How much nature is enough?
Even some enthusiastic conservationists admit that with the increase of population, the use of more resources, the warming of the climate and the migration of pests and carnivores like weeds from one place to another, the biodiversity on the earth cannot be completely maintained.
As some losses are inevitable, the debate among many experts has shifted to a disturbing topic, that is, what kind of loss level is acceptable. This discussion is going on at both local and global levels. How small can a fragment of an ecosystem be and still maintain its rich functions, so it is considered to be protected? With the decrease of global biodiversity, is it an effective backup strategy to store organisms and genes in DNA banks or similar banks in zoos, or just to justify more habitat destruction? Is nature on ice a sufficient substitute for real things? Some environmental organizations try their best to avoid or even attack such calculations and strategies. They say that as long as human beings do not have a comprehensive understanding of ecology, there will be no reduction of safe habitats. A backup strategy is unthinkable. In addition, the deep freezing of gene sequence or the bank nature in the database can't capture the context. For example, even if a disappearing bird is recombined by its genes one day, will it sing as fluently as its ancestors? On the other side of the debate, those who consider what is the smallest viable habitat or how to expand archives as an insurance policy say that recent trends have proved that the old conservation strategy is no longer enough. A few decades ago, the problem seemed quite simple: identify biological "hot spots" or species of concern, and establish as many protected areas as possible. But the situation has become blurred.
Twenty? Four years ago, Dr. Thomas E. Lovejoy and other biologists started an extraordinary fast experiment? Erosion of the edge of the rainforest near Manaus, Brazil. They established the 1 1 forest zone, with an area ranging from 2.5 acres to 250 acres, surrounded by an isolated pasture sea, similar to that around most other tropical forests. Among many findings, an analysis of birds in lower green plants published last week found that at least 2,500 acres of land were needed to prevent these bird species from decreasing by 50% in about 15 years-which was 10 times the largest piece of land in the experiment.
The new study in the Proceedings of the National Academy of Sciences concluded in a low-key scientific language: "Considering that this is unfortunate for some species? Most of the existing forests in the rich areas of the earth are less than 2,500 acres. "
Faced with this fact and other evidence, more and more conservation biologists believe that all methods should be tried at the same time. Dr. peter raven, director of Missouri Botanical Garden, said: "Obviously, the most effective way to protect biodiversity is to protect natural areas, find the most endangered creatures in nature, and try to protect their species? Cultural collections, botanical gardens, zoos, seed banks or anything else. But the most important thing, he said, is to find a way to limit the pressure of human beings on the world's last wild environment by slowing down population growth and using resources more effectively. Dr. J. Craig Venter, one of the pioneers of gene deconstruction, agrees with Dr. Raven. Dr venter has shifted from sequencing the DNA of human beings and other species to analyzing the genes of the whole ecosystem. The sargasso sea. In 50 minutes. He said that his team has found1100,000 different genes, which is a considerable gain compared with about 26,000 human genes. He added that this is the smallest scratch on the surface. His efforts are just one of many. Britain has a Millennium seed bank, which is a growing archive of all plants in the country. The San Diego Zoo has its parallel frozen zoo, an archive of thousands of DNA samples and cell lines from many species. Nevertheless, Dr. Venter added that considering the complexity of nature, "we'd better try to protect our existing diversity instead of trying to regenerate it in the future."
Even some active protectionists admit that with the expansion of population, the consumption of more natural resources, climate change and the migration of a large number of pests and predators, the biodiversity on the earth will certainly not last completely.
The focus of debate among many experts has become a disturbing topic. If some losses are inevitable, how much loss is tolerable? The debate on this issue is going on at both local and global levels: to what extent can a small part of the ecosystem still maintain its complete and rich functions, so it can be considered as protected? Is it an effective preservation strategy to keep biological organisms and genes in zoos and gene banks during the process of global biodiversity reduction? Or is it just an excuse for more habitat destruction? Can refrigerated nature completely replace real nature? Some natural resources protection organizations have been trying to avoid or even oppose such inferences and strategies. They say that as long as human beings have a little understanding of the ecosystem, there will be no safe reduction of habitats; So there is no insurance strategy. What's more, freezing the natural ecology or storing it in the gene sequence database can't preserve the relevant background. For example, even if one day an extinct bird is recombined from its genes, can its song be as melodious as its ancestors? On the other hand, those who seek the smallest feasible habitat or try to expand the existing archives as a preservation strategy say that recent trends show that the old preservation strategy is not enough. A few decades ago, this problem didn't seem so complicated: just identify those threatened ecological areas or worrying species, and then establish as many protected areas as possible. However, the current situation has become blurred.
24 years ago, Thomas? e？ Dr. Lovejoy and other biologists started a high-profile experiment near Manaus, Brazil, which is located on the edge of the rapidly eroded tropical rain forest. They have established 1 1 forest experimental areas, ranging from 2.5 acres to 250 acres, each of which is surrounded by a huge divided grassland, which is similar to the grassland that is advancing around most other tropical rainforests. Among a large number of investigation results, an analysis report on birds living in the lower green space published last week found that at least 2,500 acres of forest area-equivalent to 10 times of the largest experimental area drawn in the experiment-was needed to prevent the species of those birds from decreasing by 50% in only about 15 years.
A new special research paper published in the Proceedings of the National Academy of Sciences in the United States summed it up in scientific language without exaggeration: "When you consider that in some areas with rich species resources on earth, a large part of the remaining forests are scattered pieces of less than 2,500 acres, how unfortunate it is."
Faced with these situations and other evidence, more and more natural resources conservation biologists say that all feasible methods should be tried at the same time. ? Peter, director of Missouri Botanical Garden, USA? h？ Dr. Levin said: "Obviously, the most effective way to protect biodiversity is to protect natural habitats. At the same time, we should find out the most endangered species in nature and protect them in some way, for example, put them in species cultivation collections, botanical gardens, zoos, seed banks and so on. " He said, but the most important thing is to find a way to reduce the pressure of human beings on the last primitive ecological area in the world by slowing down population growth and using resources more effectively. One of the pioneers of gene deconstruction, J. Craig? Dr venter agrees with this view. Dr Venter has shifted from the research of DNA sequencing of human and other species to the genetic analysis of the whole ecosystem, and recently started the research of seawater in the sargasso sea. He said that his team found millions of different gene types in five 50-gallon samples collected in February, which is too many compared with about 26,000 genes owned by human individuals. He added that this only touched the surface. What he has done is only part of many efforts. There is a "Millennium Seed Bank" in Britain. It has been expanding and collecting all the plants in the country. The San Diego Zoo (USA) has a corresponding "frozen zoo", in which thousands of DNA samples and cell lines of many species are preserved. Even so, considering the complexity of nature, Dr. Venter added: "It would be wiser if we try our best to protect the diversity of existing organisms instead of trying to recreate it in the future."