There is currently a greater variety of life on our planet than ever before but the damage being caused by humanity is having a global effect on this life. The destruction of other species can be seen since the human life first started, in Africa. By the time humans were able to travel out of Africa, to other continents they were already experienced hunters. However, unlike African mega-fauna the animals in other continents were not used to humans and did not view them as a threat. Therefore, large herds of animals were wiped out, for example camel and lion in North America. That is why Africa is the only continent we can see these herds of mega-fauna today.
Most of today’s problems can be attributed to five human activities:
1. Over Harvesting
With the advances in our technology over harvesting becomes easier. Rainforests can be felled quicker and the fish can be caught on a greater scale. Currently 70% of fish are overfished or exploited.
2. Introduction of Alien Species
The introduction of alien species can have huge consequences of the native biodiversity. For example the native Hawaiian snail is facing extinction. This began at the introduction of rats to Hawaii, which ate the snails. As the rats had no natural predators on the islands their population grew, at great detriment to the Hawaiian snail. The introduction of pigs and goats also added to the snails decline as they ate the same plants that the snails fed on. Later the Giant African Snail was introduced to Hawaii, as it was considered a delicacy to humans. However, this snail also fed off the same food as the Hawaiian snail. By this point the decline in Hawaiian snails was finally noticed.
It was decided that a breed of killer snail would be introduced, to eat the African snails. However, the killer snails chose to eat the Hawaiian snails instead and are currently moving across Hawaii at a rate of 1km per year, devastating the native snail population.
3. Destruction of Habitats
Destruction of other species habitats for human agriculture and living is the human activity that is affecting species numbers the most.
An example of this destruction can be seen in Cape Town. Locally known as ‘Fynbos’ the Cape Floral Kingdom has the highest concentration of plants than anywhere else in the world, at 1,300 per 10,000 sq.km. There are 5,500 plants that grow nowhere else but 40% of this area has already been destroyed by agriculture.
4. Islandisation
Islandisation is where natural areas have been cut off or surrounded by areas that have been modified by humans. This leads to member of the same species becoming isolated from each other, making them more at risk to extinction. The smaller the ‘island’ the greater the risk is towards the species living there. It has also been discovered that the closer to the margins of the islands the lower the species diversity.
An example of islandisation can be seen in the chalk downlands of Surrey. Here, the Silver Spotted Skipper Butterfly lives in areas of grazed grass where wild flowers are able to grow. The grazing also causes patches of bare earth which the butterfly uses to bathe in and keep warm. Due to agriculture, these habitats have been Islandised. As the butterfly does not travel long distances over unsuitable habitat, members of the species have been alienated, making them more at risk of extinction.
5. Pollution
Carbon Dioxide pollution is the worst, as it is a greenhouse gas helping to cause global warming. Global warming has occurred naturally on the earth before. This can be seen due to examples such as the discovery of mammoth bones in the English Channel meaning that it was once dry land.
The earth has recovered from dramatic changes before, for example the extinction of dinosaurs. However, these five factors, causes by humans are occurring at unprecedented speeds. The situation is also unique as it is the first time that one single species, humans, are sequestering for their own use a quarter to half all the plant material that grows on the earth in any one year. If the conservation is not implemented now the earth could be facing biotic impoverishment, effects of which are yet to be seen.
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