@inbook {KNZ001114,
	title = {Ecological consequences of the replacement of native grassland by Juniperus virginiana and other woody plants},
	booktitle = {Ecological Studies Vol. 196, Western North American Juniperus communities: A dynamic vegetation type},
	year = {2008},
	pages = {156 -169},
	publisher = {Springer-Verlag, NY},
	organization = {Springer-Verlag, NY},
	abstract = {<p>Although grasslands have been altered by humans for thousands of years (Wedel 1961; Bond et al. 2003), the loss of grassland as a result of anthropogenic activities has increased dramatically over the past 150 years. When Europeans first settled the Midwest and Great Plains, the greatest threat to native grasslands was the conversion of the most highly productive of these ecosystems to row-crop agriculture (Samson and Knopf 1994). Later, with improvements in soil moisture management and irrigation technology, even low-productivity grasslands were plowed. Today, those remnants of the most productive grasslands that escaped the plow are threatened, as are most of Earth\&rsquo;s ecosystems, by a variety of global change phenomena (Vitousek et al. 1997), with the invasion and expansion of woody species into grasslands one of the greatest of these threats. The replacement of grasslands by shrubland, woodland, and forest is a concern not only in the United States but worldwide (Archer et al. 1988; Van Auken 2000; Roques et al. 2001; Silva et al. 2001). Species of woody plants that invade grasslands may include both native plants which previously existed as more minor components of the ecosystem as well as alien species (Bragg and Hulbert 1976; Harcombe et al. 1993).</p>},
	keywords = {LTER-KNZ},
	doi = {10.1007/978-0-387-34003-6_8},
	url = {https://link.springer.com/chapter/10.1007\%2F978-0-387-34003-6_8},
	author = {Alan K. Knapp and McCarron, J.K. and Silletti, A.M. and Hoch, G.A. and Heisler, J.L. and Lett, M.S. and John M. Blair and J. M. Briggs and M.D. Smith},
	editor = {Van Auken, O.W.}
}
@article {KNZ00960,
	title = {An ecosystem in transition: causes and consequences of the conversion of mesic grassland to shrubland},
	journal = {BioScience},
	volume = {55},
	year = {2005},
	pages = {243 -254},
	abstract = {Woody plant expansion is one of the greatest contemporary threats to mesic grasslands of the central United States. In this article, we synthesize more than 20 years of research to elucidate the causes and consequences of the ongoing transition of C4-dominated grasslands to savanna-like ecosystems codominated by grasses and woody plants. This transition is contingent on fire-free intervals, which provide the opportunity for recruitment both of new individuals and of additional shrub and tree species into this grassland. Once shrubs establish, their cover increases regardless of fire frequency, and infrequent fires accelerate the spread of some shrub species. This process has resulted in a new dynamic state of shrub{\textendash}grass coexistence in the mesic grasslands of North America. Important consequences of this shift in plant life-form abundance include alterations in plant productivity, species diversity, and carbon storage. Without drastic measures such as mechanical removal of shrubs, it is unlikely that management of fire and grazing regimes alone will be sufficient to restore historic grass dominance in these ecosystems.},
	keywords = {LTER-KNZ, fire, Grasslands, Grazing, tallgrass prairie, woody vegetation},
	doi = {10.1641/0006-3568(2005)055[0243:AEITCA]2.0.CO;2},
	author = {J. M. Briggs and Alan K. Knapp and John M. Blair and Heisler, J.L. and Hoch, G.A. and Lett, M.S. and McCarron, J.K.}
}
@article {KNZ001024,
	title = {Indicators of plant species richness in AVIRIS spectra of a mesic grassland},
	journal = {Remote Sensing of Environment},
	volume = {98},
	year = {2005},
	pages = {304 -316},
	abstract = {Hyperspectral imagery of the Konza Prairie Biological Station in northeastern Kansas was used to evaluate upwelling spectral radiance, prairie spectral reflectance and band ratios of each as potential indicators of vascular plant species richness in a mesic grassland. The extent to which spatial variability in these parameters related to plant species richness also was investigated. A 224 channel hyperspectral data cube acquired in June 2000 by the Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) provided complete coverage of the 400{\textendash}2500 nm range at approximately 10 nm per channel. After band deletions accounted for detector overlap and strong atmospheric attenuation features, 176 bands were retained for analysis and spanned the 404{\textendash}2400 nm range. Prairie reflectance was estimated via radiative transfer modeling and scaling to a library spectrum of highway construction material. Data were sampled from pixels having a 19 m ground sample distance (GSD) to represent each of 93 vegetation sampling transects. Reflectance and radiance at mid-infrared wavelengths (e.g., 1553 nm), and band ratios that were based on atmospheric windows in the red, near-infrared and mid-infrared spectra estimated species richness to within 6 to 7 species per transect. The 856 to 780 nm radiance or reflectance ratio yielded maximum adjusted coefficients of determination (r2) of approximately 0.4 in regressions with richness when data from bison-grazed and ungrazed areas were combined. These regressions remained significant (p <= 0.001) when only ungrazed areas were assessed although r2 reduced to approximately 0.2. Richness was related significantly also to the 433 to 674 nm reflectance ratio for grazed-plus-ungrazed and ungrazed-only areas. In contrast, the effectiveness of the 433 to 674 nm radiance ratio was reduced by atmospheric backscatter. Species richness did not correlate strongly or consistently with transect spatial variability (coefficient of variation or range) in radiance, reflectance or band ratio value, apparently as a consequence of the relatively small area sampled for each transect (approximately 0.5 ha). Relationships between richness and prairie spectral features were explained by the influence of soil exposure on both parameters. Richness and estimated soil exposure tended to increase from ungrazed lowlands, to ungrazed slopes, to ungrazed uplands to grazed areas. Remotely sensed estimates of soil exposure may be particularly useful in addressing plant species richness on grazed grasslands owing to an overall similarity in spectral reflectance among dominant plant species.},
	keywords = {LTER-KNZ, AVIRIS, Biodiversity, Bison grazing, grassland, Hyperspectral, Plant species richness, Radiance, Reflectance, Soil exposure, Spatial variability, Spectral mixing},
	doi = {10.1016/j.rse.2005.08.001},
	author = {Carter, G.A. and Alan K. Knapp and Anderson, J.E. and Hoch, G.A. and M.D. Smith}
}
@article {KNZ0011,
	title = {Assessing the rate, mechanism and consequences of conversion of tallgrass prairie to Juniperus virginiana forest},
	journal = {Ecosystems},
	volume = {5},
	year = {2002},
	pages = {578 -586},
	abstract = {We assessed the determinants and consequences of the expansion of Juniperus virginiana L. (red cedar) populations into central US grasslands using historical aerial photos and field measurements of forest extent, tree growth, fire-induced mortality, and responses in herbaceous species diversity and productivity. Photos from northeast Kansas dating back to 1956 indicate that native tallgrass prairie can be converted to closed-canopy red cedar forest in as little as 40 years (a 2.3\% increase in forest cover per year). Mean tree density in 21 forested sites ranged from 130 to 3500 trees/ha, with most sites at more than 800 trees/ha. In younger stands, maximum growth rates of individual red cedar trees exceeded 20 cm/y in height. Land management practices were critical to the establishment and growth of red cedar forest. Grazing reduced the fuel loads by more than 30\% in tallgrass prairie. Based on measurements of mortality for more than 1800 red cedar trees, fire-induced mortality in grazed areas averaged 31.6\% versus more than 90\% at ungrazed sites. When tallgrass prairie was converted to red cedar forest, herbaceous species diversity and productivity were drastically reduced, and most grassland species were virtually eliminated. Consequently, community structure shifted from dominance by herbaceous C4 species to evergreen woody C3 species; this shift is likely to be accompanied by alterations in carbon storage and other ecosystem processes in a relatively short time period. Here we present a conceptual model that integrates the ecological and socioeconomic factors that underlie the conversion of grassland to red cedar forest.},
	keywords = {LTER-KNZ, fire, forest expansion, Grazing, Juniperus virginiana, land-cover change, land-use change, red cedar, tallgrass prairie},
	doi = {10.1007/s10021-002-0187-4},
	author = {Hoch, G.A. and J. M. Briggs and Johnson, L.C.}
}
@phdthesis {KNZ00887,
	title = {Patterns of mechanisms of eastern redcedar (Juniperus virginiana) expansion into tallgrass prairie in the Flint Hills KS},
	volume = {PhD Dissertation},
	year = {2000},
	pages = {1 -106},
	school = {Kansas State University},
	type = {Ph.D. Thesis},
	address = {Manhattan, KS},
	keywords = {LTER-KNZ, tallgrass prairie},
	author = {Hoch, G.A.}
}
@proceedings {KNZ00693,
	title = {Expansion of eastern red cedar in the northern Flint Hills, Kansas},
	year = {1999},
	pages = {9 -15},
	publisher = {University of Nebraska at Kearney},
	address = {Kearney, NE},
	keywords = {LTER-KNZ},
	author = {Hoch, G.A. and J. M. Briggs},
	editor = {Springer, J.T.}
}
