Species which is a subcategory of habitat destruction/fragmentation will

Species do not become extinct as a sudden.
There are classified as vulnerable, endangered and critically endangered
depending on their rate of decline, habitat size and population size. Once
population gets small, it becomes easier for it to be affected by changes. In
small populations, inbreeding occurs and random genetic drift has more effect
than large populations. As a result of these, genetic diversity is lost and the
population becomes vulnerable to environmental effects. In harsh conditions,
population become even smaller and may go extinction. This phenomenon is called
an extinction vortex 1.

Up to date, lots of species have gone
extinct and lots of are on the red list of International Union for the
Conversion of Nature 2. Heath hens vanished from East Coast during the mid
1800s, the Tasmanian tiger which declared as extinct in 1986, Baji dolphin
which is native to China and cheetah which occupy 9% of their previous
territory now are some of the examples. Some of these losses have resulted from
natural selection; however, the much higher percentage has resulted from
anthropogenic effects.

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Declining population paradigm which
examines what drives a population to smallness points four main reasons to loss
of species diversity: habitat destruction/fragmentation, overkill, chains of
extinction and introduced species 3. In this paper, species loss resulted
from deforestation which is a subcategory of habitat destruction/fragmentation
will be investigated.

Island can be considered is the area which
is isolated from its surroundings. Species diversity on an island is directly
correlated with the size of the island. This theory is called as biogeographic
island theory. It makes a correlation between area-species diversity and it
assumes that the number of species becoming extinct can be predicted from the
shrinking habitat 4. Besides habitat size, the formula-driven also considers
species-specific index and growth rate of the population. Therefore, it can be
said that consequences of habitat loss or fragmentation can be different for
different species. More adapted ones which have a broadened niche may tolerate
whereas the ones with narrower niche may become extinct 5. In addition, there
are well-established relationships among species; therefore, effects of
deforestation on species loss may not be restricted to only species losing
their habitats but also species feeding on the ones becoming extinct or species
require symbiosis relationship with the ones becoming extinct are also
affected. For example, plants require pollinators to reproduce; therefore when
their pollinators are affected by deforestation their survival will most
probably decrease.. Therefore it can be said that deforestation results in
chain effects on survival of species.

Drivers of species loss caused by deforestation:

According to Food and Agriculture
Organization, approximately 7.3 million hectares are cleared from forests
yearly. World’s forests are being cleared mainly because of antrophogenic
activities. For instance, increased temperature due to increased emission of
greenhouse gases such as CO2 and N2O leads to wildfires.

Deforestation leads to loss of ecological
niche which is defined as conditions required for a particular species to grow,
reproduce and survive. Because there are many different species living in
forests, their survivorship declines due to deforestation. In a study, the effects
of different sources on species extinction weremcompared and it was found out
that habitat loss is far ahead for both global and Canadian species and most
affected ones from habitat loss are terrestrial organisms 11.

Even though terrestrial ones are the most
affected part, it can be seen from Figure 1 that marine species also get
affected by deforestation. In another study, responses of fish species reside
in the western Brazilian Amazon to deforestation was tested 12. This region
is suitable for research of species lost because it has gone through two
deforestation: one was in 1991 to 1995 and 19 % of it was cleared and the other
one was from 2001 to 2004 and 23% of it was cleared. They examined one stream
from a highly deforested region and one stream from a less deforested region,
and they found that species diversity was higher in less deforested stream
whereas stream taken from the highly deforested region was homogeneous which
consisted only adaptable ones 12. Regarding of this study, it can be said
that deforestation impacts species in different amounts but it results in species
diversity loss definitely.