1. Monitoring Treeline Dynamics with LANDSAT imagery: Are Forests Climbing Mountains?
Chenyang Wei & Adam M. Wilson
University at Buffalo
Presented at 4th Annual Graduate Workshop on Environmental Data Analytics
Boulder, CO ~ June 12, 2017

2. What is treeline?
Upper altitudinal (or latitudinal) line of continuous trees with a minimum height of between 2 and 5 meters
(Credit: Google Earth)
Often fragmented and stretched over the transition zone between forest and tundra in high altitude (or latitude) areas

3. How to monitor its dynamics?
Existing methods: detecting the variation of treeline location
1) Identifying the exact location of treeline could be very difficult
2) Detection results could be greatly affected by outliers
In this project: monitoring vegetation activity in the areas along treeline
Step 1 - Identifying an approximate location of treeline
Step 2 - Determining the transition zone between forest and tundra
Step 3 - Monitoring vegetation dynamics in the transition zone

4. Treeline identification
Low-NDVI Area (< 25%)
Treeline identification
Intermediate-NDVI Area (25 ~ 75 %)
High-NDVI Area (> 75 %)
(Simms & Ward, 2013)

5. Transition zone determination

6. Rocky Mountain National Park
Case studies
For each 30-m pixel
Glacier National Park
(640,462 pixels)
Rocky Mountain National Park
(1,125,497 pixels)

7. Positive trend: 59.25%
Positive trend: 82.25%

8. Rocky Mountain National Park
Case studies
Glacier National Park
Rocky Mountain National Park

9. Next step: global treeline + spatio-temporal model?
Global alpine and montane zones (Körner et al., 2011)

10. References
Fissore, V., Motta, R., Palik, B., and Mondino, E.B., The role of spatial data and geomatic approaches in treeline mapping: a review of methods and limitations. European Journal of Remote Sensing, : p
Harper, K.A., Danby, R.K., De Fields, D.L., Lewis, K.P., Trant, A.J., Starzomski, B.M., Savidge, R., and Hermanutz, L., Tree spatial pattern within the forest-tundra ecotone: a comparison of sites across Canada. Canadian Journal of Forest Research-Revue Canadienne De Recherche Forestiere, (3): p
Holtmeier, F.-K., Mountain timberlines : ecology, patchiness, and dynamics. 2nd ed. Advances in global change research, Dordrecht: Springer. x, 437 p.
Körner, C., Paulsen, J., and Spehn, E.M., A definition of mountains and their bioclimatic belts for global comparisons of biodiversity data. Alpine Botany, (2): p. 73.
Simms, É. L.,and Ward, H. Multisensor NDVI-based monitoring of the tundra-taiga interface (Mealy Mountains, Labrador, Canada). Remote Sensing, (3),

11. Thank you
Chenyang Wei
Adam M. Wilson
Website:

12. Which factors affect treeline dynamics?
Category
Variable
Coefficient
(Intercept)
4.552e-04***
Climate
(over growing season)
Precipitation trend
2.916e-05***
Max. temperature trend
8.059e-05***
Min. temperature trend
-1.295e-04***
Topography
Elevation
4.863e-05***
Slope
-2.788e-05***
Curvature
2.052e-07
Aspect (east-westness)
-3.936e-04***
Aspect (north-southness)
-5.391e-05***
Relative elevation
3.215e-05***
Solar irradiation
-1.657e-04***
Other
Zone
4.000e-05***
Tree cover
-2.730e-05***
Soil type
1.111e-04***
Which factors affect treeline dynamics?

13. Rocky Mountain National Park
Case studies
Glacier National Park
Rocky Mountain National Park