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Biol 225 Topic 28 Assignment Individual Summary

Nicole Salapic
BIOL 225- Topic 28
Describe some key human activities that contribute to biological diversity decline. Why is such
biodiversity decline a threat to us?
Some human activities that contribute to biological diversity decline are land/ forest
fragmentation, the addition of pollutants, and excessive hunting, fishing and gathering (RFC, 2018). But,
the human activity I will focus on will be land fragmentation. Some reasons why fragmentation occurs are
due to urbanization, agriculture, transportation, deforestation and to extract resources (RFC, 2018).
Fragmentation eliminates habitats for those species requiring large unbroken fragments of habitats
(Rogan and Lacher, 2018). The fragments are surrounded by unstable habitats (Stein, 2001). There are
fewer places for settling and protection and there is a shortage of food (Rogan and Lacher, 2018).
Migration is also disrupted which makes it harder for animals to move from one place to another (Rogan
and Lacher, 2018). The open land makes them more susceptible to other predators (RFC, 2018). Animals
dependence is lost slowly and can eventually lead to local extinction (Rogan and Lacher, 2018). As the
larger animals disappear there is a shift in the prey population (RFC, 2018). Most prey feed on seeds and
with an increase in their population it leaves fewer seeds from being germinated (RFC, 2018).
Most of the information presented can be summed up by the “edge” effect. When an edge is created to
any natural ecosystem and the area outside the boundary is disturbed, the natural ecosystem is affected for
some distance in from the edge (Stein, 2001). There is an increase in edge habitats and a decrease in
interior habitats (Stein, 2001). The edges expose the remaining species within the forest to different
surrounding ecosystems, reshapes the interactions between species, hosts, and pathogens by affecting
both abiotic and biotic conditions (Stein, 2001). Creating an open land/ forestry boundary, sunlight and
wind penetrate much more, drying out the interior of the forest close to the edge (Stein, 2001). Tree
mortality increases near the edges and genetic diversity in the forest declines (Rogan and Lacher, 2018).
Air temperature, soil moisture, and light intensity all change at the edge (Stein, 2001).
The decline in biodiversity is a threat to us because without it there would be no human survival
(Morton, 2015). It is essential to the economic, ecological, cultural, scientific and recreational factors of
everyday human life (Morton, 2015). The most interesting point on this topic is how humans are not
aware of the things that they are doing and don’t look at the future effects. This is interesting to me
because being unaware of things now produces problems that will be hard or impossible to fix in the
Nicole Salapic
BIOL 225- Topic 28
1. 5 Causes of recent declines in biodiversity. (n.d.). Retrieved October 8, 2018, from
http://www.rainforestconservation.org/rainforest-primer/2-biodiversity/g-recent-losses-inbiodiversity/5-causes-of-recent-declines-in-biodiversity/ (RFC,2018)
2. Morton, S. (2015, February 24). Chapter 1. What is biodiversity, and why is it important?
Retrieved October 8, 2018, from
3. Rogan, J. E., & Lacher, T. E. (2018). Impacts of Habitat Loss and Fragmentation on Terrestrial
Biodiversity. Reference Module in Earth Systems and Environmental Sciences. doi:10.1016/b9780-12-409548-9.10913-3
4. Stein, R. (2001). Lyme Disease. Encyclopedia of Environmental Health, 528-534.
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