After the Ice Age: The Return of Life to Glaciated North America
The fascinating story of how a harsh terrain that resembled modern Antarctica has been transformed gradually into the forests, grasslands, and wetlands we know today.
"One of the best scientific books published in the last ten years."—Ottowa Journal
"A valuable new synthesis of facts and ideas about climate, geography, and life during the past 20,000 years. More important, the book conveys an intimate appreciation of the rich variety of nature through time."—S. David Webb,Science
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Around 1800 years ago, there was a huge ice sheet that covered Canada and the northern part of the United States. This ice sheet melted and made the upper part of North America into what it is today. E.C. Pielou describes these processes in great depth in her book, After The Ice Age: The Return of Life To Glaciated North America, and she does a very excellent job in writing. She shows how landforms came about and how plants and animals were affected by the melting of this huge ice sheet.
Pielou I found to be very slightly wordy, but overall contained a wealth of useful information not only dealing with glaciers but the biosphere as a whole as well. Much of the earlier content is concentrated around how the hydrosphere (in glacier form) has shaped not only the biosphere, but the lithosphere as well. Part two deals with the struggles of living in a world covered in ice-our world 18,000 years ago. The next section of this work discusses how life adapted once the glaciers began to recede and ocean levels started to rise, as all living things had to adapt a great deal during this time in order to stay alive. In part four Pielou writes of the Holocene Transition which includes the transition of Prairie Grasslands from lakes, streams, or ice. At the time of publishing, “90% of all grasslands were submerged by an ice front lake or stagnant ice for a few decades following the disappearance of active ice” (p.232) The final part of the book compares and contrasts the differences between a glaciated world and the relatively warm climate we currently enjoy, most notably the increased amount of rain and more prairie and grasslands.
The two ideas that I thought matched most closely with our course of study are the concepts of Photoperiodism and Ecological inertia. Photoperiodism is a phenomenon describing the ability for plants to start to flower earlier once the number of hours of sunlight in a day begins to decrease. For example, if the climate shifts, one would expect bands of vegetation to form based on distance from the equator, but because of this phenomenon there are many layers of vegetation that cover our planet in a different, overlapping fashion. In simplest terms, photoperiodism is a vegetative form of evolution, as the plants do something different than their parents did in order to survive. Ecological inertia is a momentum of sorts created due to the fact that the competition for soil is a zero sum game, and in terms of plants it is generally much easier for a plant to inhabit and change in an area as opposed to finding a new spot to start. Ecological inertia remains true until a disturbance creates an open piece of land for a new species to inhabit, completing the circle of life. These two ideas (obviously used in conjunction with others) lead some experts in the field to question even broader concepts. Margret Davis “Plant and animal communities are in disequilibrium, continually adjusting to climate and continually lagging behind and failing to achieve equilibrium before the onset of a new climate trend.” Does being better adapted and holding your ground help the earth reach equilibrium? Or do new changes only compound the problem of reaching equilibrium? Read for yourself to find out!
PART TWO THE TIME OF MAXIMUM ICE
PART TIHREE THE MELTING OF THE ICE
PART FOUR THE PLEISTOCENE HOLOCENE TRANSITION
PART FIVE OUR PRESENT EPOCH THE HOLOCENE