I drank the heterogeneity punch during my days as a graduate student. Ecologists use the term heterogeneity to describe the notion that variability in the landscape benefits species as a whole. There are many research projects in the Great Plains that demonstrate this principle. Variability in height/density structures, ground cover, nutrient pools, plant composition, and other factors provides opportunities for organisms to obtain food, protection, and reproduction habitat needs within their home ranges. This variability supports greater biodiversity on a multitude of scales. Recently, I learned about some forthcoming research on both quail and prairie chickens that documents the need for variability for protection from heat.
Places where animals can escape hot or cold temperatures are calledthermal refugia. In grassland habitat, shade opportunities can be limited. Thermal refugia for quail and prairie chickens include tallgrass, shrubs, and adjacent trees (quail use trees, but prairie chickens avoid them). The birds in the study I read demonstrated a preference for shade in the heat of the day, which makes perfect sense. Even humans have the same tendency, whether it’s napping under the shade of a mature mango tree in the heat of the day or heading inside to the conditioned air. The role of fire in this scenario is to create or maintain the habitat variability so the right mix of shade producing plants is available without sacrificing other equally important elements of the habitat.