Plants in Lapland and the future
of species distribution modeling
Lucas Harris
Goal
• Does including plant-plant interactions
improve species distribution models?
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•
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Introduction to species distribution models
Study site and methods
Preliminary results
Future directions
Species
distribution
models
Sormunen et al. 2011
1.
2.
3.
4.
Studying where a species is found
Modeling where it is found
Evaluating the model
Predicting distributions in new areas or new
scenarios
New developments
• Goals are changing
• New model types and approaches (Elith et al.
2006, Marmion et al. 2009)
• Finer scales
• Greater complexity:
– Geomorphological variables (Sormunen et al. 2011)
– Biotic interactions (le Roux et al. 2012)
– Dispersal (Boulangeat et al. 2012)
Biotic interactions
• General interest in integrating biotic
interactions (Pellissier et al. 2010, Boulangeat et al. 2012, le Roux et al. 2012)
• In the same study site, models improved
when the cover of dominant plants was added
– although adding herbivores did not improve the
model (le Roux et al., in press)
• But, a need to take a more comprehensive
look…
Study site
• Northern areas ideal
for SDMs
• Simpler systems
• Rapid climate
change
• Rapid vegetation
change (Sturm et al. 2001,
Wilson & Nilsson 2009)
Plots on Saana
Courtesy of Peter le Roux
Courtesy of Juha Aalto
Model runs
214 species modeled
3 techniques: GLMs, GAMs, and GBMs
‘Simple’ model with abiotic variables
‘Full’ model with the cover of a single species
as a variable
• 44 species tested as variables:
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•
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– 22 vascular plants
– 13 bryophytes
– 9 lichens
Example of output
Model of Betula nana with
Empetrum hermaphroditum cover
as a variable
Lovely lichens?
Competitors or habitat indicators?
Species used as predictors
How much they improve
the models
How well the predictors are
modeled
Into the future
• SDMs were created for prediction at large
scales
• Now, they are starting to reveal what drives
species distributions
• As the models become more complex,
ecological theories come under review
• Novel techniques and higher quality data will
take the models forward
For this study:
Courtesy of Peter le Roux
• Difficult to isolate effects of plant-plant
interactions
• Next steps:
– Explain effects of particular species
– Look at differences among model types and types
of plants
– Run more models to maximize improvement
Works cited
Boulangeat, I., Gravel, D., Thuiller, W. 2012. Accounting for dispersal and biotic interactions to disentangle the drivers of species
distributions and their abundances. Ecology Letters 15: 584-593.
Elith, J., Graham, C.H., Anderson, R.P., Dukik, M., Ferrier, S., Guisan, A., Hijmans, R.J., Huettmann, F., Leathwick, J.R., Lehmann, A.,
Li, J., Lohmann, L.G., Loiselle, B.A., Manion, G., Moritz, C., Nakamura, M., Nakazawa, Y., Overton, J., Peterson, A.T., Phillips, S.J.,
Richardson, K., Scachetti-Pereira, R., Schapire, R.E., Soberón, J., Williams, S., Wisz, M.S., Zimmerman, N.E. 2006. Novel methods
improve prediction of species’ distributions from occurrence data. Ecography 29: 129-151.
Marmion, M., Luoto, M., Heikkinen, R.K., Thuiller, W. 2009. The performance of state-of-the-art modeling techniques depends on
geographical distribution of species. Ecological modeling 220: 3512-3520.
Pellissier, L., Bråthen, K.A., Pottier, J., Randin, C.F., Vittoz, P., Dubois, A., Yoccoz, N.G., Alm, T., Zimmerman, N.E., Guisan, A. 2010.
Species distribution models reveal apparent competitive and facilitative effects of a dominant species on the distribution of
tundra plants. Ecography 33: 1004-1014.
le Roux, P.C., Lenoir, J., Pellissier, L., Wisz, M.S., Luoto, M. In press. Horizontal, but not vertical, biotic interactions affect finescale plant distribution patterns in a low energy system. Ecological Society of America.
le Roux, P.C., Virtanen, R., Heikkinen, R.K., Luoto, M. 2012. Biotic interactions affect the elevational ranges of high-latitude plant
species. Ecography 35: 001-009.
Sormunen, H., Virtanen, R., Luoto, M. 2011. Inclusion of local environmental conditions alters high-latitude vegetation change
predictions based on bioclimatic models. Polar Biology 34: 883-897.
Sturm, M., Racine, C., Tape, K. 2001. Increasing shrub abundance in the Arctic. Nature 411: 546-547.
Wilson, S.D., & Nilsson, C. 2009. Arctic alpine vegetation change over 20 years. Global Change Biology 15: 1676-1684.