KPRNA is representative of pristine (unplowed) tallgrass prairie in the Flint Hills of eastern Kansas. The distinctive topography and underlying shale and limestone geology of the Flint Hills region of eastern Kansas and Oklahoma (50,000 km2) provides one basis for regional studies in this grassland ( Figure 1). Although the Flint Hills and KPRNA are located near the western, more xeric, edge of the original extent of tallgrass prairie (Figure 2), average annual precipitation and net primary productivity in this region are still substantially higher than in other North American grasslands. At KPRNA, vegetation is dominated by warm-season (C4) grasses, but there is a diverse assemblage of C3 forbs and oak-dominated gallery forests line stream channels. Belowground productivity is high, and soils of these grasslands are characterized by large stores of organic C and N. Aquatic habitats include spring-fed seeps and intermittent streams, with relatively few permanently flowing surface waters.
The most common land management practice in the Flint Hills is grazing by domestic livestock. Our research program at KPRNA includes comparative studies of the effects of grazing activities by native ungulates (North American bison) and domesticated cattle. In an effort to extend the regional applicability of our research, KPRNA has established satellite sites in SE Nebraska (9-mile Prairie), east-central (The Land Institute) and southern Kansas (The Ross Natural Area), and NE Oklahoma (The Pawhuska Preserve). These sites encompass a gradient of climatic conditions which characterize the western edge of extant tallgrass prairie, and will allow us to address the effects of these climatic gradients, as well as potential directional climate changes, on patterns and processes within these grasslands. An important component of this regionalization activity is the use of remotely sensed data ranging from SPOT panchromatic (10 m resolution) to AVHRR (1 km resolution) images to assess regional patterns and variability in key ecosystem processes.
In a broader context, the regional applicability of Konza Prairie LTER research may be extended to encompass ecological processes in North American grasslands that range from the remnant tallgrass prairies extending from the US-Canadian border to Texas, the short- and mixed-grass prairies of the Great Plains, and the desert grasslands of the southwest (Figure 2). A unifying feature of these grasslands is the historical lack of woody plant species as dominants. This cannot be explained by climatic factors alone since drier/wetter and cooler/warmer ecosystems are dominated by woody plants. Instead, we propose that interactions among fire, climatic variability and grazing activities, to varying degrees in each system, are critical for the maintenance of the structure and function of these grasslands. In this regard, the monitoring and manipulative experiments at Konza Prairie can provide the insight necessary for understanding key ecological processes across grasslands, as well as directly comparable data for ecological studies in a wide array of specific grassland types both within and outside the LTER network.
