Monday, November 29, 2010
Human Interference and the Forest by victoria, David and Fejiro
How does human interference in abiotic factors affect the biotic factors of the forest ecosystem at Nose Hill?
By Victoria, David, and Fejiro
Ever-present in a forest is evapotranspiration. Evapotranspiration is the loss of water through evaporation from soil and transpiration from plants (Biology-Online.org, 2005). The chemistry of the forest depends on evapotranspiration; this is especially true at Nose Hill where the facing of a slope is crucial to the evapotranspiration, and therefore to the entire forest. Most of the forested areas at Nose Hill are along north-facing slopes. In the Northern Hemisphere, the rate of evapotranspiration tends to be higher on south-facing slopes. This is because, following the path of the sun, north-facing slopes have morning sun while south-facing slopes have afternoon sun, and in the afternoon, the heat from the sun tends to be hotter than in the morning. The hotter an area is, the more evapotranspiration is going to occur (water will evaporate into vapour from the soil, while plants will lose more water in the heat to transpiration). Therefore, it makes sense that most of the forests at Nose Hill Park tend to be on north-facing slopes; the sun they receive in the morning is less intense heat-wise than the sun they would receive in the afternoon on a south slope. On a north-facing slope, they will lose less water through transpiration, and there will be less water loss from the soil. Water is a limiting factor for the growth and survival of trees, so trees will survive better in areas where the water content is higher and there is less transpiration (Bachman, 2004). However, just because this is a natural occurrence doesn’t mean that human impact isn’t involved. Global warming is once again affecting environments everywhere, and Nose Hill is certainly no exception. If climate change continues at its current rapid rate, higher temperatures worldwide will result in higher rates of evapotranspiration. Since the forests at Nose Hill Park are already accustomed to the specific temperature conditions in Calgary, rapid rates of climate change will only negatively impact the situation. If the amount of evapotranspiration on even north-facing slopes becomes too much for the trees in the forest to handle, it may very likely result in the trees failing to survive, which will lower the biodiversity in the forest and impact the rest of the food chain in the forest ecosystem.