Cross Timbers and Prairies 
The Cross Timbers and Prairies region is a transitional bioregion for many plants and animals whose ranges extend northward into the Great Plains or eastward into the forests. This region was named by early settlers who traversed belts of oak forest crossing strips of prairie grassland.
The average annual rainfall range is 28-40 inches per year. Upland soils are light colored, acidic sandy loam or sands. Bottomland soils may be light brown to dark gray and acidic with textures ranging from sandy loams to clays. The landscape of the region is gently rolling to hilly and elevations range from 300 to 800 feet above sea level. The region can be described as oak savannah where patches of oak woodland are interspersed with grassland.
A significant amount of information regarding the cross timbers woodlands can be found at the The Ancient Cross Timbers Project web site.
Blackland Prairie 
The Blackland Prairies region is named for the deep, fertile black soils that characterize the area. Blackland Prairie soils once supported a tall grass prairie dominated by very tall-growing grasses such as big bluestem, little bluestem, indiangrass, and switchgrass. Because of the fertile soils, much of the original prairieland was plowed by settlers to produce food and forage crops. Today it serves the same purpose and little of the prairie in its original form remains.
The average annual rainfall ranges from 28-40 inches. Typically, soils are uniformly dark-colored alkaline clays, often referred to as "black gumbo", interspersed with some gray acidic sandy loams. The landscape is gently rolling to nearly level. Elevations range from 300 to 800 feet above sea level.
Resources
Links to resources and additional information regarding North Texas biodiversity and habitat management can be accessed from the top navigation menu.
- Doug G. Pierson
Credits:
Mary G. Ramos (editor), "2000-2001 Texas Almanac", The Dallas Morning News., 2001
Gary L. Graham, Texas Wildlife Viewing Guide, Falcon Press, 1992
Dr. Harry Williams, Associate Professor of Geography, University of North Texas,