Category Acid Deposition and Energy Use

Modeling the Renewable Resource Stock

The economy and ecology of Easter Island were relatively simple, but obtaining a tractable mathe­matical representation still requires significant ab­straction and approximation. At a minimum, it is necessary to model the behavior of two ‘‘stocks’’ or ‘‘state variables’’: the forest stock and the population. In fact, it is an oversimplification to focus just on the forest stock. Even in the absence of the forest stock, grass, shrubs, and certain vegetables could be grown and this biomass was sufficient to support a diminished but significant population. Rather than introduce a third ‘‘stock’’ representing other biomass, it is simpler to aggregate the renewable resource base growing on the land into a single resource stock, denoted as S...

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A PREDATOR-PREY SYSTEM WITH UNFORTUNATE PARAMETER VALUES

2.8 Easter Island as a Predator-Prey System

As reported in 1998 by Brander and Taylor, the understanding of Easter Island can be greatly advanced by using formal mathematical analysis. The formal description provided here relies on that analysis. One key point is that the Easter Island economy can be viewed as a ‘‘predator-prey’’ system. The forest resource can be considered as the prey and the Easter Islanders as the predators. One important aspect of even relatively simple predator-prey systems is that small to moderate changes in one or more key parameters can give rise to major qualitative changes in the dynamic pattern of population growth and decline...

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Mitigating Factors and Reinforcing Factors

Various factors can mitigate Malthusian population dynamics (as Malthus recognized), including techno­logical progress and the possibility of a ‘‘demo­graphic transition’’ under which fertility declines at sufficiently high incomes. (The combination of technological progress and a demographic transition has, of course, allowed most of the modern world to avoid the Malthusian trap over the two centuries that have passed since the time of Malthus.) On the other hand, as Malthus also realized, there are factors that tend to exacerbate Malthusian dynamics, including reliance on open-access resources and lack of property rights more generally.

2.7 Easter Island and Malthusian Overshooting

At a superficial level, Easter Island might look like a simple example of Malthusian population o...

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MALTHUSIAN POPULATION DYNAMICS

2.5 A Cautionary Tale?

The basic facts regarding Easter Island are no longer in serious dispute. It is, however, important to understand why Easter Island suffered an internally generated collapse based on resource overuse. The real question is whether Easter Island is an unusual and isolated case or whether it is a cautionary tale for the modern world. It is therefore important to uncover any general principles that might be inferred from the Easter Island experience.

2.6 Malthusian Population Dynamics and Overshooting

One important idea that might shed light on Easter Island derives from Malthusian population dynamics...

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RESOURCE DEPLETION AND COLLAPSE

2.3 An End to the Golden Age

By the turn of the millennium in 1000 ad, the population was still rising and a statue-carving culture had developed. The statues were carved in Easter Island’s lone quarry and then transported to desired locations using logs as rollers. The forest stock would have been down to perhaps two-thirds of its original level and the islanders probably would have regarded as apocryphal any claims that the island was once fully forested. However, this much loss of forest cover would have begun to reduce rainfall (because low clouds could pass overhead more easily) and would also have reduced the capacity of the soil to retain water. These trends continued for the next several hundred years...

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FIRST DISCOVERY AND EARLY HISTORY

2.1 The Virgin Forest

Although there is some uncertainty about dates, it now seems that Easter Island was first discovered by a small group of Polynesians sometime between 400 and 700

ad. The striking surprise that emerged from analysis of core samples is that Easter Island was at this time covered by a dense forest of Jubaea chilensis (the Chilean wine palm). This particular palm is a large, slow-growing tree that grows in temperate climates.

2.2 The Easter Island Economy

Following first discovery of Easter Island, the new inhabitants developed an economy based on the wine palm...

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1. THE MYSTERY OF EASTER ISLAND

1.1 Early European Contact

First European contact with Easter Island occurred on Easter Day of 1722, when three Dutch ships under the command of Jacob Rogaveen stopped for a 1-day visit at the very isolated South Pacific island, just over 3000 km west of Chile. The visitors observed a small, treeless island populated by what they thought were about 3000 islanders and, to their surprise, by a large number of giant statues. The outside world had no previous knowledge of Easter Island and the islanders apparently had no awareness of the outside world. The visit must have been a shock to the Easter Islanders, but no systematic account of their reaction survives and no further contact with Europeans occurred until 1770, when a Spanish vessel made a brief stop.

The first systematic study of East...

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Easter Island: Resource Depletion and Collapse

JAMES A. BRANDER

University of British Columbia Vancouver, British Columbia, Canada

1. The Mystery of Easter Island

2. First Discovery and Early History

3. Resource Depletion and Collapse

4. Malthusian Population Dynamics

5. A Predator-Prey System with Unfortunate Parameter Values

6. The Role of Property Rights and Open Access

7. Aftermath

8. Lessons of Easter Island

Glossary

core sample A specimen obtained in a long cylinder, taken from a physical site for subsequent study; used in many fields, including oil exploration and archaeology. In archaeology, elements in the core sample can be carbon dated, allowing a reconstruction of the implicit histor­ical record.

Malthusian population dynamics A demographic theory originated by Thomas Malthus, suggesting that the human population has a nat...

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