| Titre : |
Multiple threats to widlife : climate change, acid precipitation and habitat fragmentation |
| Type de document : |
texte imprimé |
| Auteurs : |
Richard L. Wyman, Auteur |
| Editeur : |
Chapman and Hall |
| Année de publication : |
1991 |
| Importance : |
p134-155 |
| Langues : |
Anglais (eng) |
| Catégories : |
SCIENCES DE L'ENVIRONNEMENT
|
| Mots-clés : |
MENACE DE LA FAUNE CHANGEMENT CLIMATIQUE PRECIPITATION DESTRUCTION DE L’HABITAT EFFET DE SERRE |
| Résumé : |
Amphibians alone provide many examples on how to find examples of the impacts of anthropogenic environmental changes. Amphibians are often small and inconspicuous and so escape our attention . They are very abundant and occur in most forested habitats worlwide. They are also important because they consume huge numbers of invertebrates and hence may play a role in structuring the detritus-based food web. They are sensitive to the kinds of changes that are likely to occur as the earth warms in the greenhouse world. They may be among the first groups to show large scale and rapid changes in population sizes and species numbers.
Small changes in overall precipitation or slight changes in timing of precipitation events can spell doom for species that depend on water for survival and reproduction. In one case illustrated here, the yearly chance to reproduce was lost by a species of salamander that already appears to be in peril, when the usual spring rains did not fail.
Acid precipitation and climate change may act together to eliminate amphibians from forests, regardless of logging activities, which are harmful in their own right. Long-term deposition of acid on sensitive forest soils is likely to increase acidification. When soils dry, they become increasingly acidic and acid soils appear to be affecting the distribution of 10 species of amphibians in New York already. The projected increase in severity and frequency of droughts may eliminate many amphibians because of dryness, increased soil acidity or the synergistic effects of the two factors.
Fragmentation of habitats by human activity shrinks population sizes and makes them more vulnerable to extinction. Loss of migratory corridors forecloses the opportunity for new individuals to reach empty habitats. Polluting aquatic and terrestrial habitats may make them fragmented to the plants and animals that live there. For example, acid deposition may accelerate soil acidification and fragment the habitats of sensitive amphibians. Roadways may be formidable obstacles to animals that migrate among habitat patches. Deforestation shrinks and fragments habitats and produces greenhouse and acid-forming gases, which further fragments habitats.
There are too many unknowns regarding the degree and extent of changes that will occur to allow for accurate predictions of likely effects of global climate change. But there is virtual unanimity of opinion that detrimental changes are occuring. Now we are faced with a crisis that we must address and solve. The wholesale loss of habitats, due to overt and more subtle kinds of destruction , the loss of species and local populations and the polluting of our Earth represent the symptoms of the crisis.
The roots of the crisis lie in the ever-expanding size of the human population. There are now 5.3 billion people on Earth with an annual increase of 80-90 million. Each person wants clean air, clan water, a place in which to live, food, clothing and warmth. Each dream that his/her children’s children will live in a world as good or better than the one in which he/she lives. But we have built up a human population that uses both our renewable and nonrenewable resources beyond carrying capacity. Many nonrenewable resources simply are running out and we cannot support our population with the renewable ones alone. Even our once renewable resources , like our forests, do not appear to be quite so renewable anymore. The dream appears to be moving out of our reach.
|
| Numéro du document : |
A/MAC |
| Niveau Bibliographique : |
2 |
| Bull1 (Theme principale) : |
METEOROLOGIE ,ATMOSPHERE,CLIMATOLOGIE |
| Bull2 (Theme secondaire) : |
ATMOSPHERE,CLIMATOLOGIE-CONSIDERATION GENERALE |
Multiple threats to widlife : climate change, acid precipitation and habitat fragmentation [texte imprimé] / Richard L. Wyman, Auteur . - Chapman and Hall, 1991 . - p134-155. Langues : Anglais ( eng)
| Catégories : |
SCIENCES DE L'ENVIRONNEMENT
|
| Mots-clés : |
MENACE DE LA FAUNE CHANGEMENT CLIMATIQUE PRECIPITATION DESTRUCTION DE L’HABITAT EFFET DE SERRE |
| Résumé : |
Amphibians alone provide many examples on how to find examples of the impacts of anthropogenic environmental changes. Amphibians are often small and inconspicuous and so escape our attention . They are very abundant and occur in most forested habitats worlwide. They are also important because they consume huge numbers of invertebrates and hence may play a role in structuring the detritus-based food web. They are sensitive to the kinds of changes that are likely to occur as the earth warms in the greenhouse world. They may be among the first groups to show large scale and rapid changes in population sizes and species numbers.
Small changes in overall precipitation or slight changes in timing of precipitation events can spell doom for species that depend on water for survival and reproduction. In one case illustrated here, the yearly chance to reproduce was lost by a species of salamander that already appears to be in peril, when the usual spring rains did not fail.
Acid precipitation and climate change may act together to eliminate amphibians from forests, regardless of logging activities, which are harmful in their own right. Long-term deposition of acid on sensitive forest soils is likely to increase acidification. When soils dry, they become increasingly acidic and acid soils appear to be affecting the distribution of 10 species of amphibians in New York already. The projected increase in severity and frequency of droughts may eliminate many amphibians because of dryness, increased soil acidity or the synergistic effects of the two factors.
Fragmentation of habitats by human activity shrinks population sizes and makes them more vulnerable to extinction. Loss of migratory corridors forecloses the opportunity for new individuals to reach empty habitats. Polluting aquatic and terrestrial habitats may make them fragmented to the plants and animals that live there. For example, acid deposition may accelerate soil acidification and fragment the habitats of sensitive amphibians. Roadways may be formidable obstacles to animals that migrate among habitat patches. Deforestation shrinks and fragments habitats and produces greenhouse and acid-forming gases, which further fragments habitats.
There are too many unknowns regarding the degree and extent of changes that will occur to allow for accurate predictions of likely effects of global climate change. But there is virtual unanimity of opinion that detrimental changes are occuring. Now we are faced with a crisis that we must address and solve. The wholesale loss of habitats, due to overt and more subtle kinds of destruction , the loss of species and local populations and the polluting of our Earth represent the symptoms of the crisis.
The roots of the crisis lie in the ever-expanding size of the human population. There are now 5.3 billion people on Earth with an annual increase of 80-90 million. Each person wants clean air, clan water, a place in which to live, food, clothing and warmth. Each dream that his/her children’s children will live in a world as good or better than the one in which he/she lives. But we have built up a human population that uses both our renewable and nonrenewable resources beyond carrying capacity. Many nonrenewable resources simply are running out and we cannot support our population with the renewable ones alone. Even our once renewable resources , like our forests, do not appear to be quite so renewable anymore. The dream appears to be moving out of our reach.
|
| Numéro du document : |
A/MAC |
| Niveau Bibliographique : |
2 |
| Bull1 (Theme principale) : |
METEOROLOGIE ,ATMOSPHERE,CLIMATOLOGIE |
| Bull2 (Theme secondaire) : |
ATMOSPHERE,CLIMATOLOGIE-CONSIDERATION GENERALE |
|  |
Affiner la recherche Interroger des sources externesMultiple threats to widlife : climate change, acid precipitation and habitat fragmentation / Richard L. Wyman
