The first effect on the environment is the over harvesting of species. This is mainly caused due to hunting, fishing and forestry. Hunting occurs in many parts of the world to provide food and animal products. Among the many uses of animal products are skin and feathers fro clothing, ornaments and souvenirs. Sometimes animal body parts are used for making medicines. For many people, hunting is a sport, while others kill wild animals that are a threat to people or their crops and livestock. Some people who live a partly traditional lifestyle consider hunting an essential part of keeping their culture alive. Not all hunters kill the animals but some capture them for live sale which has the same effect of reducing the wild population.
Fishing provides an important food supply for many people, and is a popular sport and recreational pastime. The problem is that modern fishing involves technology that harvests the oceans so effectively that the number of species can reduce massively. Seventy percent of fish being harvested are being removed at a higher rate than at which they can reproduce. Fishing in this way is unsustainable, and other parts of the marine ecosystems are damaged as the food supply for some species is reduced.
If foresters are not careful, the harvesting of valued tree species will also become unsustainable. Forest trees take hundreds of years to mature, and with modern machinery, trees can be chopped down at a much faster rate than they can grow back. Timber is used in building and construction, and