Joint responses of vegetation and mammal communities to climate change since the Last Glacial Maximum
We are investigating mammal, vegetation, and climatic dynamics throughout the late Quaternary (from 21 thousand years ago to the present), in order to test hypotheses about whether the formation of novel floral and faunal communities was driven by climate change.
This project has three main components:
1) Chronology revision
Goal: update the fossil sites so their chronologies are as accurate as possible, with quantifiable uncertainty.
Figure 1. Benchmark (red) and other (gray) sites, for the period 10.5 to 14.5 thousand years ago. Over 400 pollen cores span the crucial Bølling-Allerød and Younger Dryas periods, yet less than 30 sites meet our criteria for benchmark sites.
2) Generalized Dissimilarity Models (GDMs) of community change
Main questions: Are no-analog mammal and vegetation communities synchronous in space and time? What aspects of climate drive their formation?
Figure 2. Spatial community dissimilarity (top row) predicted by GDM and summer temperature (middle row) at 14, 11, and 7 thousand years ago. The corresponding GDM functions of community dissimilarity along the summer temperature gradient is at the bottom, with three locations along the gradient indicated. From Blois et al, in review.
3) Biome reconstruction.
Main question: Can we use mammal fossils and trait data to reconstruct present and past biomes?
- We are currently developing a method to define present-day biomes based on mammal functional types.
- Once we have validated this method, we will use it to reconstruct past biomes and compare mammal and pollen-based biome reconstructions.
- Additional collaborators include Catherine Badgley
Blois, J.L., Williams, J.W., Grimm, E.C., Jackson, S.T., & Graham, R.W. (2011). A methodological framework for assessing and reducing temporal uncertainty in paleovegetation mapping from late-Quaternary pollen records. Quaternary Science Reviews 30: 1926-1939.
Blois, J.L., Williams, J.W., Fitzpatrick, M.C., Ferrier, S., Veloz, S., He, F., Liu, Z., Manion, G., and B. Otto-Bliesner (submitted, Ecography). Modeling the climatic drivers of vegetation compositional dissimilarity since the Last Glacial Maximum.
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