This essay looks at the recent decline in biodiversity across the globe in the late Quaternary and early Anthropocene periods. It will focus on the factors causing such a phenomenon, highlighting the impact of human activities on wildlife and its relationship with the extinction of species and, reflecting on how natural forces may not be the main causes anymore. To achieve this, the effects on animal and plant populations on land, ocean and freshwater ecosystems will be discussed.
Biodiversity, in other words, refers to “the variety of life in all its manifestations and at all spatial times” (Thomas,2016,56). Thus it involves all species alive and extinct across all ecosystems. The evolution of these organisms depends on the interaction between their communities and the physical and chemical environment in which they thrive (Rajagopalan,2016). EVIDENCE: At the moment, there are CERTAIN number of species on Earth, CERTAIN number of plants, CERTAIN number of animals, CERTAIN number of bacteria, etc. AND we can find them in all these environments: polar, desserts, oceans, etc.
Furthermore, communities of organisms and the environment create an ecosystem. This exposes a complex network of interactions related to competition for resources between organisms themselves and the whole population (Morris et al,2003). Nevertheless, such evidence demonstrates how those interrelationships can change if one of the parts fails. Therefore, if the conditions are not stable, the whole ecosystem could not manage to perpetuate itself.
As a matter of fact, such conditions are changing continuously making species go extinct. Some examples are: this and this and that and that but also this and that. EVIDENCE: a species that went extinct normally or that has disappeared in the past? This demonstrates the wide array of slow changes that could impact the survival of a species. In addition to that, there have also been cases of faster extinctions.
There have been several mass-extinctions in the past. These have occurred in a relatively small period of time due to sudden events. EVIDENCE: show a mass-extinction. Therefore, changes in an ecosystem can be both slow and sudden if an external force acts upon. However, these events are very infrequent.
Besides natural factors, a new one has appeared: human driven ones. As the human species has evolved, so has its impact within ecosystems. EVIDENCE: such a number of species have gone extinct in these years compared to such number millions of years ago. This could be explained by how human activities affect relationships between organisms and modify their environments. Nonetheless, the influence human lifestyles can have on biodiversity might be different through space and time.
Human societies have gone through several stages, from hunters and agriculturalists to industrial and technological. The change from one stage to another implies using more extra-somatic energy, which is energy available outside our bodies (Morris et al,2003). Examples are windmills, oil and electricity. EVIDENCE: hunter-gatherers did this, agriculture did that, industrial revolution did that and technological did this. The constant search for extra energy and commodities drives humans to overexploit resources, changing the landscape and interactions within ecosystems and beyond them. Some of the results are the degradation of natural habitats, the overexploitation of natural resources, pollution, the introduction of alien invasive species and climate change (Rajagopalan,2016).
The first of the main factors of loss of biodiversity caused by humans is degradation of natural habitats. Phenomena such as land conversion, deforestation, fires, agricultural intensification and road construction can trigger degradation. EVIDENCE: land conv to agriculture or animals decrease in wetlands also species loose historic habitat ALSO BOOK CHANGING ENV with table global percentages of land p.143ALSO lawns ENV AND SOCIETy, , deforestation during decade 2000-2010 world lost 13million ha of forest, news of fires and also Natural FIRES can favour biod, as stimulates vegetative reproduction of woody and herbaceous species “In many environments fire is the most effective form of decomposition, the dominant selective force for determining the relative distribution of certain species, and the means for effective nutrient recycling of whole communities” Pyne(1982:3), agr intens makes species that existed in previous agricultural landscapes disappear, road constr news os noise and mobility upset. As a result, it is understandable how the different uses and treatment humans give the land can upset relationships and favour extinctions. In addition, habitats can be highly altered if resources are exploited in their surroundings.
Another factor is the overexploitation of natural resources. This can happen via agriculture or by decimating populations through overfishing, hunting and poaching. The Green Revolution has brought genetic engineering and monocultures to agriculture. Example overfishing in CHANGING ENV and TUNA in Env and Society. Thus, inadequate management of resources and result in reducing populations and their likelihood of survival. If pollution is then added to communities that are already fragile the result can be catastrophic.
Furthermore, pollution is responsible for a large drop in populations. As it is higher than the environment can absorb. Air pollution, fertilizers, nitrogen (algae) oil spills, shit and stuff, ocean acidification. EVIDENCE: coral reef news, example frogs. If the chemical waste produced by humans was tackled species would not be as threatened. Nonetheless, some species can be more vulnerable than others, which means some can take over a whole ecosystem and upset the balance.
In addition, since the early domestication of species, the introduction of alien invasive species has played a huge role in reducing biodiversity. It can happen intentionally or non-intentionally when a certain species is introduced in an environment without any natural predators, enabling the population to establish and explode. Example, sheep in New Zealand, frogs Australia,etc, all species that have been domesticated and are used as cattle, etc. The result of the instruction of invasive species is therefore the settlement of the alien at the expense of the native species. Moreover, this might be more encouraged in the future if the climate changes and habitats become habitable for invasive species which would establish themselves.
Finally, climate change has proven itself to be a major threat to biodiversity in the near future. “Anthropogenic climate change is predicted to be a major cause of species extinctions in the next 100 years” (Cahill et al,2013,1). Sea level-rise is a threat to island and coastal ecosystems as it “destroys habitats such as that of the Bramble Cay melomys. Sea level has risen approximately 20 cm in the last century” (Beckrich,2016,1). That itself is caused by temperature rise, which also “in aquatic organisms, increased water temperatures may lead to increased metabolic demand for oxygen while reducing the oxygen content of the water” (Cahill et al,2013,1) making it harder for organisms to survive. In other words, climate change implies a modification of the physical environment within the ecosystem, which then would drive the communities within to adapt or perish. Therefore, adding climate change to the large amount of human impacts on the environment could prove to be dangerous.
Loss of biodiversity during the late Quaternary and early Anthropocene periods have been
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