Konza Prairie LTER - United States of America
Konza Prairie LTER
United States of America
Mixed riparian floodplain and gallery woodland
stream water chemistry
The primary research site for the Konza Prairie LTER program is the Konza Prairie Biological Station (KPBS), a 3,487-ha native tallgrass prairie preserve and research station jointly owned by The Nature Conservancy and Kansas State University. The KPBS is located in the Flint Hills of northeastern Kansas (39°05’ N, 96°35’ W), a grassland region of steep-slopes overlain by shallow limestone soils unsuitable for cultivation. The climate is continental, with mean annual precipitation of 835 mm yr-1, but high variability. KPBS is topographically complex (320 to 444 m asl), and soil type and depth vary with topography. Soils are silty clay loams, formed from thick colluvial and alluvial deposits ≥2 m in lowlands, while hillside and upland soils are shallow. Soils overlay alternating layers of limestone and shale, contributing to complex subsurface hydrology. Vegetation is primarily (>90%) native tallgrass prairie dominated by perennial C4 grasses, but precipitation is sufficient to support woody vegetation, making periodic drought, fire and grazing critical for maintaining grassland. Numerous sub-dominant grasses, forbs and woody species contribute to high floristic diversity (>600 plant species). The entire Kings Creek watershed, a USGS Benchmark Stream, is located on Konza. Hardwood forests occur along major stream courses. Several agricultural fields and restored prairies are located on site. Overall, the site is representative of native tallgrass prairie, with selected areas representing other contemporary land use practices (e.g., agriculture, restored grasslands, cattle and bison grazing).
General Characteristics, Purpose, History
Tallgrass prairies are affected by variable fire regimes, grazing pressures, and climate variability and change. As a result, the majority of research at Konza revolves around understanding how these forces alter community composition, ecological processes, and landscape heterogeneity. Konza LTER research is organized around four major themes - land-use change, climatic variability, altered nutrient cycles, and restoration ecology. The Konza site features a unique site-based, watershed-level fire and grazing experiment initiated in 1972, with complementary long-term plot-level and stream-reach experiments, and a network of sensors and sampling stations across terrestrial and aquatic systems. Fire treatments include replicate watersheds burned at 1, 2, 4, or 20 yr frequencies, bracketing historic fire frequencies and contemporary management extremes. Most watersheds are burned in spring, when large fine fuel loads and high frequency of lightning coincide, and when prescribed burning occurs regionally, but we also have replicate watersheds burned in spring, summer, fall or winter. We also manipulate fire in long-term plot-level experiments on Konza, where detailed ecological responses and mechanisms underlying effects of fire and other manipulations can be addressed. Bison were reintroduced beginning in 1987 to a 1000-ha area including replicate watersheds burned at 1, 2, 4 and 20 yr intervals to address the role of grazers and interactions with fire. Studies of cattle grazing began in 1992, and a large-scale experiment evaluating ecological responses to heterogeneous burning and cattle grazing (patch-burn rotational grazing) was initiated in 2010. In core LTER watersheds, long-term data on ANPP, plant species composition, plant and consumer populations, soil properties, and key above- and belowground processes are measured at permanent sampling stations stratified by treatment and topographic position. Effects of climate are addressed by long-term data collection under widely variable climatic conditions, and with studies that manipulate climate variables or hydrology.
The Konza Prairie (KNZ) LTER program is an interdisciplinary research program focused on ecological processes in tallgrass prairie and other mesic grasslands. Our long-term, site-based research focuses on tallgrass prairie, but cross-site and comparative studies extend the relevance of KNZ research to grasslands globally. KNZ was one of the first cohort of US LTER programs funded in 1980. Since its inception, KNZ research has focused on fire, grazing and climatic variability as three key interactive factors responsible for the origin, evolution, persistence and contemporary ecological dynamics of tallgrass prairie.The KNZ program has grown by building upon prior results, iteratively incorporating new questions and approaches. Early KNZ research addressed the effects of fire and grazing as influenced by a variable continental climate and heterogeneous landscape. KNZ LTER I (1981-1986) established long-term sampling sites and protocols, focusing on biotic responses to annual fire and fire suppression, topography and interannual climate variability. KNZ LTER II (1986-1990) encompassed a wider range of fire frequencies and broader spatial scales, and initiated studies on belowground processes. KNZ LTER III (1991-1996) incorporated bison and cattle treatments to understand how grazing interacts with fire across a landscape mosaic, all under a variable climate. In total, LTER I-III included studies of the major abiotic (climate, fire, topoedaphic gradients, hydrology) and biotic (herbivory, competition, mutualism) factors affecting mesic grasslands, and led to a dynamic, non-equilibrium perspective of ecological patterns and processes in grasslands. In KNZ LTER IV (1996-2002), we began a new focus on impacts of global change on grassland dynamics, with relevance to understanding, managing and conserving grasslands worldwide. The impact of global changes on grasslands and grassland streams was the central theme of LTER V (2002-2008) and LTER VI (2008-2014). Research during these LTER cycles focused on responses to changes in land-use including altered fire and grazing regimes and grassland restoration, changes in land-cover and invasive species, climate change, and altered biogeochemical cycles. Our current LTER VII (2014-2020) grant builds on a 30-yr foundation of research that includes decadal-scale experiments and measurements to understand ecological dynamics and trajectories of change in tallgrass prairie, with new complementary studies to investigate mechanisms underlying sensitivity and resilience of grasslands to global change.
Affiliation and Network Specific Information