PREVALENCE OF WOOD CHARACTERS IN EASTERN NORTH-AMERICA - WHAT CHARACTERS ARE MOST PROMISING FOR INTERPRETING CLIMATES FROM FOSSIL WOOD

The frequency of wood-anatomical characters in the eastern North America dicotyledonous tree flora shows spatial variance that can be related to climate (40% of the variation in 18 characters is explained by temperature and precipitation). Percent of taxa with rings varies with mean annual temperature, but the relationship is weak and the difficulties in making determinations as to presence or absence of rings make this character a problematic climatic indicator. Significant climate sensitivity is seen among characters pertaining to: a) vessel size and density (in diffuse-porous woods); 2) vessel arrangement; 3) parenchyma types; and 4) rays. Overall, the anatomical variables can be used to represent 82% of the variance in total precipitation and 91% of the variance in mean annual temperature within the study area. These results demonstrate the possibility of deriving a multivariate representation of the response of wood to climate that will be useful in climate reconstruction and comprise a source of information similar to that obtainable from leaf morphology and permitting estimates of precipitation as well as temperature.