@article {KNZ00231, title = {Nitrogen dynamics of soil water in burned and unburned tallgrass prairie}, journal = {Soil Biology \& Biochemistry}, volume = {21}, year = {1989}, pages = {1003 -1007}, abstract = {

Porous cup lysimeters were used to study the effects of spring burning for 5 yr on soil water N dynamics of tallgrass prairie. NO3--N concentration within the the rooting zone (20 cm depth) were unaffected by burning and averaged 27 {\ae}g 1-1. Concentrations at 80 cm were also similar for burned and unburned prairie and averaged 13 {\ae}g 1-1. Organic N was the dominant form of N in soil water, and showed a strong effect of treatment and depth. Oraganic N concentration averaged 409 {\ae}g 1-1 at 20 cm depth on unburned watersheds versus 295 {\ae}g 1-1 on burned watersheds (P\< 0.05). Values were not influenced by burning at 80 cm depths but were 30-50\% lower than those observed at 20 cm. Soil water N concentrations averaged \< 30\% of those observed in bulk precipitation inputs, and while fire is responsible for the maintenance of the tallgreass prairie flora, fire does not appear to be an important factor affecting groundwater export of N in this biome. Total N concentrations increased from an average of ca.200 {\ae}g 1-1 in 1982 to an average of ca.400 {\ae}g 1-1 during 1986, while lysimeter volumes declined from \> 400 to ca.200 sample-1. These changes were not related to precipitation, and suggests that the soil environment sampled by the lysimeters changes through time

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1016/0038-0717(89)90036-9}, author = {Hayes, D.C. and Seastedt, T.R.} } @proceedings {KNZ00252, title = {Silica, nitrogen and phosphorus dynamics of tallgrass prairie}, year = {1989}, pages = {205 -209}, publisher = {University of Nebraska Press}, address = {Lincoln, NE}, abstract = {

Experiments were conducted on big bluestem (Andropogon gerardii Vitman) in the greenhouse and on a tallgrass site on Konza Prairie to evaluate the effects of simulated grazing on the cycling of silica (SiO2), nitrogen, and phosphorus. Concentrations of all elements increased in vegetation that had been clipped or pruned. The absolute amount of nitrogen obtained by plants in the greenhouse experiment was increased by clipping foliage. Phosphorous exhibited only neutral or negative responses, while the absolute amount of silica declined in all but one experiment involving root pruning. In that experiment, the absolute amount of silica in roots was increased by 25\% by cutting a portion of the root system. These results suggest that the direct effects of clipping or pruning on the absolute amounts of elements cycled through vegetation are usually neutral or negative. Increased silicification or grazed foliage is suggested to be a consequence of delayed senescence and reduced leaf area. This interpretation provides a proximate reason why silicification is an \"inducible defense\" against herbivores. Key words: big bluestem, Andropogon gerardii, simulated grazing, nutrients, productivity, roots, Kansas

}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Seastedt, T.R. and Ramundo, R.A. and Hayes, D.C.}, editor = {Bragg, T.B. and Stubbendieck, J.} } @article {KNZ00204, title = {Factors influencing nitrogen concentrations in soil and water in a North American tallgrass prairie}, journal = {Soil Biology \& Biochemistry}, volume = {20}, year = {1988}, pages = {725 -729}, abstract = {

The influence of roots, soil fauna and microbes on nitrogen concentrations in soil water in annually-burned tallgrass prairie were evaluated using porous cup lysimeters and a series of manipulations involving an insecticide, clipping of the vegetation, and C and N additions to the soil surface. An organophosphate insecticide (isofenphos), which significantly reduced densities of certain nematode and arthropod groups, resulted in small but statistically significant declines in soil water NO3- concentrations during 2 of 3 yr of study. Organic N, the dominant form of soil water N, was unaffected by treatment. Clipping the foliage weekly during the spring resulted in significant reductions in annual foliage production, but failed to change concentrations of soil water NO3- or organic N. Nitrogen additions (10 g N m-2 as NH4NO3) greatly increased soil water NO3- concentrations; however, when 250 g C sucrose m-2 were concurrently added to plots, there was a significant reduction in soil water NO3- concentrations. Soil water NH4+ concentrations were unaffected by treatment. These studies emphasize the importance of microbes as the dominant factor affecting soil water N concentrations in carbon-rich soils. Plants, soil fauna and nitrogen fertilizers do affect N. dynamics, but, under annually-burned conditions in the tallgrass prairie, these effects are obscured by microbial processes

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1016/0038-0717(88)90158-7}, author = {Seastedt, T.R. and Hayes, D.C.} } @article {KNZ00205, title = {Maximization of densities of soil animals by foliage herbivory: empirical evidence, graphical and conceptual models}, journal = {Oikos}, volume = {51}, year = {1988}, pages = {243 -248}, abstract = {

Feeding by consumers on one portion of a plant resource often results in benefits to consumer feeding on other portions of the same resource. Moderate grazing of foliage often increases densities and biomass of belowground herbivores and detritivores in spite of a neutral or reduced root growth response to foliage removal. Graphical and conceptual models are presented to describe these responses and suggest causal relationships. Empirical data and the models indicate that the positive numerical response of soil animals to foliage herbivory results from increased quality (nitrogen concentration) of roots and changes in consumer assimilation efficiencies. Root growth and senescence and acquisition of soil inorganic nitrogen by microbes colonizing senescent roots are hypothesized as additional causal agents for the soil animal response

}, keywords = {LTER-KNZ}, doi = {10.2307/3565649}, author = {Seastedt, T.R. and Ramundo, R.A. and Hayes, D.C.} } @article {KNZ00144, title = {Root dynamics of tallgrass prairie in wet and dry years}, journal = {Canadian Journal of Botany}, volume = {65}, year = {1987}, pages = {787 -791}, abstract = {

Root dynamics were studied using root windows at Konza Prairie, a tallgrass prairie in north central Kansas, during dry (1984) and wet (1985) years. Amounts, production, and disappearance of root lengths decreased during drought but increased when rains resumed; however, standing crop remained low. The 1985 root lengths increased throughout the growing season, while production and disappearance remained constant. Yearly summaries of amounts, productivity and decomposition by 10-cm increments in soil depth show that the effect of drought on these variables decreased with increasing soil depth. Turnover rates of root length averaged 564 in the dry year versus 389\% in the wet year, with the largest difference noted in the 0 to 10 cm depth (800 in 1984 versus 540\% in 1985). Production and decay patterns observed using root windows were also noted in root biomass data (obtained from soil cores). The average total root biomass turnover rate was 31\%. Failure to sort belowground materials into tissue types (rhizome, roots) and live versus dead status result in reduced estimates of biomass turnover rates. The greatest possible separation of plant components presents the most comprehensive picture of (belowground) growth dynamics

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.1139/b87-105}, author = {Hayes, D.C. and Seastedt, T.R.} } @proceedings {KNZ00125, title = {Effects of vegetation, burning and mowing on soil macroarthropods of tallgrass prairie}, year = {1986}, pages = {99 -102}, publisher = {North Dakota State University: Tri-College Center for Environmental Study}, address = {Fargo, ND}, abstract = {

Tallgrass prairie was burned annually, mowed and raked three times yearly, or left undisturbed for two years, and soil anthropods were censused after the first and second years of treatment. Total arthropod densities increased from about 75 individuals/m2 to 132 individuals /m2 and arthropod biomass increased from about 24 kg/ha to 43 kg/ha from November 1981 to March 1983. These increases were associated with increased productivity of prairie vegetation during the initial year of the study. Annual burning resulted in increased biomass of root xylem feeders (cicada nymphs), mowing and raking resulted in increased biomass of root chewing insects (white grubs). Smaller herivores (mostly chrysomelid larvae), predaceous beetle larvae and insect detritivores were most abundant on unburned plots. Overall, arthropod biomass was highest on burned plots; however, densities of arthropods were not significantly different among treatments. Of the arthropods found to be abundant in tallgrass prairie soil, only the white grubs are known to adversely affect plant productivity. Results from this study suggest that drought or land use practices that stress the vegetation will increase densities of these pest insects

}, keywords = {LTER-KNZ, tallgrass prairie}, author = {Seastedt, T.R. and Hayes, D.C. and Petersen, N.J.}, editor = {Clambey, G.K. and Pemble, R.H.} } @phdthesis {KNZ00114, title = {Seasonal root biomass and nitrogen dynamics of big bluestem (Andropogon gerardii Vitman) under wet and dry conditions}, volume = {PhD Dissertation}, year = {1986}, pages = {1 -89}, school = {Kansas State University}, type = {Ph.D. Thesis}, address = {Manhattan, KS}, keywords = {LTER-KNZ, biomass, prairie, root}, author = {Hayes, D.C.} } @article {KNZ0081, title = {Seasonal nitrogen translocation in big bluestem during drought conditions}, journal = {Journal of Range Management}, volume = {38}, year = {1985}, pages = {406 -410}, abstract = {

This study, conducted during a severe drought in 1980, assesses the effects of burned and unburned treatments in tallgrass prairie of nitrogen content of big bluestem, Andropogon gerardii Vitman. Seasonal total nitrogen and amino-nitrogen translocations in big bluestem in the tallgrass prairie were studied on burned and unburned treatments within Konza Prairie Research Natural Area, Manhattan, Kansas. Leaf total nitrogen dropped from .71\% in June 1980 to .21\% in November with no significant difference between treatments. Rhizome total nitrogen was significantly different between treatments with a June to November increase of .46\% to .86\% in unburned and .41\% to .82\% in burned treatments. Roots averaged 72\% of rhizome total nitrogen, indicating that roots are also used as storage organs for nitrogen. Comparisons with other studies conducted in 1980 and 1971-1972 indicate that drought stress may reduce the total nitrogen content of big bluestem. In April 1980, emerging leaves on the unburned plots were significantly higher in amino acid concentration than those on the burned plots. Although leaf amino acid concentration was constant after July, the percent of total nitrogen as amino acids increased 3 to 4 fold from mid-August to October. Rhizome amino acid concentration was significantly higher on the unburned than on burned plots. The September 1980 increase in leaf amino acid concentration and percent of total nitrogen as amino acids indicate a breakdown of protein in aboveground tissue. The concurrent increase in rhizome amino acid concentration and percent of total nitrogen as amino acids supports the concept of fall translocation of nitrogen to the belowground parts which serve as storage organs

}, keywords = {LTER-KNZ, tallgrass prairie}, doi = {10.2307/3899709}, author = {Hayes, D.C.} } @mastersthesis {KNZ0031, title = {Seasonal nitrogen translocation in big bluestem, Andropogon gerardii Vitman, in Kansas during a drought year}, volume = {MS Thesis}, year = {1982}, pages = {1 -75}, school = {Kansas State University}, type = {M.S. Thesis}, address = {Manhattan, KS}, keywords = {LTER-KNZ, grassland, nitrogen, translocation}, url = {http://krex.k-state.edu/dspace/handle/2097/12760}, author = {Hayes, D.C.} }