Many years ago, wildlife biologist and ardent conservationist Aldo Leopold (1993) said, “If the biota, in the course of aeons, has built something we like but do not understand, then who but a fool would discard seemingly useless parts? To keep every cog and wheel is the first precaution of intelligent tinkering.”
Land use change is the most important factor in loss of biodiversity, and land-use changes are the greatest, by far, in the tropics. Tropical forests are less affected, probably, by changes in CO2 levels in the atmosphere, by nitrogen deposition, and by temperature change than are other ecosystems. Exotic invaders are also less detrimental in rainforests because they have so many other species with which to compete. Within forests, some habitats will be more vulnerable or endangered than others. For instance, areas along rivers (“riparian” areas) and coasts, which are often regions of high biodiversity, are also those areas which are easiest for humans to reach and the most frequently sought for development.
Until recently, conservation strategies have been devoted to saving species. This emphasis has obscured the fact that organisms and their ecosystems are completely interdependent and must be conserved together. Conservation is made difficult by the complexity of ecosystems, but is useless without considering it. We must therefore not simply attempt to conserve a random variety of species; this is like saving “living fossils.” (Erwin, 1991) We must save groups of organisms which are closely associated and which are capable of diversifying (radiating evolution), otherwise we will not have a nucleus to generate biodiversity in the future. The “endangered species” approach cannot truly help to preserve biodiversity. Therefore, documenting declines in the abundance of certain species (as has been done in the past) is less useful than identifying threats to habitats. This is difficult, as data are uneven, often unreliable, and do not comprise all possible alterations of and impacts on habitats (e.g., hunting, selective logging, water pollution, introduction of exotic species, and so forth).
Certain ecosystems are being destroyed more rapidly than others, and therefore, the organisms within them are at higher risk of extinction than others. Since, at the current rate of destruction, we cannot even list all endangered species, much less salvage all ecosystems, we must develop criteria for determining which areas must be saved, according to their conservation value, level of biodiversity, degree of endemism of their species, and the ecological value of the species within them. Methods are being developed to identify the most critically endangered regions vital to the conservation of biodiversity. Most would agree that Madagascar, China, India, and northern South America would be high on any list. (Note that all of these, other than China, are tropical countries.) In small countries, such as Madagascar and Ecuador, modest conservation efforts might generate large gains in biodiversity preservation. For instance, an improvement of the agricultural and economic sectors, along with a reduction of population growth rates, might ease the pressure for incursions into the rainforest for agricultural land. Large countries such as India and China require more radical steps to halt population growth, to mitigate the environmental impacts of industry and agriculture, and to designate and protect reserves.
The question arises whether conservation efforts should be tilted toward biodiversity conservation for its own sake or toward the conservation of ecosystem services, oriented toward what is useful for humans. As pointed out by Balvanera, et al., (2001), the latter may be used as a justification for the former goal. It has been pointed out above that high levels of biodiversity increase forest productivity, for example. Yet these goals may also be in conflict. And protecting biodiversity is usually appraised as having too high a price (too high an “opportunity cost”). Yet do we not need to conserve it? Will the costs not be too high (if not fatal) if we do not?
“Think of all those long-lived plants and animals still being harvested today at unsustainable rates…Then, there were no more moas, soon, there will be no more Chilean sea bass, Atlantic swordfish, and tuna. I wonder what the Maori who killed the last moa said. Perhaps the Polynesian equivalent of ‘Your ecological models are untested, so conservation measures would be premature’? No, he probably just said, ‘Jobs, not birds,’ as he delivered the fatal blow.” (Diamond, 2000)