Human Population and the Geography of Vulnerability
It is estimated that the number of humans living on earth has surpassed seven billion according to United Nations demographers. Our population is exploding at an exponential rate. Knowing that our future holds an ever-increasing number of humans, what does this mean for our planet? As arborists, how can we minimize our impact to the most vulnerable species?
In 1973 Congress passed the Endangered Species Act (ESA), recognizing our nation's natural heritage of, "esthetic, ecological, education, recreational, and scientific value to our Nation and it's people." This was and is landmark legislation. The ESA works well to protect endangered or threatened species and their habitats, but does little to prevent populations from becoming endangered or threatened. Once a species has become endangered, the population has a very small genetic pool to draw from and the likelihood of the species recovering gets smaller and smaller as their numbers dwindle. It is far easier and healthier for the population to be maintained in larger numbers. The key is identifying areas of concern before they become a concern. New studies on geography and human development patterns will inform conservation efforts moving forward.
The geography of vulnerability: incorporating species geography and human development patterns into conservation planning was published in Biological Conservation. This study was conducted with the understanding that the geographic distribution of species needing protection is the cornerstone of any effective conservation plan. Additionally, habitat destruction is the most frequent cause of the endangerment of species (Wilcove et all, 1998).
The study focused on limited-range species of birds and butterflies that are not currently considered endangered or threatened. The ranges for these species often crossed political boundaries into adjacent countries. However, very few countries have legal protections in place for endangered species. For this reason, it is even more important that the portion of their range that extends into the US be protected. The US breeding ranges for these birds and butterflies were identified and the overlapping areas were mapped.
Counties that contain both restricted-range birds and butterflies.
The study then used projected changes in human population density along with several measures of anticipated habitat loss including, increase in developed land area, increase in urban road mileage, and the total amount of undeveloped nonfederal land available for potential development. In general, areas with larger amounts of undeveloped land were at greater risk for habitat loss. With these parameters, Texas, Florida, and California stood out as states with a relatively large number of restricted-range species and a high likelihood of significant losses of natural areas in the near future. These areas were termed “hot spots of vulnerability” (Abbitt, Scott & Wilcove, 2000).
US counties identified as hot spots of vulnerability based on the projected population density increases and the presence of limited-range species.
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California
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Florida
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Texas
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Habitat Conservation Plans (HCPs) are used throughout the US as a way to address endangered species controversies on nonfederal land. HCPs are developed under the Endangered Species Act and help protect flora and fauna while allowing ecologically sensitive development/projects to continue with mitigations for impacts to species and their habitat. It has been encouraged for new HCPs to expand their protection to the limited-range species and their habitat. Protecting these hot spots of vulnerability will help prevent the occurrence of additional endangered species as our human population continues to expand.
As our human population grows, our impact on our surrounding ecosystem grows. As we squeeze the local flora and fauna into ever-decreasing areas, we need to be aware of the long-term consequences. Paying attention to these hot spots of vulnerability and taking extra care to protect the wildlife found in and around trees while arborists are on the job will help maintain biodiversity now and in the future.
In response to your question: "how can we minimize our impact to the most vulnerable species?" The answer is simple: reduce our population. But of course, no one wants to tackle this. We just learn to "manage" for more, which, of course, is mismanagement.
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Hi Jimi~
I think you hit upon a key idea. The primary root cause of many of our global problems is our rocketing population - water shortages, famine, habitat destruction, etc. The attempts to address these issues are many and varied, but they generally ignore the common root cause, our large numbers.
The population growth in the US is very close to the replacement rate (replacement rate is 2 kids per couple on average), indicating a relatively slow growth rate. Most of the growth is occurring in poor countries. Many scientists are of the opinion that educating women and providing access to family planning is the most efficient way to decrease the population growth in these poor countries.
While it may be difficult to have an impact on those activities as an arborist, it is within our realm to do our best to protect the wildlife we encounter in and around our job sites.
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Megan, While the population growth in the US may be close to the replacement rate NOW, my point is that the past population growth in many of the developed parts of our country has already exceeded its carrying capacity, so to speak. We may be able to keep levels somewhat fixed into the future, but the current levels are already too big. As the migration to larger metropolitan areas continues in search of jobs and a "better way of life", these areas tend to have to grow, thus, leaving a larger, irreversible, footprint on our natural world. We are seeing a fixed overall US population being concentrated into particular areas, which, on this micro-scale, creates problems.
So, in short, while lesser-developed countries may be growing and creating a larger problem, ours has already overstepped its bounds even if the population holds steady.
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