three case studies of environmental interactions · three case studies 5 sc/nats 1510, three case...

Three Case Studies

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11SC/NATS 1510, Three Case StudiesSC/NATS 1510, Three Case Studies

Three Case Studies of Environmental Interactions


Some instructive environments

Easter IslandVeniceTsavo National Park


Easter Island

One of the most remote inhabited places on earth.150 square miles in area.

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Location of Easter Island

• Lies in the Pacific about 2000 miles west of South America. Nearest inhabitable island is Pitcairn Island, 1250 miles away.


History of Easter Island

Discovery by Europeans– Discovered by accident by Europeans on

Easter Sunday in 1722 by the Dutch Admiral Roggeveen.

– He found a population of about 3000 living in primitive squalor – in reed huts or caves.

– The population engaged in almost constant warfare and resorted to cannibalism to get enough to eat.


Later contacts

The Spanish annexed the island in 1770, but did not colonize it.– In a few other visits, Europeans kidnapped

some residents to be slaves.In 1877, Peru removed and enslaved all but 110 old people and children.Eventually the island was taken over by Chile and became a vast sheep ranch.

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The Mystery of Easter Island

Scattered across the island were over 600 massive stone statues, averaging over 20 feet high.


The Mystery of Easter Island, 2

Easter Island had clearly once been a flourishing and advanced culture.

– The people found by the Europeans would not have been capable of producing and transporting these statues.


Colonization of Easter Island

A probable sequence:– The first people arrived on Easter Island in the

5th century, at around the time of the fall of Rome in Europe.

China was then still in chaos from fall of Han empire.India was at end of the Gupta Empire.Teotihuacan (in what is now Mexico) dominated Central America.

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Migration to Easter Island

Original settlers came from South East Asia, reaching Tonga and Samoa about 1000 BCE, moved further east in 300 CE, and then split in two directions: north to Hawaii and southeast to Easter Island.

– The same people appear to have colonized New Zealand about 800. They were the most widely spread people on earth.


Terrain of Easter Island

The island is made up of three extinct volcanoes.


Few natural resources

Temperature and humidity high.Soil adequate but drainage poor.Only fresh water was from lakes in the volcanic craters.Very few indigenous species of plants and animals.

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Restricted diet

Much of what the settlers brought with them for food was unsuited to the environment.Diet was based primarily on chicken and sweet potatoes.Though monotonous, this diet was not very demanding of time.


Social organization and cultural life

Settlements were scattered across the island in extended families.Crops were grown in open fields.Much leisure time was spent on ceremonies.

– Ceremonial activity centered on monument construction.

– Elaborate stone platforms were constructed on which the huge stone statues were erected.

– Some of the platforms have complex alignments to astronomical positions.


The Statues

The statues were made of stone found in two separate quarries.

– The body of the statue came from one quarry, the “topknot”on the head from another quarry.

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The Problem of the Statues

The most difficult problem was transporting statues across the island.– When the European explorers asked the

natives how the statues were transported to their platforms, they were told that they had “walked there” on their own.


The Role of Trees

It appears that the statues were dragged across the island using tree trunks as rollers.– The pollen record shows that a fruit palm tree

was native to the island and flourished for thousands of years.

– This tree was felled for transporting and raising the statues, for making canoes, for firewood, and just to make room for agriculture.


Trees and Population

The population of Easter Island grew from a few dozen in 6th century to about 7000 in the 16th century. – More people required more trees.

The rate of tree felling eventually exceeded the replacement rate and the island became completely deforested. – Easter Island is now completely treeless.

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The Collapse of Civilization on Easter Island

Around 1600, the society on Easter Island went into a sudden and irrevocable decline.– The population fell quickly from 7000 to the

3000 found by Admiral Roggeveen in 1722.The island became incapable of supporting its population.


Life without Trees

Construction and erection of statues stopped suddenly. Many statues in various states of completion were abandoned in the quarries, with no way to transport them.Without trees, houses could not be built. People resorted to living in caves and in flimsy reed huts.


The absence of trees made life untenable.

Canoes could no longer be built, making long voyages impossible.Fishing was more difficult because nets had been made of cloth from the mulberry tree.Without trees, soil erosion increased and crops failed.

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Fighting over Diminishing Resources

With crop failures, the only source of food was the chickens, which were now to be guarded against theft.

– Stone chicken coops were built during this period.Warfare became a permanent feature, fighting over the few remaining resources.

– Slavery became common.– Cannibalism followed.

The Islanders no longer knew how the statues had been constructed.


The Terrible Lesson of Easter Island

The island residents knew they were isolated from the rest of the world.They knew that their existence depended on the limited resources on the island.– Nevertheless, they cut down the last of the

trees and let the environment degrade to the point where life became impossible.


Venice

Founded in the 5th and 6th centuries as a refuge for people fleeing Germanic tribes.

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The Founding of Venice

Inhabitants from towns around the northern Adriatic fled to the marshes, where they could better defend themselves.


Founding of Venice, 2

Though first they returned home after a raid, eventually they moved permanently to the Venice lagoon.


Making a Permanent Settlement in Shifting Mud

No permanent buildings could be built on the marshes of the Venice Lagoon until the ground was stabilized.This was accomplished by felling millions of trees in the surrounding region and driving them into the mud to stabilize it.

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Santa Maria della Salute

One of the most famous sights in Venice is the baroque church of Santa Maria dellaSalute on the Outer Canal of Venice.

It has a foundation of 1,106,657 trunks of alder, oak, and larchtrees – once common in the region.


The Cultural and Commercial Centre of Europe

In the Renaissance, Venice became a great centre of art and architecture as well as a commercial trading centre.Its position on the Adriatic enabled it to be a vital port for import and export of goods.


The Extraordinary Layout of Venice

Its unique layout of landmasses interlaced with canals gave it a special character that drew people to the city.

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In Modern Times, a Major Tourist Attraction

Venice depends on its great classic beauty to sustain its economy.


Consequences of the Artificial Environment of Venice

The natural lagoon where Venice is built has been much altered over the centuries.The millions of trees and saplings that were driven into the ground at the outset.The deforestation of the surrounding region to provide the trees.The altering of the natural watercourses leading into the lagoon.


Environmental Problems

20th century industry on the nearby mainland has removed so much groundwater that the city is sinking.Floodwaters that come with winter storms now regularly flood the ground floors of buildings across Venice.

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Environmental Problems, 2

Air pollution from mainland erodes the statues in St. Mark’s Square and at the Santa Maria della Salute church.City sewage flows into the lagoon, making it toxic.Venice is dependent on the flushing action of the tides to take sewage out to sea.


Floodgates

In 1998 floodgates were installed at the outer edge of the lagoon to allow tidal waters to flow outward, but prevent their return.

– Guards against flooding during storms and against sewage being brought back before the tides can take it away.


Venice – A City with a Great Past, Fighting a Losing Battle for a Future

Venice is crumbling into the sea. The technology that built it cannot withstand the stresses it now endures.

– Venice suffers from air pollution, water pollution, unsafe architecture, constant noise, crowding, unsanitary conditions, and an economy that depends on the tourist trade.

It was an artificial environment from the start.It has no future.

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Tsavo National Park


Tsavo National Park

Tsavo is one of Kenya’s largest national parks.– It was created in 1948 as a wild game

preserve.– Its viability depended on attracting tourists to

see large animals in the wild.


The Park in Tsavo East

Tsavo National Park is huge. It has two parts, East and West.

– The east park shown in the map here covers 13 000 square kilometers.

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Starting Point

David Sheldrick was the first warden of the park, starting in 1948.– He undertook to encourage the normal

balance of wildlife to re-emerge.European settlers had shot most of the big game around the turn of the century.Of the remaining animals, black rhinoceros and elephants were in danger of being wiped out by poachers.


Making the Park

1000 miles of road were built into the park for tourist access.The Galena River was dammed. Artesian wells dug.

– This provided year-round water for the wildlife.Poaching was eliminated by a crackdown effort to catch them and/or drive them off, using Land Rovers, aircraft, and World War II repeating rifles.


The Elephants

The result was a massive buildup of elephants that had been nearing extinction in the region.

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Now, Too Many Elephants

In a short period of time, the large elephant population proved very destructive to the environment.Elephants knocked down trees and uprooted shrubs.By 1959 the once very thick vegetation, enough to hide all the elephants from tourists unless they crossed a road, was compared to a “lunar landscape.”


Tsavo at the Border of the Park

The highway, a railroad line, and a firebreak in-between separate the park, Tsavo East, on the left, from the lush natural landscape outside the park, on the right. Picture taken in 1977.


Sheldrick asks for Scientific Advice

Sheldrick wrote in a report in 1959:– “…during the past few years, the destruction of

vegetation by elephant has reached serious proportions. If present trends continue, it is doubtful if the Park can continue to support the existing population much longer. What effect this will have on other species remains to be seen, but I think it is important that we should seek scientific advice regarding this problem as soon as possible.”

Quoted in Daphne Sheldrick, The Tsavo Story (London: Collins and Harvil Press, 1973), p. 113.

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Effect of Drought and Rainfall

By 1966, there had been a series of droughts that made the problem worse, drying up the remaining vegetation.

– There was general agreement that the park could only be saved by removing a large number of elephants.

Then rains returned and the park recovered its greenery, providing more food for animals.

– Thus the elephant population increased even more.


Culling the Elephant Population

The Ford Foundation sponsored a scientific study that concluded that about 3000 elephants must be shot to keep the population down to what its food supply can support.


To Cull or not to Cull the Elephants

Sheldrick at first agreed, then reversed this decision, arguing that nature is best left alone to take care of itself. He wrote, – “the conservation policy for Tsavo should be

directed toward the attainment of a natural ecological climax…our participation towards this aim should be restricted to such measures as the control of fires, poaching, and other forms of human interference.”

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Leaving Mother Nature Alone

Sheldrick believed that the variations in the weather and other cycles would in the end balance out and produce long-term stability.– He believed that droughts were a natural

culling of the herd, bringing their numbers in line with the carrying capacity of their feeding grounds.


Too Big a Drought

In 1969 and 1970 there was a severe drought that destroyed vegetation and caused many animals to starve, including 6000 elephants.Before the last of the elephants starved, they destroyed all of the remaining vegetation, searching desperately for food.The destruction of the landscape by the desperate, starving animals, was so complete that it cannot recover in any normal time frame on its own.


To Intervene or not to Intervene

The controversy at Tsavo Park was not whether to try to preserve nature or, on the other hand, to plow ahead with industry and progress.– This controversy was all within the

environmentalist camp.

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Disagreement among the environmentalists

One view is that nature is best preserved by simply keeping human influences out.The other view is that nature varies so much that human intervention is required to restore its balance.– At Tsavo, the devastation of the environment

came from allowing nature to run its course without human intervention.


What is a “Natural” Environment?

Tsavo is a large park, but even so, it may be too small for a “natural” elephant population.Before the division of Africa into nations with boundaries (both political and man-made such as railroad lines), elephants facing a drought in one area would have migrated to another.


The Elephants and the Park now

The elephant population in Tsavo has recovered a bit since the great drought, and is now in danger chiefly from poachers.Human intervention may be necessary both to prevent too many elephants and too few.

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