Lab Group: Steffen Seamon, Simon Cohen
Date of Inquiry: 9-13-18
Land Use/Cover Change Lab Week 2
Background
In the first week of the lab, we established our site in Collins View to gather data on land use and cover change. The purpose of establishing our lab in Collins View was to observe how land use in a somewhat urban setting changes the ecosystem. Development on previously forested land has the potential to drastically change an area. It can remove previous biota. For example, the area we are observing was once forested similarly to the neighboring River View Natural Area. Now, there are only a few local trees. For the most part, the vegetation within our site consists of plants placed by people for aesthetic reasons or gardening. What we set out to find was what diversity of coverage, if any, exists within the canopy and ground coverage of an urban residential neighborhood in Portland, Oregon.
Procedure
Like last week, we walked to the house on 9633 S.W. Corbett lane. This time, we went directly to the centroid as we had already established that last week. We found the tallest object within the site to be a tree that was located about 21 meters north of our centroid. We found the height of the tree by establishing a line of sight with a clinometer and using the percentage of the angle to calculate the trees height. We added my eye level height because it is unaccounted for in the clinometer angle. Next, we set out to survey the canopy and ground coverage in a 30×30 square within the center of our site. To do this one of us had to walk 30 meters along set diagonals observing the canopy and ground coverage while the other took notes. Due to limitations of private property in our site we decided to establish our diagonals pointing roughly in the four cardinal directions. We could only go all 30 meters in two of the four diagonals since parts of the other two landed on private property that we did not have access to.
Analysis
We found that our site fell into the MUC 91 classification. This means that our site is an urban residential zone where greater than 50% of the area is urban residential property. The tallest object was a 28 meter high coniferous tree in the yard across from where we placed our centroid. 48% of our site had canopy coverage, with the most coverage of the being deciduous trees (38%). The ground was mostly uncovered, with only 18% green ground coverage and no brown ground coverage. There were some unique/nonnative plants as some of the homeowners in the site planted them.
Results
Tallest object: 28 meters
Total observations: 61
Canopy cover: 48%
Tree cover: 43%
Shrub cover: 3%
Evergreen cover: 7%
Deciduous cover: 38%
Ground Cover: 18%
Green ground cover: 18%
Graminoid cover: 0%
Forb cover: 0%
Shrub cover: 13%
Mini-shrub cover: 3%
Other (moss): 2%
Brown ground cover 0%
No Ground Cover: 82%
Discussion
Our results seem to show what would be expected for a previously forested residential area in this region. There were some native plants, like the coniferous trees. The most plant diversity came in the front yard of the house at 9633 S.W. Corbett lane. They have a well manicured garden with many different plants of all sorts. This was almost certainly done for aesthetic reasons. Most of the ground in the 30×30 square was not covered because we were walking on the paved road. It would seem that most of the diversity in plant life that exists in a residential area like this is up to the owners of the properties. They can choose to groom their land like the yard where our centroid is place. They can also choose to leave native vegetation untouched, like the tree in the yard across from the centroid. However, in some instances large native trees like this may belong to the city which could explain why it still stands. It will be valuable to compare the results of our site with those of sites in other areas to see how different types of land usage and development can affect the coverage of those areas.
Simon's Site 