Tuesday, June 11, 2013

One Chance to Get It Right: Human Impacts on Biodiversity

By: Patrick Heher

This is the only chance we have. Our only shot. If we mess this up, we won’t get to start again. We only have one Earth and it’s home to more than just us humans. Each species that goes extinct isn’t going to come back*. In 1985, biologist and author E. O. Wilson said, “The one process ongoing in the 1980s that will take millions of years to correct is the loss of genetic and species diversity by the destruction of natural habitats. This is the folly that our descendents are least likely to forgive us.” Why is this? Why is species diversity important to us or our descendents? How are humans even contributing to this loss, and can the contributions be reduced? And what is biological diversity, anyways?
Biological diversity is a broad term that can mean several things. It can mean the relative abundance of ecosystems, or populations, or species, or even genes. It can be divided into taxonomic, phylogenetic, or functional diversity. It encompasses everything, from the total sum of life on Earth to a single gene in a microscopic bacterial cell. Essentially, it refers to the variability and variety of living organisms and how they relate to the environments in which they are found (University of Michigan, 2006). 
There are many reasons why maintaining a high level of biological diversity across all organizational scales is important. Low genetic diversity in a population can lead to inbreeding depression, or reduced fitness against environmental stresses. If species diversity decreases, meaning some species go extinct, the functions that those species once fulfilled are now vacant, which could impact other species including humans. As ecosystem diversity decreases, important ecosystem services may be lost which would affect different organisms in different ways. If provisioning services are lost, humans are affected because they include food, fuel, drinking water, and building materials. Humans are also affected if cultural services are lost because they provide humans with aesthetic, educational, or recreational value. A loss of regulating services affects not only humans, but also other organisms by way of disease or pest regulation, for example. Losing supporting services such as nutrient cycling, primary production, or oxygen production impacts all organisms in that area (Green, 2013).
Source: World Conservation Monitoring Centre, "Global
Biodiversity" Chapman & Hall, London, 1992.

The main human-caused threats to biodiversity include habitat loss and fragmentation, pollution and climate change, over-exploitation, and human population growth (hdekoeijer, 2007). According to the Natural History Museum, habitat loss and fragmentation is considered by conservation biologists to be the largest cause of biodiversity loss (2013). With the near constant expansion of agriculture, logging, cities, and roads, more natural habitats are lost.  Splitting up habitats into separate, smaller ones has a large negative impact on biological diversity as well, restricting the movements of organisms, isolating them from other members of their species which can lead to a loss in genetic diversity, and increasing competition for limited resources. 
Source: Sarah. "Habitat Fragmentation." Wildflower Turf. 16 Feb. 2012
Pollution is another major contributor to biodiversity loss. Pollution can be many different things and have a wide range of effects. Some forms of pollution that reduce biodiversity include acid rain, overuse of pesticides, oil spills, waste products, and carbon dioxide. Global climate change is a product of increased greenhouse gas emissions from human activities and it has caused and will continue to cause significant changes in biodiversity and species distribution. Some areas will become too hot for some species, while other areas will become too cold. The sea levels will rise, affecting coastal habitats, and extreme climate events are becoming more frequent. Over-exploitation occurs when humans take too much from nature. This can be in the context of food (hunting, fishing, collecting), construction (timber), pets (iguanas, birds), or industrial products. Generally, there are one or two preferred species that are collected from nature, and if unchecked, can lead to the extinction of species and a reduced biodiversity. Human population growth is another factor that can lead to reduced biodiversity. As more humans inhabit the planet, we require more resources from nature to sustain us. More humans essentially exacerbate each of the problems previously mentioned. There are other factors, such as invasive species, that reduce biodiversity but are not directly related to humans, though humans may have played a part in them (hdekoeijer, 2007; Natural History Museum, 2013).
So biological diversity is important, but humans are doing a poor job of helping it. Much of the focus on protecting biodiversity is centered on “hotspots.” Hotspots are areas with a high number of endemic species (species found only in that one area), and a high level of habitat loss or other degree of threat. By protecting these hotspots, these unique species can be preserved and help maintain biological diversity.
But is there anything else that can be done? Climate change biologist Lee Hannah has a few ideas. He believes that in the face of global climate change, the animals that are finding themselves in locations that are too hot will move to cooler locales if they can, and those that are too cold will move to where it’s warmer… as long as they are able to do so. As stated earlier, fragmentation and human encroachment hinder organism movement. Hannah suggests that conservation efforts focused not only on protecting animals where they currently are, but also where they will want to move to and better survive be implemented. This includes securing pathways for these organisms to travel.
The paper Latent Extinction Risk and the Future Battleground of Mammal Conservation by Marcell Cardillo et al. arrived at a similar conclusion to Hannah. In the article, the authors explain that protecting current hotspots is a good plan, but not the only thing that we should be focusing on. There are areas that currently aren’t thought to be hotspots, but are situated in such a way that they very likely could become hotspots, and these areas need to be protected as well.
These are only a couple of ways that the threats to biological diversity might be mitigated, and there are many more out there. An easy way to start helping is to live a more sustainable lifestyle. It’s true, some species will go extinct in our lifetimes, but hopefully if we can act early enough, out descendents will perhaps find it easier to forgive us. This is, after all, our only chance, not only for us, but also for our children, and their children. We can’t afford to leave them in a world crippled by a lack of biodiversity. So let’s not mess this up.

*Some extinct species have been “brought back to life” but the process to do so is unreliable, very costly, and should not be thought of as a viable way to preserve biodiversity. Focus instead should be on maintaining current biodiversity.

Works Cited
Cardillo, Marcel, Georgina M. Mace, John L. Gittleman, and Andy Purvis. "Latent Extinction Risk and the Future Battlegrounds of Mammal Conservation." PNAS 103.11 (2006): 4157-161.
Green, Jessica. "Threats to Biological Diversity." BI 375 Biological Diversity. University of Oregon, Eugene, OR. 15 Apr. 2013. Lecture.
Hannah, Lee. "As Threats to Biodiversity Grow, Can We Save World's Species?" Web log post. Environment360. Yale, 19 Apr. 2012. Web. 29 May 2013.
Hdekoeijer. "Why Is Biodiversity Threatened?" Convention on Biological Diversity, 6 May 2007. Web. 29 May 2013. <http://www.biodiv.be/biodiversity/about_biodiv/biodiv-threat/>.
Sarah. "Habitat Fragmentation." Web log post. Wildflower Turf. N.p., 16 Feb. 2012. Web. 11 June 2013. <http://wildflowerturfblog.wildflowerturf.co.uk/2012/02/16/habitat-fragmentation/>.
UNESCO. "Learning to Protect Biodiversity." YouTube. N.p., 30 Aug. 2012. Web. 11 June 2013. <http://www.youtube.com/watch?v=kHhspf5IfdE>.
University of Michigan. "Threats to Global Biodiversity." Globalchange.umich.edu. Regents of the University of Michigan, 4 Jan. 2006. Web. 28 May 2013. <http://www.globalchange.umich.edu/globalchange2/current/lectures/biodiversity/biodiversity.html>.
"What Threatens Our Biodiversity?" The Natural History Museum, 2013. Web. 29 May 2013. <http://www.nhm.ac.uk/nature-online/biodiversity/what-is-threatening-biodiversity/>.
World Conservation Monitoring Centre. Global Biodiversity: Status of the Earth's Living Resources. London: Chapman & Hall, 1992.

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