Illustrations for a lecture called

Changing the world: Documentation of large-scale human-induced earth-surface change in images from satellites, the Space Shuttle program, and the International Space Station

This is the second of two pages presenting the illustrations for a lecture on large-scale land use given by Dr. Bruce Railsback in his GEOL 1122 course Earth's History of Global Change at the University of Georgia. The links below are to large (generally 900-pixel-wide) jpeg files. The large size of those files is to allow educators to use the images in classes and presentations. For further information, contact the author at

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The Aral Sea



The Aral Sea in 2003
The Aral Sea through time
The Aral Sea from the ground

      The Aral Sea was once the world's third or fourth largest lake, but it's not anymore. Deviation of the lake's rivers for agriculture has caused the lake to shrink and dry up, leaving behind salt pans littered with the rusting remnants of fishing boats and barges that once busily crossed the lake. Commercial fishing on the lake ended in 1982, and today the waters of the Amu Darya and Syr Darya rivers go mostly to irrigate cotton fields and rice paddies in Uzbekistan, Turkmenistan and Tajikistan. Thus the stories we encountered at Owens Lake and in the Colorado River delta are hardly unique, and the Aral Sea is almost certainly headed toward the same fate.
      One might argue that the human gain from irrigation of agricultural lands justifies the destruction of the lake. However, human loss around the lake is intense: the economy of the lake region has been devastated, water supplies are fouled or non-existent, infant mortality is soaring, and kindey and thyroid diseases flourish. Environmental change has thus allowed econimic progress in some areas, but only at the expense of human devastation in another.
     (source: "Requiem for a dying sea" -



Desertification in China



Desertification in China

      The drive to generate new agricultural land, and its results, can also be seen farther east in Asia. In China, a law enacted in 1994 requires that any agricultural land converted to non-agricultural use be replaced by new agircultural land. Provinces with urban growth thus pay remote northwestern provinces to bring marginal land into agricultural production. The land's vegetative cover is plowed up and the soil is quickly eroded, leaving a barren landscape in which little moisture can be held in the soil. The result is desertification. It is estimated that 900 square miles of land become desert each year - not because the climate is drying, but because the natural land cover has been destroyed. Among the more distal results are dust storms that reach Beijing and the Pacific.
     Source: Lester R. Brown: Another One Bites the Dust: Grist Magazine (29 May 2001) ( quoting Erik Eckholm of the New York Times.






Australia - an overview
The Wheat Belt

Farm land near Culcairn
Lands near Kosciuszko National Park
Kosciuszko National Park from the ground

Darling Downs
Southwood National Park
Darling Downs from the ground
A Jacaranda tree - one of southern Queenland's springtime jewels

Melbourne and dust

      We next travel to Australia and go west-to-east to see some contrasts between agricultural and preserved land. The first comes from southwest Australia's "Wheat Belt" country, where the Fitzgerald River National Park and Lake Magenta Nature Preserve stand out as green oases amidst the farmland.
     In far southeastern Australia, in southeastern New South Wales, the same contrast appears near Culcairn, northwest of Kosciuszko National Park. Images from the ground show the Park is a wooded (drily wooded, but wooded) landscape, as opposed to the largely deforested landscape beyond the park.
      Another example comes from Queensland's Darling Downs region west of Melbourne, and thus in easternmost Australia. Isolated green preserved patches, and especially Southwood National Park, again stand out against the brown farmland.
     Agriculture is of course a major force in the Australian economy, and it is required to sustain a human society. It helps sustain cities like Melbourne, the beautiful skyline of which is shown here. A price is paid, however, when dust storms rise off the easily eroded farmland and engulf the cities.



New Zealand



Farmland around Mt. Egmont
Mt. Egmont frm space
Views to and from Mt. Egmont

Landscape near Tokoroa, New Zealand

      We begin our visit to New Zealand near Mount Egmount, or Mount Taranaki, on the west side of the North Island. Beautfiul meadows and lush green field stretch away from us, with Mt. Egmont in the distance. A view from above shows that Mt. Egmont National Park is a circular park whose outline is very evident: the park retains its natural forest cover, whereas the surrounding land does not. The bucolic countryside was were enjoying may be aesthetic to persons trained to enjoy meadows and green fields, but its all entirely unnatural - the natural condition is forest.
      Deforestation continues today. Our second set of images comes from around Tokoroa, farther north and near the center of the North Island. A huge light green swath around Tokoroa (the grey splot in the middle) cuts across dark green forest. Southeast of Tokoroa are small brown dots connected by branching brown lines, rather like berries loosely clustered. The brown lines are logging roads, and the brown dots are where trucks pick up newly cut logs. The detailed image shows these areas in the process of clear-cutting, and larger tan swaths already clear-cut.






Rio Branco, southwestern Brazil

Deforestation in Rondonia, southwestern Brazil
Deforestation in Rondonia, southwestern Brazil - the large scale effect

South-central Brazil - an overview
Xingu national park
Views from the ground in Xingu
Far southwest in the first slide

      We begin our tour of Brazil with a look at deforestation near Rio Branco in southwestern Brazil. The large image shows the classic herringbone pattern of cutting in progress: parallel roads branching from a main road are cut into the forest, and clear-cutting then works out from those roads. The insets at right show the progress made in one year in the northern part of the large image.
      Still in southwestern Brazil, but now in the state on Rondonia, our second stop is to look at the results of clear-cutting. The image at right, in which trees are just barely recognizable individually, is a tiny part of the left red image (it's in the upper center of the left mage - use the river's curve to find it). Note the huge herringbone cuts in the left image. The second slide ("the large scale effect") shows that the left red image portrays just a tiny area in the vast area deforested here. The scale is staggering.
     Thus far, we've been looking at these images as an issue of changes in the physical or ecological landscape. The third set of slides is also from Brazil but shows the implications for the human "landscape". The first slide is an overview of a large area in south-central Brazil, with the Xingu Indigenous Park in the northwest corner of the area. The second slide shows the encroachment of clear-cutting on the park. The park was originally planned to be 120,000 square miles in area, but that had shrunk to 12,000 square mile by the time the park was actually created, and control of its borders is still tenuous. The park is home to several unwesternized cultures in seventeen indigenous nations, and thus preserves unique ways of life. As forest is removed and roads are cut into the park, those cultures are lost forever. The last of the four slides, from far south of Xingu, shows how extensive the removal of forest can be.

      If what's happening in Brazil seems an outrage, bear in mind that it simply catches in mid-stride what was done to North America from the 1700s to the early 1900s. North America's deforestation to generate farmland (and now residential land) has simply been so thorough that one can't even recognize the extent of that deforestation any more. These examples from Brazil, on the other hand, are just a work-in-progress on the same theme. Similarly, if one is concerned about the fate of indigenous tribes in Amazonia, one must also think back to the North American and Australian examples, where the aboriginal native peoples were largely exterminated (and in Tasmania, south of the Australian mainland, the extermination was complete). In fact, the motivation for deforestation in Brazil is largely driven from North America, as the land is cleared for ranches to provide beef for the U.S. market.






Deforestation in Bolivia
A view from the air
Deforestation through time

      Our first slide from Bolivia shows the progress in cutting of forest to make soybean fields in a carefully planned program of deforestation. If the geometry looks unbelievable, the second slide shows the fields that radiate from villages constructed at the centers of the clear-cuts. The third slide shows that this area (at upper left) is just a small part of the entire extent of deforestation across the region in the late 1900s.



. . . and elsewhere


Deforestation in Paraguay
Deforestation in Sumatra
Eastern Angola and surrounding countries - an overview
Deforestation in eastern Angola
Deforestation in eastern Angola
Deforestation in Angola and Zambia
Lesotho and South Africa; a contrast
Lesotho and South Africa; a contrast (detailed view)
Flooding of land in Turkey: before
Flooding of land in Turkey: after
Flooding of land in Turkey: views from the ground

      The slides at left provide more examples, but hopefully the point is made: The view from space shows that humans have changed their planet's surface at a scale most never appreciate.






Specific Conclusions
Results of change I: Loss of biodiversity
Results of change II: Physical changes in the environment
Results of change III: Atmospheric Change
Land Use and CO2

The examples above document that ecological change has been greater in geographic and ecological scale than most of us appreciate, in that almost all the land we see has been changed from its natural condition. The results of these changes are extensive too. Ecologically, loss of biodiversity means a lessening of ecological stability, a diminishing of biological resources, and a loss of natural beauty. Physically,the results include climatic change, erosion, silting of harbors and coastlines, and dust storms. Additionally, and perhaps most importantly, loss of forests and grasslands results in a transfer of carbon to the atmosphere as CO2, a greenhouse gas now widely accepted as a cause of global warming.



Closing Thoughts



Text slide: bad news and good news
New-growth forest at the UGA Botanical Gardens
New-growth forest at the UGA Botanical Gardens: Succession
New-growth forest at the UGA Botanical Gardens

Restored sand prairie, Trempealeau National Wildlife Refuge
Wildflowers in a restored sand prairie
Lupine-covered hillside in a restored sand prairie

Examples of reversal of desertification

While this presentation may seem to be a pessimistic view of how humans have changed the world, there's also good news here. Forests and grasslands can be restored. We've in fact looked at some restored prairie in the illustrations above. The first illustrations at left are from forest growing on previous farmland south of Athens, Georgia. In fact, as one of the slides indicates, this was one of the settings in which the famous ecologist Eugene Odum developed the concept of "old field succession", wherein farmland slowly but progressively returns to the ecological community natural to the environment. The second set shows a restored prairie on land that was used for farming and grazing and one which nearly all natural vegetation had been eliminated. Third set (just one slide) shows "before and after" examples of recovery of desertified land. These examples of restoration and recovery show what can be done, if we try.




Keys to Recovery
Data from the Human Footprint project

      This business of reforestation or grassland restoration can be accomplished at smale scale by individuals and groups willing to spend their money on land for new forest or grassland. At the larger scale, however, freeing land from human use requires rethinking the demands that humans place on the land. This means lessening human population and lessening per capita consumption of resources.
      There are many ways of measuring per capita consumption of resources. One way very appropriate to our theme is to look at the "human footprint" - the land area required to suport the life of one person. U.S. citizens have a human footprint twice that of people who live very comfortably in Austria and the United Kingdom.






A recovering forest (note old agricultural ditching)
Leaves of some trees here
Some plants here
Hopeful conclusion

Another example of reforestation comes from eastern Clarke County, Georgia. Old agricultural ditching and terraces dug in the 1930s and 1940s document that this land was barren of trees until at most a few decades before the pictures were taken. The present forest is relatively diverse, but it's mostly a pine-poplar forest with only small oak trees. It is presumably on its way to becoming an oak-hickory forest. This example illustrates that reforestation, while slow to reach the ecology of virgin forest, is possible and does soon produce a diverse forest.


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