulans, also played a significant role in the ecological degradation that led to deforestation on Easter Island. Some researchers believe that the island’s ancient Polynesian population imported the rat when they first arrived. Athens’ study in Hawaii provides paleoenvironmental evidence that rats greatly impacted the lowland forests on the islands, particularly vegetation within the ecosystem (Hunt and Lipo, 608). Dr. Terry Hunt hypothesizes from Athens’ research that the Pacific rat, which had no natural predators on Easter Island, multiplied explosively to an unmanageable population size. The rats would consume palm seeds and other parts of the palm trees. As time passed, the destructive behavior of the rat-outbreak prevented the Jubaea palm from successfully reproducing and stopped normal growth of Easter Island’s palm woodland (Mieth and Bork, 419). Hunt also speculates that the destruction of palm woodland from the Pacific rats preceded the impacts of ecocide or human-caused environmental degradation, because the rat populations grew more rapidly (Mann et al, 24). Rat teeth marks preserved in seed shells found in archaeological excavations show evidence for the Pacific rats’ influence on deforestation. Dransfield and Hunt studied endocarps of the extinct Jubaea palm in which all of the seeds contained gnaw marks. The results do not hold strong validity because the palm nuts they inspected were located in caves, which made the palm nuts easily accessible for rats to eat. When Dransfield and Hunt’s research is compared to other preserved and charred nutshells, less than 10% of palm nuts showed evidence of rat teeth marks (Mieth and Bork, 423). Despite a lack of evidence that proves a rat-outbreak occurred on Easter Island, some researchers believe they still held an important role in deforestation.

Deforestation was the underlying cause that ignited the collapse of Easter Island. The combination of ecocide, the local climate and soil, and the Pacific rat population created a formula of destruction the ultimately led to the Rapa Nui’s loss in ecological complexity. The extinction of their significant palm woodlands left them stranded without one of their most useful resources. Easter Island’s growing human population and even larger rat population depleted the environment of the resourceful Jubaea palm because the trees and nutshells were consumed before the palm woodland could properly reproduce and grow. The climate of Easter Island and the local soil were also a reason of why the palm forest did not replenish sufficiently. The wind patterns affected how much salt was deposited into the soil, which made it more difficult for trees to grow due to the soil’s lack of proper nourishment.

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Moai kavakava (Image provided by Carolina Barahona Geisse)

Once European settlers arrived around 1750 A.D. to 1800 A.D., the ancient population already underwent an ecological collapse. A Dutch explorer, in 1722 A.D., documented that the population already suffered from the effects of deforestation because there was no sign of any palm woodland upon his arrival (McAnay and Yoffee, 38). In 1774 A.D., Captain Cook was known to have described the Easter Island population as “small, lean, timid, and miserable”. Moai kavakava, figurines depicting a starved human, are also evident around this time which indicates that the ancient population underwent severe societal turmoil, perhaps starvation due to the soil erosion caused by deforestation (Diamond, 109). The lack of palm timber would have also limited the population from constructing canoes needed to travel for oceanic food resources. The rapidly growing construction of moai depleted Easter Island of its significant palm tree resource in order to erect the stoneheads while also demanding great labor force, which increased the need for crop cultivation leading to soil erosion. Several factors were involved in the loss in complexity on Easter Island, but ecocide remains to be the main reason for deforestation and the society’s collapse.

The Classic Maya collapse, despite being very different from the Easter Island collapse, also has deforestation as one of the main contributing factors that led to the society’s loss in complexity. The collapse did not happen at once precise moment, but rather in waves between 760 A.D. and 909 A.D. Some sites experienced a sudden depopulation while others were more slow and gradual. The unifying characteristics that define the Classic Maya culture include the Long Count Calendar, Jaguar Lords, and its instinctive art style, which included a great use of the color red. The disappearance of each of these characteristics marks the end of the Classic Maya Period (Diamond, 167). One of the main reasons of stress within this society was its inability to sustain an enormous population. Near the end of its collapse, the Classic Maya supported a population density of 6,700 people per square kilometer in central cities and 1,300 to 3,400 per square kilometer in more rural areas. As one of the highest population densities in human history, the Classic Maya’s immense population size is only rivaled by today’s population density in China and Java (Olgesby et al, 2).

The ancient Maya partook in ecocide because it developed a growing population that it could no longer sufficiently supply with the essential resources required for survival. The Maya people were aware that environmental resources should not be used excessively, but the large population size left the society with no other choice than to use their environment to its maximum potential which inevitably made it unusable for years to come. Paleoenvironmental evidence suggests that deforestation among the Classic Maya escalated during the Late Classic Period due to population increase and the rising demand for timber and croplands (Dunning, Beach and Luzzadder-Beach, 3655). The Classic Maya are known to have used a forest-fallow system in which they left standing patches of managed tropical forest and individual trees within their agricultural fields. The land used in this process was only used every ten or twenty years. However, paleoecological data shows this practice was abandoned because a greater amount of opened farmland was vital to produce enough food to feed the rising population (Dunning, Beach and Luzzadder-Beach, 3653).  Classic Maya farmers suffered the affects of crop cultivation shortfalls, a heavier demand for food, and living within a deteriorating environment (Webster, 335). Around the ninth century A.D., pollen records indicate that most of the forest had been cut down. The evidence provided by the pollen records also speculates that the majority of the land had been modified by 750 A.D. (Oglesby et al, 2). As good land became scarce, Maya farmers were forced to move onto fragile, tropical soils to produce the crops needed to feed the large population. Researchers know this process as agricultural intensification. Maya farmers began to cultivate fields more frequently and shortened fallow intervals. These changes required more human labor to manage the fields by clearing, weeding, and hoeing. Consistent cultivation, particularly in Copan and Tikal, led to nutrient depletion and erosion of the soil, which resulted in declining crop yields (Webster, 333).  Evidence from bajos in the Mirador Basin and a nearby lake also conclude that ecocide played a major role in the Classic Maya collapse. The sediment data collected suggests that the Maya Lowlands experienced widespread deforestation and soil erosion. The environmental changes within this area were a result of land clearing and quarrying for limestone to generate plaster for temples (Dunning, Beach and Luzzadder-Beach, 3654). Deforestation was a direct outcome for the rising need for farmland and timber necessary to support the immense Classic Maya population. As a result, ecocide led to another issue that worsened the progression of the Classic Maya collapse, soil erosion.

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The Mirador Basin (Image provided by Ezra Magazine)

For several regions, such as the Mirador Basin and the Petexbatun zone, heavy episodes of deforestation and soil erosion have been documented as early as the Pre-Classic Period (Webster, 330). One of the principal causes of soil erosion in tropical environments, such as Mesoamerica, is deforestation. After deforestation was in effect, soil erosion progressed rapidly which removed entire soil profiles and sediment supplies into Maya Lowland water source (Beach et al, 168).  A sign for the decline of soil fertility was recovered in Lake sediments studied in the Tikal region. The loss of tree canopy decreased the amount of volcanic ash, soot, and other forms of phosphorus needed to nourish soils (Dunning, Beach and Luzzadder-Beach, 3654).  In addition, soil erosion from deforestation washed phosphorus, an essential nutrient in soil that promotes the growth of plants, into lakes (Webster, 255). Other contributing factor that accelerated soil erosion within the Classic Maya regions include the wet season of intense convective storms, little land conservation, a high runoff in expanding clay soils, and moderate slope lengths. Slope processes that deforestation also accelerated are raindrop impact, gully, sheet, piping, water, rill, and mass wasting  (Beach et al, 169). Human-caused deforestation and its result of soil erosion created minor local climatic changes, particularly relating to drought, which drove the Classic Maya further into its collapse.

Land cover changes, specifically in tropical environment, play a vital role in affecting climate changes. For example, deforestation causes cumulus clouds to form higher in the atmosphere and later in the afternoon, which results in less rainfall Furthermore, replacing forests with open grasslands has two major effects. The first is an increase surface albedo, which is the proportion of solar radiation reflected by the landscape and controls the cooling and stabilization of the atmosphere. The albedo increase resulted in a 1°C–2°C cooling. The second climatic effect of deforestation is a significant reduction of evapotranspiration, which is the amount of moisture that is recycled into the atmosphere and falls again as rain. Rainfall reduction due to deforestation made it more difficult to store a substantial amount of water for the population to survive the dry season. The degradation of the forests due to ecocide also altered the temperature to increase (Oglesby et al, 3-6). Reduced local transpiration and precipitation due to declining forest cover significantly increased the severity of drought and also compromised soil moisture (Dunning, Beach and Luzzadder-Beach, 3654). As indicated by paleoenvironmental data, severe droughts in the Maya Lowlands began approximately around 760 A.D. This is also the time when Late Classic sites start to be abandoned (Dunning, Beach and Luzzadder-Beach, 3655). Robert J. Oglesby states that:

Recent data indicate that a major drought at this time may have been a key factor in the collapse. Research along the Holmul River, which runs through several bajos and connects 10 major Maya cities, indicates that between 750 and 850 A.D. the river either dried up or became swampy, perhaps as a result of a long period of drought. These data correlate with that of other researchers who have found evidence of a major drought at 750 A.D. in lake core sediments, one of the driest, if not the driest, in a 7,000 year period, as well as intense multiyear droughts centered at 810 A.D., 860 A.D., and 910 A.D. (3).

The dates cited in Oglesby’s research correlates with the dates given to site abandonment. For example, the city of Aguateca was abandoned approximately around 810 A.D., Tikal was abandoned approximately around 869 A.D., and the last inscription at the site of Tonina is date approximately around 909 A.D. These periods of drought significantly harmed multiple Classic Maya cities and resulted in massive depopulations because a substantial amount of water need to sustain its large population could not be stored within their bajos. Regarding soil erosion, Dunning, Beach and Luzzadder-Beach believe that, “meterological drought could quickly translate into agricultural drought because the rainfall-dependent nature of cultivation leads to socioeconomic perturbation if it is severely curtailed to food production” (3653). The combination of ecocide, soil erosion, and climatic changes due to deforestation of Mesoamerica wrecked havoc on the Classic Maya population. The most significant impact from deforestation includes lower precipitation rates and higher temperatures, which were both detrimental to Maya life (Oglesby et al, 7). The droughts the Classic Maya experienced not only provide insufficient amounts of water, but also resulted in a depletion of sufficient crop cultivation necessary to provide for its growing population.

A pollen profile collected from Tikal was researched by Rue. His findings indicate that the Maya region did not begin to recover from severe deforestation until approximately 1250 A.D. or later, which is a thousand years later from when the first signs of deforestation in 1000-1100 A.D. (Webster 314). According to paleoenvironmental data, regional forests did not return to pre-Maya levels until approximately 100 to 200 years after the area’s abandonment (Dunning, Beach and Luzzadder-Beach, 3655). Deforestation’s role in the Classic Maya collapse created a significant amount of stress upon the growing and expanding society because the available amount of agricultural and environmental resources could no longer support its population. This stress is interrelated to the increase competition among neighboring cities, which led to warfare. It also escalated peasant revolts because the lack of substantial resources made the common population question and reject the ideology behind the kingship (Webster, 328).

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Jaguar Lord pelt throne vase (Image provided by the National Gallery of Victoria)

Divine kingship while providing unquestionable power and privilege also demands that the ruler deliver rainfall, good crop yields, and successful military raids as if he were a god. If a period of misfortune took place, the king or Jaguar Lord was to blame. The combination of ecocide, soil erosion, and drought as a result of deforestation drove the Classic Maya into a period of social unrest. As the competition for resources increased, warfare became more prevalent as did peasant revolts (McAnany and Yoffee, 158). The periods of drought, which were generated by human-caused environmental degradation and soil erosion, directly affected the ancient Maya population’s stability. However, the Classic Maya collapse is one that involves a decrease in cultural complexity. Changes in ecological complexity is an underlying cause, but the end of the Classic Maya Period is marked by the loss of important cultural features. As the Long Count Calendar, the Jaguar Lords, and the distinct art style of the Classic Maya vanish, the society’s cultural complexity decreases significantly. Yet, the changes regarding ecological complexity, particularly deforestation, are the ultimate cause for the collapse because it initiated social instability, which resulted in the massive abandonment of cities.

The concept of deforestation may currently be a popular explanation for collapse amongst anthropologist due to the prevalence of Global Warming, but there are numerous studies that provide extensive evidence that environmental degradation was an issue even among ancient societies. Both Easter Island and the Classic Maya were greatly affected by the effects of deforestation. Deforestation’s relationship to ecocide, climate, and other environmental changes led each of these societies into a period of immense alterations in complexity. The ancient population of Easter Island experienced an ecological collapse because deforestation, with the help of the growing Pacific rat population, depleted the society of its major resource of the Jubaea palm as well as damaging the already unnourished soils. On the other hand, the Classic Maya did not experience an ecological collapse like Easter Island despite deforestation being a major factor in its decline. Deforestation ignited social unrest and instability due to the lack of environmental and agricultural resources. Soil erosion and drought forced urban populations to suddenly abandon cities throughout Mesoamerica. As a result of this massive depopulation, the defining cultural characteristics of the Classic Maya period disappeared by the end of the collapse. If today’s society is to learn anything from the Easter Island and Classic Maya collapse, it is to understand the severe consequences of deforestation and to acknowledge the effects of modern ecocide on global environments and climates.

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