00602nas a2200157   4500008004100000245009100041210006900132260002400201300001300225100001900238700001700257700001800274700002000292700002000312856011200332       2008                        eng d00aBiogeochemical changes associated with Juniperus virginia encroachment into grasslands0 aBiogeochemical changes associated with Juniperus virginia encroa  bSpringer-Verlag, NY  a170 -1871 aMcKinley, D.C.1 aNorris, M.D.1 aJohnson, L.C.1 aBlair, John, M.1 aVan Auken, O.W.  uhttp://knz.lternet.edu/content/biogeochemical-changes-associated-juniperus-virginia-encroachment-grasslands03122nas a2200145   4500008004100000245009900041210006900140300001300209490000800222520257200230100001702802700002002819700001802839856011902857       2007                        eng d00aAltered ecosystem nitrogen dynamics as a consequence of land cover change in tallgrass prairie0 aAltered ecosystem nitrogen dynamics as a consequence of land cov  a432 -4450 v1583 aIn recent decades, substantial areas of North American tallgrass prairie have been lost to the establishment and expansion of woodlands and forests, including those dominated by eastern redcedar (Juniperus virginiana). This shift in dominant plant life form, from C4 grasses to coniferous trees, may be accompanied by changes in productivity, standing stocks of biomass and nutrients and biogeochemical cycles. The goal of this study was to quantify and compare major pools and fluxes of nitrogen in recently established (≤ 80 y) redcedar forests and adjacent native grasslands. Three former grassland sites in the Flint Hills region of Kansas that developed closed-canopy redcedar forests in the recent past were paired with adjacent grassland sites on similar soil type and topographic position (n  =  3 sites/land cover type), and selected soil and plant nitrogen pools and fluxes were measured in replicate plots (n  =  6/site) along transects in each forest or grassland site over a 20-mo period. We found few significant differences in median soil inorganic N pools or net N mineralization rates between the forest and grassland sites, though there was a trend for greater concentrations of inorganic N in grassland sites on most sample dates, and cumulative growing season net N mineralization averaged 15% less in forest sites (14.3 kg N·ha−1·yr−1) than in grassland sites (16.9 kg N·ha−1·yr−1). Mean aboveground plant productivity of forest sites (9162 kg ha−1 yr−1) was about 2.5× greater than that of comparable grasslands (similar soils and topographic position), in spite of similar levels of soil N availability. This resulted in an ecosystem-level nitrogen use efficiency (ANPP∶litterfall N) in forests that was more than double that of the grasslands they replaced. Additional changes in N cycling associated with redcedar forest development included large accumulations of N in aboveground biomass and transfer to the forest floor via litterfall; redcedar aboveground biomass contained 617 kg N/ha, forest floor litter N was 253 kg N/ha, and litterfall N flux was 41 kg ha−1·yr−1. These are substantial increases in aboveground biomass N accumulation, surface litter N inputs, and surface litter N accumulation compared to the native grasslands characteristic of this region. These fundamental shifts in ecosystem patterns and processes have the potential to alter regional biogeochemistry and both nitrogen and carbon storage throughout areas of the eastern Central Plains where coverage of redcedars is increasing.1 aNorris, M.D.1 aBlair, John, M.1 aJohnson, L.C.  uhttp://knz.lternet.edu/content/altered-ecosystem-nitrogen-dynamics-consequence-land-cover-change-tallgrass-prairie02091nas a2200169   4500008004100000245013900041210006900180300001500249490000700264520143200271653002201703100001701725700002001742700001801762700001701780856012401797       2001                        eng d00aAssessing changes in biomass, productivity, and C and N stores following Juniperus virginiana  forest expansion into tallgrass prairie0 aAssessing changes in biomass productivity and C and N stores fol  a1940 -19460 v313 aAn increase in woody plant abundance in regions historically dominated by grasses is a recent land cover change in grasslands worldwide. In tallgrass prairies of North America, this increase in woody plant cover includes the development of dense stands of eastern redcedar (Juniperus virginiana L.). To evaluate the consequences of this ongoing land cover change for ecosystem functioning, we developed allometric equations, using data from Kansas and Oklahoma, to estimate aboveground biomass and productivity in closed-canopy redcedar stands. We then applied these equations to three closed-canopy redcedar stands, 3580 years old, which developed on sites formerly dominated by tallgrass prairie in eastern Kansas. Aboveground plant biomass for these redcedar-dominated sites ranged from 114 100 kg/ha for the youngest stand to 210 700 kg/ha for the oldest. Annual aboveground net primary productivity (ANPP) ranged from 7250 to 10 440 kg·ha1·year1 for the oldest and younger redcedar stands, respectively. Estimates of ANPP in comparable tallgrass prairie sites in this region average 3690 kg·ha1·year1 indicating a large increase in C uptake and aboveground storage as a result of the change from prairie to redcedar forests. Therefore, the widespread occurrence of redcedars across the woodlandprairie ecotone suggests that this land-cover change may have important consequences for regional net C storage.10atallgrass prairie1 aNorris, M.D.1 aBlair, John, M.1 aJohnson, L.C.1 aMcKane, R.B.  uhttp://knz.lternet.edu/content/assessing-changes-biomass-productivity-and-c-and-n-stores-following-juniperus-virginiana02202nas a2200157   4500008004100000245012000041210006900161300001300230490000700243520159400250653002201844100001701866700002001883700001801903856012301921       2001                        eng d00aLand cover change in eastern Kansas: litter dynamics of closed-canopy eastern redcedar forests in tallgrass prairie0 aLand cover change in eastern Kansas litter dynamics of closedcan  a214 -2220 v793 aIn the Great Plains region, eastern redcedar (Juniperus virginiana L.) abundance has increased dramatically in areas historically occupied by tallgrass prairie. This shift in dominant vegetation is likely to be accompanied by changes in ecosystem structure and function, including quantity, quality, and location (above- vs. below-ground) of litter inputs and subsequent effects on decomposition dynamics. The purpose of this study was to quantify and compare patterns of litterfall and decomposition in mature redcedar forests and adjacent prairie. Annual redcedar litterfall was 500 g·m-2·year-1, a large increase in foliar litter inputs compared with annually burned grassland (52 g·m-2·year-1). Using a reciprocal transplant decomposition study with four substrates, redcedar leaves and roots, and big bluestem (Andropogon gerardii Vitman) foliage and roots, we found marginal habitat effects, but greater differences between species, presumably owing to litter quality (including both C:N and lignin content). Decay rates were significantly higher in the prairie relative to the forest for each substrate. Additionally, within any particular habitat, grass litter had significantly faster decay rates than forest litter. These results suggest a shift in patterns of litter input and decomposition processes with afforestation of tallgrass prairie, which may result in long-term changes in C sequestration and storage.Key words: litter dynamics, eastern redcedar (Juniperus virginiana), big bluestem (Andropogon gerardii), decomposition, tallgrass prairie, nitrogen immobilization.10atallgrass prairie1 aNorris, M.D.1 aBlair, John, M.1 aJohnson, L.C.  uhttp://knz.lternet.edu/content/land-cover-change-eastern-kansas-litter-dynamics-closed-canopy-eastern-redcedar-forests