02440nas a2200145 4500008004100000245005800041210005800099300001500157490000700172520197500179100001702154700002002171700001702191856008602208 1997 eng d00aMycorrhizal fungi affect root stele tissue in grasses0 aMycorrhizal fungi affect root stele tissue in grasses a1778 -17840 v753 aAlthough arbuscular mycorrhizal symbiosis was initially believed to have little or no impact on root morphology, we now recognize that subtle changes do occur and that these changes may be of considerable consequence to host growth and nutrition, as well as functional growth strategy. In examining the stele and root diameters of C3 and C4 grasses, C4 grasses were demonstrated to have a significantly larger proportion of their fibrous roots occupied by stele tissue than do C3 grasses. In fact, functional growth strategy (C3 versus C4) was observed to be a relatively good predictor of stele area. Mycorrhizal fungi also influenced the amount of stele tissue, but the effect was not the same for both C3 and C4 grasses. The stele area of all C4 grasses except for Sorghastrum nutans was greater in the presence of mycorrhizal colonization. Among the C3 grasses, only Bromus inermis showed a significant increase, although Elymus cinereus and Lolium perenne displayed significant decreases in response to arbuscular mycorrhizal colonization. Changes in the stele area of the plant species were closely related to their responsiveness to mycorrhizal symbiosis and might in part explain both beneficial and detrimental responses of plants to mycorrhizae. An increase in stele circumference induced by mycorrhizae would allow for greater uptake and passage of water and nutrients to the vascular cylinder, and growth depressions could be a direct outcome of reduced stele circumference. Thus, differences in stele circumference represent a possible mechanism for mycorrhizal impacts on host plants. These findings indicate that structural differences among grasses are related to different functional capabilities and further emphasize the need for better integration of comparative anatomy and morphology procedures in the study of mycorrhizal symbiosis. Key words: stele, root anatomy, mycorrhizal dependency, functional growth strategy, mycorrhiza, C3 and C4 grasses.1 aMiller, R.M.1 aHetrick, B.A.D.1 aWilson, G.T. uhttp://knz.lternet.edu/content/mycorrhizal-fungi-affect-root-stele-tissue-grasses02108nas a2200193 4500008004100000245007500041210006900116300001300185490000700198520154100205653001601746653001501762653002201777100001901799700001901818700002001837700001701857856004001874 1996 eng d00aInterspecific nutrient transfer in a tallgrass prairie plant community0 aInterspecific nutrient transfer in a tallgrass prairie plant com a180 -1840 v833 aInterplant nutrient transfer may be an important ecological process in grasslands, and may significantly influence plant neighborhood interactions. We investigated the potential for phosphorus transfer between the dominant grass Andropogon gerardii and several neighboring plant species in tallgrass prairie via a field 32PO4 labelling experiment. The mean amount of 32P received from donor shoots differed significantly among neighboring species and decreased with increasing distance from the donor. In general, forbs and cool-season C3 grasses received more labelled 32P than warm-season C4 grasses. Phosphorus transfer occurred over distances up to 0.5 m. The effects of species and distance on movement of phosphorus changed with increasing time after labelling. The relative mass of receiver and donor shoots did not affect amounts of 32P transfer. A benomyl fungicide treatment, applied to suppress mycorrhizal activity, likely did not affect existing vegetative hyphae and did not affect the amount of 32P transferred. These studies demonstrate that: (1) phosphorus is transferred among neighboring species in tallgrass prairie plant communities, (2) phosphorus may be transferred over significantly greater distances than reported in other grasslands, and (3) there is differential transfer among co-occurring species. Hypothesized mechanisms accounting for these patterns in tallgrass prairie include mycorrhizal hyphal interconnections and/or extensive and differential root and rhizosphere overlap among neighboring species.10amycorrhizae10aPhosphorus10atallgrass prairie1 aWalter, L.E.F.1 aHartnett, D.C.1 aHetrick, B.A.D.1 aSchwab, A.P. uhttp://www.jstor.org/stable/244593602477nas a2200217 4500008004100000245011000041210006900151300001300220490000700233520169200240653002401932653002701956653003001983653002202013653002402035100002002059700001902079700001702098700001702115856012702132 1994 eng d00aEffects of mycorrhizal and plant density on yield relationships among competing tallgrass prairie grasses0 aEffects of mycorrhizal and plant density on yield relationships  a168 -1760 v723 aA replacement series experiment was used to investigate the effects of mycorrhizae, phosphorus availability, and plant density on competitive relationships between three tallgrass prairie species of varying mycorrhizal dependencies. Under mycorrhizal conditions, the obligately mycorrhizal dependent warm-season grass Andropogon gerardii (big bluestem) was a better competitor in mixture with the nonmycorrhiza-dependent cool-season grass Koeleria pyramidata (Junegrass). In the absence of mycorrhizae, however, competitive effects of big bluestem were greatly reduced and Junegrass experienced competitive release. Relative yield totals increased when mycorrhizae were suppressed, suggesting greater intensity of interspecific competition in the presence of mycorrhizae. Thus, the competitive dominance of big bluestem in tallgrass prairie is strongly related to its mycorrhizal status. Elymus canadensis (Canada wild rye) outcompeted big bluestem both with and without mycorrhizae. Relative yield totals of this species mixture were also lower under mycorrhizal conditions, indicating that mycorrhizae increase the intensity of interspecific competition between them. Relative yields of wild rye competing with big bluestem increased in the absence of mycorrhizae, suggesting that it also experiences competitive release when big blue-stem are not mycorrhizal. The outcomes of competition were generally similar among the three total plant density treatments and between P-fertilized and nonfertilized treatments. However, interactions between mycorrhizal effects and plant density confirm that outcomes of interspecific competitive interactions may be density dependent in some cases.10aAndropogon gerardii10aarbuscular mycorrhizae10ade Wit replacement series10aElymus canadensis10aKoeleria pyramidata1 aHetrick, B.A.D.1 aHartnett, D.C.1 aWilson, G.T.1 aGibson, D.J. uhttp://knz.lternet.edu/content/effects-mycorrhizal-and-plant-density-yield-relationships-among-competing-tallgrass-prairie03475nas a2200193 4500008004100000245009800041210006900139300001500208490000700223520277800230653001703008653002703025653003103052653002203083100002003105700001703125700001703142856012203159 1994 eng d00aMycorrhizal activity in warm-and cool-season grasses: variation in nutrient uptake strategies0 aMycorrhizal activity in warmand coolseason grasses variation in  a1002 -10080 v723 aBecause cool-season grasses display little or no mycorrhizal responsiveness in prairie soil, it is unclear whether the high levels of mycorrhizal activity observed previously in these grasses represent nutrient uptake by external hyphae or simply metabolism of stored fungal reserves in roots. To distinguish between these hypotheses, a warm-season grass, Andropogon gerardii, or a cool-season grass, Bromus inermis, were grown at two temperatures on one side of a pot divided by a 43-μm nylon root barrier. Mycorrhizal function was assessed by measuring the amount of 32P translocated from one side of the pot to plants on the other side. As a control, mycorrhizal hyphae crossing the barrier were severed manually. Approximately 100 times more 32P was observed in mycorrhizal B. inermis grown at 18 °C versus 29 °C, and in B. inermis with intact versus severed hyphae at the cooler temperature. In contrast, A. gerardii accumulated approximately 4 times more 32P at 29 °C than at 18 °C, and approximately 100 times more with intact versus severed hyphae at the warmer temperature. Thus, it appears that mycorrhizal hyphae are highly active in both plant species regardless of the host's mycorrhizal responsiveness. Furthermore, mycorrhizal activity is highest at the temperature that favors growth of each species. The considerable activity of mycorrhizae in B. inermis is enigmatic since it usually has no biomass response. To further clarify the relationship between nutrient uptake and biomass response, both plant species were fertilized with a range of P levels and grown at a neutral temperature that supported the growth of both species. Although the concentration of P in B. inermis plant tissue increased in response to fertilization, there was no corresponding increase in biomass. In contrast, for A. gerardii, there was a direct and positive relationship between P fertilization and biomass produced, but tissue P concentrations remained relatively stable. Mycorrhizal symbiosis had no overall effect on biomass of B. inermis but significantly improved the growth of A. gerardii. These experiments showed clear differences in the growth strategies used by these two plant species. It is unclear whether these are differences that can be attributed to warm- and cool-season grasses in general. Short-term biomass responses as a measure of a plant's reliance on the symbiosis may not entirely reflect the contribution of the symbiosis if plants store nutrients with subsequent and perhaps delayed effects on fecundity, offspring performance, or even biomass. However, if the stored nutrient merely represents luxury consumption, this could still affect competitive ability because luxury consumption preempts the availability of nutrients for competitors. 10abig bluestem10amycorrhizal dependence10amycorrhizal responsiveness10asmooth bromegrass1 aHetrick, B.A.D.1 aWilson, G.T.1 aSchwab, A.P. uhttp://knz.lternet.edu/content/mycorrhizal-activity-warm-and-cool-season-grasses-variation-nutrient-uptake-strategies02352nas a2200145 4500008004100000245009900041210006900140300001300209490000800222520179600230100001902026700002002045700001702065856012402082 1994 eng d00aMycorrhizal dependence of Andropogon gerardii and Schizachyrium scoparium in two prairie soils0 aMycorrhizal dependence of Andropogon gerardii and Schizachyrium  a366 -3760 v1323 aPrevious research in tallgrass prairie in Kansas indicated that warm-season, C4, grasses are obligate mycotrophs and do not grow normally in the absence of mycorrhizal symbiosis. However, the degree to which such grasses depend on mycorrhizae in other prairie soils has not been examined. Growth and mycorrhizal colonization of roots of Andropogon gerardii and Schizachyrium scoparium were compared in soil collected from Konza Prairie Research Natural Area (KPRNA), Riley County, Kansas and from Sand Ridge State Forest (SRSF), Mason County, Illinois. Plants of both species were grown in the two soils and were inoculated with Glomus etunicatum spores originally collected from KPRNA or colonized root pieces from S. scoparium plants collected from SRSF. Glomus etunicatum inoculum resulted in significantly greater root colonization and biomass of both plant species in steamed KPRNA soil than did root piece inoculum. There was no benefit from inoculation in non-sterile soil which contained indigenous mycorrhizal fungi. In SRSF soil, there was no response to inoculation with mycorrhizal fungi from either source. The lack of mycorrhizal response in SRSF soil is attributed to the greater plant-available P level of this soil. For S. scoparium grown in SRSF soil, plants grown in steamed soil produced more biomass than plants grown in steamed soil amended with nonsterile soil sievings (containing soil organisms other than mycorrhizal fungi), or in nonsterile soil. These differences could be due to competition for inorganic nutrients between soil microbes and the plant or antagonistic relationships between the plant or the mycorrhizal association and the soil microbes. Thus, the mycorrhizal dependence of these plant species is related to both soil and inoculum type or species.1 aAnderson, R.C.1 aHetrick, B.A.D.1 aWilson, G.T. uhttp://knz.lternet.edu/content/mycorrhizal-dependence-andropogon-gerardii-and-schizachyrium-scoparium-two-prairie-soils02481nas a2200193 4500008004100000245007800041210006900119300001100188490000700199520183600206653000902042653002202051653003602073100001902109700001802128700001802146700002002164856010302184 1994 eng d00aPlant demographic responses to mycorrhizal symbiosis in tallgrass prairie0 aPlant demographic responses to mycorrhizal symbiosis in tallgras a21 -260 v993 aThe effects of mycorrhizal symbiosis on seedling emergence, flowering and densities of several grasses and forbs were assessed in native tallgrass prairie and in sown garden populations at the Konza Prairie in northeastern Kansas. Mycorrhizal activity was experimentally suppressed with the fungicide benomyl. Flowering and stem densities of the cool-season grass, Dichanthelium oligosanthes, sedges (Carex spp.), and the forb Aster ericoides were higher in non-mycorrhizal (benomyl-treated) than in mycorrhizal plots and the magnitude of these differences was significantly affected by burning. Mycorrhizae significantly enhanced flowering of the warmseason grasses Andropogon gerardii and Sorghastrum nutans in burned prairie, but not in unburned sites. These patterns suggest that mycorrhizal effects on the dynamics of cool-season graminoid and forb populations are likely to be mediated indirectly through effects of the symbiosis on the competitive dominance of their neighbors. Seedling emergence rates of the cool-season C3 grasses Elymus canadensis and Koeleria cristata were significantly reduced in the benomyl-treated plots, whereas benomyl treatment had no significant effect on seedling emergence of the warm-season C4 grasses A. gerardii and Panicum virgatum. The forbs showed variable responses. Seedling emergence of Liatris aspera was greater under mycorrhizal conditions, but that of Dalea purpurea was unaffected by mycorrhizal treatment. These results show that effects of mycorrhizal symbiosis on the population dynamics of co-occurring prairie plants vary significantly both among species and among different life history stages within species. The results also indicate that mycorrhizas and fire interact to influence competitive interactions and demographic patterns of tallgrass prairie plant populations.10afire10atallgrass prairie10aVA mycorrhizas Plant demography1 aHartnett, D.C.1 aSamenus, R.H.1 aFischer, L.E.1 aHetrick, B.A.D. uhttp://knz.lternet.edu/content/plant-demographic-responses-mycorrhizal-symbiosis-tallgrass-prairie02569nas a2200157 4500008004100000245011400041210006900155300001300224490000700237520196900244100001902213700002002232700001702252700001702269856012502286 1993 eng d00aVA-Mycorrhizal influence on intra- and interspecific neighbor interactions among co-occurring prairie grasses0 aVAMycorrhizal influence on intra and interspecific neighbor inte a787 -7950 v813 a1 A strongly obligately mycorrhiza-dependent grass, Andropogon gerardii, and a less dependent species, Elymus canadensis, were grown in intra- and interspecific combination in a target-neighbour experiment with and without mycorrhizal fungi to examine their influence on competition. 2 Mycorrhizal fungi significantly influenced the competitive effects and responses of both plant species. Strong competitive effects of Andropogon disappeared in the absence of mycorrhizas indicating that its competitive dominance in tallgrass prairie is highly dependent upon its mycorrhizal associations. The influence of mycorrhizal fungi on Andropogon responses to neighbours decreased with increasing neighbour density indicating reduced host plant benefit from mycorrhizas under crowded conditions. 3 Effects of mycorrhizas on competition were generally smaller for the less mycorrhiza-dependent Elymus. Elymus effects on target plants were not strongly affected by mycorrhizas. Elymus target plants in competition with Andropogon neighbours performed better when nonmycorrhizal, due to the lack of significant competitive suppression by Andropogon in the absence of mycorrhizas. The influence of mycorrhizal fungi on Elymus responses to Andropogon neighbours increased with increasing neighbour density. Neither mycorrhizas nor phosphorus fertilization had a significant effect on intraspecific competition among Elymus. 4 Patterns of tiller production by target plants were similar to patterns in their total dry weight, indicating that competitive and mycorrhizal effects on target plant size were primarily a result of effects on tiller numbers rather than individual tiller size. 5 The results show that mycorrhizal symbiosis can strongly influence the patterns and intensity of both intraspecific density effects and interspecific competition between co-occurring prairie grasses and that the degree of host-plant benefit derived from mycorrhizas is density dependent.1 aHartnett, D.C.1 aHetrick, B.A.D.1 aWilson, G.T.1 aGibson, D.J. uhttp://knz.lternet.edu/content/va-mycorrhizal-influence-intra-and-interspecific-neighbor-interactions-among-co-occurring00457nas a2200121 4500008004100000245007200041210006800113300001300181490000700194100002100201700002000222856009300242 1992 eng d00aThe effect of prairie management practices on mycorrhizal symbiosis0 aeffect of prairie management practices on mycorrhizal symbiosis a522 -5270 v841 aBentivenga, S.P.1 aHetrick, B.A.D. uhttp://knz.lternet.edu/content/effect-prairie-management-practices-mycorrhizal-symbiosis00513nas a2200133 4500008004100000245008300041210006900124300001300193490000700206100002100213700001700234700002000251856010800271 1992 eng d00aMineralization of organic phosphorus by vesicular-arbuscular mycorrhizal fungi0 aMineralization of organic phosphorus by vesiculararbuscular myco a897 -9030 v241 aJayachandran, K.1 aSchwab, A.P.1 aHetrick, B.A.D. uhttp://knz.lternet.edu/content/mineralization-organic-phosphorus-vesicular-arbuscular-mycorrhizal-fungi00545nas a2200133 4500008004100000245010300041210006900144300001300213490000700226100002100233700001700254700002000271856012000291 1992 eng d00aPartitioning of dissolved inorganic or organic phosphorus using acidified molybdate and isobutanol0 aPartitioning of dissolved inorganic or organic phosphorus using  a762 -7650 v561 aJayachandran, K.1 aSchwab, A.P.1 aHetrick, B.A.D. uhttp://knz.lternet.edu/content/partitioning-dissolved-inorganic-or-organic-phosphorus-using-acidified-molybdate-and00583nas a2200145 4500008004100000245010500041210006900146300001500215490000700230653002200237100002000259700001700279700001500296856012600311 1992 eng d00aRelationships of mycorrhizal symbiosis, rooting strategy and phenology among tallgrass prairie forbs0 aRelationships of mycorrhizal symbiosis rooting strategy and phen a1521 -15280 v7010atallgrass prairie1 aHetrick, B.A.D.1 aWilson, G.T.1 aTodd, T.C. uhttp://knz.lternet.edu/content/relationships-mycorrhizal-symbiosis-rooting-strategy-and-phenology-among-tallgrass-prairie00581nas a2200133 4500008004100000245012700041210006900168300001500237490000700252653002200259100002100281700002000302856012500322 1992 eng d00aSeasonal and temperature effects on mycorrhizal activity and dependence of cool- and warm-season tallgrass prairie grasses0 aSeasonal and temperature effects on mycorrhizal activity and dep a1596 -16020 v7010atallgrass prairie1 aBentivenga, S.P.1 aHetrick, B.A.D. uhttp://knz.lternet.edu/content/seasonal-and-temperature-effects-mycorrhizal-activity-and-dependence-cool-and-warm-season00524nas a2200121 4500008004100000245011800041210006900159300001200228490000700240100002000247700001700267856011800284 1991 eng d00aEffects of mycorrhizal fungus species and metalaxyl application on microbial suppression of mycorrhizal symbiosis0 aEffects of mycorrhizal fungus species and metalaxyl application  a97 -1020 v831 aHetrick, B.A.D.1 aWilson, G.T. uhttp://knz.lternet.edu/content/effects-mycorrhizal-fungus-species-and-metalaxyl-application-microbial-suppression00576nas a2200133 4500008004100000245012600041210006900167300001000236490000700246653002200253100002100275700002000296856012600316 1991 eng d00aGlomus Mortonii sp. Nov., a previously undescribed species in the Glomaceae isolated from the tallgrass prairie in Kansas0 aGlomus Mortonii sp Nov a previously undescribed species in the G a9 -150 v4210atallgrass prairie1 aBentivenga, S.P.1 aHetrick, B.A.D. uhttp://knz.lternet.edu/content/glomus-mortonii-sp-nov-previously-undescribed-species-glomaceae-isolated-tallgrass-prairie00336nas a2200109 4500008004100000245003800041210003800079300001300117490000700130100002000137856006900157 1991 eng d00aMycorrhizas and root architecture0 aMycorrhizas and root architecture a355 -3610 v471 aHetrick, B.A.D. uhttp://knz.lternet.edu/content/mycorrhizas-and-root-architecture00555nas a2200133 4500008004100000245010000041210006900141300001500210490000700225653002200232100002100254700002000275856012600295 1991 eng d00aRelationship between mycorrhizal activity, burning, and plant productivity in tallgrass prairie0 aRelationship between mycorrhizal activity burning and plant prod a2597 -26190 v6910atallgrass prairie1 aBentivenga, S.P.1 aHetrick, B.A.D. uhttp://knz.lternet.edu/content/relationship-between-mycorrhizal-activity-burning-and-plant-productivity-tallgrass-prairie00530nas a2200133 4500008004100000245009400041210006900135300001300204490000700217100002000224700001700244700001700261856011800278 1991 eng d00aRoot architecture of warm and cool-season grasses: relationship to mycorrhizal dependence0 aRoot architecture of warm and coolseason grasses relationship to a112 -1180 v691 aHetrick, B.A.D.1 aWilson, G.T.1 aLeslie, J.F. uhttp://knz.lternet.edu/content/root-architecture-warm-and-cool-season-grasses-relationship-mycorrhizal-dependence02003nas a2200157 4500008004100000245012400041210006900165300001300234490000700247520139000254653002201644100002001666700001701686700001501703856012701718 1990 eng d00aDifferential responses of C3 and C4 grasses to mycorrhizal symbiosis, phosphorus fertilization, and soil microorganisms0 aDifferential responses of C3 and C4 grasses to mycorrhizal symbi a461 -4670 v683 a

The responses of five C4, warm-season and five C3, cool-season tallgrass prairie grasses to phosphorus (P) fertilization, mycorrhizae, and soil microorganisms were compared in greenhouse studies. The warm-season grasses responded positively to mycorrhizae and to P fertilization, but mycorrhizal plants did not respond to P. The soil microflora reduced mycorrhizal plant dry weight and root colonization. In contrast, cool-season grasses did not respond to mycorrhizae or P fertilization. Soil microorganisms did not suppress cool-season plant growth, but root colonization was reduced in nonsterile soil. For the warm-season grasses there was an inverse relationship between mycorrhizal root colonization and P fertilization and a positive relationship between root colonization and plant dry weight. For the cool-season grasses there was also an inverse relationship between root colonization and P fertilization, but the relationship between root colonization and plant dry weight was negative. In both the warm-season and cool-season grasses, low levels of mycorrhizal root colonization persisted even when P fertilization was sufficient to eliminate mycorrhizal effects on plant growth. Thus, warm-and cool-season grasses display profoundly different strategies for nutrient acquisition. Key words: cool-season grasses, warm-season grasses, vesicular-arbuscular mycorrhizae

10atallgrass prairie1 aHetrick, B.A.D.1 aWilson, G.T.1 aTodd, T.C. uhttp://knz.lternet.edu/content/differential-responses-c3-and-c4-grasses-mycorrhizal-symbiosis-phosphorus-fertilization-and02198nas a2200241 4500008004100000245010800041210006900149300001100218490000700229520139600236653002201632100002001654700001901674700001701693700001901710700002001729700001601749700001801765700001701783700001901800700001601819856012101835 1990 eng d00aField bioassessment for selecting test systems to evaluate military training lands in tallgrass prairie0 aField bioassessment for selecting test systems to evaluate milit a81 -930 v143 a

Ecosystems responses to physical or chemical stress may vary from changes in single organisms to alteration of the structure and function of the ecosystem. These responses to stress cannot be predicted exactly. Ecosystems repeatedly exposed to physical and/or chemical stress can be used to study the separate and combined environmental effects of stress. Such studies also allow the development of procedures to select test systems for the analysis of stress in ecosystems. A preliminary field survey of six military training sites at Fort Riley, Kansas, USA, was conducted to identify and verify ecological test systems for evaluating ecosystem responses to physical and/or chemical stress. Comparisons of these data with data collected concurrently from Konza Prairie Research Natural Area reference sites showed that soil microarthropods, some species of macroarthropods, small mammals, and native earthworm species were negatively affected by stress. In contrast, plant species diversity, plant foliage biomass, soil mycorrhizae, and many soil characteristics were within the boundaries of nominal variations observed on "pristine" Konza Prairie. Introduced European earthworms appeared to be positively affected by training activities. This study provided a test of systematic procedures to support impact analysis, ecological toxicology, and ecosystem risk assessment

10atallgrass prairie1 aSchaeffer, D.J.1 aSeastedt, T.R.1 aGibson, D.J.1 aHartnett, D.C.1 aHetrick, B.A.D.1 aJames, S.W.1 aKaufman, D.W.1 aSchwab, A.P.1 aHerricks, E.E.1 aNovak, E.W. uhttp://knz.lternet.edu/content/field-bioassessment-selecting-test-systems-evaluate-military-training-lands-tallgrass02091nas a2200145 4500008004100000245008900041210006900130300001300199490000700212520156100219100002001780700001701800700001801817856011001835 1990 eng d00aThe influence of mycorrhizae on big bluestem rhizome regrowth and clipping tolerance0 ainfluence of mycorrhizae on big bluestem rhizome regrowth and cl a286 -2900 v433 a

Mycorrhizal symbiosis is critical to growth of many warm-season prairie grass seedlings, but its effect on regrowth of rhizomes has not been determined. As forage species, the effect of grazing on the symbiosis is also important. When the impact of mycorrhizae on regrowth of Andropogon gerardii Vit. rhizomes was assessed, A. gerardii rhizomes collected from the field and grown with mycorrhizal inoculum produced larger plants than rhizomes grown in the absence of the symbiont. The effect of the symbiosis on clipping (simulated grazing) tolerance was quantified by growing A. gerardii in steamed or nonsterile prairie soil, with or without mycorrhizal fungus inoculation. Plants were cliped and a portion of the plants harvested at 6, 12, 18, 24, and 30 weeks after planting. As an additional control, Benomyl fungicide was applied to plants to inhibit the symbiosis. Mycorrhizal clipped plants were larger than nonmycorrhizal clipped plants, but the difference diminished with successive clippings. Mycorrhizal root colonization also decreased in response to repeated clipping. Maximum shoot and root biomass of mycorrhizal plants was produced at 12 and 18 weeks, respectively. Fungicide-treated plants did not grow appreciably after the first clipping. Thus, mycorrhizae improved clipping tolerance, but with repeated intensive clipping, significant changes in root/shoot ratio occurred and eventually mycorrhizal root colonization and growth benefit were lost. Key words: grazing, vesicular-arbuscular mycorrhizae, big bluestem, herbage yield

1 aHetrick, B.A.D.1 aWilson, G.T.1 aOwensby, C.E. uhttp://knz.lternet.edu/content/influence-mycorrhizae-big-bluestem-rhizome-regrowth-and-clipping-tolerance01078nas a2200133 4500008004100000245013300041210006900174300001300243490000700256520052200263100002000785700001700805856012200822 1990 eng d00aRelationship of native and introduced mycorrhizal fungi to mycorrhizal dependence of Andropogon gerardii and Koeleria pyranidata0 aRelationship of native and introduced mycorrhizal fungi to mycor a779 -7820 v823 a

To determine whether VAM (vesicular-arbuscular mycorrhizal) fungi from prairie soil would alter the mycorrhizal dependence of warm- and cool-season grasses or the response of these hosts to the soil microbiota, 2-wk old seedlings of A. gerardii or K. pyranidata were planted in 6x25 cm pots containing 525 g (dry weight) steam-pasteurized soil (2 h at 80 C and allowed to cool and equilibrate for 72 h thereafter), pasteurized soil amended with 100 ml/pot non-sterile soil sievings, or non-sterile prairie soil

1 aHetrick, B.A.D.1 aWilson, G.T. uhttp://knz.lternet.edu/content/relationship-native-and-introduced-mycorrhizal-fungi-mycorrhizal-dependence-andropogon00598nas a2200145 4500008004100000245010000041210006900141260004500210300001300255100002000268700001400288700001700302700001500319856011800334 1989 eng d00aAcquisition of phosphorus by Va mycorrhizal fungi and the growth responses of their host plants0 aAcquisition of phosphorus by Va mycorrhizal fungi and the growth aCambrige, UKbCambridge University Press a205 -2261 aHetrick, B.A.D.1 aBoddy, L.1 aMarchant, R.1 aRead, D.J. uhttp://knz.lternet.edu/content/acquisition-phosphorus-va-mycorrhizal-fungi-and-growth-responses-their-host-plants01862nas a2200145 4500008004100000245008600041210006900127300001300196490000700209520133400216100002001550700001701570700001801587856011101605 1989 eng d00aInfluence of mycorrhizal fungi and fertilization on big bluestem seedling biomass0 aInfluence of mycorrhizal fungi and fertilization on big bluestem a213 -2160 v423 a

The relationship between fertilization of prairie soils and mycorrhizal symbiosis in big bluestem (Andropogon gerardii Vit.) was explored. In 10 steamed prairie soils of varied P level, inoculation with a mycorrhizal fungus resulted in a 7- to 70-fold increase in big bluestem seedling biomass, compared to noninoculated controls. Fertilization with N and K (25-0-25) significantly increased biomass of mycorrhizal seedlings but did not alter growth of nonmycorrhizal seedlings. In a second experiment which assessed the impact of N and P on seedling growth, in both steamed and nonsterile soil, P fertilization did not significantly increase plant biomass, while N fertilization did substantially increase biomass of mycorrhizal, but not nonmycorrhizal plants. Fertilization with N and P together produced the greatest biomass in both mycorrhizal and nonmycorrhizal plants. Apparently, in the range soils tested N is the most limiting nutrient, despite the low P availability exhibited by these soils. In the absence of mycorrhizae, however, P is most limiting and no response to N is observed unless sufficient P is also applied. These studies confirm an extremely important role for mycorrhizal fungi on big bluestem seedling growth. Key words: phosphorous, nitrogen, Glomus etunicatum, mycorrhizae, Andropogon gerardii

1 aHetrick, B.A.D.1 aWilson, G.T.1 aOwensby, C.E. uhttp://knz.lternet.edu/content/influence-mycorrhizal-fungi-and-fertilization-big-bluestem-seedling-biomass00561nas a2200133 4500008004100000245011400041210006900155300001500224490000700239100002100246700001700267700002000284856012300304 1989 eng d00aMycorrhizal mediation of phosphorus availability: synthetic iron chelate effects on phosphorus solubilization0 aMycorrhizal mediation of phosphorus availability synthetic iron  a1701 -17060 v531 aJayachandran, K.1 aSchwab, A.P.1 aHetrick, B.A.D. uhttp://knz.lternet.edu/content/mycorrhizal-mediation-phosphorus-availability-synthetic-iron-chelate-effects-phosphorus02235nas a2200157 4500008004100000245010500041210006900146300001500215490000700230520163800237653002201875100002001897700001701917700001801934856012501952 1989 eng d00aRelationship between mycorrhizal dependence and competitive ability of two tallgrass prairie grasses0 aRelationship between mycorrhizal dependence and competitive abil a2608 -26150 v673 a

The impact of mycorrhizal symbiosis on growth of Andropogon gerardii (big bluestem) and Koeleria pyranidata (junegrass) was compared. Andropogon gerardii was 98% dependent on the symbiosis, whereas K. pyranidata displayed less than 0.02% dependence. Mycorrhizal fungus inoculation resulted in 50 times larger A. gerardii plants but did not alter growth of K. pyradidata. When competing in pairs, A. gerardii dominated when the mycorrhizal symbiosis was present and K. pyradidata dominated when it was not present. Dry weight of mycorrhizal A. perardii was altered, whether grown alone or with K. pyranidata, but mycorrhizal K. pyranidata grew well only in the absence of competition and failed to grow appreciably if A. gerardii was present. Without mycorrhizal fungus inoculation, A. gerardii did not grow and had no deleterious effects on K. pyranidata. When P. fertilization was substituted for mycorrhizal fungus inoculation, A. gerardii grew better alone than in competition with K. pyranidata at low P levels but was not affected by competition at high P levels. Koeleria pyranidata was not affected by competition at low P levels, but high P fertilization resulted in reduced dry weight of K. pyranidata plants when in competition with A. gerardii. Phenologic separation of growing seasons avoids interspecific competition between these two grasses and may be one mechanism contributing toward their coexistence. Since low temperatures limit mycorrhizal nutrient uptake, phenologic separation of growing seasons could also avoid the competitive advantage of warm-season grasses conferred by their mycorrhizal dependence

10atallgrass prairie1 aHetrick, B.A.D.1 aWilson, G.T.1 aHarnett, D.C. uhttp://knz.lternet.edu/content/relationship-between-mycorrhizal-dependence-and-competitive-ability-two-tallgrass-prairie00550nas a2200121 4500008004100000245013600041210006900177300001300246490000700259100002000266700001700286856012500303 1989 eng d00aSuppression of mycorrhizal fungus spore germination in nonsterile soil: relationship to mycorrhizal growth response in big bluestem0 aSuppression of mycorrhizal fungus spore germination in nonsteril a382 -3900 v811 aHetrick, B.A.D.1 aWilson, G.T. uhttp://knz.lternet.edu/content/suppression-mycorrhizal-fungus-spore-germination-nonsterile-soil-relationship-mycorrhizal00531nas a2200133 4500008004100000245009600041210006900137300001100206490000700217100001700224700002000241700001500261856012100276 1989 eng d00aSuppression of vesicular-arbuscular mycorrhizal fungus spore germination by nonsterile soil0 aSuppression of vesiculararbuscular mycorrhizal fungus spore germ a18 -230 v671 aWilson, G.T.1 aHetrick, B.A.D.1 aKitt, D.G. uhttp://knz.lternet.edu/content/suppression-vesicular-arbuscular-mycorrhizal-fungus-spore-germination-nonsterile-soil02115nas a2200157 4500008004100000245011400041210006900155300001300224490000700237520151900244100002001763700001701783700001501800700001701815856012501832 1988 eng d00aEffects of soil microorganisms on mycorrhizal contribution to growth of big bluestem grass in nonsterile soil0 aEffects of soil microorganisms on mycorrhizal contribution to gr a501 -5070 v203 a

Plant dry weight and mycorrhizal root colonization of big bluestem (Andropogon gerardii Vitman) inoculated with Glomus etunicatum Becker and Gerd. were suppressed if non-sterile prairie soil sievings were added to pasteurized soil. Addition of prairie soil microorganisms, isolated onto peptone yeast extract, King's B, or starch casein agar media, to pasteurized soil also reduced dry weight and mycorrhizal root colonization of big bluesteam inoculated with G. etunicatum. In contrast, addition of non- sterile soil sievings or filtrate or organisms isolated onto potato dextrose or pseudomonas isolation agar to pasteurized soil improved growth of non-mycorrhizal big bluestem. These effects of soil microorganisms on plant growth were further quantified by comparing 32P uptake by fungicide treated and untreated mycorrhizal plants and by non-mycorrhizal plants in pasteurized and non-sterile soil. Mycorrhizal plants grown in pasteurized soil absorbed approximately 10 times more 32P than mycorrhizal plants grown in non-sterile soil. Application of propiconazole (Tilt) or fenarimol (Rubigan), fungicides which inhibit non-sterile soil, respectively. Thus, more 32P is absorbed in pasteurized than in non-sterile soil, probably because soil microorganisms limit mycorrhizal activity in non-sterile soil. Assessments of mycorrhizal contribution to plant growth conducted in sterilized soil may significantly overestimate the effects of VAM fungi because other soil microorganisms are not considered

1 aHetrick, B.A.D.1 aWilson, G.T.1 aKitt, D.G.1 aSchwab, A.P. uhttp://knz.lternet.edu/content/effects-soil-microorganisms-mycorrhizal-contribution-growth-big-bluestem-grass-nonsterile01692nas a2200157 4500008004100000245010000041210006900141300001500210490000700225520110000232653002201332100002001354700001501374700001701389856012801406 1988 eng d00aMycorrhizal dependence and growth habit of warm-season and cool-season tallgrass prairie plants0 aMycorrhizal dependence and growth habit of warmseason and coolse a1376 -13800 v663 a

Warm-season (C4) and cool-season (C3) mycorrhizal grasses were 63-215 and 0.12-4.1 times larger in dry weight than non-inoculated controls, respectively. Nonmycorrhizal warm-season plants did not grow and frequently died, while cool-season plants grew moderately well in the absense of mycorrhizal symbiosis. Like warm-season grasses, tallgrass prairie forbs were highly dependent on mycorrhizal symbiosis, even though they are not known to employ the C4 photosynthetic pathway. Thus, phenology may be more critical than photosynthetic pathway in determining mycorrhizal dependence. Warm-season grasses and forbs had coarser, less frequently branched root systems than cool-season grasses, supporting the hypothesis that mycorrhizal dependence is related to root morphology. Cool-season grasses may have developed more fibrous root systems because mycorrhizal nutrient uptake was not effective in the colder temperature environment in which they evolved. In contrast, warm-season plants and dependence on mycorrhizal fungi may have coevolved, because both symbionts are of tropical origin

10atallgrass prairie1 aHetrick, B.A.D.1 aKitt, D.G.1 aWilson, G.T. uhttp://knz.lternet.edu/content/mycorrhizal-dependence-and-growth-habit-warm-season-and-cool-season-tallgrass-prairie-plants03487nas a2200157 4500008004100000245012000041210006900161300001100230490000800241520289500249100002003144700001703164700001703181700001503198856011603213 1988 eng d00aPhysical and topological assessment of vesicular-arbuscular mycorrhizal fungus on root architecture of big bluestem0 aPhysical and topological assessment of vesiculararbuscular mycor a85 -960 v1103 a

The influence of vesicular-arbuscular (VA) mycorrhizal fungus, phosphorus (P) fertilization, and soil microorganisms on growth and root architecture of big bluestem (Andropogon gerardii Vitman) was investigated. In pasteurized soil, mycorrhizal inoculation significantly improved plant growth and increased root length and the number and the diameter of the primary, secondary and tertiary roots. These differences between mycorrhizal and non-mycorrhizal plants diminished with added P. In pasteurized soil amended with non-sterile soil sievate, differences between mycorrhizal and non-mycorrhizal plants were still obvious, but in may treatments these plants grew more poorly (had less dry weight, root length, number or diameter) than their counterparts in unamended pasteurized soil. Growth in non-sterile soil was also suppressed, and mycorrhizal responses were not detected since all of the plants in non-sterile soil became mycorrhizal whether or not they were inoculated. Two analyses of calculated parameters which describe root- system architecture were conducted. The first, specific root length (SRL), revealed that mycorrhizal symbiosis dramatically alters root morphology in soils of low fertility. These changes were similar to the changes evoked by added P. The second, path length (Pe) revealed that mycorrhizal fungi (and to some degree other soil microbes) significantly alter root architecture by reducing the relative amount of root branching. Apparently, mycorrhizal plants develop a more elongate, exploratory growth pattern which permits the fungal hyphae to extract nutrients from a larger volume of soil. In contract roots of non-mycorrhizal plants maintain a more highly branched pattern of root growth, and the roots themselves play a more critical role in the direct extraction of nutrients from the soil. These differences in root topology were not directly associated with the concentration of exogenous P, but instead appeared to be controlled by the mycorrhizal fungi themselves. Thus, while internal P content of plants mediates the establishment of the mycorrhizal symbiosis, the fungi can alter the root architecture of the plant to a form which best accommodates the symbiosis under the prevailing fertility and rhizosphere conditions in the soil. By altering root-system architecture in this manner, the mycorrhizal fungi can control, at least to some degree, the dependence of the host on the symbiosis. Thus, the topology of the root system is contingent upon the microflora in the rhizosphere. The topological analysis revealed differences in root architecture not detected by any of the other measures of root morphology. These differences suggest that mycorrhizal fungi affect root architecture and plant growth in ways not directly associated with phosphorus uptake. Key words: path length, phosphorus, root morphology, specific root length

1 aHetrick, B.A.D.1 aLeslie, J.F.1 aWilson, G.T.1 aKitt, D.G. uhttp://knz.lternet.edu/content/physical-and-topological-assessment-vesicular-arbuscular-mycorrhizal-fungus-root01963nas a2200145 4500008004100000245012100041210006900162300001300231490000800244520138500252100001501637700002001652700001701672856012801689 1988 eng d00aRelationships of soil fertility to suppression of the growth response of mycorrhizal big bluestem in nonsterile soil0 aRelationships of soil fertility to suppression of the growth res a473 -4820 v1093 a

When growth of vesicular-arbuscular (VA) mycorrhizal and non-mycorrhizal big bluestem was evaluated in 15 soils, three different growth response groups were evident. Group one, which included the prairie soils, displayed high mycorrhizal dependency as well as significant suppression of plant growth in non- sterile soil. Group two showed no mycorrhizal dependency; however, plant growth was suppressed in non- sterile soil. The last group exhibited no mycorrhizal dependency or suppression in non-sterile soil. Mycorrhizal dependency of big bluestem was not highly correlated with any individual soil parameter; however, concentrations of soil K, Ca, Cu, and Fe were used to successfully classify "high" and "low" mycorrhizal dependency. Suppression of plant growth in non-sterile soil was also related to soil fertility. The magnitude of non-sterile suppression was described by equations using soil Na, Zn, Mn, organic matter, Mg, and NH4. The mechanism of this suppression is still unclear; however, the nutrients which predict suppression may be related to the development of mycorrhizal symbiosis or in demand by plants and other microbes, while those nutrients which predict mycorrhizal dependency may be related to those supplied to the plant by the symbiosis. Key words: Glomus etunicatum, mycorrhial ependency, vesicular-arbuscular mycorrhizas

1 aKitt, D.G.1 aHetrick, B.A.D.1 aWilson, G.T. uhttp://knz.lternet.edu/content/relationships-soil-fertility-suppression-growth-response-mycorrhizal-big-bluestem-nonsterile01545nas a2200145 4500008004100000245010700041210006900148300001300217490000700230520098200237653002201219100001701241700002001258856012101278 1988 eng d00aTopographic and fire effects on composition and abundance of VA-mycorrhizal fungi in tallgrass prairie0 aTopographic and fire effects on composition and abundance of VAm a433 -4410 v803 a

The species composition of vesicular- arbuscular mycorrhizal fungi (VAM) are described from experimental plots in tallgrass prairie at Konza Prairie Research Natural Area, Manhattan, Kansas. Treatments include topography (four positions downslope) and burning frequency (annually burned and infrequently burned). Multivariate and univariate analyses indicate that gradients of variation in VAM species are related primarily to topography and burning frequency, and secondarily to original plot position within experimental rows. Spore numbers of seven of the most abundant species are directly related to topography; three of these also show an interaction with burning frequency. Although the distinction between direct and indirect effects of topography and burning frequency cannot be made with these data, a parallel response of vascular plant species frequency to the topographic gradient was observed. Key words: fire, tallgrass prairie, topography, VA mycorrhizae

10atallgrass prairie1 aGibson, D.J.1 aHetrick, B.A.D. uhttp://knz.lternet.edu/content/topographic-and-fire-effects-composition-and-abundance-va-mycorrhizal-fungi-tallgrass01281nas a2200157 4500008004100000245010300041210006900144300000900213490000700222520069000229653002200919100001800941700001900959700002000978856012500998 1985 eng d00aVesicular-arbuscular mycorrhizae and greenhouse production of three native tallgrass prairie forbs0 aVesiculararbuscular mycorrhizae and greenhouse production of thr a24 -0 v313 a

Seedlings of Baptistia leucantha (Atlantic wild indigo), Liatris aspera (rough gayfeather), and Asclepias tuberosa (butterfly milkweed) were grown in 165 cc tubes containing 1:1:1 peat:perlite:soil (v) or 1:1 soil:sand (v), both of which had been amended with 0, 41.6 phosphorus, or 83.2 g/P per cubic foot of media in the form of superphosphate (0-46-0). The tubes were inoculated with Glomus etunicatum, G. fasciculatum, G. macrocarpum, G. mossae, or remained uninoculated. After five months total dry weights and percentage root colonization were determined for one-half of the replications. The remaining plants were outplanted in the field to study transplant establishment

10atallgrass prairie1 aZajicek, J.M.1 aAlbrecht, M.L.1 aHetrick, B.A.D. uhttp://knz.lternet.edu/content/vesicular-arbuscular-mycorrhizae-and-greenhouse-production-three-native-tallgrass-prairie01612nas a2200169 4500008004100000245011300041210006900154300001500223490000700238520100300245653001001248653001401258653001001272100002001282700001401302856012601316 1983 eng d00aVesicular-arbuscular mycorrhizal fungi associated with native tall grass prairie and cultivated winter wheat0 aVesiculararbuscular mycorrhizal fungi associated with native tal a2140 -21460 v613 a

More vesicular- arbuscular mycorrhizal (VAM) fungal species and significantly more fungal spores were recovered from undisturbed prairie soils than four winter wheat field soils in Kansas through the 1980-1981 growing season. Two previously undescribed sporocarpic species of Engogonaccae were found in prairie samples but have not been successfully established in pot culture, leaving the genus to which they belong unclear. Though variable, 11-50% VAM root colonization was evident in all prairie grass roots sampled throughout the year. In contrast, no identifiable VAM root colonization was evident in wheat until May after flowering when 27% root colonization was observed. During the 1981-1982 growing season, roots of two other wheat fields were sampled with similar results. No colonization occurred until May when 8% root colonization was evident. The possible influence of such low levels of root colonization occurring quite late in the growing season of winter wheat is discussed

10afungi10atallgrass10awheat1 aHetrick, B.A.D.1 aBloom, J. uhttp://knz.lternet.edu/content/vesicular-arbuscular-mycorrhizal-fungi-associated-native-tall-grass-prairie-and-cultivated