The Effects of Urbanization May Be More Hopeful Than You Think

Urbanization is defined as a continuously expanding urban area or core municipality [1]. Urbanization is becoming increasingly prevalent as the human population grows. This is the main cause for habitat loss and fragmentation, two driving forces in the current extinction rate, which is 1000 times that of the historical rates [2]. Species capable of living in the urban environment tend to exhibit specific characteristics. These characteristics include high thresholds for fear (cortisone levels), short flight distance, high reproductive rates, capability of maintaining high densities (of the same species), and species adapted to high disturbance and/or edges [3]. Animals without these characteristics (and plants without the last three) are unlikely to thrive in urban development [3]. Over time this may cause a homogeneous landscape where plant and animal species are increasingly more alike and species that cannot survive in these areas to go extinct [3,4].

In a recent study conducted in Southern Australia, Isaac and colleagues used habitat selection to examine the behavioral responses of 6 arboreal marsupial species in Australia to increasing levels of urbanization [4]. There were three similar sized areas used in the study, a highly developed area with mostly impervious surfaces, an urban fringe area with a mix of impervious and other land cover, and a completely tree covered area [4]. Throughout the experiment, each marsupial species selected different habitats based on their development level splitting into three groups across the landscape: a disturbance-intolerant group (3 species), a moderate tolerance group (1 species), and a disturbance tolerant group (2 species) [4]. Therefore the potential for habitat to be suitable for these marsupials was significantly based on the urbanization gradient [4].

This study gives hope for the future of biodiversity, as it can be applied to urban development everywhere. It will be virtually impossible to stop urbanization from occurring more frequently, however people can build a civilization that is more integrated with the native environment. By creating this urban gradient some species diversity can be sustained. However, a critical piece to this is a need for ample area in the urban fringe and forest cover environments like in the marsupial study discussed above [4]. If the urban areas continue to expand, then the urban fringe section for the moderate tolerance group and the forest cover patch for the disturbance-intolerant group can get too small to sustain populations [4].

Now is a time when human development choices can forever alter life on earth. Instead of thinking of humans as a separate entity from nature why not think of them as interconnected? Debating whether something is “natural” due to amount of human influence may be irrelevant to present and future biodiversity [5]. Humans have been altering ecosystems for centuries and some of those changes are positive. For instance, pre-Columbian indigenous people in the Amazonian rainforest would compost to create sustainable forest gardens [5]. These ancient gardens continue to show a positive ecological footprint as Amazonian Dark Earth (ADE) which is one of the only soils rich in carbon found in these forests today [5]. Given the marsupial study, it is possible that present day animals have an ability to coexist with humans based on an urban gradient. This would mean that human disturbance like urbanization is capable of maintaining biodiversity if it is conducted in a sustainable way.

– Savannah Maynard


Works Referenced

  2. Carolan, Michael S. “Greenhouse Gases: Warmer Isn’t Better.” Society and the Environment: Pragmatic Solutions to Ecological Issues. Boulder: Westview, 2013. 15-39. Print
  4. Isaac, Bronwyn et al. “Simplification Of Arboreal Marsupial Assemblages In Response To Increasing Urbanization.” Plos ONE 9.3 (2014): 1-15. Academic Search Premier. Web. 3 Mar. 2015.

17 thoughts on “The Effects of Urbanization May Be More Hopeful Than You Think

  1. kburrus

    I was intrigued to read the title of your post. It is very interesting to hear the other point of view on urbanization. A lot of the time you hear how bad humans are for the environment and how bad the growth of urbanization is. I agree with you in the fact that humans are apart of this world and we contribute to the biodiversity of this world. I think that it would be nearly impossible to take back what humans have done without eliminating humans all together, which is not an option. I also think that it is possible for humans and wildlife to interact in a positive way with the correct recourses and education just like the example you presented about the forest gardens in the Amazon rainforest.

    1. Savimay Post author

      Thanks for reading Kasey! I agree, I think people can contribute to biodiversity. We hear a lot about the negative side of urbanization because people have built cities in the past that were not very conducive to biodiversity conservation (e.g. homogenization of the landscape). However, I believe this was more due in part to the way that cities were built than to the building of cities themselves. For instance if there was no forest cover area in the marsupial study that would likely cause the rapid decline of the disturbance-sensitive group. Cities need to be more aware of the native species around them and urbanize in a way that better supports these populations.

  2. ematth

    I agree with both you and Kasey in that it is impossible to reverse the urbanization that has already occurred, so we might as well learn to adjust our usage of the environment in such a way that it benefits both humans and the natural world. Environmental/wildlife conservation and urbanization are not two black and white topics, they should be a blending of each other.

  3. amajor

    I agree with you that humans shouldn’t be treated as separate from the natural world, but should be treated as a part of the natural world because like it or not, we’re stuck on this planet with the natural world and we either had to learn how work things out or just give up and giving up in NOT an option. I’m pretty glad to see that there are thing in urban development that can preserve the biodiversity of our planet. We can’t stop urbanization, but we can alter how it affects the environment, for better or for worse. The example you’ve presented with the Amazon Rainforest is a grand example, since it is a no brainer that the Amazon is suffering from urbanization (along with deforestation) and if the green jungle and the urban jungle can coexist, than there is hope for the rest of the world.

  4. leorah

    It seems like the key here is the gradient of urbanization, and the sustainable size of each portion thereof. I think that this gradient is easy to see in places like the Western USA, where everything is spread out, including the cities, but I’m wondering about places like the East Coast, or similar areas of the world (Chinese densely populated cities come to mind). I wonder if there are good ways to incorporate and retain the necessary gradient of urbanization as we continue to expand in places where the edges are pretty defined…?

    1. Savimay Post author

      That is a big part of my post that I was trying to get at. The gradient of urbanization is what’s really important for maintaining some diverse wildlife. So just like you said in areas like islands, India, and the eastern part of China urban sprawl is a huge problem for wildlife because the population size is very large or there just isn’t very much space. If cities build up rather than out and condense rather than sprawl allowing for these urban gradients is more probable and more beneficial for future biodiversity.

  5. mberne

    I have never thought to look at the ‘benefits’ of urbanization and how it may increase biodiversity. I do think that urbanization in large cities such as Denver, Chicago and New York have a more negative effect than positive one (due to increased pollution and noise etc), but areas that are much more spaced out may have some sort if benefit to them. Since nothing can really be done about the ever increasing population size and need for more urban developments it is important to take these kinds of things into consideration rather than just building wherever seems suitable. Certain places may respond better than others.

    1. Savimay Post author

      I agree that densely populated cities likely have more of a negative effect on diversity. However, I want to clarify that urbanization with gradients of proper size increase diversity compared to urbanization without these gradients. I am not trying to say that having these gradients will increase biodiversity compared to not having urbanization in the area at all. It is more so a way to maintain some of the biodiversity that would otherwise be completely lost with urban sprawl.

  6. Lisa Angeloni

    I appreciate the optimistic, “glass-half-full” perspective of Savannah’s post. It’s true that urbanization often occurs in a gradient, and we can at least be thankful that some species persist in urban areas and that not all areas are equally urbanized and homogenized, allowing for increases in biodiversity as the landscape becomes more natural with distance from urban areas. I don’t see this as a benefit of urbanization, but I do see it as an incentive to maintain natural areas in the face of increasing urban sprawl.

  7. amccoy15

    I agree with Leorah, I can see how this applies to places where cities are more spread out, but how does this apply to more populated areas. How can those populated areas contribute to increasing biodiversity or does this just pertain to the less populated areas where biodiversity can still happen?

  8. Lacey Humphreys

    Urban areas have high mortality rates so it would make sense that animals with K selected life history traits (slow growth and reproduction) would be in danger due to humans expanding their cities. I think that implementing more natural areas and protected land where no development can take place is key. Also, do you think that “eliminating concrete” in ways like planting rooftop gardens in the city or in backyards would help build species diversity in urban areas?

  9. Amy D'Arcey

    There are so many ways that we can build our cities so that they help mitigate the damage we do to ecosystems. I feel like slowly more people are becoming interested in building in more sustainable manners.

    This link shows 5 buildings that incorporate trees into their designs, they won’t provide habitat for bears or wolves but they will for bees and birds.

    1. Savimay Post author

      Awesome link thanks Amy! I have heard of this before as well, it was called the living wall. They are supposed to implement one of these into Fort Collins soon!

  10. sberg

    I feel like if people start to think that animals and human as one entinity then there is a way we all can live on this planet. I also like the idea of builders thinking about the animals when building the houses or huge town homes and such. Because it just is a friendlier route to the environment that these animals have to live in and adapt to now that we people are just going to keep growing.

  11. reneev

    I liked the idea of an urban gradient, how there are different individuals with different tolerance levels. I wonder if over hundreds of years, those individuals that are more tolerant towards humans might become a different species or sub species all together, since they are living in more urban environments than their friends who are living far away from humans.

    1. Savimay Post author

      That’s an interesting idea Renee. I bet if individuals in the species are isolated they would eventually turn into different subspecies. In the study I read, the groups of animals were separated by species. So each group had its own species. There weren’t individuals within each species split across the gradient, but I wonder if that happens in other places? Very interesting concept, thanks for bringing that up!

  12. ssteele1

    I just had a lecture on urban ecology today with some of the same topics. This is a really prevalent issue with such high development rates. In that lecture we also talked about some of the behavioral characteristics of animals that live in urban areas (i.e. scavengers, mesopredators, flight-adapted species, etc.) The lecture also went into detail about something called “Conservation Development”. This is a neat idea that has actually turned into an organization that develops areas with conservation in mind. The intention is to not completely fragment the land. The development aims to leave large corridors, open spaces, and native plants so animals can remain in the area. The plots for homes are a lot smaller, but considered even more profitable for developers because its near naturalistic elements. I thought this was a cool idea and related to your article! Either way, great blog!

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