02758nas a2200253 4500008004100000245008300041210006900124300001300193490000700206520200300213653001302216653002402229653001302253653000902266653001202275653001602287100001502303700001902318700002402337700002002361700001802381700001802399856008702417 2010 eng d00aDevelopment of soil microbial communities during tallgrass prairie restoration0 aDevelopment of soil microbial communities during tallgrass prair a302 -3120 v423 a

Soil microbial communities were examined in a chronosequence of four different land-use treatments at the Konza Prairie Biological Station, Kansas. The time series comprised a conventionally tilled cropland (CTC) developed on former prairie soils, two restored grasslands that were initiated on former agricultural soils in 1998 (RG98) and 1978 (RG78), and an annually burned native tallgrass prairie (BNP), all on similar soil types. In addition, an unburned native tallgrass prairie (UNP) and another grassland restored in 2000 (RG00) on a different soil type were studied to examine the effect of long-term fire exclusion vs. annual burning in native prairie and the influence of soil type on soil microbial communities in restored grasslands. Both 16S rRNA gene clone libraries and phospholipid fatty acid analyses indicated that the structure and composition of bacterial communities in the CTC soil were significantly different from those in prairie soils. Within the time series, soil physicochemical characteristics changed monotonically. However, changes in the microbial communities were not monotonic, and a transitional bacterial community formed during restoration that differed from communities in either the highly disturbed cropland or the undisturbed original prairie. The microbial communities of RG98 and RG00 grasslands were also significantly different even though they were restored at approximately the same time and were managed similarly; a result attributable to the differences in soil type and associated soil chemistry such as pH and Ca. Burning and seasonal effects on soil microbial communities were small. Similarly, changing plot size from 300 m2 to 150 m2 in area caused small differences in the estimates of microbial community structure. In conclusion, microbial community structure and biochemical properties of soil from the tallgrass prairie were strongly impacted by cultivation, and the microbial community was not fully restored even after 30 years.

10a16S rRNA10aBacterial community10aCropland10aPLFA10aprairie10arestoration1 aJangid, K.1 aWilliams, M.A.1 aFranzluebbers, A.J.1 aBlair, John, M.1 aColeman, D.C.1 aWhitman, W.B. uhttps://www.sciencedirect.com/science/article/abs/pii/S0038071709004222?via%3Dihub02616nas a2200133 4500008004100000245010600041210006900147300001300216490000700229520208500236100001702321700001902338856012502357 2010 eng d00aMicrobial protein in soil: influence of extraction method and C amendment on extraction and recovery0 aMicrobial protein in soil influence of extraction method and C a a390 -3990 v593 aThe capacity to study the content and resolve the dynamics of the proteome of diverse microbial communities would help to revolutionize the way microbiologists study the function and activity of microorganisms in soil. To better understand the limitations of a proteomic approach to studying soil microbial communities, we characterized extractable soil microbial proteins using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Two methods were utilized to extract proteins from microorganisms residing in a Quitman and Benfield soil: (1) direct extraction of bulk protein from soil and (2) separation of the microorganisms from soil using density gradient centrifugation and subsequent extraction (DGC–EXT) of microbial protein. In addition, glucose and toluene amendments to soil were used to stimulate the growth of a subset of the microbial community. A bacterial culture and bovine serum albumin (BSA) were added to the soil to qualitatively assess their recovery following extraction. Direct extraction and resolution of microbial proteins using SDS-PAGE generally resulted in smeared and unresolved banding patterns on gels. DGC–EXT of microbial protein from soil followed by separation using SDS-PAGE, however, did resolve six to 10 bands in the Benfield but not the Quitman soil. DGC–EXT of microbial protein, but not direct extraction following the addition of glucose and toluene, markedly increased the number of bands (~40) on the gels in both Benfield and Quitman soils. Low recoveries of added culture and BSA proteins using the direct extraction method suggest that proteins either bind to soil organic matter and mineral particles or that partial degradation takes place during extraction. Interestingly, DGC may have been preferentially selected for actively growing cells, as gauged by the 10–100× lower cy19:0/18:1ω7 ratio of the fatty acid methyl esters in the isolated community compared to that for the whole soil. DGC can be used to isolate soil communities and provide microbial protein that can be characterized using PAGE.1 aTaylor, E.B.1 aWilliams, M.A. uhttp://129.130.186.12/content/microbial-protein-soil-influence-extraction-method-and-c-amendment-extraction-and-recovery02641nas a2200193 4500008004100000245013300041210006900174300001100243490000700254520196500261653002302226653002102249653001202270653003902282653000802321100001902329700001202348856008702360 2009 eng d00aCharacterization of the water soluble soil organic pool following the rewetting of dry soil in a drought-prone tallgrass prairie0 aCharacterization of the water soluble soil organic pool followin a21 -280 v413 a

To better understand the nature of the C flush that follows the rewetting of dry soil, we chemically characterized the water soluble pools following rewetting of soil dried to several different water potentials. To assess the impact that historical soil water status has on the size of the rewetting labile soluble pool, a laboratory water stress gradient was applied to soils that were collected from drought-prone and irrigated tallgrass prairie soils. In the laboratory, soils were either incubated at −33 kPa or dried steadily over a 0.6, 1, 2, or 3 day period to −1.5, −4, −15, and −45 MPa respectively. On the 4th day, samples were wetted back to −33 kPa and immediately assayed for soluble, microbial, or respiratory pools of carbon. After extraction, samples were also assayed using NMR, GC–MS, and LC–MS to assess carbohydrate, amino acid, osmolyte and sugar pools. The greater the degree of drying before rewetting was associated with greater concentrations of microbial, soluble and respiratory pools of carbon, increasing by 50, 400 and 250%, respectively, in the most water stressed compared to continuously moist soil. Compared to drought-prone soils, the amount of soluble C released as a result of rewetting was 30 to 50% greater in soils that were irrigated for 11 years. The pool of organics was not completely characterized and only small amounts of TBDMS and TMS derived compounds accounting for 2–4% of the soluble C pool were detected. In contrast, oligosaccharides constituted approximately 20–25% of the sample C. Our results suggest that the flush of C following wetting of a dry soil is not dominated by common microbial osmolytes (e.g. proline, glycine betaine, ectoine, glycerol, mannitol, trehalose). In light of this finding more research is needed to better understand the adaptations that microbial communities utilize to respond to the rewetting of dried soil.

10aCompatible solutes10aDrying-rewetting10aGC–MS10aMicrobial response to water stress10aNMR1 aWilliams, M.A.1 aXia, K. uhttps://www.sciencedirect.com/science/article/abs/pii/S0038071708002800?via%3Dihub02683nas a2200145 4500008004100000245010800041210006900149300001500218490000700233520205900240653007302299653002302372100001902395856012302414 2007 eng d00aResponse of microbial communities to water stress in irrigated anddrought-prone tallgrass prairie soils0 aResponse of microbial communities to water stress in irrigated a a2750 -27570 v393 aTo better understand how water stress and availability affect the structure of microbial communities in soil, I measured the change in phospholipid fatty acids (PLFA) and the incorporation of 13C-labeled glucose into the PLFA following exposure to water stress. Overlaid on the laboratory water stress treatment, samples were collected from drought-prone and irrigated (11 years) tallgrass prairie soil (0–10 cm depth). In the laboratory, soils were either incubated at −250 kPa or dried steadily over a 3-d period to −45 MPa. On the fourth day, the dried samples were brought up to −250 kPa and then all samples received 250 μg of glucose-C (+4000 δ13C-PDB) solution that brought them to −33 kPa matric water potential. Samples were then extracted for PLFA following 6 and 24 h of incubation (25 °C). Non-metric multidimensional scaling (NMS) techniques and multi-response permutation procedure (MRPP) showed that the largest effect on the mol% distribution of PLFA was related to the field scale water addition experiment. In response to irrigation, the PLFA 16:1ω5, 18:1+, and 18:2ω6,9 showed increases, and a15:0, a17:0, and cy19:0 showed decreases in their respective mol%. Effects related to the induction of laboratory water stress were predominantly associated with a decrease in the mol% distribution of the putative fungal biomarker (18:2ω6,9) with little to no change in the mol% distribution of the bacterial biomarkers. Interestingly, the flow of C to the microbial community was not strongly related to any single PLFA, and differences were rather subtle, but multivariate MRPP detected change to the community structure related to the laboratory water stress treatment but not related to the 11 years of field irrigation. Our results suggest that both the total and the actively metabolizing bacterial community in soil were generally resistant to the effects of water stress brought by rewetting of dry soil. However, more research is needed to understand the nature of the fungal response to drying and rewetting in soil.10a13C-PLFA compound-specific isotope analysis of microbial communities10aDrying–rewetting1 aWilliams, M.A. uhttp://129.130.186.12/content/response-microbial-communities-water-stress-irrigated-anddrought-prone-tallgrass-prairie03036nas a2200205 4500008004100000245014400041210006900185300001300254490000700267520228400274653002402558653001502582653000902597653001102606653002902617653002302646100001902669700001702688856012502705 2007 eng d00aSeven years of enhanced water availability influences the physiological, structural and functional attributes of a soil microbial community0 aSeven years of enhanced water availability influences the physio a535 -5450 v353 aWater availability is known to influence many aspects of microbial growth and physiology, but less is known about how complex soil microbial communities respond to changing water status. To understand how long-term enhancement of soil water availability (without flooding) influences microbial communities, we measured the seasonal dynamics of several community-level traits following >7 years of irrigation in a drought-prone tallgrass prairie soil. From late May to mid-September, water was supplied to the irrigated treatments based on calculated plant water demand. Phospholipid fatty acids (PLFA) were used to assess changes in microbial community structure and physiology. To assess the community-level physiological profile, microbial utilization of BIOLOG substrates was determined. After incubation for 2 days, the distribution of added 13C-glucose in microbial and respired pools was used as an index of substrate utilization efficiency. We also measured the relative contribution of fungi and bacteria to soil microbial biomass via substrate-induced respiration (SIR). Multivariate analysis of mol% PLFA and BIOLOG substrate utilization indicated that both water availability and sampling time influenced both the physiological and structural characteristics of the soil microbial community. Specific change in biomarker PLFA revealed a decreased ratio of cyclopropyl to ω7-precursors due to water addition, suggesting community-level stresses were reduced. Over the growing season, continuously greater water availability resulted in a 53% greater ratio of fungal to bacterial biomass using SIR, and a 65% increase in fungal PLFA. The number of substrates utilized by the cultivable microbial community tended to be greater in continuously wetted soil, especially during periods of low rainfall. While water dynamics appeared to be associated with some of the shifts in microbial community activity, structural and functional changes in the community appeared to be more closely linked to the cumulative effects of water regime on ecosystem properties. Seasonality strongly influenced microbial communities. The environmental factors associated with seasonal change need to be more closely probed to better understand the drivers of community structure and function.10aMicrobial community10aphysiology10aPLFA10aStress10aSubstrate use efficiency10aWater availability1 aWilliams, M.A.1 aRice, C., W. uhttp://129.130.186.12/content/seven-years-enhanced-water-availability-influences-physiological-structural-and-functional02151nas a2200145 4500008004100000245009700041210006900138300001300207490000700220520160800227100001901835700001701854700001801871856011601889 2006 eng d00aNatural 15N abundances in a tallgrass prairie exposed to 8 years of elevated atmospheric CO20 aNatural 15N abundances in a tallgrass prairie exposed to 8 years a409 -4120 v373 a

After 8-y of elevated CO2, we previously detected greater amounts of total soil nitrogen, suggesting that rates of ecosystem N flux into or out of tallgrass prairie had been altered. Denitrification and associative N fixation rates are the two primary biological processes that are known to control N loss and accumulation in tallgrass prairie soil. Therefore, our objective was to assess the natural abundance of plant and soil 15N isotopes as a cumulative index of potential change in efflux or influx of N into and out of the tallgrass prairie after 8-y of exposure to elevated CO2. Aboveground plant delta 15N values of Andropogon gerardii were close to zero and more positive as a result of elevated CO2, but whole-soil values at the 5–30 cm depth were significantly reduced (6.8 vs 7.3; P<0.05) under elevated CO2-chamber (EC) relative to ambient CO2- chamber (AC). Total, aboveground plant biomass, root-in-growth, extractable N, microbial biomass N, and soil pools collectively exhibited a range of delta 15N values from −2.8 to 7.3. Measurements of surface soil 15N indicate that a change in N inputs and outputs has occurred as a result of elevated atmospheric CO2. In addition to possible changes in denitrification and N2 fixation, other sources of N such as the re-translocation of N to the surface from deeper soil layers are needed to explain how soil N accrues in surface soils as a consequence of elevated CO2. Our results support the notion that C accrual may promote N accrual, possibly driven by high plant and microbial N demand amplified by soil N limitation.

1 aWilliams, M.A.1 aRice, C., W.1 aOwensby, C.E. uhttp://129.130.186.12/content/natural-15n-abundances-tallgrass-prairie-exposed-8-years-elevated-atmospheric-co202310nas a2200145 4500008004100000245007600041210006900117300001500186490000700201520180500208100001502013700001902028700001702047856010002064 2005 eng d00aPartitioning of nitrogen over five growing seasons in tallgrass prairie0 aPartitioning of nitrogen over five growing seasons in tallgrass  a1280 -12870 v863 aAnnual spring burning of tallgrass prairie increases plant biomass production despite losses of N and lower net N mineralization. To better understand how burning influences the cycling of N in prairie, 15N was injected to soil as NH4+, and the partitioning between plant and soil N pools was followed over five growing seasons in annually burned and unburned prairie. Applied 15N was rapidly immobilized with <2% and 11% of the 15N remaining in inorganic forms six days after application in burned and unburned prairie, respectively. Seventy-seven percent (burned prairie) and 70% (unburned prairie) of the applied 15N was initially recovered as soil organic N (oN), with a majority accounted for in microbial biomass. Plants contained ∼20% of the applied N with the largest portion recovered from roots regardless of burning. At the end of the first growing season, only 55% of the applied 15N was recovered from the unburned prairie, while 85% was recovered from burned prairie. The total 15N content of the plants changed little during the first growing season, but the portion recovered in the rhizomes increased, indicating belowground N storage. Total recovery and distribution of applied N changed little from the end of the first to the end of the second season growing season. Accumulations of 15N within the plants decreased greatly between the second and fifth growing seasons, but N lost from plants was accounted for in oN. Conservation of N by plants and tight cycling of N within the root zone suggest mechanisms by which prairie can be a highly productive ecosystem despite limited N availability. The immobilization of potentially mineralized N within the root zone increased with burning, offsetting the loss of N to fire probably by reducing leaching and denitrification losses.1 aDell, C.J.1 aWilliams, M.A.1 aRice, C., W. uhttp://129.130.186.12/content/partitioning-nitrogen-over-five-growing-seasons-tallgrass-prairie02165nas a2200157 4500008004100000245008800041210006900129300001300198490000700211520161100218100001901829700001701848700001301865700001601878856011301894 2004 eng d00aCarbon and nitrogen pools in a tallgrass prairie soil under elevated carbon dioxide0 aCarbon and nitrogen pools in a tallgrass prairie soil under elev a148 -1530 v683 a

Soil is a potential C sink and could offset rising atmospheric CO2 The capacity of soils to store and sequester C will depend on the rate of C inputs from plant productivity relative to C exports controlled by microbial decomposition. Our objective was to measure pools of soil C and N to assess the potential for C accrual and changes to N stocks as influenced by elevated atmospheric CO2 Treatments (three replications, randomized complete block design) were ambient CO2—no chamber (NC), ambient CO2—chamber (AC), and two times ambient CO2—chamber (EC). Long-term (290 d) incubations (35°C) were conducted to assess changes in the slow soil fractions of potentially mineralizable C (PMC) and potentially mineralizable N (PMN). Potentially mineralizable C was enhanced (P < 0.1) by 19 and 24% in EC relative to AC and NC soil at the 0- to 5- and 5- to 15-cm depths, respectively. Potentially mineralizable N was significantly greater by 14% at the 0- to 5-cm depth in EC relative to AC, but decreased by 12% in EC relative to NC (P < 0.1). Measurements of PMC indicate that increases in total soil C under elevated CO2 in a previous study were a consequence of accrual into the slow pool. Relatively large amounts of new C deposited as a result of elevated CO2 (Cnew) remained in the soil after the 290-d incubation. In contrast to accumulation of C into the slow fraction, Cnew was integrated into a passive fraction of soil organic matter (SOM). Accumulation of N was also detected in the whole soil, which cannot be explained by current estimates of ecosystem N flux.

1 aWilliams, M.A.1 aRice, C., W.1 aOmay, A.1 aOwensby, C. uhttp://129.130.186.12/content/carbon-and-nitrogen-pools-tallgrass-prairie-soil-under-elevated-carbon-dioxide00550nas a2200133 4500008004100000245008300041210006900124260004300193300001100236490002100247653002200268100001900290856010700309 2001 eng d00aAlterations in carbon and nitrogen cycling in irrigated tallgrass prairie soil0 aAlterations in carbon and nitrogen cycling in irrigated tallgras aManhattan, KSbKansas State University a1 -2060 vPhD Dissertation10atallgrass prairie1 aWilliams, M.A. uhttp://129.130.186.12/content/alterations-carbon-and-nitrogen-cycling-irrigated-tallgrass-prairie-soil02347nas a2200157 4500008004100000245009300041210006900134300001300203490000700216520177500223653002201998100001902020700001702039700001802056856011502074 2001 eng d00aNitrogen competition in a tallgrass prairie ecosystem exposed to elevated carbon dioxide0 aNitrogen competition in a tallgrass prairie ecosystem exposed to a340 -3460 v653 aBecause N is a limiting nutrient in tallgrass prairie and most ecosystems, changes in N availability or N cycling could control the long-term response of ecosystems to elevated atmospheric CO2 If more C is sequestered into the soil, then greater microbial demand for N could decrease plant-available soil N. Alterations in N dynamics such as plant uptake, N fixation, nutrient cycling, microbial utilization, and partitioning of N into plant and soil fractions ultimately could affect the capability of ecosystems to sequester C. Our objective was to determine if competition for N between plants and microorganisms changes after 8 yr of elevated CO2 relative to ambient conditions. Treatments (three replications, randomized complete block design) were ambient CO2–no chamber (NC), ambient CO2–chamber (AC), and 2 × ambient CO2–chamber (EC). Several short laboratory incubations assessed whether turnover rates of N in soil would be altered under elevated CO2 Gross transformations of N were not altered significantly under elevated CO2 compared with ambient conditions. To examine plant–microbial competition and altered allocation patterns of N under elevated CO2, 15NH4–N was added to 25-cm-diam. polyvinyl chloride (PVC) cores (15-cm depth) in the field, which were destructively sampled after ≈5 mo. Microbial biomass contained ≈75% of the total 15N that occurred in the soil organic matter (SOM) and, thus, appeared to be a significant regulator of plant-available N. The SOM under elevated CO2 contained significantly more (>27%) 15N compared with ambient CO2 conditions. Though a chamber effect was apparent, greater 15N in the SOM pool and greater percentage 15N SOM/percentage 15N plant suggest greater microbial demand for N under elevated CO210atallgrass prairie1 aWilliams, M.A.1 aRice, C., W.1 aOwensby, C.E. uhttp://129.130.186.12/content/nitrogen-competition-tallgrass-prairie-ecosystem-exposed-elevated-carbon-dioxide02659nas a2200205 4500008004100000245010000041210006900141300001300210490000800223520195400231653001702185653002302202653002202225653001702247653001502264100001902279700001702298700001802315856012002333 2000 eng d00aCarbon dynamics and microbial activity in tallgrass prairie exposed to elevated CO2 for 8 years0 aCarbon dynamics and microbial activity in tallgrass prairie expo a127 -1370 v2273 aAlterations 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 5–15 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 5–15 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.10aelevated CO210amicrobial activity10aMicrobial biomass10aSoil C and N10asoil water1 aWilliams, M.A.1 aRice, C., W.1 aOwensby, C.E. uhttp://129.130.186.12/content/carbon-dynamics-and-microbial-activity-tallgrass-prairie-exposed-elevated-co2-8-years00517nas a2200133 4500008004100000245007000041210006900111260004300180300001100223490001400234653002200248100001900270856009400289 1998 eng d00aSoil and microbial responses in tallgrass prairie to elevated CO20 aSoil and microbial responses in tallgrass prairie to elevated CO aManhattan, KSbKansas State University a1 -1110 vMS Thesis10atallgrass prairie1 aWilliams, M.A. uhttp://129.130.186.12/content/soil-and-microbial-responses-tallgrass-prairie-elevated-co2