2. Major factors of biodiversity loss risk

Biological extinction – the disappearance of a species from part or all of its range.

Extinct species – species which do not longer exist.

Endangered species – those plants and animals that are currently in imminent danger, at risk of extinction

Threatened species – those plants and animals that are still abundant in its natural range but, its numbers are declining, are likely to become endangered in the near future and extinct in time.

Endemics – species that are localized and may have just one population that inhabits a small area.

The number of the world endangered species:

• 25. 000 species of plants (flowering)

• 6. 000 species of animals (vertebrates)

Two most important factors of biodiversity loss (extinction):

• Habitat alternation and destruction

• Commercial harvesting/ hunting

The most important cause of current extinction is the alternation and destruction of habitats caused by human activities. When a habitat id destroyed or fragmented, it means fewer places for individuals to live. Consequently, populations became smaller and more vulnerable to being wiped our by harsh weather or food shortages.

Table “The range of extinction causes”

N	Extinction causes	Impact to extinction, %
1	Habitat alteration	40
2	Commercial hunting	23
3	Competition with introduced species	16
4	Pest control	7
5	Hunting for food	6
6	Captured to serve as pets	5
7	Killed because of superstition	2
8	Pollution	1

Some estimates put the current extinction rate, due to human activity, at 20.000 species/per year, which will result in a loss of 10% of all world’s species by 2025. Because of interconnections of species the loss of one species can lead to the disappearance of many others which cannot survive without it. Although life bounced back from extinction in the past, the recovery often takes millions of years.

In addition to hunting animals for food, many species ate hunted for body parts, such as the ivory tusks of elephants. There is also an enormous market in live exotic animals.

Table “Yearly trade in wildlife products”

Animals/plants or their body parts	Number /year
Live primates	26 600
Cat skins	44 800
Live birds	933 700
Reptiles skins	9 132 600
Live cacti	919 500
Live orchids	1 293 700