User: | Open Learning Faculty Member:
The organism that I plan to study is the Trembling Aspen Populus tremuloides , found in a pure stand on the west side of my study area. The Aspen tree is found throughout the province of BC and grows best in moist, well-drained soils. It produces root suckers that grow into clones that become a colony over time(British Columbia, n.d.). The Trembling Aspen prefers to grow in full sun as it is intolerant of shade.
My study area is an open field in a Regional Park that is surrounded by forest. These Aspen trees are comprised of a pure stand that is of mixed age and are located in a small area approximately 150m by 200m in size. There are a variety of different diameter sizes and height differences in the stand of trees, the larger of them are further west, deeper into the forested area, whereas the smaller trees are found closer to the open field. The soil was compact throughout the stand but was drier at the north end and moist at the south end. It appeared that there was a higher density of smaller diameter trees at the south end, closest to the open field.
Since the Trembling Aspen is shade intolerant, the new suckers and clones will likely survive best if they grow in the full sun, closer to the open field then under the dense forest canopy. Also, since the soil appeared to be more moisture on the south end, perhaps this is also a limiting factor to new tree growth. I predict that within the Trembling Aspen stand there will be a gradient, a higher abundance of younger trees (smaller trunk diameter) closer to the field and south and lower (larger diameter) as I move inward to the forest and north.
The response variable is the size / age of the Aspen trees (diameter of trunk) and the explanatory variable would be the availability of sunlight and soil moisture. Both the response and explanatory variables would be continuous.