Uncategorized – Page 2 – Mackenzie Hoult

While continuing our study of land use cover change in the Portland area, we have started to map our data from our other labs in order to analyze change which may have occurred since 1931. Our last labs, posted here, were used to collect data from our specific site, a residential home in Collins View, as well as gain data from 11 other sites that our peers took, including Collins View, Riverview and Lewis and Clark, 4 groups in each area respectively.

For this specific lab, we took all our data which we organized in our last lab, and began adding it to ARCGIS. This is a program that can give us an aerial map view of the sites separated by color, and the field points indicated, as you can see in the base map below in figure 1. The pink indicates the RVNA area that 4 groups went to, showing one outlier as one group went slightly farther than the designated area. The orange indicating the Collins view boundary, which had 4 more groups and the red indicates the Lewis and Clark boundary which also contains all 4 groups. Once we added the three separate locations of study, we entered all the collected data we comprised last week. This data consisted of humidity, temperature, canopy cover, ground cover, and more data from the past labs. We looked at many different versions of this map by applying different layers as well as adding 3 overlaying pictures. These 3 pictures showed the same area in 1939, 1961 and 1982 respectively. This allowed us to overlay different data points found by our teams of current data, over the older maps to analyze the land cover change, as you can see below.

Starting by mapping temperature compared to canopy cover (figure 2). It’s important to note that percent canopy cover and average temperature, as illustrated in figure 2, seem to be inversely correlated as the canopy cover goes down, the average temperature rises. We suspected this in our last lab but now that we can see the data on top of each other, it is clear that the amount of tree canopy removed over the years has affected the areas temperature. We chose to focus on two data points that seemed to have visually changed the most over the years. From the archives, we were able to overlay 4 different aerial photos from the area, a 1939 photo, 61’ photo, 82’ photo and the 2018 google maps photo. We used these different photos and the 12 data points to observe the change in land use since 1939. We used the 1939 map as a base year for what we would compare all the other maps to, as thats the oldest we were able to compare to. For out site in collins view, (45.46, -122.68), land use is visibly changed from the 39 photo (figure 4)and 61(figure 5). The most significant change is the agriculture around the area, and some canopy cover, but not too significantly. The time period between 39 and 61 we see the whole area shifting into a more suburban setting. The Lewis and Clark campus also shifts a lot during this time period, as after 1934 the red area was bought in order to create Albany college. By 1939, you see can see this shift in the Lewis and Clark area. By 1961 Collins view has shifted into a larger residential area, similar to today, and Lewis and Clark has formed into a college.

RVNA, on the other hand, stays pretty consistent if you compare the 1939 photograph to the current google maps photo, there is not much canopy cover change in the area. In comparison, the two other sites canopy cover was vastly altered in the 80 year period. We noted this in our last lab as well, as the large shift in canopy cover was a larger data point for those two groups. Looking at figure 2 again, it seems like the shift in canopy cover has affected the temperature range of the areas. As you can see that the less canopy cover percentage, the larger the temperature max.

The change in canopy and ground cover could also be a concern for biodiversity in the area. From these three areas we can see how we’ve used the land and affected biodiversity potentially. As Collins view and Lewis and Clark we saw from our data, share many of the same attributes, compared to Riverview which has stayed relatively consistent. Because of this, Riverview represents how the land used to act like. As far as biodiversity is concerned, I am curious as to how these canopy and ground cover changes may be advantageous or possibly disadvantageous. To better understand the full impact on the area over the years we would need more data from additional areas to compare the effect on the environment. As well as accounts from people living in the area for a long time might aid in our research.

This Lab has to due with the previous land use cover data we recorded in the Lewis and Clark Community. As stated in our past lab, our group went to the Collins view neighborhood and recorded, temperature, humidity, canopy cover and ground cover. In order to compare our data to the larger Portland area, there were two other sites that had data collected from them, RVNA (River view natural area) and Lewis and Clark Campus. There were 4 groups for each area in order to get a wide data set for each location. After all groups collected their separate information over the past two weeks, we all entered it into the same document in order to analyze all the results. These procedures are similar to that of larger scale experiments done by Globe and others on a worldwide basis.

In the Collins View neighborhood, our site had a central tree in the backyard of a residential home. In terms of the temperature we recorded compared to the three other sites in Collins view, our temperature min and max stayed within 2 degrees of all other Collins view sites. Overall, for all 4 Collins view groups, we had an average temperature range of .8 degrees celsius, compared to the humidity range which was larger at a range of 3.9. In order to compare all the average temperatures for all three locations, you can refer to graph 1 below. All 4 averages stayed relatively close to our average, which makes sense because they are all in a close enough radius that they wouldn’t have wildly different weather and temperature patterns. Looking at humidity, in table 2 below, our site had a lower humidity then most sites by about 3 degrees celsius. RVNA was an exception though, with an additional 14 degrees celsius min humidity, while the max humidity stayed within 1-2 degrees celsius from our Collins view location. Overall the three locations lay in fairly close vicinity to one another (a one mile radius) so the average data points all were very similar.

Graph 1

Average Humidity

Table 2

River View	61.475
Collins View	59.025
Lewis and Clark	57.65

The largest changes we saw in the data were from RVNA compared to Collins and River view. In terms of canopy cover, as you can read from the table below, Collins and River view stayed in between 40-47% canopy cover, where as RVNA almost doubled their percentage at 82%. This would make sense as River and Collins view tend to be more residential areas who have had a lot of manmade change over the years, depleting the amount of overall tree coverage. Whereas RVNA is an open, relatively untouched area, that has big tree and forest areas. RVNA also had the lowest temperature max by 4 degrees celsius which could be due to the large amount of canopy cover in the area.

Average Percent Canopy cover

Table 3

Collins view	47.5
RVNA	82.6875
Lewis and Clark	40.2

RVNA, unlike Collins and River view, has not been altered as much since 1939. As you can see from the aerial photograph, the residential areas have had their canopy’s altered for buildings, homes, roads etc. We can see this change from the temperature, canopy cover and humidity data as comparing them shows how different a change in land use can affect a small area. Lewis and Clark compared to Collins view are very similar in that they have both been altered since 1939, and they show that in the data as they both have similar data sets. In order to really differentiate between the land use of Collins View and Lewis and Clark, additional data points should be taken. Additionally, more information on how the land has changed since 1939 between the three locations could help us better interpret our data.

Category: Uncategorized

Land Use Cover Change in Greater Portland area IV

Land Use Cover Change in the Greater Portland Area part III