External Influences

Impact of Man Constructed Urbanization on Ecosystem

By Zack Allen
DATE: May 19, 2007
ABSTRACT: When studying nature, there is widespread evidence of humans impacting the environment in non-beneficial ways. In this research paper, several identified human oriented external influences will be discussed including, the impact of roadways such as Highway 101 and the devastating effects of off road vehicles on vegetation and surrounding environment, and finally the byproduct of these human activities, water, noise, soil and air pollution. This report is an effort to study the effects of human culture on an isolated ecosystem, in terms of the repercussions of our actions. It is critical to examine the associated products of human activities if we wish reverse current trends of a degrading planet in hopes to maintain a stable and pristine atmosphere.
INTRODUCTION: After choosing an ecosystem to research and looking at the surrounding habitat, what perplexed my interests the most was what impact man made, unnatural influences had on our subject site. The first impression is that humans toll is minimal, however as one begins to look at the situation more in depth, it is understood that humans have largely shaped and altered the environment. Major roadways like Highway 101, which is directly adjacent to our ecosystem have heavy traffic; vehicles emit chemical gases and particles which pollute the air, some of these containments will fall to ground and other will make their way into the water ways. Vehicles that have traveled over our ecosystem disrupt vegetation directly and indirectly, they disrupt the surface by shear stress parallel to the surface and compressive stress normal to the surface (Shipley, Nakata and Wilshire 1978).
MATERIALS AND METHODS: For the most part, I gathered data for my research project by finding external, reliable and suitable information pertaining to my subject. The internet was the main instrument used to gain information but not solely. Furthermore, as would be expected I used dependable sources from the internet, including databases provided by Sonoma State that provided scientific and scholarly articles. However, alternative I also used textbooks as well as previously acquire knowledge and information. A majority of my research has been hands off, book work because I feel that I would be inadequately prepared to investigate the results of human activities directly in the field, so I reframed from approaching any direct statistical conclusion in my analysis.
DISCUSSION: On all roadways but most severely on major routes, cars emit and distribute various chemical gases such as carbon monoxide, nitrous oxides, polyaromatic hydrocarbons, they also discharge particles and elements like lead, carbon, bromide and chloride, they often leak oil, gas, brake fluid, windshield detergent, engine coolant and worn metal particles, tires leave a residue of zinc and other pollutants as they wear. However, the distribution of pollution from such influences is variable, certain elements or components of pollution settle is distributed patterns which are individually unique. For example, the amount of bromide increased with depth while the amount of lead decreased. Certain factors, such as wind speed, traffic speed, methods of road construction (curbs) and surrounding urbanization (buildings), effect, change, contain or allow pollution to spread. Other measures to insure road safety also change the surrounding environment such as the addition of salt in the winter time to prevent icy conditions. Most build up of pollution from vehicles tends to remain in close proximity, with the exception of the pollution that enters and contaminates waterways which has rapid access to extreme movement (Al-Chalabi and Hawker 1997). However,”pollutants are often transported by winds and waterways hundreds or even thousands of kilometers from their source. Lead from automobile exhausts has been found in the snow of Antarctica” (Gabler, Petersen and Trapasso 2007).








Direct damage caused by vehicles that travel over terrain are the disruption of vegetation by crushing of foliage, root systems and seedlings, from the wheels, small plant cover is uprooted and large plant roots system are disrupted by sheer stress infliction. Additionally, plant foliage and stems can be damaged and plants uprooted by the superstructure of vehicles; thus plant damage can occur over a larger area than just the width of a tire track. The indirect damage caused by vehicles on vegetation includes the undercutting of root structures, burial of plants and vegetation by debris eroded from the areas used by the vehicles and the reduction of biological capability of the soil by modifications of the soil remnants and removing of upper more fertile soil layers by erosion (Shipley, Nakata and Wilshire 1978). Moderate to heavy traffic over land leads to significant compaction and changes the natural structure of the soil. Increased soil density can extend to over a meter deep and density has been shown to persist from 7 to 40 years (in heavily logged areas). By stripping vital fertile top layer soils and changing the structural integrity by compaction, restoration of plants and vegetation is inhibited. Also, repressing the restoration of plants is the loss of moisture in the soil due to compaction which retards most biological and chemical process in the soil. Moreover, the average diurnal soil temperature of the soil is changed significantly about 12C compared to undisturbed soil (Wilshire, Shipley, Nakata and Prestegaard 1978).









One significant factor largely pertaining to our ecosystem is noise pollution from traffic. The level of highway traffic noise depends on three aspects, the volume of the traffic, the speed of the traffic, and the ratio of trucks in the amount of traffic. Generally, the loudness of traffic noise is increased by heavier traffic volumes, higher speeds, and a greater number of large trucks. Vehicle noise is a combination of the noises produced by the engine, exhaust, and tires. The loudness of traffic noise can also be increased by defective mufflers and other faulty equipment, which frequently occurs. Any conditions, such as a steep incline or hill that causes heavy laboring of engines will also amplify the levels of traffic noise. There are several more complicated factors that effect traffic noise levels; distance, terrain, vegetation, tress and natural or manmade obstacles all can reduce noise levels. Traffic noise is not usually a serious problem for people or ecosystem that are more than 500 feet from heavily traveled freeways or more than 100 to 200 feet from lightly traveled roads depending on the topography and other environmental conditions (Federal Highway Administration).
RESULTS AND CONCLUSIONS: The proximity of Highway 101 that I eventually thought would have noticeable impacts on our ecosystem turned out to be an adequate distance to be minimally affected As previously mentioned, toxic byproducts of traffic that penetrates the soil is closely distributes nearby to the roadway of origin. Air pollution, generally irrelevant in the greater Ukiah valley disburses and is unnoticeable around our area. Undoubtedly, some pollution is drains into our ecosystem by runoff but with another minor road way in between our ecosystem and Highway 101 most of the major pollution is isolated into a barren strip of land between the two roadways. Furthermore, noise pollution also dampened by environmental barriers is minor. However, the effect of off road vehicles on our ecosystem is probably the largest external man made influence. There is a clear cut, defined dir road way through our ecosystem established and created by vehicles that have significantly altered the face of the environment by disrupting the natural vegetation. From the repetitive trips of vehicles plant restoration has been inhibited and the extensive dirt tire tracks remain for months even though vehicles may not currently be traveling on the road.


Abdul Sahib Al-Chalabi and Darryl Hawker. 1997. Distribution of Vehicular Lead in Roadside Soils of Major Roads of Brisbane, Australia. Griffith University, Queensland, Australia.12 pp.
Federal Highway Administration. 2007. Highway Traffic Noise.12 pp
Howard Wilshire, Susan Shipley and John Nakata. 1978. Impacts of Off Road Vehicles on Vegetation. US Geological Survey, Menlo Park, California. 10 pp.
Howard Wilshire, Susan Shipley, John Nakata and Karen Prestegaard. 1978. Impacts of vehicles on natural terrain at seven sites in the San Francisco Bay area. 19 pp.
Robert Gabler, James Petersen and Michael Trapasso. 2007. Essentials of Physical Geography. 8th Ed. 658 pp.