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Plants make important contributions to green roof ecosystem service provision through evapotranspiration, canopy shading, and water retention. Because these plant communities are a critical component of green roof design and function, both seasonal and interspecific variation of these plant communities are important factors in evaluating green roof performance. This study examines variation in both species abundance and 9 leaf traits throughout the 2015 growing season of four New York City green roofs. While community composition varied significantly between each month (pANOSIM = 0.036), three major plant families (Asteraceae, Lamiaceae, and Poaceae) consistently had the greatest green cover and were present during the entirety of the growing season. For leaf traits, period of the growing season had a significant impact on most of the traits measured. Leaf thickness, leaf relative water content (RWC) and saturated water content (SWC) decreased as the growing season progressed, while leaf dry matter content (LDMC) and stomatal density increased, likely due to a seasonal decrease in rainfall as species-level variance in these water traits is low (7.40% and 0.88%, respectively). We also ranked planted and spontaneous species in accordance to both cover and functional trait values, and identified 11 species suitable for green roofs in NYC: Pycnanthemum tenuifolium (Lamiaceae), Symphiotrichum leave, Symphiotrichum pilosum, Rudbeckia hirta, Solidago odora (Asteraceae), Panicum virgatum, Sorghastrum nutrans, Schizachyrium scoparium, Dichanthelium clandestinum, Deschampsia flexuosa (Poaceae), and Oenothera biennis (Onagraceae). Understanding the temporal responses of plant communities and their constituent species is critical in optimizing green roof ecosystem services.

Some taxonomic groups impose the need to use continuous morphological characteristics in taxon delimitation, and the grass genus Sorghastrum is a clear case of this necessity. Sorghastrum canescens was described based on the length of its awns. However, insufficient and scattered sampling has obscured the identity of this species for at least 137 years, while it was considered synonym of S. incompletum var. incompletum. In this study we evaluate statistical differences in the original and current morphological concepts of S. canescens using analysis of variance and posterior pairwise comparison of means and medians. We also retrieved the nomenclatural history of the binomial S. canescens to clarify possible errors in the synonymization of this species. All the statistical evidence refutes the hypothesis that S. canescens is a synonym of S. incompletum var. incompletum. Historical data revealed an error in the identification of the correct basionym of S. canescens and this error has been repeated in several taxonomic revisions. We were also able to establish an approximate date for the type-collection of S. canescens. We therefore propose the reestablishment of the name Sorghastrum canescens and provide morphological descriptions and illustration of this species.

We studied the breeding biology of the Lesser Grass-Finch (Emberizoides ypiranganus), a bird with a little-known life history, in upland grassland of the Atlantic Forest (Mata Atlântica) Biome in southern Brazil. We collected data for 93 nests over two breeding seasons (2012–2014). We assessed how some covariates influence the daily survival rates and affect nest survival, building models in Program MARK. Breeding begins in early October, peaks in late November, and continues until early March, lasting approximately 150 days. The mean size of breeding territories was 1.1 ha, and territories located in burned areas were smaller than those in unburned areas. Only the females build the small open-cup nests, in clumps of grass (mainly composed of Andropogon lateralis, Schizachyrium tenerum and Sorghastrum setosum) at 36.2 cm above the ground. The clutch size is three (67%) or two eggs (n = 52), and laying occurs on consecutive days. Incubation is performed by the female and lasts 13.7 days. The mea...

Grasslands of the central United States are expected to experience severe droughts and other climate extremes in the future, yet we know little about how these grasses will respond in terms of gene expression. We compared gene expression in Andropogon gerardii and Sorghastrum nutans, two closely related codominant C4 grasses responsible for the majority of ecosystem function, using RNA-seq. We compared Trinity assemblies within each species to determine annotated functions of transcripts responding to drought. Subsequently, we compared homologous annotated gene-groups across the two species using cross-species meta-level analysis and functional clustering based on key terms. The majority of variation was found between species, as opposed to between drought and watered treatments. However, there is evidence for differential responses; Andropogon allocated gene expression differently compared to Sorghastrum, suggesting Andropogon focuses on stress alleviation (such as oxygen radical scavenging) rather than prevention. In contrast, Sorghastrum may employ a drought avoidance strategy by modulating osmotic response, especially with hormonal regulation. We found Sorghastrum tended to be more sensitive within 10 key gene-groups related to stress, abscisic acid and trichomes, suggesting gene expression may mechanistically parallel sensitivity at the physiological level. Our findings corroborate phenotypic and physiological differences in the field and may help explain the phenotypic mechanisms of these two species in the tallgrass prairie community under future drought scenarios.

Este estudo teve como objetivo avaliar, no outono, as características morfogênicas de oito gramíneas nativas da região central do Rio Grande do Sul, classificadas sob uma tipologia funcional, segundo o teor de matéria seca e a área foliar específica em A, B, C, D: Axonopus affinis (A), Andropogon lateralis (B), Paspalum notatum (B), Paspalum plicatulum (C), Piptochaetium montevidense (C) Aristida laevis (D), Saccharum angustifolius (D) e Sorghastrum pellitum (D); submetidas a dois níveis de nitrogênio (zero e 200kg ha-1 de N). O delineamento experimental foi o inteiramente casualizado com arranjo fatorial 8 (espécies) x 2 (níveis de N) ou 4 (tipos funcionais) x 2 (níveis de N), ambos com três repetições. As plantas foram submetidas a cortes segundo diferentes durações de elongação foliar, definidas por médias das espécies por tipo funcional. As variáveis foram analisadas estatisticamente usando testes de aleatorização com o software MULTIV. Não houve diferença significativa entre os níveis de N, porém houve entre as espécies e entre os tipos funcionais. As variáveis morfogênicas são coerentes com a tipologia funcional utilizada como referência, baseada em atributos foliares. Os níveis de nitrogênio não alteram a morfogênese das espécies na estação do outono, sendo seu uso desaconselhado nesse período.

Morphogenetic and structural characteristics of the native grasses of the Pampa Biome Andropogon lateralis, Aristida laevis, Axonopus affinis, Erianthus angustifolius, Paspalum notatum, Paspalum plicatulum, Piptochaetium montevidense and Sorghastrum pellitum were evaluated as to the effect of nitrogen (N) fertilization (zero and 100 kg N/ha). The experimental design was of randomized blocks with three replicates in a 8 × 2 (native grasses × N) factorial arrangement. Accumulated thermal sums of 350 and 700 degree days determined the interval between cuts for prostrate and caespitose growth habit species, respectively. Species considered of resource conservation (A. laevis, E. angustifolius, P. plicatulum and S. pellitum) had the highest leaf elongation rate when they received N. For leaf appearance rate, phyllochron, leaf senescence rate, leaf lifespan, number of green leaves and final length of leaf blades, there was difference between the evaluated species.

Hybridization within sorghum [Sorghum bicolor (L.) Moench] has been the primary means of creating genetic diversity for improvement. While considerable variation exists within S. bicolor, traits such as biotic stress tolerance could be improved if secondary and tertiary germplasm pools were accessible through hybridization. Sorghum germplasm possessing the inhibition of alien pollen (iap) allele has enhanced the ability to make successful wide hybridizations between secondary and tertiary gene pools. However, the range of this efficacy has not been tested. Pollen from Miscanthus Andersson, Pennisetum Rich., Sorghastrum Nash, and Zea L. was transferred to the stigmas of S. bicolor lines Tx3361 (with the iap allele) and ATx623 (without the iap allele). Pollen of all genera exhibited tube growth, but the frequencies of germination and growth rates varied among species and accessions within a genus. Significantly more pollen germinated and grew into the pistils of Tx3361 than ATx623. Pollen grains were noticeably more numerous on stigmas of Tx3361, implying that factors within Tx3361 may also affect pollen adhesion. The results indicate that the potential for intergeneric hybridization of S. bicolor via Tx3361 will vary based on the individual species and accessions within a species that are used as pollinators.

The objectives of this research were to determine the effect of N levels and plant maturity on the nutritive quality of four warm-season grasses, and to evaluate relationships between forage quality and morphological development. Indiangrass (Sorghastrum mutans L. Nash), big bluestem (Andropogon gerardii Vitman), Eastern gamagrass (Tripsacum dactyloides L.), and switchgrass (Panicum virgatum L.) were grown in four replications, applied with 3N levels (0, 65, and 140 kg/ha), and harvested on ten dates at approximately 2-week intervals for first seven harvest dates and 3-week intervals for last three harvest dates. For all species, harvesting at early maturity increased (P 0.05) the IVDMD value for the other three species in 2007. The concentration of CP for all four warm-season grass species increased (P 0.05) for eastern gamagrass.

Atmospheric CO2 enrichment usually changes the relative contributions of plant species to biomass production of grasslands, but the types of species favored and mechanisms by which change is mediated differ among ecosystems. We measured changes in the contributions of C3 perennial forbs and C4 grasses to aboveground biomass production of tallgrass prairie assemblages grown along a field CO2 gradient (250–500 lmol mol 1 ) in central Texas USA. Vegetation was grown on three soil types and irrigated each season with water equivalent to the growing season mean of precipitation for the area. We predicted that CO2 enrichment would increase the forb contribution to community production, and favor tall-grasses over mid-grasses by increasing soil water content and reducing the frequency with which soil water fell below a limitation threshold. CO2 enrichment favored forbs over grasses on only one of three soil types, a Mollisol. The grass fraction of production increased dramatically across the CO2 gradient on all soils. Contribution of the tall-grass Sorghastrum nutans to production increased at elevated CO2 on the two most coarse-textured of the soils studied, a clay Mollisol and sandy Alfisol. The CO2-caused increase in Sorghastrum was accompanied by an offsetting decline in production of the mid-grass Bouteloua curtipendula. Increased CO2 favored the tall-grass over mid-grass by increasing soil water content and apparently intensifying competition for light or other resources (Mollisol) or reducing the frequency with which soil water dipped below threshold levels (Alfisol). An increase in CO2 of 250 lmol mol 1 above the pre-industrial level thus led to a shift in the relative production of established species that is similar in magnitude to differences observed between mid-grass and tallgrass prairies along a precipitation gradient in the central USA. By reducing water limitation to plants, atmospheric CO2 enrichment may alter the composition and even structure of grassland vegetation.

Information about the interaction of harvesting and N fertilization on composition of warm-season grasses grown as biofuel feedstocks is limited. Our objective was to determine composition of warm-season grasses as influenced by N fertilization rates and harvest dates. A field study was conducted near Ames, IA, during 2006 and 2007. The experimental design was a split-split plot arranged in a randomized complete block with four replications. Big bluestem (Andropogon gerardii Vitman), eastern gamagrass (Tripsacum dactyloides L.), indiangrass (Sorghastrum nutrans L. Nash), and switchgrass (Panicum virgatum L.) were main plots. Three N application rates (0, 65, and 140 kg ha -1 ) were subplots, and 10 harvest dates were sub-subplots. In both years, delaying harvest increased cellulose, lignin, and C concentrations, but decreased ash and N concentrations, however, the magnitude of these effects varied among species. On average, big bluestem had the highest cellulose (430.5 g kg -1 ) and C concentration (450.5 g kg -1 ) while switchgrass had the highest lignin concentration (58.5 g kg -1 ) among four species. Big bluestem had the lowest ash concentration (47.5 g kg -1 ) whereas indiangrass had the lowest N concentration (5.5 g kg -1 ). With increasing rates of N, average N, C, cellulose, and lignin concentrations increased 19 to 29%, 0.6 to 2.2%, 0.7 to 5.7%, and 5.6 to 23.9%, respectively, whereas ash concentration declined 1.8 to 18.4%, varied among species. Our results indicated that in general, warm-season grasses supplied with N fertilizer at 140 kg ha -1 and harvest delayed until fall have the optimal composition for biomass feedstock production.

Atmospheric carbon dioxide (CO2) enrichment may increase plant growth more than the uptake of chemical elements from soil. Increased CO2 also may alter element levels in biomass from multi-species vegetation by changing plant species abundances. We measured concentrations of ten elements in aboveground tissues of three C4 grasses that had been exposed for 2-3 growing seasons to a continuous gradient in CO2 from 250 to 500 lmol mol -1 . The grasses, Bouteloua curtipendula, Schiz- achyrium scoparium, and Sorghastrum nutans, are competitive dominants in assemblages of tallgrass prairie vegetation growing on each of three soil types along a field CO2 gradient in central Texas, USA. Our objective was to determine whether CO2 influences element concentrations in grass mixtures by changing concentrations in individual species or shifting spe- cies abundances. Increased CO2 had little effect on element concentrations in grasses compared to differences observed among grass species and soils. Increasing CO2 from the pre-Industrial to elevated levels reduced the phosphorus concentration in grasses grown on a clay and sandy loam soil. Concentrations of most other elements did not respond to CO2 treatment. Cover of the mid-grass Bouteloua declined at higher CO2 levels as cover of the taller grass Sorghastrum increased. Concentra- tions of several elements were lower in Bouteloua than Sorghastrum; hence, this exchange of species at higher CO2 increased element concentrations in grass assemblages. Potential consequences include an improvement in the nutritional quality of plants for herbivores. Results highlight the underappreciated impact that CO2 enrichment may have on ecosystem functioning by changing plant composition.

The flowering of grasses is a process critical to plant population dynamics and genetics, herbivore performance, and human health. To better understand the climate factors governing grass flowering, we analyzed the patterns of culm production over 25 years for three perennial tallgrass prairie species at Konza Prairie in Kansas, USA. The three species (Andropogon gerardii, Sorghastrum nutans, and Schizachyrium scoparium) all utilize the C4 photosynthetic pathway and were measured annually at the same locations for the past 25 years in an annually burned watershed. Culm production of all three species increased with higher growing-season soil moisture and precipitation but differed in their responses to water availability at different times during the growing season. Relative to Andropogon, Sorghastrum responded more to precipitation early in the growing season, and Schizachyrium responded more to precipitation late in the growing season. Flowering by each species also revealed a threshold relationship with late-season soil moisture at approximately 1 m depth, which likely is a proxy for season-long water balance. Although flowering can be influenced by conditions antecedent to the current growing season, neither soil moisture nor precipitation during the previous year influenced flowering over the 25-year period. Flowering culm production averaged 9% and 7% of total graminoid aboveground net primary production (ANPP) in the uplands and lowlands, respectively. Interannual variation in ANPP correlated only with Sorghastrum flowering, suggesting a predominant role of the species in ANPP responses to climate.

While recent research has focused on the effects of exotic plant species on ecosystem properties, less is known about how restoring individual native plant species, differing in biomass and tissue chemistry, may impact ecosystems. We examined how three native C(4) prairie grasses affected soil C and N cycling 11 years after reintroduction into successional old-field communities dominated by non-native C(3) grasses. The species examined in this study differ in traits that are expected to influence soil C and N cycling (biomass and tissue chemistry). Thus, we hypothesized that cycling rates would decrease, thereby increasing pool sizes in soils under C(4) species compared under C(3) species. As predicted, the C(4) species had greater biomass and more recalcitrant tissue [higher C:N, acid detergent fiber (ADF):N] compared to the dominant C(3) species. The three C(4) species did not differ in tissue C:N, ADF:N, or root biomass, but Andropogon had more than twice the shoot biomass of Schizachyrium and Sorghastrum. Soils under the C(4) species did not differ in inorganic N levels, but levels were lower than in soils under the C(3) species, and soils under Andropogon had slightly lower in situ net N mineralization rates compared to those under C(3) species. We found little evidence of larger surface soil C pools under C(4) species versus C(3) species after 11 years and no differences in subsurface soil C or N among species. The C(4) species contributed a significant amount of C to both soil depths after 11 years. Our results demonstrate that C(4) species reintroduction into old-fields can alter C and N cycling on relatively short timescales, and that individual C(4) species differ in the magnitude of these effects. Improving our understanding of how species influence ecosystem properties is essential to predicting the ecosystem-level consequences of plant community alterations due to land use changes, global change, and species introductions.

Establishment and management of North American prairie grasses by field sowing was investigated at the Royal Horticultural Society Garden at Wisley, Surrey, in Southern England. Untreated seed of little bluestem (Schizachyrium scoparium (Michx.) Nash); indian grass (Sorghastrum nutans (L.) Nash); and prairie dropseed (Sporobolus heterolepis (A.Gray) A.Gray.) was sown in May 1997 at 550 seeds/m2 onto topsoil plots (control), topsoil with charcoal mulch, and topsoil covered with transparent, perforated crop polyethylene post sowing. Highest percentage emergence was recorded in the clear polyethylene mulch followed by the charcoal mulch. Weed competition was managed by cutting to 75 mm (≅ 3 in) above the soil surface. Dry weight of prairie grass seedlings in October 1997 was strongly negatively correlated with percentage weed cover in June 1997. Despite the weed competition, on plots where sufficient seedlings survived, Schizachyrium and Sorghastrum were eventually able to dominate Agrostis stolonifera, the most abundant weed, when burnt annually in April. No regeneration of prairie grasses from self-sown seed was observed within the experimental treatments over an 8 year period. The application of this research to more sustainable horticultural practice in urban landscapes is discussed.

Witchweeds (Striga spp.) are noxious parasitic weeds that cause considerable crop damage in the semiarid tropics. Genetic control of striga is effective, although sources of resistance are limited in most crops. Useful resistance sources have been obtained in sorghum [Sorghum bicolor (L.) Moench], an important host crop that has coevolved with the parasite. Fifty-five wild accessions within the primary gene pool of sorghum and 20 sorghum cultivars were screened for resistance to Striga asiatica L. Kuntze in the laboratory. Wild sorghums assayed included S. almum Parodi, S. bicolor subsp. drummondii (Steud.) De Wet, race drummondii and race hewisonni, S. bicolor subsp. verticilliflorum (Steud.) Piper with races aethiopicum, arundinaceum, verticilliflorum, and virgatum; S. halepense (L.) Pers.; S. miliaceum; S. rhizomatores; S. sorghastrum; and S. usamberense. Wild sorghum accessions varied in their effects on S. asiatica at the preattachment level of association. Potential striga-resistance mechanisms of low germination stimulant production, germination inhibition, and low haustorial initiation activity were observed in this collection of sorghums. Some of these potential striga-resistance mechanisms, reported here for the first time, appear to be unique to wild sorghums. The results described in this study offer the possibility of introgressing valuable resistance genes from wild to cultivated sorghum.

Plant/soil microbial community feedback can have important consequences for species composition of both the plant and soil microbial communities, however, changes in nutrient availability may alter plant reliance on mycorrhizal fungi. In this research, we tested whether plant/soil community feedback occurs and if increased soil fertility altered the plant/soil community interactions. In two greenhouse experiments we assessed plant and AM fungal performance in response to different soils (and their microbial communities), collected from under three co-occurring plants in serpentine grasslands, and nutrient treatments. The first experiment consisted of two plant species (Andropogon gerardii, Sorghastrum nutans), their soil communities, and three nutrient treatments (control, calcium, N-P-K), while the second experiment used three plant species (first two and Schizachyrium scoparium), their soil communities collected from a different site, and two nutrient treatments (control, N-P-K). Plant/soil community feedback was observed with two of the three species and was significantly affected by nutrient enrichment. Negative Sorghastrum/soil feedback was removed with the addition of N-P-K fertilizer at both sites. Andropogon/soil feedback varied between sites and nutrient treatments, while no differential Schizachyrium growth relative to soil community was observed. Addition of N-P-K fertilizer to the nutrient poor serpentine soils increased plant biomass production and affected plant/soil community interactions. Calcium addition did not affect plant biomass, but was associated with significant increases in fungal colonization regardless of plant species or soil community. Our results indicate that nutrient enrichment affected plant/soil community feedback, which has the potential to affect plant and soil community structure.

International audience; Dendritic phytoliths that precipitate in grass inflorescences are often used in archaeology to trace the use of cereals (i.e. grasses harvested for their edible grain) and their domestication by early human societies. High amounts of these morphotypes are sometimes interpreted in terms of cereal accumulation in archaeological contexts. In sub-Saharan Africa, few cereals were domesticated during the mid-Holocene, but many wild grasses are still largely harvested by modern societies for food. The harvesting of wild cereals is also considered as one of the first stages toward early grass domestication. To evaluate how well dendritic phytoliths and/or other phytoliths produced in the grass inflorescences could help trace the use of wild cereal grains in sub-Saharan Africa, we analyzed the phytolith content of 67 African species (including 20 wild cereals), and 56 modern soils. We used test-value analysis and ANOVA to evaluate how well grass inflorescences could be distinguished from leaf/culm parts based on their phytolith content. We also measured the abundances of these phytoliths in natural soils from sub-Saharan Africa to provide a benchmark percentage abundance above which anthropogenic accumulation may be suspected in archaeological deposits. Our results confirm that, although rondel type phy-toliths are abundant, only the dendritic phytolith morphotype is exclusive to the grass inflorescences. Yet, dendritic phytoliths do not occur in all species. They happen to be most frequent and found in greatest abundance (>34% relative to total phytolith count) in Panicoideae grasses (Sehima ischaemoides, Sorghastrum stipoides, and Sorghum purpureo-sericeum), and in one Eragrostideae species (Eragrostis squamata), which are not considered cereals. Inflorescences of the wild African cereals studied here do not happen to be particularly rich in dendritics (>3% relative to sum of grass silica short cell phytoliths plus dendritics are likely to indicate anthropogenic accumulation of grass inflorescences. Yet, the absence or low abundance of dendritic phytoliths in archaeological deposits may not always indicate the absence of anthropogenic accumulation of grass inflorescence material.

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.

Field studies were conducted in 1994 and 1995 to determine the phenology, leaf and tiller characteristics and yield of 22 warm-season grasses in south western Quebec, Canada. Cordgrass (Spartina pectinata L.), two cultivars of Indiangrass [Sorghastrum nutans L. (Nash)], two cultivars of big bluestem (Andropogon gerardii Vitman), 12 cultivars of switchgrass (Panicum virgatum L.) and five cultivars of prairie sandreed [Calamovilfa longifolia (Hook) Scribn., were included in the study. In terms of initial spring growth, CWNC (cordgrass) and New Jersey 50 (switchgrass) were the earliest and latest, respectively. Initial spring regrowth from sandreeds was predominantly from continued growth of biennial tillers, from rhizomes in cordgrass and from buds on stem bases for the other species. The earliest maturing entries were ND3743, Dakota, Ottawa3 (switchgrasses) and Bison (big bluestem). New Jersey 50 and CWNC were the latest maturing. CWNC had high tiller numbers throughout the season while the rest of the entries showed increases in tiller numbers in summer. There were significant differences among entries in height development across the season. Biomass yields ranged from 65 to 861 g per plant. Lignocellulose concentration was high in all entries with neutral detergent fiber (NDF) and acid detergent fiber (ADF) ranging from 770–860 g kg−1 and 460–540 g kg−1, respectively. Nitrogen and ash concentrations ranged from 4–10 and 40–70 g kg−1, respectively. The results indicate potential for cordgrass (CWNC) and several switchgrasses for biomass production in the short season areas of Quebec.

Degradation of Great Plains rangelands can be linked to past management practices that reduced native species diversity and accelerated establishment and expansion of exotic weeds and less desirable native species. Leafy spurge is an exotic perennial weed that infests more than 1 million ha in the northern Great Plains and reduces rangeland carrying capacity by competing with desirable forages and causing infested areas to be undesirable to cattle and wildlife. Research was conducted to determine the feasibility of using herbicides to suppress leafy spurge and other resident vegetation, which facilitated planting and establishment of native tallgrasses. Four experiments were conducted where 0.28, 0.56, and 0.84 kg ai/ha imazapyr and 0.1 kg ai/ha sulfometuron were applied alone and in combination and 0.84 kg ai/ha glyphosate was applied to leafy spurge-infested range sites in fall 1991 near Ainsworth, NE, and in fall 1991, 1992, and 1993 near Ansley, NE. Research areas were burned about 200 d after herbicide application to reduce plant residue. Monoculture stands of big bluestem and switchgrass were then no-till planted in each experiment and indiangrass was no-till planted in experiments initiated at Ansley in 1992 and 1993. Yields of the planted grasses, leafy spurge, and other vegetation were measured in August at each location starting the year after planting. Imazapyr was an essential component of treatments applied before planting to facilitate establishment of highly productive stands of the tallgrasses. Generally, yields were maximized by fall treatments of 0.28 kg/ha imazapyr + 0.1 kg/ha sulfometuron for big bluestem, 0.84 kg/ha imazapyr for indiangrass, and 0.84 kg/ha imazapyr + 0.1 kg/ha sulfometuron for switchgrass. Yields of the planted grasses were frequently four times greater where these herbicides were applied compared to where glyphosate or no herbicide were applied. Leafy spurge yields were usually reduced in areas where tallgrass yields were greatest. The sequential combination of suppressing vegetation with fall-applied herbicides, burning standing dead plant residue, then no-till planting desirable native tallgrasses in the spring increased productivity of these leafy spurge-infested range sites. Nomenclature: Imazapyr, (? +)-2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo1H-imidazol-2-yl]3-pyridinecarboxylic acid; glyphosate, N-(phosphonomethyl)glycine; sulfometuron, 2-[[[[(4,6-dimethyl-2-pyrimidinyl)amino]carbonyl]-amino]sulfonyl]benzoic acid; leafy spurge, Euphorbia esula L. #3 EPHFS; big bluestem, Andropogon gerardii Vitman 'Pawnee' # ANOGE; indiangrass, Sorghastrum nutans (L.) Nash 'Holt'; switchgrass, Panicum virgatum L. 'Trailblazer' # PANVI. Additional index words: Biological diversity, prescribed fire, grassland restoration, imazapyr, glyphosate, sulfometuron, native plants, warm-season grasses, cool-season grasses. Abbreviations: SE, standard error of the mean.

Cette étude a été réalisée dans les pâturages soudano-guinéens de la forêt classée de Wari Maro au centre du Bénin. Quatre types de pâturage y ont été distiCette étude a été réalisée dans les pâturages soudano-guinéens de la forêt claes à Schizachyrium sanguineum et Sorghastrum bipennatum des dépressions, des savanes à Andropogon schirensis et A. chinensis, des savanes à Pennisetum unisetum et Chasmopodium caudatum et enfin des jachères à Pennisetum polystachion et Andropogon gayanus. La biomasse produite en fin de saison pluvieuse a varié de 3,45 ± 0,50 à 5,19 ± 0,86 t MS/ha. La biomasse la plus élevée a été obtenue dans le pâturage à Schizachyrium sanguineum et Sorghastrum bipennatum des dépressions. La capacité de charge périodique après le passage des feux de brousse a été estimée à 0,16 unité de bétail tropical par hectare (UBT/ha), soit une charge de saison sèche de 17 200 UBT pour une superficie de 107 500 ha. En saison humide, la conduite des troupeaux et l'exploitation des pâturages étaient liées à l'évolution de la phytomasse et à la disponibilité en eau dans le système d'élevage extensif en cours dans la zone d'étude.

Plants with the C4 photosynthetic pathway have predominantly one of three decarboxylation enzymes in their bundle sheath cells. Within the grass family (Poaceae) bundle sheath leakiness to CO2 is purported to be lowest in the nicotinamide adenine dinucleotide phosphate-malic enzyme (NADP-ME, EC 1.1.1.40) group, highest in the NAD-ME (EC 1.1.1.39) group and intermediate in the phosphoenolpyruvate carboxykinase (PCK, EC 4.1.1.32) group. We investigated the hypothesis that growth and photosynthesis of NAD-ME C4 grasses would respond more to elevated CO2 treatment than NADP-ME grasses. Plants were grown in 8-1 pots in growth chambers with ample water and fertilizer for 39 days at a continuous CO2 concentration of either 350 or 700 µl l−1. NAD-ME species included Bouteloua gracilis Lag. ex Steud (Blue grama), Buchloe dactyloides (Nutt.) Engelm. (Buffalo grass) and Panicum virgatum L. (Switchgrass) and the NADP-ME species were Andropogon gerardii Vittman (Big bluestem), Schizachyrium scoparium (Michx.) Nash (Little bluestem), and Sorghastrum nutans (L.) Nash (Indian grass). Contrary to our hypothesis, growth of the NADP-ME grasses was generally greater under elevated CO2 (significant for A. gerardii and S. nutans), while none of the NAD-ME grasses had a significant growth response. Increased leaf total non-structural carbohydrate (TNC) was associated with greater growth responses of NADP-ME grasses. Decreased leaf nitrogen in NADP-ME species grown at elevated CO2 was found to be an artifact of TNC dilution. Assimilation (A) vs intercellular CO2 (Ci) curves revealed that leaf photosynthesis was not saturated at 350 µl l−1 CO2 in any of these C4 grasses. Assimilation of elevated CO2-grown A. gerardii was higher than in plants grown in ambient CO2. In contrast, B. gracilis grown in elevated CO2 displayed lower A, a trait more commonly reported in C3 plants. Photosynthetic acclimation in B. gracilis was not related to leaf TNC or nitrogen concentrations, but A:Ci curves suggest a reduction in activity of both phosphoenolpyruvate (PEP) carboxylase (EC 4.1.1.31) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39). Some adaptation of stomatal functioning was also seen in B. gracilis and A. gerardii leaves grown in elevated CO2. Our study shows that C4 grasses have the capacity for increased growth and photosynthesis under elevated CO2 even when water and nutrients are non-limiting. While it was the NADP-ME species which had significant responses in the present study, we have previously reported significant growth increases in elevated CO2 for B. gracilis.

Con el objetivo de caracterizar las fracciones proteicas de Sorghastrum setosum durante el proceso de degradación ruminal, se tomaron 3 g de polvo acetónico obtenido a partir de muestras sometidas a distintos tiempos de incubación ruminal (0; 6; 12; 24; 48; 72 y 120 h). Las proteínas presentes en los residuos acetónicos fueron solubilizadas en buffer Tris pH 8 y cuantificadas por el método de Lowry. La caracterización se realizó por electroforesis desnaturalizante en placa (gel con gradiente de poliacrilamida 12% conteniendo SDS), de acuerdo al sistema de buffer discontinuo de Laemmli modificado (1970). El análisis cualitativo realizado a la hora cero mostró bandas de 87; 64; 58; 55; 51; 47; 46; 44; 42; 27 y 14 kDa. En el perfil proteico se detectaron bandas intensas de 46, 42 y 14 kDa, otras de menor intensidad de 64, 58 y 51 kDa, y un grupo de alto peso molecular en la región de 87 kDa. Se observaron modificaciones del perfil proteico a lo largo del proceso de degradación, detectándose nuevas bandas de alto y medio PM, así como la aparición e intensificación de bandas de bajo PM. Durante el proceso de degradación ruminal, se observó que las bandas de 24, 14 y 55 kDa estuvieron presentes durante las 120 horas de estudio; esta prolongada permanencia indica la escasa degradabilidad ruminal de esta gramínea. With the objective of characterize the protein fractions of Sorghastrum setosum (“sandysoil indiangrass”) during its ruminal degradation, 3 g of acetone powder obtained from samples subjected to different ruminal incubation times were taken (0; 6; 12; 24; 48; 72 and 120 hours). Proteins present in the acetone residue were solubilized in Tris buffer pH 8 and quantitated by the Lowry method. The characterization was carried out by denaturing polyacrylamide gel electrophoresis (12% containing SDS) according to the modified Laemmli buffer system (1970). The qualitative analysis performed at zero hour showed intense bands of 87; 64; 58; 55; 51; 47; 46; 44; 42; 27 and 14 kDa. For the protein profiles, intense bands of 46; 42 and 14 kDa were detected, as well as others of lower intensity of 64; 58 and 51 and finally a group of high molecular weight in the region of 87 kDa. During the degradation process, modifications of the protein profile were observed, being detected new bands of high and half PM, as well as the appearance and increase of low PM bands. During the process of ruminal degradation it was observed that the bands of 24, 14 and 55 kDa were present during the 120 hours of study; this prolonged permanency indicates the scarce ruminal degradability of this gramineous. EEA Colonia Benitez Fil: Slanac, Alcides L. Universidad Nacional del Nordeste. Facultad de Ciencias Veterinarias. Cátedra de Fisiología; Argentina Fil: Sgroppo, Sonia Cecilia. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas, Naturales y Agrimensura. Cátedra de Bromatología; Argentina Fil: Kucseva, Cesar Daniel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Colonia Benítez; Argentina Fil: Balbuena, Osvaldo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Colonia Benítez; Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Veterinarias. Cátedra de Nutrición y Alimentación; Argentina

We measured leaf-level stomata1 conductance, xylem pressure potential, and stomate number and size as well as whole plant sap flow and canopy-level water vapour fluxes in a C4-tallgrass prairie in Kansas exposed to ambient and elevated C02. Stomata1 conductance was reduced by as much as 50% under elevated CO2 compared to ambient. In addition, there was a reduction in stomate number of the C4 grass, Andropogon gerardii Vitman, and the C3 dicot herb, Salvia pitcheri Tort, under elevated CO2 compared to ambient. The result was an improved water status for plants exposed to elevated CO2 which was reflected by a less negative xylem pressure potential compared to plants exposed to ambient CO*. Sap flow rates were 20 to 30% lower for plants exposed to elevated CO2 than for those exposed to ambient CO*. At the canopy level, evapotranspiration was reduced by 22% under elevated C02. The reduced water use by the plant canopy under elevated CO2 extended the photosynthetically-active period when water became limiting in the ecosystem. The result was an increased above- and belowground biomass production in years when water stress was frequent.

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.

Dynamic global vegetation models simulate feedbacks of vegetation change on ecosystem processes, but direct, experimental evidence for feedbacks that result from atmospheric CO2 enrichment is rare. We hypothesized that feedbacks from species change would amplify the initial CO2 stimulation of aboveground net primary productivity (ANPP) of tallgrass prairie communities. Communities of perennial forb and C4 grass species were grown for 5 years along a field CO2 gradient (250-500 μL L(-1) ) in central Texas USA on each of three soil types, including upland and lowland clay soils and a sandy soil. CO2 enrichment increased community ANPP by 0-117% among years and soils and increased the contribution of the tallgrass species Sorghastrum nutans (Indian grass) to community ANPP on each of the three soil types. CO2 -induced changes in ANPP and Sorghastrum abundance were linked. The slope of ANPP-CO2 regressions increased between initial and final years on the two clay soils because of a positive feedback from the increase in Sorghastrum fraction. This feedback accounted for 30-60% of the CO2 -mediated increase in ANPP on the upland and lowland clay soils during the final 3 years and 1 year of the experiment, respectively. By contrast, species change had little influence on the ANPP-CO2 response on the sandy soil, possibly because Sorghastrum increased largely at the expense of a functionally similar C4 grass species. By favoring a mesic C4 tall grass, CO2 enrichment approximately doubled the initial enhancement of community ANPP on two clay soils. The CO2 -stimulation of grassland productivity may be significantly underestimated if feedbacks from plant community change are not considered.

A tallgrass prairie ecosystem was exposed to ambient and twice-ambient COz concentrations in open-top chambers and compared to unchambered ambient CO* during the entire growing season from 1989 through 1991. Dominant species were Andropogon gerardii (Cd), A. scoparius (Cd), Sorghastrum nutans (CA) and Pea pratensis (CA). Nitrogen and phosphorus concentrations in A. gerardii, P. pratensis and dicotyledonous herbs above ground biomass were estimated by periodic sampling throughout the growing season in 1989 and 1990. In 1991, N and P concentrations in peak biomass were estimated by an early August harvest. N and P concentrations in root production as a function of treatment were estimated using root ingrowth bags that remained in place throughout the growing season. Total N and Pin above- and belowground biomass were calculated as products of concentration and peak biomass by species groups. N concentration in A. gerardii and dicotyledonous herb aboveground biomass was lower and total N higher in elevated CO2 plots than in ambient CO* plots. N concentration in P. pratensis aboveground biomass was lower in elevated CO2 plots than in ambient, but total N did not differ among treatments in 2 out of 3 years. In 1990, N concentration in root ingrowth bag biomass was lower and total N greater in elevated CO;? than in ambient CO* plots. Root ingrowth bag biomass N concentration did not differ among treatments in 1991, but total N was greater in elevated COz plots than in ambient CO2 plots. P concentration was lower under elevated CO2 compared to ambient in 1989, but did not differ substantially among treatments in 1990 or 1991. In all years, total P in aboveground A. gerardii and root ingrowth bag biomass was greater under elevated CO2 than ambient. P concentration and total P in P. pratensis was similar among treatments.

Development of compatible, persistent, warm-season grass-legume mixtures could increase forage yield and quality during summer months. We established a trial to determine forage yield, quality, species compatibility, and persistence of binary mixtures of warm-season grasses with selected legumes, five of which are native to the central USA. Grass entries were switchgrass (Panicum virgatum L.), sideoats grama (Bouteloua curtipendula Michx.), and indiangrass [Sorghastrum nutans (L.) Nash]. Legume entries were purple prairieclover [Dalea purpurea Vent.; syn. Petalostemon purpureum (Vent.) Rydb.], roundhead lespedeza (Lespedeza capitata Michx.), leadplant (Amorpha canescens Pursh), Illinois bundleflower [Desmanthus illinoensis (Michx.) MacMill., B. Robins. & Fern.], catclaw sensitive brier [Schrankia nuttallii (DC.) Sandl.], and cicer milkvetch (Astragalus cicer L.), a cool-season species

Arbuscular mycorrhizal fungi (AMF) were studied in the rhizosphere of 3 Poaceae with meta- bolic pathway C3 (Briza subaristata Lam., Deyeuxia hi- eronymi (Hack.) Turpe and Poa stuckertii (Hack.) Par- odi), 2 Poaceae with C4 metabolic type (Eragrostis lu- gens Nees and Sorghastrum pellitum (Hack.) Parodi.), and a Rosaceae (Alchemilla pinnata Ruiz & Pav.) from a natural mountain grassland in Central Argentina (South America). Host species, their metabolic type, seasonal changes, and grazing effects over AM fungal diversity were analyzed. Seventeen mycorrhizal fungi taxa were found, widespread in all families of Glom- ales. Density of endomycorrhizal fungi was found to be strongly influenced with seasons and host meta- bolic pathway, although biodiversity (H), richness (S) and evenness (E) did not change. In most cases graz- ing did not affect these variables.

Scanning electron micrographs of the foliar epidermes of all 17 species of Sorghastrum are presented. A description of foliar epidermal micromorphology for the genus is followed by short descriptions of the individual species, emphasizing their epidermal differences. Papillar morphology is variable but taxonomically informative in distinguishing among the species of Sorghastrum. Based on the absence or presence of papillae, and differences in papillar morphology, three informal groups within Sorghastrum are recognized: 1) the nonpapillate group including S. balansae, S. rigidifolium, S. setosum, S. contractum, S. minarum, and S. viride; 2) the globose-papillate group including S. elliottii, S. incompletum, S. nudipes, S. nutans, S. scaberrimum, S. secundum, and S. trichopus; and 3) the elongate-papillate group including S. brunneum, S. stipoides, S. chasae, and S. pellitum. No correlation between papillar development and habitat is evident; however, a correlation exists between papillar development and the geographic distribution of the species of Sorghastrum.

Six genera of warm-season grasses were grown in Pennsylvania for 9 yr on a fine-loamy, mixed mesic, Aquic Fragiudult, to determine their potential as forage grasses on droughty sites. Effects of applied N on yield, plant morphology, and N composition of forages were studied during Years 4 through 7, when N was applied to half of each plot area. (...)

Andropogon nutans Linnaeus, Species Plantarum 2: 1045. 1753. "Habitat in Virginia, Jamaica." RCN: 7547. Lectotype (Hitchcock in Contr. U. S. Natl. Herb. 12: 125. 1908): Kalm, Herb. Linn. No. 1211.3 (LINN; iso- US). Current name: Sorghastrum nutans (L.) Nash (Poaceae). Note: Baum (in Canad. J. Bot. 45: 1850. 1967) rejected Hitchcock’s typification, proposing instead that Sloane’s cited t. 14, f. 2 (1707) should be the type. However, the material designated as type was evidently original material for A. nutans, and so Hitchcock’s choice has priority. Later authors concurring with Hitchcock’s choice include Voss (in Michigan Bot. 11: 31. 1972), McVaugh, (Fl. Novo-Galiciana 14: 142. 1983) and Veldkamp (in Taxon 33: 97. 1984)., Published as part of Jarvis, Charlie, 2007, Chapter 7: Linnaean Plant Names and their Types (part A), pp. 252-342 in Order out of Chaos. Linnaean Plant Types and their Types, London :Linnaean Society of London in association with the Natural History Museum on page 292, DOI: 10.5281/zenodo.291971