Landscape Change Through Before-and-After Photos

Julie Fortin, M.Sc. Candidate, University of Victoria

J. Fortin was also a 3MT participant. Watch the presentation here.

Keywords: landscape change, repeat photography, mountains, forest, biodiversity

Let’s start off with an exercise. Take a few seconds to spot the differences between the images on the left and the images on the right (Figure 1). What did you notice? What has changed? I’ll give you the answer below. First, let’s find out where these pictures came from.

About 100 years ago, when European settlers were making their way west across Canada, there were surveyors hired by the government to systematically take pictures of the mountains and use those pictures to create topographic maps (1–3). Luckily for me, the pictures have been preserved in archives for the last century, so they still exist today.

Figure 1: Landscape change through before-and-after pictures

My Master’s research involved going back to the exact same peaks as those surveyors, retaking the exact same photos, and then comparing them to see what has changed.

A question I often get asked is: “How close do you actually get to where the historical surveyors stood?” I tested this by running an experiment on Mount Tolmie in which I took pictures, moved the camera around, took more pictures, and measured my alignment accuracy, and I found that I can often get to within about 1 metre of where they stood.

Now we know where these pictures came from, and we know that I took the repeats from the right spot, so they line up well. Let’s get back to our game of spot the differences.

The main thing you probably noticed is that there’s a lot more dark green, or coniferous forest cover, on the right. This is a trend that I noticed across all the images in my study area (the Willmore Wilderness Park in Alberta): forest cover has increased. This might seem counterintuitive to some, but in my study area, they suppress wildfire (4,5), there is no timber harvesting (6–8), and because of climate change, treeline is creeping higher up slopes (9,10), so it makes sense that there is more forest now than in the past.

Another thing you probably noticed is that there’s less yellow, and yellow represents alpine meadows. In fact, in my study area, every category except for forest has decreased.

Okay, so we’ve spotted the differences. Why do they matter?

They matter because the landscape in these pictures provides habitat for a variety of wildlife species. You might be thinking: “Oh, well that’s great! There’s more forest now than in the past!” And indeed, that is great – for forest-loving species. But there are other species that are rare and better adapted to rare habitat types (like alpine meadows), and I found that those species have been negatively impacted by the homogenization of this landscape.

My point is that by looking at before and after pictures, we can understand a lot about how human activities and climate change are impacting the landscape, and hopefully, make more informed decisions about biodiversity conservation.

References

1.     Bridgland MP. Photographic Surveying. Ottawa, Ont.: Canada Department of the Interior. Topographical surveys branch.; 1924.

2.     Bridgland MP. Photographic surveying in Canada. Geogr Rev. 1916;2(1):19–26. doi:10.2307/207459.

3.     MacLaren IS, Higgs E, Zezulka-Mailloux G. Mapper of Mountains: M.P. Bridgland in the Canadian Rockies, 1902-1930. University of Alberta; 2005. 314 p.

4.     Edgecombe AH. The last patrol: Willmore Wilderness Park management report. Edmonton, AB: Alberta Forest Service; 1982.

5.     Keane RE, Ryan KC, Veblen TT, Allen CD, Logan J, Hawkes B. Cascading effects of fire exclusion in Rocky Mountain ecosystems: a literature review. USDA Forest Service; 2002 p. 24. (Rocky Mountain Research Station). Report No.: RMRS-GTR-91.

6.     Fisher JT, Bradbury S, Anholt B, Nolan L, Roy L, Volpe J, et al. Wolverines (Gulo gulo luscus) on the Rocky Mountain slopes: Natural heterogeneity and landscape alteration as predictors of distribution. Can J Zool. 2013 Oct 1;91:706–16. doi:10.1139/cjz-2013-0022.

7.     Fisher JT, Anholt B, Volpe JP. Body mass explains characteristic scales of habitat selection in terrestrial mammals. Ecol Evol. 2011 Dec 1;1(4):517–28. doi:10.1002/ece3.45.

8.     Mucha D. Acquiring an Improved Understanding of Willmore Wilderness Park Visitors, Alberta, Canada [Internet] [M.A.]. [Edmonton]: University of Alberta; 2013. Available from: https://era.library.ualberta.ca/items/100a021b-1516-4d76-8c23-fed4b8cda4c5

9.     Falk J. Historical Landscape Change in Remote Mountainous Parks: Management Challenges Observed Through a Repeat Photographic Lens [Internet] [M.A.]. [Victoria]: University of Victoria; 2014. Available from: https://dspace.library.uvic.ca//handle/1828/5305

10.     O’Neill NA. Transboundary Regional Planning Collaboration for Climate Change Adaptation: A Case Study of Jasper National Park, Mount Robson Provincial Park, and Willmore Wilderness Park. [Internet]. University of Waterloo; 2011. Available from: https://uwspace.uwaterloo.ca/handle/10012/5931