Mapping Historical & Modern Grasslands
Reconstructing the historical distribution of Southeastern grasslands requires detective work—looking for existing remnants; sifting through early historical documents, maps, and land surveys; consulting studies of fire history, and determining the present distribution of grassland-dependent plant and animal species. There is much research still needed to accurately map our grasslands.
Paul Nelson of the Central Hardwoods Joint Venture has completed mapping tens of thousands of acres of rocky grasslands (glades) of Missouri and Arkansas.
Similar mapping efforts are urgently needed for other regions within SGI's focal area. Before we can fully address conservation of our grasslands, we have to know what remains.
Continued work is needed to search historical writings, unpublished early journals, notes by early settlers, county histories, and state and federal archives to uncover rich quotes that document and describe the early landscape of the Southeast.
SGI is working to compile quotes like the one below from Tennessee. Eventually, these will be part of an interactive geospatial database.
"The top of the mountain is...a vast upland prairie, covered with a most luxuriant growth of native grasses, pastured over as far as the eye could see, with numerous herds of deer, elk and buffalo, gamboling in playful security over these secluded plains….” (Ramsey 1853)
Place names lend important clues to historical vegetation. Many landmarks were named early in a region’s history, often dating back to first settlement.
Names such as Barren Plains, Prairie Creek, Price’s Meadow, Pleasant View, Oak Grove, Strawberry Plains, Glade Branch, Hazel Green, Meadow Creek, and Crab Orchard refer to historical grasslands.
With GIS it is now possible to query place names. Mapping these could reveal patterns to help us better understand historical locations of grasslands, especially ones not previously considered.
Mining GLO Land Survey Maps
As the western parts of the Southeast and adjacent portions of the Midwest were being settled in the early 19 century, Government Land Office (GLO) surveyors mapped areas in 1 square-mile blocks. They would make detailed notes of the landscape, vegetation, and often would map prairies.
Dr. John Barone (Columbus State University, GA) has been leading the charge to mine these old surveys and has been mapping prairies in GIS. He has completed mapping for much of Alabama, Mississippi, and Arkansas.
Witness Tree Records
Some Southeastern states used a different survey method from the GLO mapping method noted above. Instead, they surveyed individual properties and used trees or other markers to denote property boundaries. The types of trees or lack of trees can be used to infer location of historical grasslands.
Decades of work remains to be done to mine these data from state and county archives and to enter these data into geospatial databases.
The map below shows the collective distribution of about 100 rare, grassland-conservative plant species in Tennessee. It reveals striking patterns. In most cases, the clusters of specimen records closely coincides with the pre-settlement distribution of grasslands in Tennessee.
Mapping & Modeling Potential Natural Vegetation
The Central Hardwoods Joint Venture has used GIS to evaluate a number of abiotic factors (e.g. topography, slope) to model potential natural vegetation of the Interior Plateaus and Interior Highlands Physiographic Regions.
New models are needed that incorporate all of the various forms of evidence cited above (existing remnants, historical descriptions, place names, land survey records, locations of grassland plants and animals) in addition to using abiotic parameters (fire compartment size, geology, soils, degree of slope, moisture, topography, lightning strike frequency, etc.).