key points:Conservation efforts can be more effective if we are smart: which means applying facts and principles learned in Biology. #1) In history, some societies have damaged their ecology enough that ecosystems were ruined, destroying society. Easter Island had been like the Garden of Eden, until humans reached it, and human populations rose exponentially to 7000, and then crashed permanently to 1000, with no more trees, and most species extinct, and everyone permanently poor. Iraq and Iran never recovered from Mongol invasions ~1200 Destruction of irrigation, expansion of deserts, etc. (And then it was too early to blame Israel or the US) Areas of South America are now being changed into deserts. Deserts are easier to create than gardens, and more permanent. If the ice-caps melt, the N.C. coast will be about at I-95. (So it will be a lot shorter drive from here!) #2) Biological phenomena that seem strong and stable, really are equilibria, in which opposite forces are exactly balanced.
It is the way of such equilibria to resist disturbance very effectively, UNTIL the disturbance gets a tiny bit too strong. Most people base their intuition on other kinds of strength; which often makes their expectations about equilibria very wrong. Codfish and many other ocean fish have become quite scarce. If people had been just a little easier on that ecosystem, they could have continued forever catching many more than now; and the changes may be permanent. People wouldn't believe the warnings, until it was too late. #3) Extinction of species is (only) the most obviously irreversible change. Our generations may go down in history as the ones who killed off the last elephants, the last gorillas, the last chimpanzees, and rhinos, & many others. Will we have so little self-respect as to let that happen?
#4) Small populations become genetically inbred, which makes them more vulnerable to diseases. Deliberate cross-breeding between populations can be a big help.
#5) Wildlife refuges can be very much more effective if big enough, because of "edge effects". #6) Various strategies are used to try to optimize the effectiveness of land preservation. "Wildlife Management" is one of the career paths for students interested in nature and wild animals and plants. Careful studies are needed of where different species live, how much they need to move around, what they eat & what eats them. One favorite strategy is to choose "umbrella species", like Red Cockaded Woodpeckers in eastern N.C. But this can sometimes be a bad idea, if wrong species are chosen. You need to save the whole food chain, not just certain parts. If the insects that pollinate a certain kind of plant are all killed then that will kill every other species that depends on that plant. Quite often, when some dam project is going to cause extinction of a certain kind of fish (the "Snail Darter") etc., that's because it is also going to kill off the last of some ecosystem. Politicians can make it seem crazy to save that one little species, but doing so may also save a whole ecosystem, and anyway "Whatsoever ye do unto the least of these, My brethren..." #7) Each species of wild animal and plant (normally) has its own certain geographical range; shown in maps in field guides. Boundaries of these ranges tend to be approximately the same, for many hundreds or even thousands of species. (that is an exaggeration; but there are definite patterns) For us extreme nature lovers, it can be exciting to drive cross-country because "Now we are in the range of alligators!", or of a certain kind of oak tree, or a species of butterfly. (It can also be relief to get OUT of the range of rattlesnakes) Each such region used to be called a biome. For example, southeastern pine forest area might be the name of the biome that we are just west and north of. Or the Sonoran Desert, in contrast to the Chihuahuan Desert. The word biome seems to be a little out of style. According to one definition, biomes are "the largest useful subdivision" of the natural environment. When you are driving cross-country, and you notice a fairly quick change in the kinds of trees and other plants, this is probably because you have crossed the boundary from one biome to another. And if you get out and walk around, you may notice there are also new kinds of birds, new kinds of snakes, maybe new kinds of ants, etc. etc. #8) In addition, there are usually several alternative "communities" within a given biome: such as swamps, meadows, forests (or coral reefs, sand bottoms, sea-grass areas, etc.). Each community is inhabited by a particular sub-set of the various animals and plants that live in that biome. Stages of succession (for example, after fires, or when fields are left to become forests again, are also counted as different communities. In order to save the maximum number of species from extinction, there should be parks and game refuges in each different biome; and these should include areas containing all the different communities characteristic of that biome #9) The term "ecological niche" difficult to define exactly, but means the combination of methods of life, including food and habitats, on which the life of a given species depends. By some people's definitions, two species cannot stably occupy the same niche (or if they did, they would claim that's because it was really two niches), otherwise one species would have driven the other species to extinction. "Competitive exclusion" refers to this tendency, of the most directly competing species to drive the other to extinction. Sometimes, it has been discovered that 2 or more species were not really so much directly competitive with each other as they seemed to be: One kind of bird may specialize in feeding in the tops of trees, etc. etc. with all kinds of subtle differences. Introduced alien species sometimes can cause extinction of a native species, to the extent they occupied the same niche. So it is an important form of conservation NOT to introduce outside species, like Starlings, Gypsy Moths and African Honey Bees (killer bees; which really have killed many people) (On the other hand, Honey Bees were not native to North America, and were introduced by the colonists!) #10) On a more positive note, species on different continents often occupy almost the same niche as each other, even though they evolved from rather different groups. Natural selection tends to make them look very similar. This is called "convergent evolution". In Australia, there are marsupial moles, marsupial rats, etc. But whose niche do kangaroos occupy? Perhaps that of hoofed mammals? #11) Ordinary grass lawns are ecologically somewhat sinful, in my opinion: They imitate the ecology of rich old English estates. Native wild plants are much more interesting.
#12) Always rescue turtles off the highway: (even if already hurt) -----
Questions that you should be able to answer about this material:a) What are some specific ecological concepts that one needs for effective conservation of species?b) Why does Easter Island have no native trees? Was it necessary to remove them in order to support the current population size? c) If a given population or other natural variable is maintained by an equilibrium between opposed forces, how will it respond to human disturbance? [Hint: Small disturbance? Larger disturbance? Disturbances that are a little bit too large]. d) What are some kinds of large mammals that are about to become permanently extinct? e) What is the genetic problem with very small populations, that may result in extinction? *f) If you had the responsibility of choosing which areas of land to set aside as nature preserves, what are some of the ecological principles that you could apply? g) What is meant by "umbrella species"? How can they be useful in conservation? h) Do different kinds of animals and plants each live just in certain parts of the country, or what? Do scientists keep track of which areas each species does and does not live? i) Are there natural correlations between the distributions of different species of animals and plants? j) What are biomes, and how are they related to the answer to the previous question? k) What do ecologists mean by "communities"? Is it the same as a biome, or what? [hint" no] Why are there more communities than biomes? l) What do ecologists mean by "succession"? *m) If you were choosing land for nature preserves, would you need to save part of each biome, or part of each community, or what? *n) Might you also need to keep causing succession to occur? o) What word is used to refer to the collection of food, habitats etc. used by a given species? *p) Does the niche concept apply only to animals, or only to plants, or to both? q) What is the relation of competitive exclusion to ecological niches? r) What is the relation of convergent evolution to ecological niches? s) How can introduction of foreign species result in extinction of native species? How is that related to competitive exclusion? t) What should you do when you see a turtle crossing the highway? **u) Why do foreign species usually die off when released, but sometimes take over from the equivalent wild species comparable to them?
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