RELATIONSHIPS  OF  TREE  SPECIES  TO   ENVIRONMENTAL   FACTORS   IN
PRESETTLEMENT FORESTS IN THE LA CROSSE, WI AREA

Nicole M. Hartz 1, 2 and Robin W. Tyser 1, 2.
1 U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, 
WI 54603; and 2 River Studies Center, University of Wisconsin-La Crosse, WI 54601.

Recent investigations have used records from the pre-1850 General Land Office (GLO) 
survey to reconstruct vegetation patterns in the Upper Mississippi River (UMR) valley 
that existed in the presettlement era.  These studies suggest that present forests are 
more closed than presettlement forests and more dominated by single species.  In 
addition, they have documented the profound effects of impoundment and 
urbanization on forest in the UMR valley.  Questions that remain to be addressed 
include roles that disturbance, including fire and flooding, played in the structure and 
regeneration of presettlement forests in the UMR floodplain.  In addition, relationships 
of presettlement forests to important environmental factors such as slope and 
elevation have not been well defined.  In this study, we use a geographical 
information systems (GIS) approach to assess distribution patterns of several tree 
species, including ash (Fraxinus spp.), maples (Acer spp.), and oaks (Quercus alba, Q. 
velutina, and Q. macrocarpa), that were commonly recorded by GLO surveyors in the 
La Crosse, WI area.  Spatial data for tree species were derived from section and 
quarter section information provided by the Wisconsin DNR and from witness tree 
data transcribed from GLO records.  Spatial data for environmental factors (slope, 
aspect, and elevation) were derived from a digital elevation model.  Preliminary 
inspection of our results suggests that important differences exist among species with 
respect to these environmental factors.  Further analyses will clarify these patterns 
and consider the possible role that fire played in maintaining floodplain forests.

Keywords:  presettlement forests, Mississippi River, GIS, DEM, disturbance
_________________________________________________________________________________






































                           1