Monday, November 28, 2011

Once more into the Forest, by Grace and Jaqueline

                                     Figure 1. The appearance of the aspen poplar trees
                                 (illustrating the relative circumferences) around or transect.

When we walked into Nose Hill Park, we were amazed at how the various ecosystems within the park were able to thrive the way it was, situated in the middle of the urban city, Calgary, in the north-west area. The first thing we noticed about the park was that there were three distinct ecosystems within the park: ponds, forests, and grasslands. We’ve decided to focus our research of the park on the forest ecosystem due to our curious nature of the plant life that might be located in the forest; the various plant life that is often overlooked.
When we walked into a deciduous forest located in Nose Hill, we automatically noticed the diverse range of plant life located in the forest and wondered: what are the factors that affect how these plants thrive in such an environment? We set up a 1.00m by 10.00m transect in a random area in the forest and narrowed our studies in that area.
            The most obvious aspect of the forest that we noticed right away was its abundance in Aspen poplar trees. In our transect, there were 7 aspen poplar trees but most of the trees were clustered towards the middle of the transect. We wanted to investigate why this was, so after drawing the hill profile for our transect, we realized that the angle of the hill where most of the cluster of aspen poplars stood were in an area of the hill where the angle was not as steep (angle of the slope in this area only ranging from 12.4o to 13.4o). 
            There was one tree on each of the ends of the transect, where the angle of the slope was 20.2o on one end and 20.4o on the other end. The trees in these areas of the transect were shorter and smaller in circumference (estimated average height of 11.0m and average circumference of 29.5cm) when compared to the cluster of trees towards the centre of the transect (estimated average height of 15.5m and average circumference of 40.7cm). One reason for this occurrence might be because in areas where the slopes are steep, there the runoff of water is more rapid and therefore, does not effectively infiltrate the soil. If the slope is not very steep, the water that falls on the surface on the area does not run off as fast and will have a chance to infiltrate the soil, which will better allow the plants in that area to absorb the water needed for photosynthesis.  When the runoff of the water is fast, as it is when the slope that the vegetation on is steep, it also increases the erosion of the soil. Fast erosion of the soil results in less nutrients in the soil for the vegetation, which will decrease the rate at which the vegetation in that area will grow. These reasons support why there was only 1 tree on either ends of the transect, where the average angle of the hill is quite a bit steeper than the average angle of the hill where the trees are. These reasons also support why the average circumference and average height of the trees in the middle of the transect are much greater than the two trees on either sides of the transect.

                   The relative height, position, and circumference of the trees are shown in the hill profile as well.

Figure 3.  The soil profile of the forest.
             While we were at the forest, we also took a soil sample from our transect using a soil corer. To determine another factor that affects how plants thrive either positively or negatively, we decided to test the pH of the soil. The standard way to test the pH of the soil is to take 1.00g of soil and dissolve it into 100.0mL of distilled water and then filter the soil out of the water. The acidity of the filtrate will be the relative acidity of the soil. We carried out this process and it was concluded that the pH of the soil in our transect in the forest was 6.43, which is slightly acidic. In the transect that we decided to study, the area is highly abundant in a plant known as the Prickly Rose (Rosa acicularis). It turns out that the Prickly Rose thrives in areas where the acidity of the soil is moderately acidic, which ranges from a pH of 6.5 to 5.6. After researching the other plants that were abundant in our transect, which included Yarrow (Adillea millefolium), Blueberry Willow (Salix myrtillifolia), and the Bristly Black Currant (Ribes lacustre), it turns out that all of these plants thrive in soil conditions that are slightly acidic. The soil in this ecosystem becomes acidic because the acid rain falls on the soil and is infiltrated. The hydrogen ions present in the acid rain adds to the acidity of the soil when the acid rain infiltrates it. Also, Al3+ ions that are already present in the soil will become more soluble because of the acid rain, and will react with water when the pH of the surroundings is between a pH of 4 and 6. This reaction will form aluminum hydroxide ions, which will release more hydrogen ions into the soil, further contributing to its acidity. Also, when the pH of the soil is slightly acidic, between a pH of 5.5 and 6.6, the nutrient deficiencies within the soil can be avoided because the nutrients within the soil such as nitrogen, potassium, phosphorous, magnesium, calcium, and sulphur, can be better dissolved and absorbed by the plants. The reasons provided support that the acidity of the soil does in fact affect the plant growth: the pH of the soil in our transect was tested to be a pH of 6.43. Furthermore, the plants identified that were abundant in this transect (as in the prickly rose) grow best in slightly acidic soils.

Figure 3. The abundant presence of the prickly rose in our transect with a soil pH of 6.43.

            The soil sample inside the soil corer was also very moist and throughout the research of the plant species found in the transect, it was seen that the plant species that were abundant in the transect thrive best in moist soil conditions. All of the trees in the forest were
 Aspen Poplar, meaning that they were deciduous.  Deciduous trees and plants with leaves require plentiful amounts of water to stay alive because the large leaves. The moist soil means that there is water held within the soil, which allows all the plants in the forest at Nose Hill to successively carry out photosynthesis to stay alive. Therefore, the moisture and the level of water in the soil is one main factor that affects plant growth in the forests of Nose Hill Park.

Figure 4. The Yarrow plant that was extremely abundant in our transect.

            As we set up our transect to study the forest in Nose Hill, we noticed that the area was extremely disturbed by factors outside the ecosystem, the biggest disturbance being a vague trail up the hill where our transect was set up.  There was little vegetation up along the trail near our transect, however, we were surprised to find abundant numbers of Yarrow (Adillea millefolium) near the disturbed area and inside our transect. After researching Yarrow plants, it turns out that these plants often thrive on disturbed ground.
Most commonly, vegetation cannot grow on disturbed grounds because when the soil is disturbed erosion occurs and the nutrients can be washed away. With this said, without the proper nutrients there cannot be sufficient plant growth. Therefore plants cannot grow as well when the area is disturbed. This justifies why there were not an abundance of trees. However, with the Yarrow plants, they have adapted to this condition and are able to thrive amongst disturbance. 
            Having visited the immediate forest in Nose Hill to gather information for further research, we can conclude that the slope of a hill, the pH of the soil, the level of water in the soil and the disturbance the soil receives can affect the growth of plants, whether negatively or positively. The forest of Nose Hill in which we gathered our information was located in the area of the park at the intersection between Shaganappi and John Laurie Boulevard. In essence, we need to take care of our parks if we want to sustain the diversity of the ecosystems within the park.
                                      Figure 2. The hill profile of our transect in the forest of Nose Hill Park.

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