Islandification

Islandification had been the single most important fundamental ecological process of the of the twentieth century. The cause of islandification is the rising tide of human beings. Islandification has been the main cause of species extinctions, with an effect larger than all other causes put together.

Example of islandification adapted from J. Weiner, The Next one Hundred Years, 1990.

"Today the number of islands on this planet is increasing much faster than at the end of the Ice Age. The cause is not a change in sea level, for sea level is not rising that much, yet. The cause is the rising tide of human beings. All over the planet, the biosphere is tending more and more toward a checkerboard. Look out a plane window. There are exceptions, but as a rule the longer a place has been inhabited the more fragmented is the landscape. In the United States the checkerboard was drawn in first in the east and spread west."

"The last pioneers in the United States are now busy in the last wilderness. The flight from San Francisco to Seattle, Washington follows the Cascade Range, some of the most spectacular and lonely wilderness in North America. Even in those jagged mountains, which are really rows of young volcanoes -- and even within a few miles of the smoking crater of Mount St. Helens -- one can see the outlines of the universal checkerboard being sketched in. Valleys and ridges are dotted with houses. Forests are bisected and trisected with roads. The biosphere is being carved into thousands of odd-shaped fragments of dark pelt."

"The smaller the island and the farther it lies from the mainland, the greater the disparity between the rate of extinction and the rate of replacement. The result is a decline in the number of species: an island effect.

Lovejoy

"Lovejoy's archipelago became the biggest planned experiment in the history of ecology. ...almost thirty islands, including a giant of ten thousand hectares."

"First, the birds flocked in. Tropical ecologists can count birds by stringing invisibly fine nets- mist nets- across clearings in the forests before dawn. In newly isolated forests, the rate at which the ecologists caught birds in the mist nets doubled. This is a refugee effect. Birds have been displaced and they flock to the island in the middle of the new field as if alighting upon an ark."

"Six months later, the population of refugees crashes. Trees at the edge of the forest begin to crash, too. They are not used to so much sunlight. Sun is stronger in tropics than anywhere else on earth because it is directly overhead. But in the thick uncut rain forests there are so many layers of forest canopy that very little light gets through to the bottom. Now trees from the dark heart of the forest had been placed on the edge of the forest."

"Monkeys were in trouble, too. The band of golden-handed tamarins fled across the new fields and were seen no more. Saki monkeys normally range in troops across hundreds of hectares. Two of them were marooned together on the little island. They ate almost all the fruits and seeds of the trees in their reserve. Then the saki monkeys disappeared."

"Troops of army ants live in a month-long cycle. For part of each month each colony camps in a bivouac of half a million ants or more. But for a time during each cycle, they swarm. Each day the troop advances as a front across the floor of the rain forest, flowing under leaves and up over tree trunks like a stream of molten tar.
Insects on the forest floor normally sit still and try to be inconspicuous. But when the army ants are coming, they abandon their hiding places and flee for their lives. they leap into the air, or hop ahead, anywhere they can go. The march of the army ants is a sight to see, with thousands of multicolored butterflies, exotic grasshoppers and giant cockroaches bursting into the air in front of it.
Certain birds take advantage of this panic. They fly above the troops of army ants like air force above infantry. The birds swoop low and filch fleeing grasshoppers in mid-air before the ants can get them. Half a dozen species of birds in this part of the Amazon are professional ant-followers. They have pursued the trick for so long that it has become obligatory. Without the army ants to beat the bushes, the birds would starve to death.
A single army ant colony ranges across about thirty hectares of rain forest. So the troops of army ants on the new ten-hectare island soon disappeared. The guilds of ant followers disappeared, too. A conspicuous portion of the fauna of the rain forest had vanished."

"Associations still more peculiar began to fall apart. The ecologists monitoring the island had expected trouble for the ant following birds. They had also expected that the islands would be too small for the great, pig-like peccaries. but they had not imagined that somethins as small as a frog would suffer. However, when the peccaries disappeared, their muddy wallows on the edge of the island began to dry up in the hot sun. Frogs had lived in the puddles in those peccary wallows. These frogs now fell silent."

"On the windward side of the island, the number of wind-thrown and broken trees was striking. Lovejoy attributes their falls to the high winds that blew in from the open pasture-- another edge effect. Each tree-fall opened up more of the forest within to sunlight, which meant weeds from the pasture could creep further into the forest. The edge crept inward.
Indeed the ten-hectare plot was really all edge. There was no core where the forest was untouched or unchanged-- even in the very center of the reserve. Lovejoy says, 'The number of standing dead trees jumped dramatically from nine in 1981 to sixty-five in 1982.'"

"Volunteers who had explored and surveyed before the island's ceation began to find the place unfamiliar. The dawn chorus of the birds and the midnight chorus of the frogs had been silenced. The familiar butterflies that had lived near the ground were nowhere to be seen. The air was hot and dry, and each week there were fewer catches in the mist nets."

"Events like those that created Lovejoy's islands are being repeated at a rate of about one acre per second in rain forests around the world, and despite an infinity of local variations on the theme, everywhere there will be the same pattern of attrition. The only fundamental difference is that here the losses are being watched."

Jonathan Weiner, The Next One Hundred Years, 1990

"Who gives a hoot about habitat?"

Good luck with web searches on this subject: