New York, Touchstone Books, 1984
Nineteen degrees latitude places Cayman Brac in the sub-tropics, not the tropics, but this book has been very helpful in understanding the sub-tropical forest here on Cayman Brac. It is particularly useful for a person coming here from the temperate zone. It explains concepts foreign to one’s temperate zone experience, especially the concept of very high local diversity. There are no natural monocultures here! Instead of being in a grove of hemlock, you’re in a forest of trees of many different species. Most often the tree next to the one you’re studying will be a different species. Turning your body through a slow 360 degrees, you may count up to twenty species of trees, not to mention shrubs and other plants.
Rather than a rain forest, Cayman Brac has a DRY sub-tropical forest built on limestone. We have little rain (being in the rain shadow of the Sierra Maestra), few snakes, and the forest bottom is not totally dark. Aside from that, this book about the wet tropics applies quite well. Here are a few things you will discover if you read though each well-planned chapter.
“… the tangle of diversity that characterizes life in the humid tropics can perplex and confuse on first exposure. It can be extremely difficult to identify some of the most conspicuous organisms in a tropical rain forest. Ecuador, a county no larger than the state of Colorado, has over 1300 species of birds, almost twice as many as in all of Canada and the United States. … A naturalist in New England can easily learn all the species of native trees in the region in a single summer, but there are few people who, even after a lifetime of study can confidently identify most of the trees in a patch of tropical American rain forest. p. 2
“… there is no terrestrial habitat on earth that compares with lowland tropical rain forest in its richness of life. Most temperate zone habitats have certain species of plants and animals that are common and distinctive and that give each habitat a recognizable integrity. Such is not the case in the lowland tropical rain forest. Virtually every tree you walk by will be different — they may look alike near the ground, but they are distinct species… you will soon realize that almost everything you see is different. This, more than any iconic indicator species, characterizes the tropical train forest environment.” p. 197
THE PARADOXICAL WEAKNESS OF THE SOIL
“But when these forests were cut and the slash burned off, a few crop plantings showed the soil weak and easily exhausted. Where there once flourished massive trees and a wonderland of lianas and vines, fields of manioc and maize gave only mediocre and ever-decreasing yields. Viewed against the lush backdrop of primeval forest, the crops were thin and pitiful.” p. 18
“When divergent populations reach the point where they can no longer interbreed, they are considered to be distinct species… There is no single moment when you can say isolated populations have become new species. Speciation is a process that can be studied at any point, and often it will not be possible to determine which populations are distinct species and which are not, particularly if they remain isolated from one another. There is no way you can make rigid definitions along a continuum… With exceedingly rare exceptions, they breed only among themselves, and they are discrete natural units in any sense you care to examine them.” p. 200
ORIGIN OF SPECIES
“The contradiction between the idea of ancient, unchanging tropical rain forests and the basic tenet of geographical speciation, isolation, should be apparent. If the tropical rain forest is so stable, how did all of its species originate?………The hard evidence for climatic shifts in the tropics has come from pollen samples.
………Core samples taken from lakes in different regions of tropical America have demonstrated regular cycles of climatic change even deep within the tropics, cycles that seem to correlate with Pleistocene glacial cycles in the temperate zones. During the periods when the glaciers advanced across North America, the tropics became cooler and drier … When the northern glaciers retreated, it was warmer and wetter in the tropics. …These alternating cycles of cool, dry climates and warm, wet climates occurred several times during the
Pleistocene….” pp 200 – 202
LOSS OF THE WILD
It’s sad that conservationists have made so little headway. The authors quote Alfred Russel Wallace from 1911, “It is really deplorable that in so many of our tropical dependencies no attempt has been made to preserve for posterity any adequate portions of the native vegetation, especially of the virgin forests”. P. 207. Here we are in 2011, in the Cayman Islands which is an overseas dependency of the United Kingdom (one of “our tropical dependencies”) and my island of Cayman Brac is being burned steadily and remorselessly, acre by acre. In some countries the trade-off is oil and gas versus forest preservation — people may choose oil and gas. But more sadly, people also choose a seeded grass lawn versus native vegetation! But then, they also choose their cat, when it’s tabby cat versus wild iguana. They choose to import sunflower seeds for unnecessary bird feeders, versus leaving somebody’s forest untouched for birds!
“The symbol of modern deforestation is the road.” p. 209. This is as true here on Cayman Brac as it is in the Amazon. “The rate at which tropical rain forest is disappearing is hard to comprehend …” p. 210 (The same is true of our sub-tropical dry, limestone deciduous forest.) “Economic growth and exploitation still take precedence over environmental concerns.” p. 211. Locally, our government is still stalling on the environmental law we’ve never had, as of this writing (May 2011).
“There is still time to slow down, perhaps even to stop the present trend of tropical deforestation.” p. 216. (I wish I could share this optimism.) “The land set aside for parks in Costa Rica was chosen to be representative of the diverse habitats in this tropical country.” p. 217. And finally:
“We must resist the coming of the dark age of biological simplicity that rain forest destruction will bring.”
This reviewer adds: This applies to Sub-tropical dry forest destruction too! We are denuding our land. We are depriving ourselves and our children of the peace and wonder of the woods. We are wrecking the aboriginal order.
Some believe in Mother Nature, that she will correct everything. It’s true that NATURE WILL CONTINUE. There will be birds – but which birds? Chickens? Unless we are careful we won’t have Vitelline Warblers and our beautiful parrots. Instead, the birds will be European pigeons in the park, eating popcorn and despoiling statues; European starlings flocking and discoloring populated areas; chickens and roosters grubbing on the ground, getting killed on the roads, and pecking at your feet in open-air restaurants. The latter is the case already, here in these Cayman Islands, as in many warm countries where domestic fowl being mashed on roads is not considered a problem requiring a solution.
We could have done better. Perhaps we could still do better. But the changes required, mostly cultural, are immense. And the process has yet to begin.
PS A note about the photos. NOT Cayman Brac! These are the real tropics, taken by the author during a two-year work assignment in Papua New Guinea.