@article {KNZ001234, title = {Annual fire and mowing alter biomass, depth distribution, and C and N content of roots and soil in tallgrass prairie}, journal = {Plant and Soil}, volume = {323}, year = {2009}, pages = {235 -247}, abstract = {

Management practices, such as fire and mowing, can affect the distribution and quality of roots and soil C and N in grasslands. We examined long-term (13 years) effects of annual fire and mowing on fine (\<2 mm) roots and soil C and N content in a native tallgrass prairie at Konza Prairie Biological Station in northeastern Kansas, USA. Using 90 cm deep soil cores, we determined that fire and mowing independently and interactively influenced the quantity and depth distribution of fine root biomass, root C and N concentration, and soil C and N content. Annual burning increased total fine root biomass by 48\% and total C storage in roots by 47\% compared to unburned unmowed plots, and resulted in a deeper distribution of roots. There was a significant interaction of fire and mowing, whereby mowing reduced root biomass and root C storage by ~30\% in annually burned plots, but did not affect total root biomass in unburned plots. Mowing also resulted in shallower distribution of roots regardless of fire treatment. Root N concentration was reduced by 15\–25\% in plots that were burned, mowed, or both. Mowing effects on soil C and N were restricted to surface soils (0\–10 cm), where mowing reduced soil C concentrations by ~20\% and N concentrations by 17\% regardless of burning treatment. In contrast, burning alone did not significantly influence soil C and N concentrations. In general, root biomass, root C and N mass, and soil C and N concentrations declined with depth, and most responses to burning and mowing exhibited significant interactions with depth. Different long-term fire and mowing regimes can significantly alter belowground root biomass and C and N dynamics in grasslands, and in particular at depths in the profile that are not typically sampled.

}, keywords = {LTER-KNZ, fire, grassland, Mowing, Root biomass depth distribution, Soil C and N, tallgrass prairie}, doi = {10.1007/s11104-009-9931-2}, url = {https://link.springer.com/article/10.1007\%2Fs11104-009-9931-2}, author = {Kitchen, D.J. and John M. Blair and Callaham, M.A.} } @article {KNZ00752, title = {Carbon dynamics and microbial activity in tallgrass prairie exposed to elevated CO2 for 8 years}, journal = {Plant and Soil}, volume = {227}, year = {2000}, pages = {127 -137}, abstract = {Alterations in microbial mineralization and nutrient cycling may control the long-term response of ecosystems to elevated CO2. Because micro-organisms constitute a labile fraction of potentially available N and are regulators of decomposition, an understanding of microbial activity and microbial biomass is crucial. Tallgrass prairie was exposed to twice ambient CO2 for 8 years beginning in 1989. Starting in 1991 and ending in 1996, soil samples from 0 to 5 and 5 to 15 cm depths were taken for measurement of microbial biomass C and N, total C and N, microbial activity, inorganic N and soil water content. Because of increased water-use-efficiency by plants, soil water content was consistently and significantly greater in elevated CO2 compared to ambient treatments. Soil microbial biomass C and N tended to be greater under elevated CO2 than ambient CO2 in the 5{\textendash}15 cm depth during most years, and in the month of October, when analyzed over the entire study period. Microbial activity was significantly greater at both depths in elevated CO2 than ambient conditions for most years. During dry periods, the greater water content of the surface 5 cm soil in the elevated CO2 treatments increased microbial activity relative to the ambient CO2 conditions. The increase in microbial activity under elevated CO2 in the 5{\textendash}15 cm layer was not correlated with differences in soil water contents, but may have been related to increases in soil C inputs from enhanced root growth and possibly greater root exudation. Total soil C and N in the surface 15 cm were, after 8 years, significantly greater under elevated CO2 than ambient CO2. Our results suggest that decomposition is enhanced under elevated CO2 compared with ambient CO2, but that inputs of C are greater than the decomposition rates. Soil C sequestration in tallgrass prairie and other drought-prone grassland systems is, therefore, considered plausible as atmospheric CO2 increases.}, keywords = {LTER-KNZ, elevated CO2, microbial activity, Microbial biomass, Soil C and N, soil water}, doi = {10.1023/A:1026590001307}, author = {Williams, M.A. and C. W. Rice and Owensby, C.E.} }