Effect of Deforestation on Global Warming / Wildlife and Nature

EXTINCTION

Historical mass extinctions
The most significant loss to the most enduring effects resulting from the continued destruction of wildlife will be the massive extinction of species that offer the Earth its biodiversity. Although many species have died out in the past , none have died out so quickly or been the result of the actions of a single other species. The current extinction rate could be 1,000 to 10,000 times the biological normal, or by experience, the extinction rate is 1 to 10 species per year.
At the moment there is no evidence for massive extinctions of species predicted by the species curve in the table below. However, it is possible that the extinction of species, such as global warming, is shifted in time, and that the loss of species due to deforestation may not be visible nowadays. Ward (1997) uses the term "extinction debt" to describe such extinction of species and populations long after habitat damage:

Decades or centuries after a habitat has been disturbed, some species could still disappear, consequences of this disturbance. This is perhaps the least understood and most insidious aspect of habitat destruction. A forest can be deforested and the number of extinct species low, but in fact much of the species will be extinguished in the future. There will be a debt of extinguishment which will have to be paid. . . We can very well limit the hunting when some species have only a small number of representatives and think that we managed to "save" the species in question, when in reality we created a debt which will have to be paid in full. . . The debts of

For example, the loss of important pollinators will not cause the immediate extinction of arbress species whose life cycles are measured in centuries. Similarly, a study of West African primates found an extinction debt of over 30% of the total primate fauna resulting from historical deforestation. This suggests that protection of the remaining forests in these areas may not be sufficient to prevent extinctions caused by previous habitat loss. While we can predict the effects of the loss of some species, we know too little about the vast majority of species to make correct predictions. The unexpected loss of unknown species will have an amplified effect in the long term.

The process of extinction is extremely complex, probably the result of hundreds or even thousands of factors, many of which scientists (not to mention normal people) do not understand. The extinction of small populations, either endangered or isolated from the main genetic pool by fragmentation or by natural barriers such as water or mountain ranges, is the most common and best understood form of extinction. Since MacArthur and Wilson set a standard in their masterpiece The Theory of Island Biogeography (1967), much work has been done to establish models of the effects of population size and territory on survival of the species.

The number of individuals in any population always fluctuates because of several factors, from extrinsic changes in the surrounding environment to intrinsic forces in the very genes of a species. The fluctuation of this population is particularly a problem for populations in isolated forest fragments and species that are globally endangered. When a population falls below a certain number, known as the minimum viable population (MPV), it is unlikely that it will recover. Thus the minimum viable population is often considered the extinction threshold for a population or species. There are three common forces that can drive a species with a population below the MPV to extinction:

Demographic stochasticity includes the birth and death rates of individuals within a species. As the size of the population decreases, random quirks in mating, breeding, and survival of young can have significant results for a species. This is especially the case for species with a low birth rate (eg some primates, birds of prey, elephants), as their populations take longer to recover. Social dysfunction also plays an important role in the survival or death of a species. Once the size of a population falls below a critical number, the social structure of a team may not work. For example, many gregarious species live in herds or packs, which allows them to defend themselves against predators, find food, or choose partners. In these species, once the population is too small for the herd or pack to be effective, the population may be extinguished. Among species that are very much like a cat, finding a partner may be impossible once the population density falls below a certain point. Many insect species use chemical odors or pheromones to communicate and attract their partners. As population density decreases, an individual's chemical message is less likely to reach a potential partner, and the reproductive rate may decrease. Similarly,

Environmental stochasticity is caused by changes occurring at random over time (weather) and food supply, and natural disasters such as fire, floods and drought. In populations confined to a small area, a simple drought, a bad winter, or a fire can eliminate all individuals.

Reduced genetic diversity is a substantial barrier preventing small populations from rebuilding. Small populations have a smaller genetic base than larger populations. Without the influx of individuals from other populations, the genome of a population stagnates and loses the genetic variability to adapt to changing conditions. Small populations are also more prone to genetic derivations where rare traits are more likely to disappear with each new generation.

The smaller the population, the more vulnerable it is to population stochasticity, environmental stochasticity, and reduced genetic diversity. These factors, often in concert, tend to decrease the size of the population even more and lead the species to extinction. This trend is known as vortex extinction. See the table on the right for an example of vortex extinction .

Some ecological calculations have suggested that population fluctuations could be governed by chaos properties that make the behavior of the system (the fluctuation of the population size of a species) almost impossible to predict because of complex dynamics within each population. ecosystem.

ESTIMATES OF CURRENT EXTINCTIONS
Estimation and Estimation Method
% Global Loss
per decade

10 million sp.
Annual loss

30 million sp.
Annual loss

Source

0.2-0.3% per annum based on a rate of deforestation of 1% per year
2-3%

20,000-30,000

60000-90000

Wilson
(1989, 1993)

2-13% loss between 1990 and 2015 using the species zone curve and increasing rates of deforestation
0.8 to 5.2%

8000-52000

24000-156000

Reid
(1992)

Loss of half the species in the area likely to be deforested by 2015
8.3%

83,000

250,000

Raven
(1988)

Adjusted exponentel extinction functions based on IUCN red books
0.6 to 5%

6000-50000

18000-150000

Mace
(1994)

Tropical species are not only directly threatened by deforestation, but also by global cliamtic change. Even if species survive in protected reserves, they risk perishing due to rising sea levels and climate change. Many tropical species are accustomed to an environment of constant temperature and humidity throughout the year. They may not adapt to climate change even though it is only 1.8F (1C). Changes in the length of seasons, rainfall, and the intensity and frequency of extreme events that could occur if global warming could impact biodiversity in seasonal tropical forests and cloud forests. Studies show that unusual weather conditions - such as those in El Niño and La Niña - can cause population fluctuations in many forest animals.If the frequency and intensity of such extreme events were to reach the level populations are unable to return to their normal level between events one could witness localized extinctions and serious changes in the ecosystem. In particular, climate change could have an impact on sensitive ecosystems such as cloud forests, which could be dramatically affected by the lowering of the cloud ceiling. One of the often overlooked consequences of rising temperatures is the spread of disease among wildlife. For example, there is a good chance that avian malaria and fowl pox could be brought into the upland Hawaiian forests by mosquitoes that currently do not rise above 4,800 feet (1,500 m) because of temperature. The spread of these diseases to upland forests would likely mean the extinction of many endangered bird species.

Many forest communities have survived global climate change in the past by "migrating" to the north or south. Today, however, because of fragmentation and human development, there are few corridors of wilderness for these migrations. Highways, car parks, plantations, housing estates, and farms hinder the slow but necessary movement for many communities to survive changing weather conditions. Unable to escape change, many species within these communities will have to struggle or risk extinction. One of the factors contributing to the global decline of amphibian populations could be the gradual climatic change over the last 100 years, which when paired with an increase in UVB rays, could have weakened their defenses against a previously innocuous fungal infection . This fungus has been detected on dead or dying frogs in several places around the world.

Global climate change may have had an impact on the extinction of the North American megafauna at the end of the Ice Age about 10,000 years ago. One of the main theories for the disappearance of these mammals-which included wild animals such as giant sloths, mammoths, saber-tooth felines, and huge horses and rhinos-is that fragmentation of habitat, caused by global climate change, separated the species into smaller populations, making them more likely to go extinct. As the last ice age ended and the huge ice covers receded, an additional factor came into play: the presence of hungry human hunters. Some models (the model Moisimann and Martin of 1975, modified by Whittington and Dyke in 1989) suggests that by killing only 2% of the mammoth population each year, year after year, the entire species would be doomed to extinction in the next 3 or 4 centuries. These natural influences (climate change) and artificial (human) working in concert have surely condemned to disappear some of the most magnificent species ever seen by man. Today is facing a similar situation, except that this time we could be responsible for both factors, global climate change and overexploitation. These natural influences (climate change) and artificial (human) working in concert have surely condemned to disappear some of the most magnificent species ever seen by man. Today is facing a similar situation, except that this time we could be responsible for both factors, global climate change and overexploitation. These natural influences (climate change) and artificial (human) working in concert have surely condemned to disappear some of the most magnificent species ever seen by man. Today is facing a similar situation, except that this time we could be responsible for both factors, global climate change and overexploitation.

The extinction of a large number of species is very likely because of the complex relationships between species. David Quammen (1981) explains:

A logical deduction is that each plant species supports 10 to 30 animal species depending on it. Eliminate only one species of insect and you may have destroyed the only specific pollinator of a flowering plant; when this plant disappears completely, 29 other species of insects that use it for food could do the same; each of these 29 other species may be an important pest for another insect species, a plague, which if left unchecked by parasitism will destroy other important tree populations, which themselves were important because ... .

The complexity of the tropical forest makes it impossible to anticipate when species will disappear.

In addition to losing unique species that have lived on the planet longer than us and have as much right to exist as we do, we are losing an incredible pool of genetic diversity that we could exploit to help our own species. Whenever a species disappears, a unique gene combination that has been produced over thousands of years is lost and will not be a substitute for our time. We are heading towards an impoverished future of these magnificent beasts that we remember to have discovered as young: ferocious tigers; battleship rhinoceros; shimmering macaws; frogs and colorful toads. As species disappear from the surface of the globe, the world is truly a poorer place. EO Wilson, one of the greatest biologists of our time, believes that one can expect a 20% extinction rate of all species by 2022 (Wilson 1992).