This the map of the segments at Don River. Our segment starts where it says Beginning of stretch 9.
Images taken of Don River Segment 9 at Glendon York University. The image at the top left with the pine tree is the start of our segment and the bridge is the end of our segment.
What did we see at the Don River?
We (Jennifer and Katherine) went to document the Don River at Glendon York University on November 11, 2016 from 1:03- 2:03pm. The temperature was 7°C and the weather was sunny and windy. From the images above you can see that there were larger rocks which looked man made that were there to stabilize the river on the other side of the bridge (last picture bottom right). On our side of the river from the images above you can see that there were no rocks or fences used to stabilize the banks. The trees barks near the river looked like they were going to fall in. There were logs of trees in the river. The trunks of trees looked thinner as you get closer to the river. The roots of the trees near the river looked exposed. There were not many animals near the river or in the trees (i.e birds or squirrels in the trees). On the trail near the river, a few people did walk their dogs without their leash. This was the only type of animal movement that we saw that day. These dogs did not go near the river since the more dense trees near the trail which prevented them from entering the river.
Why were the roots of the trees exposed?
According to Schenk et al. 2002 the amount of water a plant can take depends on the amount of water availability, climate, soil, lateral spread of the roots and the overlap of the roots. They found that the lateral spread of roots would be bigger in wetter systems since plants are often bigger. This is true in our case since most of the vegetation found were tall trees. Schenk et al. 2002 also found that if the canopy size is bigger the roots would also be larger. We also found that there was a large canopy cover of the trees. They also found that superficial lateral roots are beneficial to anchor trees if the tree had more above ground plants. Due to the close proximity of the river the roots of tree do not need to go as deep into the soil to get the water. Schenk et al. found that root systems depth is not in response to soil texture, rather the root density responds to soil texture. They found that plants in water limited areas have more root activity in tip where there could be more water available.
Possible stabilization method
Since there was no stabilization done in our segment of the river the use of rip-raps is a possible methods. Ripraps are essentially rocks that are pile on top of each other on the shore. These rocks should be able to fit into each other like a puzzle since you do not want water to get through the holes of the rocks which may lead to soil erosion. Severson et al. 2009 said that hydrophytic vegetation does not benefit from a normal riprap. In our area there was no hydrophytic vegetation. They also did their study in a reservoir which is different from our river. Since our river is narrow minimum amount of rocks should be used and the placement of these rocks should not affect the roots of the trees near the river bank.
Schenk, H. J., & Jackson, R. B. 2002. Rooting depths, lateral root spreads and below-ground/above-ground allometries of plants in water-limited ecosystems. Journal of Ecology, 90(3), 480-494
Severson, J. P, Nawrot, JR, Eichholz, MW . 2009. Shoreline stabilization using riprap breakwaters on a Midwestern reservoir. Lake and Reservoir Management. 25(2): 208-216.