Monday, December 6, 2010

human interference in abiotic factors of the grassland, by Victoria, David, and Fejiro

The Nose Hill Park of Calgary, Alberta, Canada is a significant example of the Rough Fescue grassland left on the Canadian prairies. Created to preserve a part of Alberta’s natural environment among the rapidly expanding City of Calgary, the park includes vast expanses of grassland. Although a grassland may seem simple enough (grass, dirt, grasshoppers, more grass), there are in fact many factors that make up a grassland. There are also many factors that can influence it. Of these factors, most of them have been caused or contributed to by human impact. From agricultural history to fossil fuel pollution, there are many topics that could easily become heated discussions. For today, we will discuss some of the abiotic factors of the Nose Hill grassland and how those factors are being affected by humans.
            As with many grasslands, Nose Hill Park was once used for ploughing, the planting of crops, and keeping of cattle. Although it has been decades since these actions were implemented on the park, the effects are still seen today. Early actions by humans have shaped the park since before its creation in the 1980s and even before then when the European settlers and Aboriginal people of Canada used the land. Nose Hill Park has restored itself fairly well since its days of abuse (ranching area has returned to native grassland and natural flora and fauna species have also returned), but now the park is facing other kinds of issues. First, there is the concern of global warming. Grassland areas all over the world are slowly being converted to deserts because of temperature increases in the global climate, which reduce the already low water supply of these areas (grassland biomes receive up to 150cm of precipitation less than boreal forest biomes) (Bourne, et al, 2004). If precipitation levels get too low, combined with increased evapotranspiration due to higher temperatures, there is the potential of grassland destruction. Since global warming includes all biomes, Nose Hill is definitely affected by this trend. Using a 45.75g sample of soil from the Nose Hill Grassland, we found that the soil was 19.3% water. This is a significantly lower value than the water content we measured for the Nose Hill forest, which was 40.7%. From this data we can infer that the grassland uses and requires less water than the forest. This is due to the fact that grasslands tend to be drier than forests through evapotranspiration (they most often cannot support trees, which require large amounts of water), and evaporation of water from the soil is most likely to occur in the grassland because the ground is not as sheltered from the sun, which triggers increased evaporation due to increases in temperature, as the forest (trees can block sunlight from reaching the forest floor, therefore preventing extensive water loss from the soil). The amount of water in the soil also helps to explain why Nose Hill is mostly grassland, with small forest communities. Due to the level of precipitation that Calgary receives, as displayed in Figure 2, our climate can more easily support grassland ecosystems as opposed to forests. As previously mentioned, forests require a much higher amount of water which is not always available due to low precipitation levels. Therefore, the majority of natural areas in southern Alberta are in fact grasslands. Now, how does this all relate to human impact? The effects of global warming tie in nicely with precipitation levels and water content. As the temperature of the atmosphere increases from trapped greenhouse gases that absorb heat from the sun, worldwide levels of evapotranspiration (the loss of water through evaporation from soil and transpiration from plants) will increase while precipitation will decrease (, 2005). A serious threat to the grassland due to these elements is that it may become even drier and eventually turn into a desert. Then, it would not be able to support even the limited biotic community that it does as a grassland.
            Nutrients are a very limiting factor to the types of organisms an ecosystem can support. A noticeable fact about the Nose Hill grassland soil is that it has a rather low phosphate level of 0.25ppm. Phosphate typically comes from two sources: the weathering of sediments and fertilizers. Therefore, from the evidence of a low phosphate level, we can infer that this is either due to a lack of sediments or rock in the Nose Hill grassland (any sediments present would be buried under the soil, and rocks/mountains do not have a direct impact on the grassland), or to a lack of industrial sources of phosphate (fertilizers in particular). This is good because it indicates that the grassland has not been largely impacted by fertilizers, despite run-off from domestic sources in the city such as people’s lawns. However, it is also important that the soil contains some phosphate, as it is essential to root growth in plants and is needed for the transfer and utilization of energy in the bodies of animals (Chase, et al, 1999). The small concentration in the grassland soil can be seen as something positive because the amount is not so high that it saturates the soil and supports the extensive growth of weeds and other pests which can result in interspecific competition (a simultaneous demand for resources within an ecosystem that occurs between individuals of different species) (, 2007).
The pH of the grassland is also an indicator of the soil content of the area. The grassland was found to have a pH of 6, which is slightly more basic than the forest pH of 5. The acidity or alkalinity of soil can be affected by the concentration of calcium in the soil; the more calcium there is, the more basic the soil will tend to be (Kansas, Collister, 2006). This information leads us to believe that the level of calcium in the grassland soil is higher than the level in the forest because it is more alkaline. Since the forest and grassland are adjacent to one another in the park, it is likely that they share the same or similar abiotic characteristics. However, since they are classified as being different biomes and therefore ecosystems, differences between them will always exist, no matter how close they are to one another.
            Of the abiotic factors composing climate, wind is a significant one in a grassland. Winds tend to be faster in grasslands because of the open space as opposed to in wooded areas where trees and larger plants can block wind and therefore slow it down. Since Nose Hill is a vast park that consists mainly of grassland, wind speeds can be much higher on the hills than in the rest of the city. Nonetheless, the wind tends to be impacted by the city of Calgary. Urban morphology (the form, function, and layout of a city and the study of these features) can significantly affect the intensity and patterns of wind flowing around and above cities (Hang, J., et al, 2008). Therefore, wind disruptions caused by the infrastructure within the city can impact the grassland community. Some plants are better adapted to windy areas than others, with deep, strong roots to anchor themselves and prevent stress caused by the inability to absorb water and nutrients from the soil if roots are tugged and pulled by the plant swaying in the wind. As the city of Calgary continues to grow and engage in more construction, this can indirectly impact the grasslands of Nose Hill Park. The grasslands may have problems adapting to changing wind patterns caused by the growth and expansion of the city that surrounds it.
            A factor that is probably the most obvious in the Nose Hill Park is the use of the park by the residents of Calgary and other areas. The park has undergone extensive studies to ensure minimal impact of the area by creating pathways, hiking trails, off-leash dog areas, and washroom facilities. However, the park is still widely used and enjoyed by humans. Trampling is one of the most common results of human interaction with the Nose Hill grassland; despite the paths, people do not always respect the park as a natural area and take advantage of it in their use. This includes having dogs off leashes in areas where leashes are required, as well as hiking or biking off the designated pathways. This disrupts not only the vegetation (grass can get squished if tread on too often, or even torn up by dogs and humans), but also the animals who inhabit the grasslands. Humans scare off the animals, and can severely impact the lives of animals that live at the park if they do not respect the wildlife. Too much human interaction can cause stress to the wildlife, which then impacts the rest of the ecosystem in a negative way. That is why it’s so important to appreciate the park and treat it as nicely as possible. This also includes littering. Littering is frowned upon in today’s “green” society, but this has yet to stop many people from doing it. Litter not only destroys the natural beauty of the park, but can harm various animal species (discarded containers can trap small animals, choke/suffocate birds, and poison larger animals that may ingest it). Again, these effects have ways of cycling through the ecosystem along with the biota of an area and can impact many different aspects of the environment. Toxins in the food web from one animal eating something contaminated that someone carelessly left in the park or its decomposition into the soil is a major example; this can result in toxic bioaccumulation in the ecosystem (the increase in concentration of a toxin as it travels up the food chain). Substances that bio accumulate are often fat-soluble, which means that they cannot be broken down by the organism and tend to stay in the organism’s body. If another organism eats a contaminated one, the toxins intensify further, and continue to intensify along the food chain. This can be detrimental to the health of an ecosystem, and can result in decreases in plant and animal populations and biodiversity. At Nose Hill, litter from users of the park can contribute to the build-up of poisons in the environment, depending on what the litter is. As the toxins undergo bioaccumulation, it can not only impact the exclusive ecosystem of the grassland but transfer to other areas in the park, such as the forest, or even other areas in Alberta due to the migration of birds and other animals.
            The health and vitality of the grassland at Nose Hill Park is a delicate balance, mostly due to the fact that the natural area is in the middle of a large city. Its location contributes to its vulnerability as a sustainable environmental community, and the struggle to keep Nose Hill natural will continue on into the future. Some of the impacts on the grassland are ones that we in Calgary can help prevent, such as littering, while others are bigger than us, such as climate change. For the benefit of all natural grasslands (as well as other ecosystems), a global effort is required to keep the environment as in-tact as possible. There will always be pollutants and changes in the environment, but that doesn’t mean that we humans can’t do everything in our power to help these ecosystems that are incapable of helping themselves. By analyzing the factors that influence the biotic and abiotic aspects of the Nose Hill grassland, we can determine what there is to be done about keeping the grassland at an optimal state and work on plans of action in terms of this natural maintenance.

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