Wednesday, November 30, 2011

Life in Forest vs. the Life in Grassland Ecosystems, by Sina

            On September 23rd 2011 we visited Nose hill National Park of Calgary on a fairly hot sunny day.  Two major ecosystems present in the park of were the grassland ecosystem observed by Yuchen Tang and Justin Lin, and the forest ecosystem observed and analyzed by Pranav Ambhorkar and Sina Dolati. The 10.0 metres by 1.00 metre forest transect that that we analyzed was located on a hill with increasing elevation. The elevation at the right corner of the most  downhill most point of the forest transect was 1281 metres; the latitude was 51o 6.799 minutes W, and the longitude was 114o 7.61 minutes W and was located 70o clockwise from North (downhill). The 10.0 metres by 1.00 metre grassland transect that that Yuchen and Justin analyzed was also located on a hill with increasing elevation The elevation at the right corner of the most downhill point of the grassland transect was 12001 metres the latitude was 51o 6.815 minutes N. Longitude 114o 7.716 minutes. The conclusions we made are based on the plant samples, bug samples and other observation that we made in Nose Hill Park.

Grasslands are normally used for grazing cattle, farming and cultivating crops due the vast concentrated quantity of grass and wheat; whereas wood in the forests is the main valuable resource which is gathered by cutting down trees. Forests are complex ecosystems of multiple levels wherein there is lots of biodiversity whereas grasslands seem to be simpler ecosystems with less biodiversity. The overall humidity is higher in forests and the overall wind penetration is higher in grasslands. The soils of both ecosystems are different in ways that can support the plant life that are present in the ecosystem.
The forest ecosystem is dense, full of plants and shrubs, however the soil found in forests is not very fertile. Even though forests are full of plant life, forests also have high precipitation rates. These high precipitation rates have led to the nutrients in the soil getting washed away. Trees depend on soil for; stability, nutrients, and water. Most nutrient cycling takes place in the top two feet of soil where supplies of air, water and food allow microorganisms to thrive. These include bacteria, fungi and algae. These microorganisms work in conjunction with insects and burrowing animals to break down dead or dying plant and animal life. In the process they release carbon dioxide into the air and nutrients into the soil. A good soil is a living body made up of inorganic material, decaying organic matter, water, air and billions of organisms. Some organisms such as earthworms form partnerships with tree roots helping them to extract nutrients from the soil. Others are important in breaking down organic matter and cycling nutrients, making them available to the next generation of plants and animals. Precipitation in Calgary is especially high in Calgary, making Calgary one of the major Canadian cities with the highest precipitation.  As our transect was located at the bottom of the hill, the rain water running off trees gets trapped in the soil like a sponge where it is retained for trees and plants as a water source with nutrients running off from all around the hill.
The soil Yuchen and Justin found in the grassland was deep and dark.  The upper layers are the most fertile because of the build-up of many layers of dead branching stems and roots.  These organic matters on the surface and in the dead roots provide a great degree of nourishment for the living plants. The rainfall in Calgary is fairly high and considering that the topography of the grassland ecosystem was relatively flat to the forest ecosystem, this would mean that there will be less run off of nutrients from the soil therefore the soil found at the Nose Hill Park’s grassland ecosystem is very fertile.  Also In grasslands, soil leaching is very low due to the scarcity of percolating water and due to low solubility of the minerals in basic solutions and the slowness of their release from humus. The pH of the soil in the grassland ecosystem of nose-hill will be lower due to a relatively plain topography and therefore less run off of acid that comes with acid rains.
            In the 10.0 m x 1.00 m grassland sector, Yuchen and Justin found tens and tens of bugs of various species such as weevils, root flies and lygus bugs. In our forest sector, we found a ladybug, and a very few species of spiders. The Grassland area contained a high concentration of tall grass, and the bugs hiding under the layers were not visible to us until the grass was swept.  The grass and branches in the forest sector had more air space between them. Concentrated grass areas are good hiding places for the insects since the grass easily hides them from threats of predators. The lack of light in the bottom layers also makes locating the bugs harder for the predators. This also explains the abundance of insects in the area. However, in the forest ecosystem that we observed, we barely found any insects. This is due to the low concentration of the plant life. More light and air space between the plants makes the insects more visible and therefore more vulnerable to the predators. (insert pic 5 and 6 here) We found a species of spider that had produced spider webs in a depression on a tree trunk in our sector. While this tree branch provides the space for the spider to live, the depression allows the spider to hide from the sight of possible predators. (insert pic 2 and 3 here)
 We observed a few plants that had spikey branches. These types of plants have adapted to this in order to be equipped with a defense mechanism against trespassers that might step on them. These branches also provide more surface area for the plant, that allows the process of photosynthesis to occur more efficiently.
            There is more variety in the species of plants found in the grasslands area. Other than the tall grasses and golden western wheat, a variety of plants has been found by Yuchen in the grassland area such as bull thistles and astargalus birsolcatus. In the forest ecosystem which we studied, we did not find a large variety of plant species. We found two trees and a high number of green and yellow grasses in low densities. We observed that the high levels of the forest ecosystem which includes the leaves of tall trees blocked most of the sunlight and did not allow much light to enter the lower levels. This is possibly the reason for the low variety of plant species at the lower levels of the forest. (insert pic 4 and 5 here)
            The air temperature at 2 metres above ground in the forest ecosystem that we measured a using a thermometer was 21o C. According to researchers, leaves in different types of ecosystems with different types of climates such as boreal and subtropical climates can regulate the temperature inside their leaves so that photosynthesis can take place at the most efficient rate possible. They have found that the optimal temperature at which green plants and tree leaves can photosynthesize most efficiently is at 21o C. The air temperature of 2 metres above ground in the grassland ecosystem measured by Yuchen and Justin was 24o C. We can see that the higher temperature in the grassland ecosystem does not allow the growth of trees. This is one of the reasons that we can observe trees in forests but not in grasslands.
            We did not find any flowering plants in the forest ecosystem, but a few species were identified in the grassland area. This is most likely because of more winds speed of higher speeds that flows through both the ecosystems. Wind penetration and wind speed vary in both grassland and forest ecosystems at nose hill. Wind is a really important factor that affects pollination in flowering varieties. Pollination is a stage of asexual reproduction in plants .The male sex cell is inside a pollen grain which is on the surface of the stigma. The female sex cell (the ovule) is inside the carpel which is located in a different part of the flower. The male and the female sex cells of these plants need to get together for asexual reproduction. As most plants cannot move this wind is needed to accomplish this task. The wind transfers these pollen grains male that end up on the tip of the female gamete. The pollen tube grows through the stigma, style and into the carpel. Eventually it reaches an ovule and the male and female sex cells meet and fuse together. There is less wind penetrated into the lower levels of the forest ecosystem since the leaves of higher levels in the forest blocks the winds, and decreases the wind speed. Due these dense and congested structures at the center of the forest ecosystem, flowering plants do not grow in the center as the pollen grains are not transported from one place to the other due to low wind levels. However, flowering plant can be found at the edges of forests due to the wind coming from outside of the forest ecosystem which occasionally carries pollen grains from variety of flowering plants. The grassland ecosystem is far more open and thus there is more wind penetration and a higher wind speed in this ecosystem. The flowering plants were mainly found in this ecosystem. These plants normally reproduce through pollination. Grasses like the Rye grass usually have their stamens loosely joined to the filaments and vibrate even in the slightest breeze. They release large quantities of very small and light pollen grains which are easily carried away by the wind. Other flowering plants found in the grassland ecosystem that reproduce through pollination with the help of wind, are the bull whistles and the astargalus birsolcatus. These species of plants also can only reproduce in grasslands that have high wind levels.
            As we can observe, there are many factors that distinguish between a forest and grassland ecosystem that are interestingly only a few meters apart from each other!

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1. Freeman, S. (2008). Biological Sciences. San Francisco: Pearson Benjamin Cummings Publishing.
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5. Rafferty F. (2011).Forest and grasslands. New York: Britannica educational services.

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