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The objective of this study was to test the effects of protein supplementation strategy and different stockpiled forage species on growth, nutritional status, and reproductive performance of yearling beef heifers. In a 5-yr study, yearling beef heifers (n = 266) were stratified by body weight (BW) at weaning to 1 of 3 stockpiled forages: 1) endophyte-infected tall fescue (TF, Schedonorus arundinaceus (Schreb.) Dumort; 7.21% crude protein [CP] and 67.13% neutral detergent fiber [NDF], dry matter [DM] basis), 2) big bluestem (Andropogon gerardi Vitman) and indiangrass (Sorghastrum nutans L.) combination (BI; 4.32% CP and 71.06% NDF, DM basis), or 3) switchgrass (SG,Panicum virgatum L.; 3.87% CP and 76.79% NDF, DM basis). Forage treatments were then randomly assigned to receive 1 of 2 supplement types: 1) 0.68 kg heifer-1 d-1 of dried distillers grains with solubles (DDGS: 28% CP and 108% total digestible nutrients [TDN]) or 2) 0.22 kg heifer-1 d-1 of blood meal and fish meal (BF: 72.5% CP and 77.5% TDN), resulting in a 3 × 2 factorial arrangement of treatments. Each year, twenty-one 1.2-ha pastures (7 pastures per forage type) were utilized with 2 to 3 heifers per pastures. Treatments were initiated in January and terminated in April at the initiation of breeding. Initial BW was not different (P ≥ 0.22) by forage or supplement type. During the rest of the grazing period, BW was greater (P < 0.01) for TF heifers. However, average daily gain (ADG) was greater (P < 0.01) for BI and SG heifers from breeding to final pregnancy diagnosis. Heifers grazing TF pastures had greater (P < 0.01) overall ADG than their counterparts. The percentage of mature BW (MBW) at breeding was greater (P < 0.01) for TF heifers. Heifer BW and ADG was not influenced (P ≥ 0.06) by supplementation strategy. Serum glucose concentrations were not different (P ≥ 0.44) among forage type or supplement strategy. Pregnancy rates at fixed timed-artificial insemination and overall pregnancy rates did not differ (P ≥ 0.38) by forage or supplement treatment. Owing to forage nutritive value differences, heifers grazing low-quality, warm season grasses lost BW prior to the initiation of the breeding season. However, a negative BW gain prior to breeding did not negatively impact overall pregnancy rates.

Native warm-season grasses (NWSGs) have demonstrated potential to reduce summer forage variability, and furthermore, there has been growing interest in the use of NWSGs as lignocellulosic biomass crops. Th e objective of this research was to determine if there was a diff erence in net returns for full-season summer grazing beef steers (Bos taurus) on three NWSGs. Additionally, the expected price for biomass that a beef producer would need to break even between using the dual-purpose early-season grazing and biomass system and the full-season grazing system was calculated for these three NWSGs. Weaned beef steers grazed switchgrass (Panicum virgatum L.) (SG), a big bluestem (Andropogon gerardi Vitman) and indiangrass [Sorghastrum nutans (L.) Nash] mixture (BBIG), and eastern gamagrass [Tripsacum dactyloides (L.) L.] at Grand Junction (AP) and Highland Rim (HR), TN, from 2010 to 2012. Th e dual-purpose grazing occurred for 30 d beginning in early May, with subsequent growth harvested as biomass post-dormancy, and full-season grazing occurred for 90 d beginning in early May. Budgets were developed for each NWSG to calculate net returns, and mixed models were used to determine diff erences in beef yield and net returns across each NWSG and location. Expected yield and net returns to full-season grazing were not diff erent among NWSGs at AP. However, net returns to full-season grazing were higher for BBIG than SG at HR. A profi t-maximizing, risk-neutral individual would increase net returns by grazing any of the NWSGs over marketing calves at weaning. Th e breakeven biomass prices ranged between US$10 and US$98 Mg–1 depending on the NWSG and location.

Premise of research. The tribe Andropogoneae (Poaceae) is a morphologically diverse clade that is distributed worldwide; members of the tribe are ecological dominants in some of the world’s most expansive grasslands. Inflorescence morphology in the tribe is variable and does not indicate relationship, creating problems for systematic treatments of morphological characters. Closely related taxa may have different pollination syndromes and ecological roles, correlating with substantially different morphology.Methodology. To determine when morphological differences arise in developmental time, we investigated three species endemic to North American tallgrass prairies: big bluestem (Andropogon gerardi), little bluestem (Schizachyrium scoparium), and the inbreeding broomsedge bluestem (Andropogon virginicus). These species are widespread, common, and often ecologically dominant, but their development has never been studied. We used SEM to sample inflorescences from initiation to anthesis.Pivotal results. Both ...

We assessed the total length of external arbuscular mycorrhizal hyphae as a function of plant species and functional form richness in restored northern tallgrass prairies. Total hyphal length increased with species and functional form richness. Hyphal length also increased when plant communities were dominated by species with high root density, high root to shoot ratios, and high nitrogen use efficiency. Hyphal length was positively correlated with the biomass of late successional C4 grasses (Andropogon gerardi Vitman, Panicum virgatum L., Schizachyrium scoparium [Michx.] Nash-Gould, and Sorghastrum nutans L.), which are obligately mycorrhizal and characterized by high root to shoot ratios, and high root surface area per unit of root biomass. We thus conclude that in order to recover extraradical arbuscular mycorrhizal hyphal length in restored northern tallgrass prairies, at least three factors need to be given priority: 1) achieving high levels of species and functional form richness; 2) making sure that late successional C4 grasses are present; and 3) making sure that the seed mixture includes species that are characterized by high root to shoot ratio, high root density, and high nitrogen-use efficiency.

Establishment of grasslands can be an effective means of sequestering soil organic carbon (SOC) and reducing atmospheric CO 2 that is believed to contribute to global warming. This study evaluated the vertical distribution and overall sequestration of SOC and total nitrogen (N) under warm-season native grasses (WSNGs) planted 6–8 years earlier relative to a corn ( Zea mays L.)–soybean ( Glycine max L.) crop sequence, and switchgrass ( Panicum virgatum ) relative to tall mixed grasses of big bluestem ( Andropogon gerardi ), indiangrass ( Sorghastrum nutans ), and little bluestem ( Andropogon scoparius ). Paired soil samples from 0–15, 15–30, 30–60 and 60–100 cm depth increments were taken from WSNGs and adjoining croplands at 10 locations, and from switchgrass and adjoining tall mixed grasses at four locations in three major soil types of alfisols, mollisols, and entisols in Montgomery County, Indiana. Significant differences in SOC and N concentrations of WSNGs and croplands were limited to the surface 30 cm. On average, SOC concentrations in the surface 15 cm depth were higher in WSNGs than croplands (average: 22.4 and 19.8 g kg −1 C, respectively) but significant differences were observed in just 4 of 10 locations. Similarly, surface soil SOC concentrations were not different for switchgrass (22.1 g kg −1 ) relative to tall mixed grasses (21.4 g kg −1 ). Soil N concentrations never differed significantly among land use treatments. On average, SOC mass calculated to 1.0 m depth was 9.4% higher under WSNGs than cropland ( P P −1 yr −1 more than the corn–soybean sequence.

N by leaching not only increases the environmental hazard, but it reduces N available for assimilation by crops. The role of alfalfa (Medicago sativa L.) in extracting NO3‐N from The movement of NO3‐N through a soil profile is deep soils of areas with cold, short growing seasons, such as western directly linked to the movement of water through the Canada, is not well understood. A study was established in 1990 to determine NO3‐N extraction ability to 300 cm; initial soil NO3‐N soil profile (Nielsen et al., 1982). Preferential flow of concentrations were high (. 8m g kg 21 ). Systems included continuous soil water down structural pathways in the soil profile alfalfa; annual rotations of spring wheat (Triticum aestivum L.), field can also be responsible for the rapid movement of appea (Pisum sativum L.), and barley (Hordeum vulgare L.); a native- plied N fertilizers (Coles and Trudgill, 1985). Although grass system [big bluestem (Andropogon gerardi Vitman) and western NO3‐N movement is primarily downward, Boswell and wheatgrass (Agropyron smithii Rydb.)]; and continuous fallow. The Anderson (1964) indicated that upward movement of annual rotation effectively lowered NO3‐N to ,2.3 mg kg 21 in the NO 3‐N might also occur when evaporation exceeds pre30- to 90-cm depth. By the 4th yr, alfalfa had reduced NO3‐N concen- cipitation. Leaching of NO 3‐N is often greatest in wet

A common explanation for the changes in species abundance following a fire is a shift in competitive ranking. However, experimental tests have been inconsistent and gen- erally do not support this explanation. I examined the competi- tive ability of an abundant C 4 grass, Andropogon gerardii, and a C 3 forb, Ratibida pinnata, in a prairie remnant in northern Ohio, USA, for each of three years following a spring burn in 1996. While the abiotic environment directly influenced both species similarly, relative competitive abilities in terms of growth changed markedly: in 1996 Andropogon was less inhib- ited by neighbors; in 1997 both Andropogon and Ratibida had similar competitive abilities; and in 1998 Ratibida was less inhibited by neighbors. This shift in competitive response rank- ing paralleled the changes in relative abundance for the two species. In contrast, the effect of neighbors on survival changed markedly over time but did not differ among the two species. Thus, fire may influence species abundance through changing species competitive response ranking, at least in terms of growth.

I measured competitive responses of experimentally-established populations of the perennial grass, Andropogon gerardi, across a complex gradient of standing crop and species composition in the successional grasslands of southwest Michigan. The goal was to assess whether long-term (three year) population-level responses of Andropogon to competition matched the inferences made from a previous phytometer study that examined transplant responses to competition across this same gradient over a single growing season.

1 In this study the potential role of competition in influencing the distribution of three displaced native perennial grasses across complex gradients of plant productivity and species composition was investigated in Michigan old-fields. To do this plant removal and propagule addition experiments were conducted at nine old-field sites to examine the effects of living plant neighbours and litter on seedling establishment and growth of target species in relation to community biomass. 2 For two target species, Andropogon gerardi and Schizachyrium scoparium, living plant neighbours suppressed establishment from seed at most sites, and suppressed the growth of transplants at all sites. 3 Plant litter strongly inhibited the seedling establishment of both Andropogon and Schizachyrium at sites of high community biomass and litter accumulation, but had little impact on the growth rate of transplants at any of the sites. 4 The total suppressive effect of the plant community on seedling establishment and transplant growth of both Andropogon and Schizachyrium increased in magnitude in a non-linear fashion with community biomass. These effects increased in magnitude more rapidly across sites of low to medium biomass than sites of medium to high biomass. 5 The results suggest that these native grasses may be restricted to low productivity habitats within this landscape because of strong competitive interference with establishment by the existing vegetation in the most productive sites.

Host-range tests were conducted in a greenhouse using 9 European and 11 U.S. strains of Fusarium spp. pathogenic to Euphorbia spp. Plants of 12 grass species native to the rangelands of North America were raised from seed, planted in soil infested with each strain, and assessed for dry weight after 24 weeks. Five of 11 U.S. strains of Fusarium spp. significantly reduced the dry weight of at least 1 species of grass native to North America. Only 3 native grass species were affected: Idaho fescue ( Festuca idahoensis ), big bluestem ( Andropogon gerardi ), and big bluegrass ( Poa ampla ). Mean reductions ranged from 56 to 92%. A single European strain caused a 53% reduction in dry weight of 1 grass species, sand lovegrass ( Eragrostis tichodes ). Root-dip assays of 3-week-old seedlings in the greenhouse, with assessment over 3 weeks followed by 9 weeks of further observation and recording of dry weights of surviving plants were used to assess pathogenicity to 27 cultivated plant species. Two of the 3 most virulent U.S. strains failed to cause disease on any crop species according to these criteria. Three U.S. strains were positive in root-dip assays, each to a single crop species, causing vascular discoloration of flax ( Linum ussitatissimum ) and root necrosis of okra ( Hibiscus esculentus ) and cotton ( Gossypium hirsutum ). Neither of the 2 most virulent European strains exhibited pathogenicity to any of 12 crop species. Two other European strains exhibited host ranges comprised of 3 and 4 crop species. Two strains of F. proliferatum from the U.S. and Europe differing in host range were vegetatively compatible. The greater frequency of disease incidence on Euphorbia in Europe and the narrow host range and apparently greater virulence of European strains indicate that strains well-adapted to leafy spurge might best include Fusarium spp. occurring in Europe.

We conducted a field experiment in a successional grassland to investigate the short-term effects of nitrogen enrichment and plant litter on plant species richness and on the establishment of a native grass (Andropogon gerardi) that was experimentally introduced to the study site as seed. Additions of nitrogen fertilizer to experimental plots over two growing seasons increased plant production as indicated by increases in both living plant biomass and litter biomass. Increased productivity reduced species richness by effectively preventing the seedling establishment of the subordinate forb species and reduced the recruitment of Andropogon gerardi by inhibiting both germination and survival. Litter removals carried out at each of two levels of nitrogen enrichment (no nitrogen, nitrogen added) showed that litter significantly reduced species richness by the same amount in fertilized and unfertilized plots, suggesting that living biomass and litter were purely additive, rather than interactive in their effects. In contrast, the results of litter additions suggested that the declines in richness associated with fertilization could largely be due to the suppressive effects of increased litter biomass alone. As a whole, the results indicate that litter and living biomass are largely substitutable in their inhibitory effects on species richness in highly productive successional grasslands due to their independent and equivalent capacities to attenuate light to very low levels. This study highlights the combined roles of competition and plant litter in influencing the diversity of grasslands through effects on seedling establishment.

Plant-soil feedbacks can alter N cycling rates in terrestrial ecosystems, but the mechanistic relationship between species characteristics, soil properties, and N dynamics is unclear. Plant species may affect patterns of soil aggregation, which can affect soil C and net N mineralization. This mechanism was examined in two common garden experiments : one containing five tree species (European larch [Larix decidua Miller], red oak [Quercus rubra L.], red pine [Pinus resinosa Ait.], white pine [Pinus strobus L.], and Norway spruce [Picea abies (L.) Karst]) and one containing six grass species (big bluestem [Andropogon gerardi Vitm.], indiangrass [Sorghastrum nutans (L.) Nash], prairie sandreed [Calamovilfa longifolia (Hook) Scrib.], switchgrass [Panicum virgatum L.], little bluestem [Schizachyrium scoparium (Michx.) Nash.], and sideoats grama [Bouteloua curtipendula (Michx.) Torr.]). The grass monocultures are burned annually. Soils were wet sieved into four size classes (>2000, 250-2000, 53-250, and 2000 μm) C concentration ranged from 15 to 26 g kg -1 , and was lowest for Norway spruce and red oak (P = 0.07). Aggregate WMD correlated weakly (and negatively) with potentially mineralizable N (r = -0.57) and in situ net N mineralization (r = -0.67), but positively (again weakly) with potentially mineralizable C (r = 0.49). Grass species had no effect on aggregate-size distribution or organic matter concentration in spite of twofold differences in root biomass and threefold differences in N cyding rates. Species-induced changes in soil aggregation explained little of the variation in whole-soil C and N cycling rates, and are therefore unlikely to be an important mechanism explaining species effects on ecosystem processes.

We examined the effects of living plant neighbors and litter on the perfor- mance of a native C4 grass, Andropogon gerardi, at five old-field sites that differ in com- munity biomass and soil fertility. We used plant removal experiments in which both living neighbors and litter were manipulated in a factorial arrangement of treatments over one growing season. Andropogon was added to treatment plots as seeds and as established transplants to examine the effects of the surrounding plant community on the recruitment and established phases of its life history. Neighbors negatively affected Andropogon performance at all sites, indicating that resource exploitation by living plants was an important constraint to seedling recruitment and growth across the range of community biomass examined. Plant litter negatively affected recruitment at sites with the greatest community biomass, but had no effect on the growth of established transplants at any of the sites. The total effect of the surrounding plant community on recruitment was positively correlated with community biomass due to an increasing impact of plant litter. However, the total effect of the surrounding community on the growth of established transplants was unrelated to community biomass. The results suggest that it may be during the recruitment phase of the life history, when seeds and seedlings are especially susceptible to the effects of both litter and living neigh- bors, that Andropogon is most sensitive to variation in community biomass. Variation in the effects of litter on recruitment may be important in regulating plant species diversity and the distribution of native C4 grasses along old-field biomass gradients in southwest Michigan.

Experimental microcosms (40 X 52 X 32 cm) containing an assemblage of eight tallgrass prairie grass and forb species in native prairie soil were maintained under mycorrhizal (untreated control) or mycorrhizal-suppressed (fungicide-treated) conditions to examine plant growth, demographic, and community responses to mycorrhizal symbiosis. The fungicide benomyl successfully reduced mycorrhizal root colonization in the fungicide-treated microcosms to only 6.4% (an 83% reduction relative to mycorrhizal controls). Suppression of mycorrhizas resulted in a 31% reduction in total net aboveground plant production and changes in the relative production of C4 and C3 plants. The C4 tallgrasses Andropogon gerardi and Sorghastrum nutans produced less plant biomass in the fungicide-treated microcosms, and had a greater ratio of reproductive to vegetative biomass. Cool-season C3 grasses, Koeleria pyramidata and Poa pratensis accumulated more biomass and were a significantly greater proportion of total community biomass in mycorrhizal-suppressed microcosms. Forbs showed variable responses to mycorrhizal suppression. The two legumes Amorpha canescens and Dalea purpurea had significantly lower survivorship in the fungicide-treated microcosms, relative to the controls. The results confirm the high mycorrhizal dependency and growth responsiveness of dominant prairie grasses, and indicate that differential growth and demographic responses to mycorrhizal colonization among species may significantly affect plant productivity and species relative abundances in tallgrass prairie.

Using an indirect immunofluorescence technique, we have provided further evidence on the subcellular localization of the NADP-dependent malic enzyme (EC 1.1.1.40) in the bundle sheath chloroplasts of some C4 grasses, including the two bluestem grasses Andropogon gerardi Vitman and Schizachyrium scoparium (Michx.) Nash, common C4 grasses of the prairies in the Great Plains. Leaf carbon isotope fractionation studies of the two bluestem species, grown in close proximity to each other, indicate that though both belong to the NADP-malic enzyme subtype of C4 plants, their δ 13 C values differ by 1.5‰.

Quantitative in vitro methods using commercial cellulase (CEL), pectinase (PECT), and hemicellulase (HCEL) preparations were developed to simplify prediction of digestibility of cool- and warm-season forage grasses. Samples of orchardgrass (Dactylis glomerata L. var. Pennlate), tall fescue (Festuca arundinacea Schreb. var. KY 31) (cool-season grasses), big bluestem (Andropogon gerardi Vitman var. NY 1145), and switchgrass (Panicum virgatum L. var. KY 1625) (warm-season grasses) were taken at advancing stages of maturity. Isolated cell-wall material (CWM) was prepared by repetitively extracting lyophilized, ground tissue with aqueous and organic solvents. Relative solubilities of CWM digested individually with CEL, HCEL, or PECT were 100:30:40, respectively. When enzyme preparations were used sequentially, the influence of CEL, HCEL, and PECT on CWM solubility depended on the order in which the enzyme preparations occurred in the sequence. The fraction of CWM solubilized with CEL was similar to that obtain...

We analyzed changes in the stable C isotope composition (s3'C) of bulk tissues and lignin fractions during a 2-yr decomposition study in east-central Minnesota (USA) of aboveground and belowground litter from four perennial grass species: Schiza- chyrium scoparium (C4), Agropyron repens (C3), Poa pratensis (C3), and Agrostis scabra (C3). Although lignin concentrations increased for all litter types during decomposition and lignin fractions were consistently depleted in '3C compared to bulk tissues (3.6%o more negative on average), we found neither convergence of bulk tissue sl3C values towards lignin s13C values, nor greater stability of sl3C values for lignin fractions. Furthermore, s'3C values of C3 and C4 species shifted in opposite directions during decomposition. Thus, our data do not support the hypothesis that s'3C values decrease during decomposition because of the selective preservation of lignin and we instead suggest that isotopic shifts are caused by the incorporation of new C from soil organic matter into litter by microbial decomposers. We estimate that this new C comprised 12-19% of the total litter C, depending on species, at the point of 70% mass loss. In monocultures of these four species plus another C4 grass (Andropogon gerardi) growing on initially homogeneous soils with a predominantly C3 isotopic signature, soil s'3C values increased 1.6-2.2%o for the C4 species and remained relatively unchanged for the C3 species after 4 yr. Averaging across the C4 species and the experimental soil organic matter gradient, 14% of the total soil C in these plots must be new C4 C to account for this isotopic shift. We estimate that this amount of new soil C equals 30% of NPP summed over 4 yr in these plots.

Experiment was conducted during four years 2003-2006. Materials used were three genus grass species of C-4 photosynthesis: Andropogon gerardi Vitman, Panicum virgatum L. and Miscanthus sacchariflorus (Maxim.) Hack. Plants were planted at spring 1998. Agrotechnical part of experiment was conducted in Botanical Garden of Plant Breeding & Acclimatization Institute in Bydgoszcz and analytical part in Department of Animal Nutrition and Feed Management, Faculty of Animal Breeding and Biology of University of Technology and Life Science in Bydgoszcz. Forage from grass C-4 photosynthesis were material of good ensilage suitability. High structural carbohydrates (NDF, ADF) contents in tested forage dry matter suggest ensilage at early phases of plant development. Above results suggest to possibility of usage of forage from grass C-4 carbon fixation group for animal feeding purposes. C-4 grass forage should be recognized as a supplementary source of green matter in periods of insufficient access to traditional silage sources., Badania przeprowadzono w okresie od 2003-2006 roku. Badaniami objęto 3 gatunki traw fotosyntezy C-4: Andropogon gerardi Vitman, Panicum virgatum L. i Miscanthus sacchariflorus (Maxim.) Hack., wysadzone wiosną 1998 r. Agrotechniczną część badań prowadzono w Ogrodzie Botanicznym IHAR w Bydgoszczy, część analityczną w Katedrze Żywienia Zwierząt i Gospodarki Paszowej Wydziału Hodowli i Biologii Zwierząt Uniwersytetu Technologiczno- Przyrodniczego w Bydgoszczy. Trawy C-4 fotosyntezy były dobrym materiałem kiszonkarskim. Wysoka zawartość węglowodanów strukturalnych wskazuje na konieczność zakiszania tych traw we wczesnych fazach wegetacji. Potrzebę zastosowania tych gatunków w Polsce uzasadnia brak rodzimych wieloletnich, wysokowydajnych gatunków traw, dostosowanych do uprawy na glebach lekkich i słabo uwilgotnionych oraz wzrastające zapotrzebowanie na biomasę do celów energetycznych.

Five grass species (Agrostis scabra, Agropyron repens, Poa pratensis, Schiz- achyrium scoparium and Andropogon gerardi) were grown in monoculture for 3 yr on an experimental nitrogen gradient. The species differed significantly in the levels to which they reduced soil solution (0.01 mol/L KCl extractable) nitrate and ammonium concentrations and light penetration to the soil surface. Soil nitrate concentration was an inverse function of root mass, which explained 73% of the observed variance in nitrate. Other species differences explained an additional 9.2%, and total soil N an additional 5% of this variance. Extractable soil ammonium also depended on these variables, but total soil N explained the most variance. Light penetration to the soil surface in these monocultures was a negative exponential function of aboveground biomass (R2 = 0.79). Schizachyrium and Andropogon, the species that reduced soil solution N to the lowest levels on infertile soils, had lower vegetative growth rates, higher root allocation, lower reproductive allocation, and lower tissue N than the other species. Many of these traits are associated with plants of infertile habitats, suggesting a direct link between ecophysiology, resource reduction, and distributional patterns. Because all species survived on even our most nitrogen-poor soil (subsurface sand), differential nutrient reduction, not tolerance, may be the main mechanism favoring these traits in infertile habitats. On infertile soils, the three earlier successional species (Agrostis, Agropyron, and Poa) allocated more to reproduction (rhizome or seed) than the later successional species, but did not reduce soil solution nitrate and ammonium to as low levels. This suggests that our early successional species may be superior colonists but inferior nitrogen competitors compared to the prairie bunchgrasses. Our results can be used to make explicit predictions as to the outcome of nitrogen competition among all possible combinations of these five species.

The US DOE at the Fermi National Accelerator Laboratory in Batavia, Illinois, prairie restoration is taking place in order to conserve the rich topsoil. This is the largest of many prairie restoration experiments. Big bluestem grass (Andropogon gerardi), blue grama (Bouteloua gracilis), and buffalo grass (Buchloe dactyloides) are the main initial grasses grown. After their growth reaches enough biomass to sustain a fire, other prairie plants such as purple prairie clover and dropseed grass appear. The goal of this is to provide a generous refuge for disappearing native plants and animals, a site for scientific research, and a storehouse of genes adapted to a region that produces much of the worlds food. Plans for restoring the marsh and oak savanna, also native to the Fermilab site are also in the works.

Two experiments were conducted to evaluate digestion kinetics of alfalfa (Medicago sativa L.) substitution for grass hay in beef cattle. In Exp. 1, forage combinations evaluated in situ consisted of 0% alfalfa-100% big bluestem (Andropogon gerardi Vitman), 25% alfalfa-75% big bluestem, 50% alfalfa-50% big bluestem, and 100% alfalfa-0% big bluestem. Nonlinear regression was used to determine the immediately soluble fraction A, the potentially degradable fraction B, the undegraded fraction C, and the disappearance rate of DM and NDF. Dry matter fraction A increased linearly (P = 0.03), and DM and NDF fraction B decreased linearly (P = 0.01) with increasing alfalfa substitution. Rate of DM and NDF disappearance increased linearly (P ≤ 0.02) with increasing alfalfa substitution. In Exp. 2, treatments were arranged as a 2 x 2 factorial testing alfalfa substitution [none or 25% (as-fed basis)] to orchardgrass hay (Dactylis glomerata L.) and intake level [restricted to 1% of BW daily (DM basis) or ad libitum]. Nutrient intakes were lowest (P ≤ 0.05) by steers fed restricted diets, intermediate by steers fed orchardgrass ad libitum, and greatest by steers fed orchardgrass plus alfalfa ad libitum. Intake level and forage source had no effect (P ≥ 0.23) on total tract apparent digestibility of all nutrients except CP. Steers fed orchardgrass plus alfalfa had 33% greater (P = 0.01) total tract apparent digestibility for CP than those fed orchardgrass alone. Lag time of DM and NDF disappearance was not affected (P ≥ 0.20) by alfalfa supplementation or intake level. Rate of DM and NDF disappearance of orchardgrass was faster (P ≤ 0.01) in steers fed orchardgrass plus alfalfa, at both restricted and ad libitum levels of feeding, than in animals fed orchardgrass alone. Mean retention times of large and small particles of orchardgrass tended to be shorter (P ≤ 0.06) when steers consumed ad libitum vs. restricted diets. Small orchardgrass particles tended to have a faster (P = 0.09) rate of passage under ad libitum feeding conditions and with alfalfa addition. Ad libitum intake was associated with a shorter mean retention time of orchardgrass and faster rate of passage of small orchardgrass particles, whereas alfalfa addition increased the rate of passage of small orchardgrass particles and the rate of DM and NDF disappearance.

In this study, we evaluated methodology to determine risks to terrestrial native plant species from potential herbicide drift, focusing on 1) selection of native species for testing, 2) growth of these species, and 3) variability in herbicide response among native species and compared with crop plants. Native plant species were selected for initial testing on the basis of spatial analysis, which indicated that species from Illinois, USA, were at potential risk for off-target effects of herbicide drift. On the basis of preliminary seed germination tests, 5 native plant species (Andropogon gerardi, Polygonum lapathifolium, Solidago canadensis, Symphyotrichum lateriflorum, and Tridens flavus) were selected for comparison with crops grown in Illinois, normally used in the US Environmental Protection Agency's (USEPA's) Vegetative Vigor Test (Avena sativa, Daucus carota, Glycine max, Solanum lycopersicon, and Zea mays), or both. When treated with low concentrations of a test herbicide, sulfometuron methyl, 2 native species, P. lapathifolium and S. canadensis, were as sensitive as the 5 crop species. The effective herbicide concentrations producing a 25% reduction in shoot dry weight (EC25) for these species, ranged from 0.00015 to 0.0014 times a field application concentration of 52 g/ha active ingredient of sulfometuron methyl. S. lateriflorum and T. flavus were less sensitive than the other native species, whereas A. gerardi was tolerant to sulfometuron methyl with no growth reduction at any herbicide concentration tested. This study indicated that native species can be successfully selected and grown, used in the suite of species used in the USEPA's phytotoxicity test to assess risks of chemical herbicides to nontarget plants. It also showed (with a limited number of species) that native species varied more in sensitivity to simulated herbicide drift than crop species often used in phytotoxicity testing and that a Weibull function was useful to calculate EC25 values when low concentrations of herbicides was used.

Grazing system and stocking rate effects on forage standing crop of tallgrass prairies in north-central Oklahoma were evaluated from 1989 to 1993. Twelve experimental units, consisting of pastures dominated by big bluestem [Andropogon gerardi Vitman], little bluestem [Schizachyrium scoparium (Michx. Nash], indiangrass [Sorghastrum nutans (L.) Nash], and switch grass [Panicum virgatum L.], were arranged in a completely randomized design with either a short duration rotation or continuous grazing system and stocking rates ranging from 127 kg animal live-weight/ha to 222 kg live-weight/ha. Yearling steers grazed the units from late April to late September. Herbage standing crop was sampled in July and September. Total, live, and dead standing crops did not differ significantly between the 2 grazing systems in July. Total standing crop was significantly higher in the rotation units in September (3,600 versus 3,020 kg/ha, P < 0 .05). Dead standing crop was also higher in the rotation units in September (1,950 versus 1,570 kg/ha, P < 0 .05). Evidence suggests the difference in standing crop between systems is due, in part, to reduced forage intake by the livestock. Grazing system did not interact with either stocking rate or year. Stocking rate had significant effects on total, live and dead standing crops at both sample dates. The slope of the total standing crop-stocking rate relationship varied over years and ranged from -12 to -36 kg/ha per kg live-weight/ha in July and from -12 to -27 kg/ha per kg live-weight/ha in September. Higher standing crop at the end of the grazing season in the rotation units would mean greater soil protection and higher fuel loading for prescribed burning, and would suggest a lower impact on plant vigor. However, if the higher standing crop is a result of lower forage intake, we would expect livestock weight gains to decline.

This study was initiated to determine the effects of defoliation frequency (based on amount of growth present), intensity, and length of grazing season on quantity and quality of big bluestem (Andropogon gerardi Vitman) in the Southern corn belt and to provide further data regarding the reasons for rapid quality decline of warm-season grasses. Three clipping frequencies (when plants reached heights of 30, 41, 51 cm) at 2 intensities (stubble heights of 10 and 20 cm) were imposed on established plots of pure big bluestem (cv. Kaw). Harvest season length was studied by terminating clipping on 15 August and 15 September as 2 separate treatments. Two years of data indicated that big bluestem regrows insufficiently after 15 August to warrant additional harvests under the imposed managements. Prolonged regrowth and leaving a short stubble of 10 cm resulted in greatest yield. Short stubble led to greater reductions in nonstructural carbohydrates, but did not damage the stand compared to pre-study measurements. Nonstructural carbohydrate levels and stand composition improved with taller stubble. In vitro dry matter digestibility and crude protein were higher on treatments clipped to leave a 10-cm stubble. The greatest proportion of leaves resulted from treatments where a 20-cm stubble remained. These results agree with studies indicating that leaf maturity is more responsible for lower quality forage than is the amount of stem material present in the stand. Our results indicate heavy use can be more safely accomplished in the Southern corn belt than for areas to the west because big bluestem can be more intensively defoliated in the Southern corn belt (10-cm) than that recommended for other areas (20 to 40 cm).

Forage intake is perhaps the most critical parameter in understanding performance of ruminants on pasture. The Thermal Conductivity Cannula (TCC) is an animal-carried device that measures forage intake without disturbing normal grazing patterns by counting the number of boli swallowed over time. To evaluate its accuracy, studies of the effects of animal size, forage availability, quality, and species differences were conducted. In a grazing study, bolus weights of heavy (533 kg) and light (360 kg) esophageally fistulated steers were monitored on 2 different grazing systems [tall fescue (Festuca arundinacea Shreb) + red clover (Trifolium sp.) season-long vs. tall fescue + red clover in spring and fall and bit bluestem (Andropogon gerardi Vit; cv. Kaw) in summer]. Boli weight differences between steer weights indicated that TCC intake estimation will require calibration for steer weight or use of uniform steers. Boli weights of heavy steers varied (P < 0.05) within (9.0 to 19.4 g) and among (19.4 to 30.2 g) forage species. That did not occur with light steers (average = 6.25). Analysis of data on a metabolic weight basis indicated that size of the oral cavity and the 'critical mass' needed to stimulate swallowing may be a factor as well as weight. Sward characteristics and quality parameters were poorly correlated with bolus weight. An indoor study using 3 steer weights (heavy-546 kg, medium-486 kg, and light-220 kg) fed orchardgrass (100%), alfalfa (100%), and orchardgrass X alfalfa hay (50/50) indicated that heavier steers always produced heavier boli but that the weight differences between steers had to be greater than 86 kg to be significantly different. Light steers produced most consistent boli weights over all feeds.

KALIsz, P. J. AND S. E. BOETTCHER (Department of Forestry, University of Kentucky, Lexington, KY 40546-0073). Phytolith analysis of soils at Buffalo Beats, a small forest opening in Southeastern Ohio. Bull. Torrey Bot. Club 117: 445-449. 1990.-Analysis of the mass and morphology of opaline phytoliths extracted from soils was used to test the hypothesis that the 1-ha calcareous clay lens of Buffalo Beats had a vegetative history different from that of the surrounding acid shale substrate. The mass of opal from the 0- to 10-cm depth under prairie and transitional vegetation on the lens was approximately three times greater than from the same depth under the surrounding forest. Phytoliths diagnostic of grasses were seldom encountered in any soils. Early descriptions of forb-dominated communities on calcareous lenses in other parts of the region and the present high coverage by forbs on Buffalo Beats along with high phytolith concentrations in the foliage of some of these forb species, suggest the possibility that forbs rather than grasses may have dominated this opening over some portion of the postglacial period.

Atrazine [2-chloro-4-jethylamino)-6-(isopropylamino~s-~iazine] effectively controls many annual weeds in established warm-season range grasses but can damage some of these grasses in the early seedling stage. This study determined the relative atrazine tolerance of seedlings of selected warm-season grasses and evaluated the effectiveness of a greenhouse bioassay for seedling atrazine tolerance in range gasses. Seed of 'Pathfinder' switchgrass [Panicum virgatum L.], 'Nebraska 54' indiangrass [Sorghastrum nutans (L.) Nash], 'Butte' side-oats grama [Bouteloua curtipedula (Michx.) Torr.], an experimental blue grama 'PMK 1483' [ B. gracilis (H.B.K.) Lag ex Steud], 'Plains' bluestem (Bothriochloa ischaemum var ischaemum (L.) Keng), 'Caucasian' bluestem [B. caucasica (Trin.) C.E. Hubbard] 'Blaze' little bluestem [Schizachyrium scoparium (Michx.) Nash], and a Nebraska experimental prairie sandreed [Calamovilfa longifolia (Hook) Scribn.] were planted in the greenhouse in a 1:l soilsand mixture that contained O,1,2, or 3 mg kg-' atrazine. Seed lots from one cycle of field selection for atrazine tolerance of indiangrass and side-oats grama were included. A field study was also conducted on a silty clay loam (Typic Argiudoll) and on a loamy sand (Lrdic Haplustoll) site using little bluestem, blue grama, prairie sandreed, Caucasian bluestem, and Plains bluestem. Survival ranking at 3 mg kg-' atrazine, in the greenhouse, was: Caucasian bluestem = switchgrass > Plains bluestem > prairie sandreed > indiangrass (check) = indiangrass (cycle 1) > side-oats grama (cycle 1) = side-oats grama (check) = blue grama. Atrazine also reduced height in the surviving seedlings. Height reduction in did not appear to be related to seedling survival. Greenhouse data correlated closely with the loamy sand site because the bioassay used a soil-sand mixture. Excellent stands of Plains and Caucasian bluestem were obtained on the silty clay loam site a t all atrazine rates. The bioassay was an effective screen to separate grasses with differing atrazine tolerances. Additional index words: Switchmass. Side-oats wama Indiangrass, Blue grama, Little bluest* Caucasian bGesteh, Plains bluestem, Prairie sandreed, Herbicide tolerance. A TRAZINE [2-chloro-4-(ethy1amino)-6-(isopropy1amino)-s triazine] controls a wide variety of annual weeds in certain warm-season range grasses. However, many grasses that are tolerant to atrazine when established are susceptible as seedlings. Martin et al. (1982) demonstrated a wide range of tolerance among warm-season range grasses. Switchgrass [Panicum virgatum L.] and big bluestem (Andropogon gerardi Vitman) seedlings were atrazine tolerant. However, indiangrass [Sorghastrum nutan (L.) Nash], sideoats grama [Bouteloua curtipedula (Michx.) Torr.], and sand lovegrass [Eragrostis trichodes (Nutt.) Wood] were not sufficiently tolerant to use atrazine at establishment. Tolerance to the s-triazines is probably due to metabolic degradation. Detoxification of atrazine has been documented in corn [Zea mays (L.)] and sorghum (Sorghum vulgare Pers.). Detoxification can occur through modification of the atrazine molecule by Ndealkylation, 2-hydroxylation, or glutathione conjugation or any combination of the above pathways (Shimbukuro, 1967, Lamoureux et al., 1970; LamouContribution from the Dep. of Agronomy, Univ. of Nebraska, and the USDA/ARS published with the approval of the Director, Nebraska Agric. Exp. Stn., Journal Series Paper no. 7239. Received 29 Aug. 1983. Published in A ron. J. 76:891-895. ' Graduate student, researcf geneticist-USDA/ARS and professor, respectively, Dep. of Agronomy, Univ. of Nebraska-Lincoln, Lincoln, NE 68583. reux et al., 1973). Giant foxtail (Setaria faberi Hem. ) , fall panicum (Panicum dichotomiJlorum Michx.), and large crabgrass [Digitaria sanguinalis (L.) Scop.] metabolize atrazine via N-dealkylation and 2-hydroxylation pathways (Thompson, 1972). Their tolerance to atrazine is directly related to the rate of atrazine detoxification. In a study of 53 grass species of the subfamilies Festucoideae, Panicoideae, and Eragrostoideae, Ndealkylation, 2-hydroxylation, and glutathione conjugate catabolism pathways were found to occur in all species (Jensen et al., 1977). The major difference found between the species was the rate at which atrazine was metabolized. Species that showed atrazine tolerance all formed the atrazine-glutathione conjugate, which is a completely detoxified form of atrazine. Big bluestem and sand bluestem (Andropogon hallii Hack), in the seedling stage, appear to detoxifl atrazine through glutathione conjugation (Jensen et al., 1977). Reaction to atrazine also depends on soil properties. Lavy (1 968) reported that the adsorption of the s-triazines increased and plant uptake of C14 atrazine decreased as soil acidity, organic matter, and clay content increased. LeBaron (1 970) also showed that atrazine activity in soil was reduced by increased soil acidity and organic matter. Tests for atrazine resistance in higher plants have involved bioassays using soil-incorporated atrazine (Winkle et al., 1981); floating leaf disks in broadleaf weeds (Hensley, 1981); or etiolated growth in coolseason grasses (Young and Evans, 1978). The purpose of this study was to determine the relative atrazine tolerance of common warm-season prairie grass seedlings used in the midand north central USA and to evaluate a bioassay as a technique for detecting atrazine-tolerant plants. MATERIALS AND METHODS

Vegetational development of big bluestem (Andropogon gerardi Vitman) and indiangrass (Sorghastrum nutans (L.) Nash) was studied during 19 consecutive months. All big bluestem tillers arose extravaginally (penetrated the sheath of the subtending leaf) during late April and early May. Each tiller lived only during one growing season. Vegetatively reproductive tillers consisted of a rhizome, four to six adventitious roots, and an aerial shoot, and developed mature buds in leaf axils on their rhizomes. Reproductive tillers averaged two tiller offspring each during the succeeding growing season. About half of all big bluestem tillers were vegetatively non-reproductive, produced no mature buds on their rhizome, and were rootless. Indiangrass tillers arose extra- and intravaginally (the shoot remained within the subtending leaf's sheath) during late spring, early summer and autumn. Most tillers were biennieal. Extravaginal tillers were vegetatively reproductive and each produced three to five adventitious roots from the rhizome portion of the tiller. By autumn, about half of all indiangrass shoots were first-year tillers that had emerged from parent-tiller buds during that growing season. Intravaginal indiangrass tillers were vegetatively non-reproductive, rootless, and usually short-lived. Total non-structural carbohydrates (TNC) in rhizomes of both species reached maximum concentrations during winter and were depleted during late spring. TNC levels recovered partially during the summer, and declined slightly for a short time during late August. Total Kjeldahl nitrogen (N) concentrations in rhizomes of both species was highest during winter, declined during late spring, remained low through mid-summer and began to recover during late summer.

Yearly rates of nitrogen fixation associated with seven species of grass were measured on two artificially-established prairies. The C2H2 reduction method was used to measure the activity of soil cores taken within the stands of grass. Nitrogenase activity was specifically associated with Panicum virgatum and Sporobolus heterolepis, which had activities estimated at 3.6 and 2.9 kg N ha-1 yr-1. Fixation in stands of the other grasses ranged between 0.2 and 1.8 kg N ha-1 yr-1; free-living organisms might have fixed the N2 without specific association with the grasses, which were Andropogon gerardi, Andropogon scoparius, Spartina pectinata, Stipa spartea, and Poa pratensis. Three relic prairies were also examined, but the rates of fixation were no higher, except for S. heterolepis, which at one relic prairie had rates that extrapolated to 9 kg N ha-1 yr-1. The choices made for core location, size, depth, length of C2H2 incubation, and the time of day of sampling did not appear to have a substantial effect on the accuracy of the measurements. The organisms associated with S. heterolepis required O2 for N2 fixation, and they were located in the soil or on the smaller roots which remained when the major roots were removed from the soil. re]19750217

Animal production in New England has been limited by inadequate forage during mid- to late summer when cool-season grasses are in summer dormancy. Big bluestem (Andropogon gerardi Vitman), indiangrass [Sorghastrum nutans (L.) Nash] and switchgrass (Panicum virgatum L.) are warm-season grasses that may be a perennial source of summer forage. Since production of these warm-season grasses would be limited to the less fertile soils of the region, a greenhouse study was conducted to examine the growth and quality of these species in five acid, infertile soils as well as fertilizer-amended soils. The soils were fertilized with limestone (L), limestone plus nitrogen (LN), limestone, nitrogen plus phosphorus (LNP), and limestone, nitrogen, phosphorus plus potassium (LNPK). Limestone was applied to adjust soils to a pH of 6.5. Fertilizer was applied at rates of 45, 117 and 111 kg/ha of N, P and K, respectively. First harvest yields were greatest for switchgrass and big bluestem, but indiangrass produced significantly greater yields than either of the other grasses in the second harvest. In both harvests, the yields of all grasses were greatest under the LNP and LNPK fertility regimes. Nitrogen, without P, did not significantly increase yields above the control treatment in the first harvest. Yield responses to P fertilization varied with soils. Although P appeared to be the limiting factor insofar as growth was concerned, the yield response from P fertilization would probably be limited without N fertilization. Indiangrass was significantly higher in crude protein and K concentration and significantly lower in Ca concentration than big bluestem and switchgrass. Phosphorus concentrations were below the recommended levels for ruminant nutrition.

A very-fine-range resolution Frequency Modulated-Continuous Wave radar, operating at X-band, was used to evaluate the primary backscattering contributors to the radar signal from a tall-grass prairie. Defoliation was used to help measure relative backscatter from various components of the canopy with both linear polarizations and at 30 deg and 50 deg incidence angles. Variation of the average returned power with incidence angle was greatest for the natural prairie at horizontal polarization and was the least for vertical polarization. Vertical polarization seemed to be more sensitive to the upper portions of the plants, whereas horizontal polarization was to the lower portions. Attenuation for horizontal polarization was only half that for vertical polarization. Dielectric measurements of the grass and some of the canopy components were conducted as well.

Millions of hectares of pasture in the Northeast have low available soil P levels. Introducing forage species that produce well on these soils could increase forage production with minimum economic input. The objective of this study was to compare the performance of warm and cool-season grasses under low or high available P. Several warm and cool-season forage grasses were grown on a Berks shaly silt loam soil (Typic Dystrochrept; fine, loamy, skeletal, mesic), low in native available P (5 ppm Bray and Kurtz #1 extractable P), with and without added P. The warm-season grasses included two Old World bluestems, ‘Caucasian’ Bothriochloa caucasica (Trin.), C. E. Hubh. and “B”-strain, B. intermedia (R. Br.) A. Camus; three big bluestem cultivars, Andropogon gerardi Vitman; three little bluestem cultivars, Schizachyrium scoparium, Michx.; six switchgrass cultivars, Panicum virgatum L.; and two indiangrass cultivars, Sorghastrum nutans (L.) Nash. The cool-season grasses were Ky 31 tall fescue, Festuca arundinacea Schreb., ‘Pennlate’ orchardgrass, Dactylis glomerata L., and ‘Tioga’ deertongue grass, Dichanthelium clandestinum (L.) Gould. Yields of most warm-season grasses nearly doubled from 1977 to 1978, whereas yields of the cool-season grasses decreased. Forage yields and P concentrations of all cultivars generally were greater with applied P both years. At the low P level, warm-season grass yields in the second year were up to three times higher than yields of cool-season grasses, whereas P concentrations in forage of cool-season grasses were twice those of warm-season grasses: The warmseason grasses, Ky 729 and ‘Blackwell’ switchgrass, Ky 2 Caucasian and B-strain Old World bluestems, and NJ 1617-72 indiangrass absorbed more total P than all other cultivars. Warm-season grasses had relatively low crude protein and IVDMD levels, ranging from 4.7 to 8.5% and 34.0 to 52.3%, respectively. Of the warm-season grasses, Old World bluestems, Caucasian and B-strain, had the highest IVDMD values, 52.2 and 51.2%. The cool-season grasses had an average crude protein level of 14.6% and IVDMD value of 59.4%, respectively. The two Old World bluestems, Ky 729 and Blackwell switchgrasses, and NJ 1617-72 indiangrass appear to have the highest potential to produce forage on soils with low levels of available P.

Sparse species have chronically small local population sizes, even though they occur in several habitats over a wide geographic range. Greenhouse de Wit replacement series with seven species of sparse and common perennial grasses of tallgrass prairie were performed with seedlings and tiller fragments for 5, 10, and 15, mo. As younger and older seedlings, sparse grasses overyielded and were advantaged by the interaction with common grasses. The common grasses underyielded and were disadvantaged in mixture with sparse grasses. As tillers, the interaction was less antagonistic, and both common and sparse grasses either overyielded or were unaffected by the interaction. Seedlings of sparse species were largest when planted in low proportion, surrounded by individuals of a common grass. Because the sparse species are not disadvantaged by interactions with their common neighbors, their competitive abilities are not implicated as a cause of their local rarity. Rather, the good competitive abilities of these spar...

Yield responses by native range to fertilization has often been disappointing in the tall grass prairie, and the results were confounded by changes in species composition. This study evaluated the response to N and P fertilizer by monocultures of three native species ‘Kaw’ big bluestem (Andropogun gerardi Vitman), ‘Caddo’ switchgrass (Panicum virgatum L.), and indiangrass [Sorghastrum nutans (L.) Nash] and an introduced grass, weeping lovegrass [Eragrostis curvula (Shrad.) Ness]. Rates of N fertilizer were 0, 45, 90, and 180 kg/ha in all combinations with P at 0 and 40 kg/ha. Forage production, crude protein, fertilizer N recovery, stand longevity, and soil fertility changes were evaluated. Excellent forage yield responses to N fertilization were obtained from the native species in monoculture. Switchgrass and weeping lovegrass were the most productive species at 180 kg N − 40 kg P/ha, but had different seasonal production. All native grasses produced one flush of growth and very limited regrowth when compared with weeping lovegrass. Indiangrass had significant reductions in stand at 90 kg N and 180 kg N/ha and was the first species each year to show visual symptoms of drought stress. Severe lodging of big bluestem at 180 kg N/ha limited its potential. Fertilizer N recovery of all species was most efficient at the 90 kg N − 40 kg P/ha treatment being 52 to 66% for native grasses and 84% for weeping lovegrass. Soil tests revealed P accumulations with P fertilization, decreased soil pH associated with N fertilizer and soil K changes in relation to forage removal. The native species have some characteristics which limit their potential for use in fertilized meadows.

Plant-climate-soil relationships were studied during the years 1968 and 1969 on the basis of the phenological pattern of appearance of the first leaf in spring of four perennial species, spirea (Spirea spp L.), orchardgrass (Dactylis glomerata L.), fall aster (Aster azureus L.), and big blue stem (Andropogon gerardi L.). Plantings of these species were previously established in plots adjacent to official weather stations at all five locations in Indiana. Comparisons between the environmental factors and the appearance of the first leaf were made using two multiple regression analysis methods. First leaf appearance during the 2 years did not follow Hopkins' bioclimatic law at these locations. In a northern Indiana muck soil at Wanatah, the growing season began 6 to 10 days later in the 1969 year than on a sandy loam soil located only 250 m from that location. Appearance of the first leaf at all locations for the four species over both years was 2 or 3 weeks earlier at the southern location than on the heavier soils in central and northern Indiana. Regression analysis show that six parameters contributed to much of the R² value, with each independently contributing to a high R² value. The regression included those factors that would develop R² values to .9000+. Parameters consistently contributing to this value were daylight hours and soil temperatures at 20, 5.0, and 2.5 cm (base OC bare soil). Daylight hours from the last frost to first leaf were the most consistent parameter correlated with appearance of the first leaf. Soil temperature at 20 cm was also important and contributed to increasing R² Soil differences, based on detailed physical and chemical analyses, accounted for plant response variation indirectly, especially as related to texture that influenced water-holding capacity and subsequently temperature. This is an interesting parameter as it relates to soilplant-climate interactions in heavy-textured soils. The correlation for soil and air temperature relationship was linear. Degree-day accumulation was different in the 2 years, indicating that other factors, such as the soil temperature-moisture interaction, minutes of sunshine, net radiation, etc., may be important environmental parameters involved in initiation of plant growth in the spring as indicated by the appearance of the first leaf.

MCMILLAN, C. (U. Texas, Austin.) Nature of the plant community. V. Variation within the true prairie community-type. Amer. Jour. Bot. 46(6): 418-424. Illus. 1959.-Population samples of grass species were transplanted to Lincoln, Nebraska, from two grassland communities within the general distribution of the true prairie community-type. These represented extensive grassland areas near Watertown, South Dakota, and Manhattan, Kansas. True prairie relicts near Colorado Springs, Colorado and in the Black Hills of southwestern South Dakota were also studied in the transplant garden. Only in one species, Stipa spartea Trin., were the transplanted populations essentially similar in behavior. In 8 of the species, Koeleria cristata (L.) Pers., Bouteloua gracilis (H.B.K.) Lag., B. curtipendula (Michx.) Torr., Schizachyrium scoparium Nash, Andropogon gerardi Vitman, Panicum virgatum L., Sorghastrum nutans (L.) Nash, and Sporobolus heterolepis (A. Gray) A. Gray, the Manhattan populations were the latest flowering. In Elymus canadensis L., the Manhattan population was the earliest flowering. The abstraction of two communities into a true prairie type of community with other communities of similar species-populations is a convenient method for discussing distributional phenomena. However, extreme caution must be used in generalizing about characteristics other than distributional. If the 10 species in the present study were designated by letters, the Watertown and Manhattan communities could be compared ecologically as a b' c d e f g h i j and a b c' d' e' f' g' h' i' j'. The use of taxonomic relationship in vegetational studies is convenient for the reduction of sample size, but the vital aspect of studying variation within the species is in the determination of harmony between vegetation and its habitat. The relict communities are in adjustment with their habitats and represent the results of natural selection in favoring early-flowering variants within a number of different species. The key to distribution of the true prairie vegetation, widespread or relict, lies in the harmony between a habitat variable and a vegetation variable. Through natural selection, each stand of true prairie may be fundamentally different from any other stand. THE EXTENT of a regional grassland climax, as interpreted by Clements (1936), was based primarily upon 2 criteria. The first, the life form of the dorninants, the perennial grasses, provided the visible unity of the climax. The second, involving the widespread occurrence of certain genera and the geographic repetition of certain combinations of species and genera, was drawn from distributional data. Both of these criteria, one, physiognomic, and the other, distributional, can be used in delineating the present extent of a regional grassland vegetation in North America. Clements (1936) recognized that the climate and the grassland climax were not "matched by a similar uniformity," although this seems to have been overlooked by a number of his critics (Malin, 1956; Whittaker, 1957, among others). Clements noted that the' average period without killing frost is about 9 mo. in the south "but in the Canadian provinces it is less than 3, while the mean annual temperatures are 700 and 33?F., respectively." Furthermore, he noted that the maximum rainfall at the extrenies of the climatic pattern not infrequently amounted to 3 and 4 times that of the minimum. He stated that the difference in climate from Texas 'Received for publication January 30, 1959. This study was aided by funds from National Science Foundation Grant G-3809 and the Nebraska Agricultural Experiment Station. to Manitoba and Saskatchewan was particularly striking because only 1 association (mixed prairie) was involved. The difference in climate within the area of the true prairie type of community is equally noticeable. Although Clements devoted little writing to the apparent disharmony of vegetation and climate, he suggested in 1928 (p. 128) that "while there is every certainty theoretically that the responsive unit, the formation," (the climax) "is in harmony with the causal unit, the habitat, our present knowledge is inadequate to prove this." There can be only speculation on the reasoning that Clements may have used in resolving this apparent lack of correlation between uniformity of vegetation and non-uniformity in the climate. Clements and Shelford (1939) suggest that the chief explanation of this seeming anomaly is to be found for plants in the evasion of temperature extremes; however, this apparently has primary reference to the life form, the visible unity of the grassland. The results of his many transplant studies (Clements et al., 1950), indicating that highly plastic behavior is a common characteristic of plants, may have provided Clements with the basis for his resolution of the distributional non-correlation. The present study has the goal of furthering our understanding of the nature of grassland vegetation, particularly that with the composition referable to

Thicknesses of three Mollisols (Tama. Elburn, and Drummer series), developed from Wiaconsinan-age material in a toposequence in Central Illinois, were considerably greater (18 to 68 cm) when their lower boundaries were determined by the depth of rooting of native perennial big bluestem (Andropogon gerardi) than when determined by the lower limit of the balm A combination of four criteria—structural development, significant clay accumulation, significant clay Alms, and the presence of completely unleached material—probably gave the best measure of solum thickness of these soils. However, evidence of some clay movement below the solums and the greater depth of rooting of native perennial grass, and also of such crops as corn (sea mays L.), suggests that material beneath the solum Is important in the behavior, definition, and classification of many of these kinds of soils in the north-central region of the U.S. Additional Hey Words for Indexing: pedon boundary, sal= thickness, soil classification, Andropogon gerardi rooting.

Three grasses–Calamagrostis canadensis, Andropogon gerardi, and Koeleria cristata–were grown for 13 months on two soil slopes in a greenhouse. One slope was composed of sand and the other loamy sand; the water table of each was controlled to create equal catenas with sites ranging from dry to wet. All three grasses were seeded uniformly over each tank. Competition was limited as each grass found its own niche above— and below—ground. Some interspecific competition resulted from shading by Koeleria, while the density of Calamagrostis was reduced by intraspecific competition on the better soil (loamy sand) and where the moisture level was most favorable. The density of Andropogon was greatest on the loamy sand and reached its maximum at a very moist site on both soils. Koeleria produced its maximum shoot weight at a greater depth to water table than either of the other two species. During the final month of the study watering was discontinued and a more natural pattern resulted as Calamagrostis died back to the moist sites while Koeleria was able to survive at drier levels. Roots of each species occupied soil stratum, with Calamagrostis having the least flexible root system and Koeleria exhibiting a very flexible root system which readily adjusted to decreasing moisture supply.

THE GRASSLAND type of community is an ideal experimental unit. Its structure allows a multiplicity of approaches toward a fuller understanding of the nature of the plant community. In two previous studies (McMillan, 1956a, b) of this fundamental ecological unit, transplanting of members to a uniform garden proved helpful in understanding behavior within grassland communities. In the present evaluation, the separation of habitat effects from genetic controls within the community is approached by the reciprocal transplanting of members of a prairie community and a sandhill community. Such a separation of habitat and genetic controls proved to be valuable in interpreting community phenomena in non-experimental habitats. A plant community as used in this discussion is a piece of vegetation around which a boundary can be drawn. The boundary imposed on the experimental community would include the members of each experimental population investigated. The community site from which the experimental populations are removed obviously can be carved up into numerous small communities or be treated as one large community. Here it is treated as one community. The earlier studies by Steiger (1930) at the prairie collection site separated the vegetation into smaller units which were placed in a number of categories or types of communities. Recent studies of communities in sandhill areas of Nebraska include those of Frolik and Shepherd (1940) and Tolstead (1942). METHODS AND MATERIALS.-A community from the loess hills, 9 miles west of Lincoln, Nebraska, was selected for comparison with one in the sandhills ca. 225 miles west of Lincoln. The sandhill location was in an ungrazed, unmowed area within the Nebraska National Forest at Halsey. The Lincoln area, the site of Steiger's investigation (1930) of the structure of prairie vegetation, has received annual mowings. The two community sites have obvious soil and climatic differences. However, they contain a surprisingly similar list of species. In both areas occur Andropogon scoparius Michx., Sorghastrum nutans (L.) Nash., Koeleria cristata (L.) Pers., Stipa spartea Trin., Bouteloua gracilis (H.B.K.) Lag., B.hirsuta Lag., Panicum virgatun L., Elymus canadensis L., Andropogon gerardi Vitman, Helianthus rigidus (Cass.) Des'f., Artemisia gnaphalodes Nutt., and Rosa arkansana Porter. Such grasses as

Three plant communities near Hays, Kansas, showed considerable change in the composition of their dominant vegetation over the 30—year period from 1932 to 1961. The short grass community was dominated by Buchloe dactyloides and Bouteloua gracilis in 1932 and dominated only by Bouteloua gracilis in 1961. The little bluestem community was dominated by Andropogon scoparius during favorable years but by Bouteloua curtipendula and Bouteloua gracilis during drought years. The dominants of the little bluestem—big bluestem community were Andropogon scoparius and Andropogon gerardi in 1932 but by 1961 Andropogon gerardi was the only dominant. Two droughts periods, 1933—39 and 1952—56, were important in affecting these vegetation changes. See full-text article at JSTOR

In China and Japan bamboo shoots have long served as victuals, but no such use has yet developed in the New World, except for imports of the canned article. Edibility tests on 27 kinds growing in Puerto Rico are here reported, but large plantations and propaganda to create a demand for the shoots would be necessary to establish them as items of diet in America.