PARENT SESSION
Contributed Oral Session 49: Climate and Vegetation Dynamics
Tuesday, August 9, 8:00 AM - 11:30 AM, Meeting Room 520 C, Level 5, Palais des congrès de Montréal
Higher taxa as environmental predictors for modern and fossil plant communities.
Boyle, Brad*,1, Enquist, Brian1, Meyer, Herb2, 1 University of Arizona, Tucson, AZ, USA2 Florissant Fossil Beds National Monument, Florissant, CO, USA
ABSTRACT- We used a large dataset of temperate and tropical forest inventories, compiled from the online database SALVIAS, to test the effectiveness of higher taxa as predictors of climate for modern and fossil plant assemblages. We performed weighted-averaging partial least squares regression (WAPLS) on a training set of 121 modern forest inventories to develop taxonomically-based models of total annual precipitation, mean annual temperature, and variance of mean monthly temperature. Presence-absence of genera and families was used to permit comparison with fossil data. For a test dataset of 121 modern inventories, R2 values for predicted versus observed climatic values range from 0.75-0.82, indicating a moderately strong relationship between higher taxonomic composition and climate. When applied to the Florissant fossil flora of Colorado (late Eocene, 34 MYA), our taxonomically-trained model estimated values of temperature and precipitation equivalent to a modern-day wet middle-elevation forest at warm temperate to subtropical latitudes. This result was corroborated by the results of both cluster analysis and non-metric multidimensional scaling of higher taxonomic composition, which placed Florissant as taxonomically intermediate between the cloud forests of northeastern Mexico and the deciduous broad-leaved forests of the eastern United States. Despite the presence of a some non-analog elements, Florissant showed a high degree of concordance at higher taxonomic levels with extant forests. The observed agreement between taxonomic composition and climate suggests that many physiological and evolutionary traits related to environmental tolerance are highly conserved within major lineages. Such conservatism underlies the effectiveness of higher taxa as environmental predictors for both modern and fossil assemblages.
Key words: climate, calibration, paleoecology, vegetation