Wednesday, November 30, 2011
A Soil composition of grasslands in Nose Hill Park, by Lily and Selina
Nose Hill Park is located in Calgary, AB. Created in 1980, this 11 km squared grassland is one of the few remaining remnants of the high plains which originally covered the area. Over thousands of years, the constant erosion by glaciers shaped this hill. There are valleys and lowlands surrounding the hill, which makes the hill itself stand out in height. There is also other evidence of glacier erosion. There are clusters of rocks and debris carried by the glacier and deposited on the hill. Some of these rocks were once part of Mount Edith Cavell, now in Jasper National Park.
Later, when European explorers came, they started to farm the land. Large areas of present day Nose Hill were used for agriculture. The increasing of population also affected the land use. However, since citizens started preserving this rare grassland, the native species have slowly come back, resulting in our Nose Hill Park today.
Nose Hill park is a grassland biome. Grasslands are typically low in precipitation and have moderate temperature variations. Grasses are the dominant plants, although there are some trees that can withstand the dryness. Grasslands also have fertile soil because of the numerous plants that die and decay. This fertile soil is great for growing crops, which is why Nose Hill was used for agriculture.
Figure 1. The picture of the transect we were working on in Nose Hill Park, Calgary, Alberta, taken by Lily Hou. The
location of our transect was 51° 6.813 minutes N, and 114° 7.780 minutes W, at an altitude of 1195m.
Since Nose Hill's fertile soil was used for agriculture, we were interested to see what the soil composition is for the grasslands of Nose Hill now after the native species redeemed it. We also wanted to see how soil composition affected the organisms which inhabited the area.
Table 1. Soil tests on our sample in the grasslands area of Nose Hill.
Figure 2. A soil core sample taken in the transect we were working in. The temperature of the soil was 19°C, taken at 5cm below the ground. The core sample was taken by Lily Hou and Selina Fan. The soil sample had a length of 22cm. The top layer of the soil was loosely packed and had many roots in it. The lower part of the soil was tightly packed and was very close to a layer rocks. There were less roots in the bottom part than the top.
First, pH has a large effect on soil. pH is defined as the power of hydrogen. The number of hydrogens determines how acidic or basic a solution is. When the pH is less than 7, it is acidic. When it is at 7, it is neutral, and when it is greater than 7 it is basic. Plants, like other living organisms, have an optimal pH in which they can live in, which is usually around neutral. pH also determines what form nutrients will take when in the soil, and also their availability for plants. It also affects the soil bacteria present in the soil that decomposes dead organic material. The optimum pH for these bacteria are 6.3 to 6.8, while the optimum pH for fungi, mold and anaerobic bacteria are more acidic.
The availability of nutrients is also affected. Nitrogen is required by plants in a “fixed” form (ammonium NH4+ and nitrates NO3-). The bacteria that “fix” the nitrogen into the soil tend to work the fastest in neutral pH, while in more acidic soil it is slower. Nitrogen is most abundant from pH 6.0 to 8.0; once outside that range the quantity decreases. Also, phosphorus (in phosphates) is important to plant growth. This is most abundant when the soil is around pH 9.0, then it decreases as the pH gets more acidic.
pH in soil can be affected by many factors. Precipitate, such as acid rain, could increase the acidity. Also, human impact, such as waste, fertilizer run off, and exhaust from cars could change the pH drastically. Luckily, the area that we studied did not have much human impact because it was away from the trails.
However, the nitrate levels in our soil were at 0.00 mg/L. This might be because its autumn. The cold weather may have slowed the fixing of nitrogen as well. Plants used up all the nitrates available in the soil, and will soon die and release nitrates back to the soil. So, we inferred that the nitrates are stored in the plants.
Phosphate levels were also at 0.00 mg/L. This may also be because the phosphates stored inside plants. Also, since there is little precipitation, phosphates in rocks don’t get washed away to the soil. Nitrates and phosphates are both present in fertilizer, but since our area is not near any human activities, excess nitrates and phosphates are not present in the soil
Ammonia in soil is produced from the decaying of plants and animals. When there’s ammonia in the soil, it means the plants and animals around the location of the soil sample are dying and decomposing. This is a good thing, because the plants growing in that soil will benefit from the ammonia in the soil. Amino acid, which is the building block of proteins, is essential to both plants and animals, and nitrogen is needed to make amino acids. As we all know, there are around 78% nitrogen in the air we breath. However, most living organisms aren’t able to use this nitrogen straight from the air. The nitrogen need to be “fixed” before they can be used by organisms. The nitrogen in the atmosphere can be fixed either by lightning, or bacteria living in the roots of plants. These bacteria combine the nitrogen gas in the atmosphere with hydrogen ions in the soil, and produce NH3(g), which is ammonia. Ammonia is changed into ammonium from the addition of hydrogen ions in the soil.
Figure 3. A picture taken by Selina Fan of a Canadian Gooseberry plant found in our transect at Nose Hill Park.
As seen in Figure 1 and Figure 3, there aren’t any tall trees in the area we were. This is because there isn’t enough ammonia in the soil to support tree growth, as trees need a lot of nutrients. The low level of ammonia in the soil means only small plants, such as grass and bushes can grow in the area. Due to the limitation of the producers that can be grown in the area, the organisms found in the area are also limited. Only certain organisms can survive off of these plants. For example, lions can’t survive only on these plants, therefore there aren’t any lions or bigger organisms. We only found small insects, such as grasshoppers, spiders and ladybugs.
Figure 4. The insects we captured in our transect, using the insect capturing net and Ziplock bags.
. After examining all the chemical properties of the soil sample found in our transect, we discovered that the soil had sufficient nutrient to support small plants, and small organisms. There isn’t much human impact in our transect, because we didn’t find any traces of litter. The low level of excess nutrients in our soil sample suggested the absence of fertilizer application and human impact.