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Gamba grass (Andropogon gayanus Kunth) is a tussock-forming forage species adapted to acid soils of Brazilian savannas and cultivated for grazing pastures. Four decades since its release, Planaltina prevails as the most commercialized cultivar of the species, even though the new cultivar BRS Sarandi could be a better alternative for Gamba-grass-based farms by presenting a greater leaf:stem ratio. The objective of this study was to evaluate the average daily live weight gain (ADG) of Nellore bulls (Bos indicus) for two Gamba grass cultivars—Planaltina and Sarandi. The experiment was conducted in Planaltina, Federal District, Brazil, for 3 years, namely 2018, 2018–2019, and 2020. The experimental design was a completely randomized block design with two treatments and three replicates, each one continuously stocked at three stocking rates (SR)—1.3, 2.6, and 4 young bulls/ha. Canopy height (CH), forage mass (FM), plant-part proportion (green leaf, stem, and dead material), and nutritive value were evaluated. In 2018, mean ADG for Sarandi pastures was greater (0.690 kg/bull/d) than that of Planaltina (0.490 kg/bull/d) (p < 0.10). In the subsequent year (2018–2019), there was no effect of cultivar (p > 0.10), while in 2020 the ADG was again affected by cultivar (p < 0.10), confirming the advantage of Sarandi (0.790 kg/bull/d) over Planaltina (0.650 kg/bull/d). In 2018 and 2020, the percentage of stems for Sarandi was about 3–6 pp less than for Planaltina (p < 0.10). As well as for stems, Sarandi pastures presented a shorter CH in 2028 and 2020 (6–7%) (p < 0.10). The positive high correlation of leaf:stem ratio with ADG (r = 0.70) probably predisposed the superiority of Sarandi over Planaltina. The distinguishing plant-part composition of Sarandi canopy promotes increasing weight gain of beef cattle when compared to cv. Planaltina. [ABSTRACT FROM AUTHOR]

Background: Understanding the biomass accumulation and growth rate of the forages to feed the animal throughout the year is critical for improved earnings and long-term livestock production. This was found in forage maize (Zea mays), forage millet (Echinochloa utilis), elephant grass (Pennisetum purpureum) and Gamba grass (Andropogon gayanus). The experiment was place at Federal University Oye Ekiti in Ekiti State, Nigeria, in latitude N 07°48.308, longitude E 005°29.573 and elevation 548.4 meters above sea level, with an annual rainfall of 1778 mm. Methods: Planting four rows in a complete randomized design (CRD with four replications) was used to test the forage crops. Before planting, the soil in the experimental field had 49.96% organic matter and 33.59% after the crops were harvested. During the growth season, Pennisetum purpereum had the maximum plant height and sward height. Result: The Zea mays plant had the maximum leaf breadth (5.44 cm at 8 weeks) and the most leaves. Zea mays had the largest biomass accumulation (BC) of 113.80% after 8 weeks, followed by Andropogon gayanus with 67.15 per cent, Pennisetum purpureum with 56.24 per cent and Echinochloa utilis with 51.63%. Although there were no significant differences p≤0.05 in the crude protein levels of the different species, samples from the latest cuts (8th week) had the greatest crude protein content (11.88% in Andropogon gayanus). Crude protein levels were shown to rise in lockstep with grass growth. Although there was no significant difference between the grass species, the crude fibre content of the three grass species was discovered to vary with the growth phase. The greatest fibre content of 13.58% in Zea mays was reported during the 6th week, which might be attributable to lignin encrustation in grasses that were harvested late. All of the plant samples of crops showed the same irregular pattern in crude fiber, moisture content and fat content, with no significant variance. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the response of Andropogon gayanus Kunth to inoculation with Glomus cubense and Azospirillum brasilense, in the presence of drought stress. Materials and Methods: In an established area of A. gayanus, an establishment cutting was performed after seed harvest and inoculation was done with EcoMic® (Glomus cubense) and INICA-8. The experimental design was a complete randomized block, with seven treatments and eight replicas. The treatments consisted of: EcoMic® immediately after cutting, INICA-8 immediately after cutting, INICA-8 + EcoMic® immediately after cutting, EcoMic® a t c utting+ I NICA-8 (15 d ays), I NICA-8 a t c utting + E coMic® (15 days), absolute control and fertilized control (150 kg N/ha, NH3NO4). The dry weight of the aerial part, stem length, length of the flowering section of the stem, length of the inflorescence, dry weight of the racemes and flowering were evaluated. Variance analysis was performed. Differences among means were determined by Fisher's LSD. Results: Area dry weight was higher (p < 0,0001) in the fertilized control than in all treatments (12 036,1 kg/ha). The EcoMic® (9 612,5 kg/ha), EcoMic®+INICA-8 (8 475,0 kg/ha) and EcoMic® (cutting)+INICA-8 (15 days) treatments were superior to the absolute control (6 822,2 kg/ha), as well as to the other inoculated treatments. The EcoMic®+INICA-8 treatment showed statistical superiority in stem length (189,7 cm), raceme dry weight (0,071 g) and flowering (0,4462 %). EcoMic® (cutting)+INICA-8 (15 days) was higher in inflorescence length (16,39 cm) and in length of the flowering section of the stem (56,08 cm), although the fertilized control did not differ from these treatments. Conclusions: The single application of INICA-8 had no higher effect on any of the studied variables. However, EcoMic®, at the time of cutting, alone or combined with Azospirillum, was determinant in most of the variables. These results prove the importance of the application of EcoMic® in this crop under drought stress conditions, as well as the synergy among the microorganisms that were inoculated, when combined with each other due to a higher effect on the plant. [ABSTRACT FROM AUTHOR]

The objective of this research was to determine the pasture structure, nutritional value, animal behaviour, intake, and performance of Santa Inês sheep grazing pastures with various mixtures of grass (Andropogon gayanus) and forage legume (Stylosanthes sp. and Calopogonium mucunoides). A randomized block design was adopted with the treatments arranged in a 3 x 2 factorial scheme, with the factors consisting of cropping systems and grazing cycles. Grass in the mixed species pastures had a greater leaf/stem ratio than in the monoculture. Total forage mass was greater in the mixed pastures, which had the highest concentrations of crude protein and total digestible nutrients, the lowest fibre concentration, and the highest in vitro dry matter digestibility. Legumes were grazed with the highest frequency, and biting rate was highest in Andropogon gayanus with Stylosanthes sp. The highest intake (kg/day) was found in the mixed swards and the highest animal weight gain (143 g/day) in the mixed pastures. The pastures of Andropogon gayanus mixed with Stylosanthes sp. and C. mucunoides showed improved forage nutritive value and intake compared with the grass monoculture. [ABSTRACT FROM AUTHOR]

Foliar epidermal studies were carried out on accessions of Andropogon gayanus-Andropogon tectorum complex collected in Southwestern Nigeria with a view to providing additional characters of the two species of Andropogon to enhance the understanding of the taxonomic relationship between the two species. The epidermal preparation of the adaxial and abaxial surfaces of the leaf blade was made from the median part of well-matured leaf samples by the scrapping method. The analysis of both qualitative and quantitative characters revealed that study revealed that the costal zones of both adaxial and abaxial surfaces of all accessions studied showed similar features with little or no variation in their expression; epidermal cells are mostly rectangular with wavy walls, and the stomata encountered are paracytic. There was a unique occurrence of cluster of cells at the base of the macro hairs present in A. gayanus which is a diagnostic feature for its accessions collected. Kiwani, an unidentified polyploid accession, has the highest number of bands, the stomata are bigger, which is consistent with gigas effect occasioned by its polyploidy status. Glandular trichomes were present in both diploid and tetraploid of A. tectorum, a diagnostic feature for the species. [ABSTRACT FROM AUTHOR]

Cow–calf operations constitute the main land-use system in the 18 million ha of well drained tropical savannas of Colombia located in the Orinoco basin. There, numerous sex and age animal categories are present, ranging from suckling calves to old cull cows and steers, which in variable proportions are stocked at one animal unit (AU)/5–10 ha, depending on the ranch and distance from markets. In parallel, early-on farm observations showed that when sown pastures are introduced, graziers recur to opportunistic partial fattening of cull animals for a rapid economic return. The paper reports animal weight gains of cull cows, old steers, and young heifers and yearlings over seven consecutive years grazing on a low fertiliser-input well managed Andropogon gayanus -based pasture and four contemporary years on Brachiaria humidicola. The first 2 years involved three stocking rates (SR; 1.38, 1.85 and 2.32 animal units/ha), whereas a single SR of 1.33 animal units/ha was used for the remainder. A large database that included chemical, and in vitro and in vivo digestibility, values for all forages involved, was used as an input to a mathematical model to estimate methane (CH4) emissions. Estimations were compared with weight-based predictions derived from chamber measurements recorded recently in tropical Australia. Faecal mineral concentration varied little (not significantly) among SR and animal categories. Weight gains of old steers were 4–24% larger than those of cull cows, which, in turn, were larger than those of young steers and heifers (P < 0.01). Excepting one year, the performance of cull cows and old steers did not differ between pastures, confirming earlier on-ranch observations of reasonable weight gains of adult cattle on both pastures. The predicted carcass composition of cull cows and old steers did not differ between pastures either. Over the length of the experiment, cull cows emitted significantly less CH4 than did old steers (129 vs 141 g/day) on A. gayanus , while emissions on B. humidicola amounted to 128 and 137 g/day respectively. Despite between-year differences in animal performance, they are indicative of well managed pasture sustainability. They also show some of the trade-offs involved in the use of contrasting animal categories and pastures in terms of weight performance and predicted carcass composition and CH4 production. The authors expect that the present results will contribute to a rational, science-based discussion of the role of beef systems vis-à-vis environment in a region with limited production alternatives. In a tropical savanna environment, beef systems produce a variety of animal types differing in feed efficiency and meat yield, but the environmental impact of the systems is still limited. Growth on pastures in decreasing order were steers, cull cows, yearlings and heifers. Compared to steers, daily methane emissions were lower in cows, but their emissions per kg of edible protein were slightly higher. Trade-offs between growth, carcass characteristics, and methane emissions faced by the beef industry are illustrated but need further study. [ABSTRACT FROM AUTHOR]

Fire disturbance in tropical savannas is integral to maintaining habitat heterogeneity and biodiversity, but its impact on avian species is highly variable. Savannas in northern Australia have recently been invaded by gamba grass (Andropogon gayanus), a perennial tussock grass that fuels late season fires at eight times the intensity of native vegetation. As gamba grass rapidly outcompetes native species and promotes more frequent and intense fires, it greatly decreases landscape heterogeneity and alters the effect of fire in tropical savannas. To investigate how a small passerine, the red‐backed fairywren (Malurus melanocephalus), responds to fire disturbance and gamba grass cover, we studied their fine‐scale habitat use throughout the dry season before and after a high intensity fire. We used two spatially distinct approaches, radio‐telemetry and a transect‐based population census, to quantify fairywren habitat use at the group and population level, respectively. Radio‐telemetry and transect surveys revealed no direct mortality associated with the severe bushfire during the middle of the study season, suggesting fairywrens are resilient in the short‐term to fire disturbance. Our results indicate that fairywrens are largely flexible in their habitat use – instead of relocating after fire, they re‐centre their home range around the most photosynthetically productive habitats, dominated by saplings. While we found substantial variation in habitat use among social groups, red‐backed fairywren groups generally avoided dense habitat areas dominated by mature gamba grass. We conclude that red‐backed fairywrens are resilient to fire and flexible in their habitat use in the short‐term; however, in the long‐term, gamba grass may pose a threat to population viability. The importance of flexible behavioural strategies in tropical passerines will increase as fire regimes are exacerbated by invasive species and climate change. [ABSTRACT FROM AUTHOR]

The biosorption of strontium(II) from aqueous solutions using dead bacteria biomass was investigated in this study. Phylogenetic analysis based on 16S rDNA sequence demonstrates that the isolated strain belonged to Bacillus cereus. The bacteria exhibited the highest strontium sorption capacity at an initial pH of 5.0, contact time of 50 min, biomass dosage of 3.0 g L−1 and agitation speed of 120 rpm. The adsorption profile was better matched by Langmuir than Freundlich model. The maximum biosorption capacity obtained by Langmuir model was 58.79 mg g−1. Adsorption kinetics indicate that the pseudo-second order model was appropriate to describe the biosorption process. Fourier transform infrared (FT-IR) spectroscopy analysis indicates that the main functional groups responsible for biosorption of strontium(II) were hydroxyl, carboxyl and amino. The isolated bacteria B. cereus can be a great potential biosorbent to remove strontium ions from aqueous solutions. [ABSTRACT FROM AUTHOR]

Globally, invasive grasses are a major threat to protected areas (PAs) due to their ability to alter community structure and function, reduce biodiversity, and alter fire regimes. However, there is often a mismatch between the threat posed by invasive grasses and the management response. We document a case study of the spread and management of the ecosystem-transforming invasive grass, Andropogon gayanus Kunth. (gamba grass), in Litchfield National Park; an iconic PA in northern Australia that contains significant natural, cultural and social values. We undertook helicopter-based surveys of A. gayanus across 143,931 ha of Litchfield National Park in 2014 and 2021–2022. We used these data to parametrise a spatially-explicit spread model, interfaced with a management simulation model to predict 10-year patterns of spread, and associated management costs, under three scenarios. Our survey showed that between 2014 and 2021–22 A. gayanus spread by 9463 ha, and 47%. The gross A. gayanus infestation covered 29,713 ha of the total survey area, making it the largest national park infestation in Australia. A. gayanus had not been locally eradicated within the Park's small existing 'gamba grass eradication zone', and instead increased by 206 ha over the 7-year timeframe. Our modelled scenarios predict that without active management A. gayanus will continue spreading, covering 42,388 ha of Litchfield within a decade. Alternative scenarios predict that: (i) eradicating A. gayanus in the small existing eradication zone would likely protect 18% of visitor sites, and cost ∼AU$825,000 over 5 years – more than double the original predicted cost in 2014; or (ii) eradicating A. gayanus in a much larger eradication zone would likely protect 86% of visitor sites and several species of conservation significance, and cost ∼AU$6.6 million over 5 years. Totally eradicating A. gayanus from the Park is no longer viable due to substantial spread since 2014. Our study demonstrates the value of systematic landscape-scale surveys and costed management scenarios to enable assessment and prioritisation of weed management. It also demonstrates the increased environmental and financial costs of delaying invasive grass management, and the serious threat A. gayanus poses to PAs across northern Australia. • Invasive grasses are a growing challenge for protected areas managers worldwide. • Landscape-scale survey is essential to understand invasive grass distribution/spread. • Our survey showed Andropogon gayanus increased by 9463 ha in 7 years, to cover an area of 29,713 ha. • Delaying management action has doubled cost of achieving weed management goals. • Park managers should use systematic surveys and costed scenarios to prioritise weed management. [ABSTRACT FROM AUTHOR]

Given the environmental damages caused by invasive species, it is critical to allocate limited management budgets carefully. To address this need, there are a variety of approaches for analysing invasive species risk and designing management strategies; these range from pre-border risk assessment through to local-scale prioritisation of management actions. Risk assessment can be broadly characterised into three components: risk analysis, risk characterisation and risk management. For each component we give a brief review of current approaches and then present innovative tools being developed and applied in northernAustralia.We use gamba grass (Andropogon gayanus Kunth.) as a case study to contrast the benefits of the different approaches presented.With our case study, we demonstrate the practical application of novel risk management tools, with results from these tools that are being used locally to prioritise management actions. Lastly, we note that for even greater benefit to be achieved, the new spatial prioritisation approaches presented must be accompanied by further development of data and methods to accommodate planning for multiple weed species and incorporation of further human dimensions (e.g. social and cultural values). [ABSTRACT FROM AUTHOR]

The spread of an alien invasive grass (gamba grass-Andropogon gayanus) in the tropical savannas of Northern Australia is a major threat to habitat quality and biodiversity in the region, primarily through its influence on fire intensity. Effective control and eradication of this invader requires better insight into its spatial distribution and rate of spread to inform management actions. We used full-waveform airborne LiDAR to map areas of known A. gayanus invasion in the Batchelor region of the Northern Territory, Australia. Our stratified sampling campaign included wooded savanna areas with differing degrees of A. gayanus invasion and adjacent areas of native grass and woody tree mixtures. We used height and spatial contiguity based metrics to classify returns from A. gayanus and developed spatial representations of A. gayanus occurrence (1 m resolution) and canopy cover (10 m resolution). The cover classification proved robust against two independent field-based investigations at 500 m2 (R2 = 0.87, RMSE = 12.53) and 100 m2 (R2 = 0.79, RMSE = 14.13) scale. Our mapping results provide a solid benchmark for evaluating the rate and pattern of A. gayanus spread from future LiDAR campaigns. In addition, this high-resolution mapping can be used to inform satellite image analysis for the evaluation of A. gayanus invasion over broader regional scales. Our research highlights the huge potential that airborne LiDAR holds for facilitating the monitoring and management of savanna habitat condition. [ABSTRACT FROM AUTHOR]

BACKGROUND Plants from West Africa commonly used in both human and veterinary medicine contain various secondary metabolites. However, their potential in mitigating ruminal methane production has not been explored. This study examined the effects of seven essential oils ( EOs) from plants acclimated to Benin at four dosages (100, 200, 300 and 400 mg L−1), on in vitro rumen microbial fermentation and methane production using Andropogon gayanus grass as a substrate. RESULTS Compared to control, Laurus nobilis (300-400 mg L−1), Citrus aurantifolia (300-400 mg L−1) and Ocimum gratissimum (200-400 mg L−1) decreased ( P < 0.05) methane production ( mL g−1 DM) by 8.1-11.8%, 11.9-17.8% and 7.9-30.6%, respectively. Relative to the control, reductions in methane ( mL g−1 DM) of 11.4%, 13.5% and 14.2% were only observed at 400 mg L−1 for Eucalyptus citriodora, Ocimum basilicum and Cymbopogon citratus, respectively. These EOs lowered methane without reducing concentrations of total volatile fatty acids or causing a shift from acetate to propionate production. All EOs (except M. piperita) reduced ( P < 0.05) apparent dry matter ( DM) disappearance of A. gayanus. CONCLUSIONS The current study demonstrated that EOs from plants grown in Benin inhibited in vitro methane production mainly through a reduction in apparent DM digestibility. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

A grass-fire cycle in Australian tropical savannas has been postulated as driving the regional decline of the obligate-seeding conifer Callitris intratropica and other fire-sensitive components of the regional flora and fauna, due to proliferation of flammable native grasses. We tested the hypothesis that a high-biomass invasive savanna grass drives a positive feedback process where intense fires destroy fire-sensitive trees, and the reduction in canopy cover facilitates further invasion by grass. We undertook an observational and experimental study using, as a model system, a plantation of C. intratropica that has been invaded by an African grass, gamba (Andropogon gayanus) in the Northern Territory, Australia. We found that high grass biomass was associated with reduced canopy cover and restriction of foliage to the upper canopy of surviving stems, and mortality of adult trees was very high (>50%) even in areas with low fuel loads (1 t.ha -1). Experimental fires, with fuel loads >10 t.ha -1, typical of the grass-invasion front, caused significant mortality due to complete crown scorch. Lower fuel loads cause reduced canopy cover through defoliation of the lower canopy. These results help explain how increases in grass biomass are coupled with the decline of C. intratropica throughout northern Australia by causing a switch from litter and sparse perennial grass fuels, and hence low-intensity surface fires, to heavy annual grass fuel loads that sustain fires that burn into the midstorey. This study demonstrates that changes in fuel type can alter fire regimes with substantial knock-on effects on the biota. [ABSTRACT FROM AUTHOR]

Andropogon gayanus is an important grass due to its high biomass production, drought tolerance and favorable growth on low fertility acidic soils. Currently, there is little research on the impact of growth stage on the nutritional quality or the degree of CH4 production that may arise from this forage during ruminal fermentation. The objectives of this study were to determine the effects of regrowth stage of A. gayanus on its chemical composition, in vitro production of gas and CH4 , as well as in vitro dry matter (DM) digestibility when grown under tropical Brazilian conditions and conserved as hay or as silage. The nutritional value of A. gayanus grass declined with increasing maturity; however digestible DM yield linearly increased. After 112 d of regrowth, A. gayanus produced higher quality silage (higher lactate and lower pH and butyrate content) and higher DM yield. However, the low levels of crude protein at this time would make protein supplementation a necessity for proper rumen fermentation. No differences in CH4 kinetic parameters were found with advancing maturity or preservation method (hay or silage). [ABSTRACT FROM AUTHOR]

It is increasingly acknowledged that invasive plant management, although a significant global issue, is a matter of coexistence rather than control. Nevertheless an adversarial rhetoric dominated by discourses of war and winning persists. This paper focuses on the bodies of plants, the animals with which they become entangled, and the humans who are charged with eradicating them. Plants help to rethink bodily difference beyond the human, extending feminist theories that have contributed to increased recognition of nonhuman difference. Bodies are a barely acknowledged scale of invasive plant management, which is usually conceptualised in landscape terms. Our empirical focus is the eradication of three species in northwestern Australia: Mimosa (Mimosa pigra), Gamba Grass (Andropogon gayanus), and Neem (Azadirachta indica). By paying attention to plant difference and illuminating the experience of invasive plant managers, we show how eradication manages the intersecting timespaces of different bodies in order to stop plants becoming collectives. We identify contradictions in the regulation and application of borders, which are less permeable for some animals than for all humans. We also draw attention to the questions of risk--for humans and others--in the process of killing plants. For embodied geographies, a plant perspective opens up new ways of thinking about bodily boundaries: in particular the individual/collective divide. The implication for invasive plant management is that, even at the eradication end of the spectrum, effective management is an uncertain process that involves living in association with invasive plants rather than living separately from them. [ABSTRACT FROM AUTHOR]

Abstract: Twenty-five 5-month-old Red Sokoto male goats of 7.50±0.52kg live weight (LW) were used to investigate the feeding value of Pterocarpus erinaceus (PE) and its combinations with Andropogon gayanus (AG) grass as feed to goats using completely randomized design. The treatments were five PE:AG ratios: 0:1000 (solely AG), 250:750, 500:500, 750:250 (forage combinations) (FC) and 1000:0 (solely PE). Intake of AG (199.7g/day) decreased linearly, while intake of PE (197.1g/day) and condensed tannins (CT) increased linearly (P<0.01). Intakes of dry matter (DM), organic matter (OM), acid detergent fibre (ADF) and final LW had a quadratic (P<0.01) response. Intakes of crude protein (CP), lignin(sa), neutral detergent fibre (NDF), hemicellulose, cellulose, digestible CP (DCP) and OM (DOM), and N showed both linear and quadratic trends (L:P<0.01; Q:P<0.01). Diet effects on feed conversion ratio (FCR), digestibilities of DM, OM, fibre fractions and hemicellulose, DOM and DCP (g/kg), digestible energy (DE) and metabolizable energy (ME), faecal N and N retention (as g/kg of N intake) were linear and quadratic (L:P<0.01; Q:P<0.01). Live weight gain, average daily gain (ADG), DOM intake and OM digested in the rumen (OMDR), DE and ME intake, and microbial protein synthesis (MPS) were linearly and quadratically affected by diets (L:P<0.05; Q:P<0.01). Digestible CP (g/kg W0.75) had linear and cubic (P<0.01) trends. Diets had both linear and cubic effects on urinary N (P<0.01) and linear, quadratic and cubic effects on total N excretion (P<0.01). Treatment effects on digestibility of CP, N balance and retention (as g/kg of N absorbed) (L:P<0.01; Q:P<0.01; C:P<0.01) and N absorbed (L:P<0.01; Q:P<0.01; C:P<0.05) were significant. Dry matter, nutrient and CT intakes, growth performance, FCR, digestibility, nutritive value, intakes of digestible nutrients and energy, N intake, excretion, absorption, balance and retention, and MPS were higher (P<0.01) in FC compared to single forages (SF). Intakes (g/kg W0.75) of CP, NDF, lignin(sa), hemicellulose, cellulose, CT and DCP (P<0.01), and intakes of DOM, energy and N (g/day) (P<0.05) were higher for PE than for AG. Pterocarpus increased ADG, FCR, digestibilities of DM, CP, OM, cellulose and hemicellulose, nutritive value, and N excretion, absorption, balance and retention more than AG (P<0.01). Digestibilities of fibre fractions, OMDR and MPS were higher (P<0.05) for PE than for AG. It is concluded that maximum nutritional benefits of PE can be achieved if used as supplement up to 750g/kg DM rather than as a sole feed, and the sole PE is better than sole AG. [Copyright &y& Elsevier]

The use of grasses toleram to shade is essential to the sustainability of the' Farming-Livestock-Forest Integration System. The performance of Panicum maximum cv. 'Tanzania' and Andropogon gayanus cv. 'Planaltina' under different levels of shading and times of entry under the shade were studied. We used designs in randomized blocks with four replications in a factorial scheme with two types of shading: 30% and 50%; three times of entry into the shade after transplantation (07, 14 and 21 days) and a witness, kept in full sun. Seedlings 8 to 12cm high of both species, pre-cultivated in styrofoam trays were transplanted to pots and maintained in their respective environments under the shade or full sun for 90 days in normal growth. The time of entry into the shade does not interfere with productivity and leaf chlorophyll content of cultivars, as well as in the bromatological composition. The fresh and dry matter of the cultivars of both 'Planaltina' and 'Tanzania' were higher in shaded environments rather than those in full sun. The two forage grasses when shaded increase the chlorophyll a content, but no change of chlorophyll b was thereof observed. The positive adaptation of cultivars in the shaded environments becomes promising in systems of integration of pastures with trees. [ABSTRACT FROM AUTHOR]

1. The understanding of large-scale patterns in expanding populations of alien invasive plants can be used to infer the environmental limiting factors, habitat heterogeneity and, ultimately, the range expansion potential of invasive plants. 2. We used multivariate analysis and a novel quantile regression technique accounting for spatial autocorrelation to compare and contrast factors influencing the abundance and distribution of the African grass Andropogon gayanus (gamba grass) at two large-scale invasion sites in the tropical savanna region of Australia. We collected data using aerial and ground surveys and tested for limiting factors using three landscape-scale indices related to soil quality, soil moisture and invasion history. 3. In one site, gamba grass was principally colonising drainage lines and riparian areas. Occupation of these areas was limited in proportion to the distance from the original gamba grass source. In the second site, gamba grass abundance was independent of distance from the original source and was well established in all vegetation communities, although abundance was also limited in higher elevation sites away from drainage lines. 4. Comparisons between these sites with different patterns of invasion enabled the estimation of both the invasion pathways and range expansion potential of gamba grass. Our results indicated that gamba grass spreads from riparian communities to invade upland sites and has the potential to invade 70% of north Australia's upland savanna communities. 5. Aerial surveys comprehensively assessed patterns over a larger area than ground surveys and were much more economical. 6. Synthesis and applications. Large-scale surveys across multiple sites are critical to understanding the dynamics of recent alien species invasions where little is known about the pattern and potential range of spread. The application of quantile regression and aerial surveys shows promise as aerial surveys are efficient at capturing a large amount of data. The novel quantile regression technique we demonstrate here can account for both spatial autocorrelation and noisy ecological data from aerial surveys while returning robust results. We were thus able to demonstrate widespread colonisation of creek lines by gamba grass and recommend that management focuses on detection and eradication along drainage lines in addition to the present focus on transport corridors. [ABSTRACT FROM AUTHOR]

El experimento se condujo para desarrollar una estrategia que determine con mayor precisión, mediante la combinación de indicadores edafoclimáticos y el análisis multivariado de componentes principales y conglomerados, la producción de semillas pratenses tropicales. Los datos se tomaron de fincas de semillas en regiones específicas de Cienfuegos, Villa Clara, Sancti Spiritus, Camagüey, Granma y Guantánamo. Las especies utilizadas fueron: Panicum maximum, Andropogon gayanus, Brachiaria decumbens, Brachiaria brizantha, Chloris gayana, y Cenchrus ciliaris. Los resultados mostraron la preponderancia de las variables precipitación total y en lluvia; temperatura máxima, mínima y media; profundidad del suelo, pedregosidad, fósforo y drenaje. El método de conglomerado produjo cuatro grupos: Cienfuegos; Guantánamo, Villa Clara y Camagüey; S. Spiritus y Granma. Estas variables explican 88.8 % de la variabilidad en el análisis de conglomerados. El análisis matemático mostró que no hubo relevancia para el rendimiento, que varió entre 147.8 y 240 kg/ha. Esto puede indicar que el comportamiento de las especies no varía de manera relevante entre regiones. Se concluye que el método combinado fue útil para estudiar la influencia de la combinación de factores edafoclimáticos, especies y regiones del país. [ABSTRACT FROM AUTHOR]

Se diseñó un experimento en el que se utilizó la metodología desarrollada por Torres et al. (2007), que permite conocer el índice de impacto La aplicación de esta técnica admite combinaciones de especies dentro de cada región edafoclimática. El índice de impacto depende de los indicadores de mayor preponderancia que aparecen en el análisis de los componentes principales y que se corresponden con los mismos El resultado genera valores que, de acuerdo con su jerarquía numérica, expresan el mayor o menor efecto de cada indicador por región Los datos provienen de fincas de semillas, ubicadas en regiones específicas de las provincias Cienfuegos, Villa Clara, Sancti Spíritus, Camagüey, Granma y Guantánamo. Las especies utilizadas fueron: Panicum maximum, Andropogon gayanus, Brachiaria decumbens Brachiaria brizantha, Chloris gayana y Cenchrus ciliaris. Los resultados mostraron la preponderancia de los factores precipitación total y en la época de lluvia, temperaturas máximas, media y mínima; profundidad efectiva, pedregosidad y horas luz. Los indicadores de la primera componente tuvieron más alto índice de impacto en Guantánamo, le siguieron Granma y Camagüey. Reflejaron menor valor en Cienfuegos con cifras más negativas. En el primer índice de impacto se encontraron 45.4 % de los indicadores de mayor preponderancia en el análisis de componentes principales. Andropogon gayanus alcanzó los mayores valores en Guantánamo, Granma y Camagüey. Le siguieron Panicum maximum, Cenchrus ciliaris y Brachiaria brizantha, respectivamente. Este resultado indicó una relación más estrecha entre las especies en las regiones señaladas. Se concluye que los métodos matemáticos utilizados fueron potenciados a partir de la determinación del índice de impacto. Se discute la importancia de la metodología utilizada, así como del estudio de las localidades y del posible efecto del índice de impacto en la interacción genotipo ambiente. [ABSTRACT FROM AUTHOR]

Aim This study aimed to quantify changes in fire severity resulting from the invasion of Australia’s tropical savannas by the African grass Andropogon gayanus Kunth. (gamba grass). Location Mesic savannas of the Northern Territory, Australia. Method Byram’s fire-line intensity (I f), fuel load and architecture, and two post-fire indicators of fire intensity – scorch height (SH) and char height (CH) of woody vegetation – were determined for fires in native grass savanna and A. gayanus invaded savanna. Leaf scorch is the height at which the fire’s radiant heat browns leaf tissue, and leaf char is the height that radiant heat blackens or consumes leaf tissue and provides an indirect measure of flame height. These data, and 5 years of similar data collected from the Kapalga Fire Project in Kakadu National Park, were used to develop empirical relationships between I f and the post-fire indices of fire intensity. Results A relationship between A. gayanus I f and SH could not be developed because complete canopy scorch occurred in most A. gayanus fires, even at low I f. In contrast, A. gayanus I f was strongly correlated with CH. This empirical relationship was substantially different from that for native grass fires. For a given I f, there was a significantly greater CH in invaded sites. This increase in radiant heat is attributable to the increased biomass (mean 3.6 t ha−1 in native grasses compared to 11.6 t ha−1 in A. gayanus) and height (approximately 0.5 m in native grasses compared to 4 m in A. gayanus) of the standing fine fuel. Main conclusion Andropogon gayanus invasion resulted in substantial changes in fire behaviour. This has important regional implications owing to the current (10,000–15,000 km2) and predicted (380,000 km2) area of invasion and the negative consequences for the native savanna biota that has evolved with frequent but relatively low-intensity fire. [ABSTRACT FROM AUTHOR]

From August 2003 to December 2004 a field test was carried out during two rainy seasons in the Municipality of Cotaxtla, Veracruz, Mexico, in order to determine the effect of different treatments to control weeds on the production and quality of Gamba grass. A completely randomized block design with four replications was used. The treatments were: 1. Picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid) + fluroxypir (4-amino-3,5-dichloro-6-fluoro-2-pyridyloxyacetic acid) (40 g + 40 g/100 l water), 2. Picloram + 2,4-D (2,4-dichlorophenoxyacetic acid) (64 g + 240 g/100 l water) 3. Mowing with machete, and 4. Weedy check. The treatments were applied once per rainy season in the same experimental plots. Weed population density was determined before treatment application, whereas weed control and forage production and quality were evaluated at 42, 98, 160 and 223 days after application (DAA) during the first rainy season and at 34, 72, 112 and 163 DAA during the second one. The two herbicide treatments resulted in a higher weed control than the mowing treatment, which was reflected in the last treatment in a reduction of the forage production 17,4 to 66,6% lower than the average obtained with the herbicide treatments. During the lowest moisture periods, the crude protein content of the Gamba grass was significantly higher at least in one of the herbicide treatments in relation with the weedy check. [ABSTRACT FROM AUTHOR]

Abstract: Changes in land use affect soil properties. In most West-African farming systems forest-fallow management intended to restore soil fertility no longer functions efficiently because the duration of the fallow periods has been shortened and the fallow areas have been reduced. Alternative practices must, therefore, be adopted. This study tested the efficiency of short periods of improved fallows (Andropogon gayanus and Acacia holosericea) in regenerating soil microbial properties, compared to the efficiency of a natural long-term fallow. The microbial community was studied by cloning and sequencing 16S rDNA and by analyzing enzyme activities (alkaline phosphatase, β-glucosidase). The study was carried out at the soil aggregate scale to test how the microbial community in different micro-habitats reacted to the different fallow practices. The 4-year-old Acacia holosericea and Angropogon gayanus fallows did not regenerate soil properties as efficiently as the 21-year-old natural fallow. However, Andropogon gayanus could be used to restore soil properties quickly. Three different aggregate-size fractions were affected by fallow management: organic residues, the >2000μm fraction and the 2–50μm fraction. These microhabitats were enriched with bacteria belonging to the Telluria genus and more generally to β-Proteobacteria. [Copyright &y& Elsevier]

Many tropical forage grasses and legumes grow well in acid soils, adapting to excess aluminum (Al) and phosphorus (P) starvation stresses by using mechanisms that are still unclear. To determine these mechanisms, responses to Al toxicity and P starvation in three tropical forages were studied: two grasses, Brachiaria hybrid cv. ‘Mulato’ ( B. ruziziensis clone 44-06 × B. brizantha cv. ‘Marandú’) and Andropogon gayanus , and one legume, Arachis pintoi . The tropical grasses tolerated high levels of Al toxicity and P starvation, with the Brachiaria hybrid maintaining very low levels of Al concentration in shoots. 27 Al Nuclear Magnetic Resonance spectroscopy (NMR) analysis revealed that, in the Brachiaria hybrid, Al makes complexes with some ligands such as organic-acid anions in the root symplast. The forages probably adapted to P starvation through high P-use efficiency. These experiments provide the first direct evidence we know of that organic acid anions within root tissue help detoxify Al in non-accumulator species such as the Brachiaria hybrid. [ABSTRACT FROM AUTHOR]

Research on habitat utilization by the Nile rat (Arvicanthis niloticus) was carried out in the Guinea Savanna of Nigeria to determine food preference, parts of plant utilized as sources of food and their proximate composition. Indirect field observations as well as direct ex situ methods of observation were made. A vegetation analysis of preferred habitat was also carried out to determine the floral composition. A proximate analysis of some of the preferred forage species and their parts was carried out as well. Data obtained from the proximate composition of forage species were subjected to statistical analysis. The result of the vegetation analysis revealed that Imperata cylindrica (speargrass) and Hyparrhenia dissoluta (roofing grass, thatching grass) were the dominant grass species while Dactyloctenium aegyptium (cowfoot-grass) and Andropogon gayanus (gambagrass) were fairly abundant. The field observations also revealed that the Nile rat preferred young shoots of Andropogon gayanus, Panicum maximum (guineagrass), Hyparrhenia dissoluta and inflorescence of Dactyloctenium aegyptium. Ex situ observations revealed that roots and shoot-meristem of Andropogon gayanus and Hyparrhenia dissoluta were eaten in preference to other parts of the plant. Proximate composition showed that crude protein content was inversely related to fibre level. Inner shoot-meristem (IM) of these preferred forage species contained the highest (P < 0.05) level of crude protein. Roots were also selected despite their lower protein and high fibre content. [ABSTRACT FROM AUTHOR]

Land use patterns affect soil nutrient transformation and availability. The study determined the distribution of phosphorus (P) fractions and sorption in five pasture fields composed of Andropogon gayanus , Brachiaria decumbens , Chloris gayana , Digitaria smutsii , and Stylosanthes guianensis . The objectives were to characterize P fractions in improved pastures and to determine the effect of forage species on soil P lability. Total P (P t ) across the pastures was not significantly different. Organic P (P o ) accounted, on the average, for 64% of P t . Resin-P, considered the plant-available P, ranged from 4 to 10 mg kg -1 , suggesting acute P deficiency in the pastures. The sum of P fractions extracted by 0.5 M NaHCO 3 , 0.1 M NaOH, and 1.0 M HCl, together with the resin-P, accounted for less than 35% of P t . Factor analysis indicated that plant-available P approximated by resin-P was furnished by &sbnd;HCO 3 -P o mineralization and HCl-P. The highest concentrations of &sbnd;HCO 3 -P o and &sbnd;OH-P o were maintained by Brachiaria decumbens . Grouping P i and P o fractions into labile and nonlabile fraction showed that Brachiaria decumbens maintained the greatest concentration of labile P as a proportion of its P t . The pasture soils sorbed between 31 and 65% of added P from a standard concentration of 50 mmol kg -1 . Phosphorus sorbed by soils from the pasture fields was in the order: Digitaria smutsii = Stylosanthes guianensis > Brachiaria decumbens = Chloris gayana > Andropogon gayanus , whereas resin recovery of sorbed P was greater in Brachiaria decumbens than other pastures. Between 82 and 92% of sorbed P was bound irreversibly. It was concluded that the relatively high concentration of labile P maintained by soil under Brachiaria decumbens was probably related to its capacity to sequester more carbon than the other pastures. [ABSTRACT FROM AUTHOR]

The nutritive values of seven native grass species collected in North Sumatra, Indonesia, during dry and rainy seasons were evaluated. The chemical composition, in vitro dry matter digestibility (IVDMD), in vitro organic matter digestibility (IVOMD), in vitro crude protein digestibility (IVCPD), macro mineral concentrations of calcium, phosphorus and magnesium, in vitro gas production profile and metabolizable energy (ME) content of the grasses varied greatly among species and seasons. The crude protein content ranged from 6.6 ( Andropogon gayanus) to 16.2% dry matter ( Cynodon plectostachyus) in the rainy season, with a significant ( P < 0.05) reduction in the dry season. Data on the fiber fraction showed that the grasses contained more neutral detergent fiber (NDF) and acid detergent fiber (ADF) in the dry season and it significantly ( P < 0.05) decreased in the rainy season, except for Panicum maximum and Pennisetum purpureum for NDF content and C. plectostachyus, P. maximum and Brachiaria decumbens for ADF content. Data on the mineral concentration showed that C. plectostachyus in the dry and rainy seasons had a higher calcium content than those of other species. The overall means of the seven grasses for IVDMD, IVOMD and IVCPD were significantly higher ( P < 0.05) in the rainy season than in the dry season. The in vitro gas production and ME concentration were numerically higher in the rainy season than in the dry season. In conclusion, the nutritive value of the observed grasses in North Sumatra was relatively higher during the rainy season compared with the dry season. Among the species of grass, P. purpureum and C. plectostachyus had a higher nutritive value in both the dry and rainy seasons. [ABSTRACT FROM AUTHOR]

An assessment of different livestock alternatives for milk production including an improvement of native grasslands based on an association of Andropogon gayanus cv. CIAT 621 and climatic adaptation to Camagüey province northern savannas with dominant red brownish ferromagnesial fersialitic soil, was carried out. The alternatives applied were cattle fattening, and milk production associated to sheep breeding. A farm located in the area and showing all the tipical ecological characteristics mentioned above was selected for the study . Forage and other food balance was performed to obtain a positive response to grassland sowing and food supplementation, and a partial budget analysis for a net change in sach variant utilities was carried out. Estimates were made in USD according to the costs and price in 2003. In relation to fattening variants, sowwing of the associated grass in an extent of 25 and 40% within the area including food supplementation or not, achieved the highest net changes in utilities compared to milk production, while milk production associated to sheep breeding alternative showed better advantages for a 40% improvement of native grassland in both cases. Results concerning milk production indicated that the best options for cattle management and native grassland improvement based on grass association are cattle fattening with a 25 and 40% grassland improvement with or without food supplementation and milk production associated to sheep breeding with a 40% grassland improvement. [ABSTRACT FROM AUTHOR]

Abstract. Invasive alien grasses can increase fuel loads, leading to changes in fire regimes of invaded ecosystems by increasing the frequency, intensity and spatial extent of fires. Andropogon gayanus Kunth. (Gamba grass), a tall perennial grass from Africa, is invading ecosystems in the Top End of northern Australia. To determine whether A. gayanus alters savanna fire regimes, we compared fuel loads and fire intensities at invaded sites with those from native grass savannas. Savanna invaded by A. gayanus had fuel loads up to seven times higher than those dominated by native grasses. This higher fuel load supported a fire that was on average eight times more intense than those recorded in native grass savannas at the same time of year (means 15700 ± 6200 and 2100 ± 290 kW m-1 , respectively), and was the highest early dry season fire intensities ever recorded in the Northern Territory. These results suggest that A. gayanus is a serious threat to northern Australia's savannas, with the potential to alter vegetation structure and initiate a grass-fire cycle. [ABSTRACT FROM AUTHOR]

The behavior of six improved grassies under cutting on a lower-fertility red-brownish ferromagnesial fersialitic soil was studied. A completely randomized design with three replicas consisting in 0,25 ha spots under grazing conditions every 30 to 35 days during rainy season and 40 to 50 days during dry season with 12 lambs/ha load was applied. Grassy species were fertilized with N, P, and K at a ratio of 100; 80 and 100 kg/ha/year, respectively. Nitrogen was fractionated during the rainy season. Availability was measured by rotational grazing, and botanical composition was determined at the initial and final stages of the experiment. Andropogon gayanus cv. CIAT 621 showed the highest dry matter availability, followed by Brachiaria decumbens cv. CIAT 606, which showed no significant differences in relation to Andropogon in the first year during the rainy season and the second and third years during the dry season. In contrast, Brachiaria purpurascens cv. Aguada showed the worst behavior to the above mentioned index. Andropogon and Brachiaria 606 endurance was higher (P<0,001), but the other species population decreased by the third year. It is recommended to spread Andropogon gayanus cv. CIAT 621 and Brachiaria decumbens cv. CIAT 606 over the region due to edaphic and climatic conditions in this place. [ABSTRACT FROM AUTHOR]

The article presents a study which examines the potential for the dissemination of weed seeds in clothing such as the Gamba grass in northern Australia. It asserts to consider the type of seed dispersal, such as the unintentional dissemination by farm machinery and transport vehicles, in the management and conservation of untroubled environments. It highlights the negative environmental aspects of Gamba grass which should be discouraged by land managers of being dispersed in non-invaded savannas. The strategies for reducing the unintentional spreading of Gamba grass seeds which include the wearing of shirts and trousers without pockets, carrying of backpacks without exterior seed traps, and performing a full body check for seeds after working in invaded areas are also mentioned.

A letter to the editor is presented in response to the article concerning the introduction of elephants in Australia as a cost-effective way in controlling invasive gamba grass by David Bowman in the 2012 issue.

The author discusses the environmental problems facing Australia, with particular focus on wildfires and invasive species. He proposes the solution of introducing large herbivore mammals such as the elephant to Australian ecosystems, arguing that it would address both concerns through restabilizing the food chain, controlling flammable gamba grasses through grazing, and conserving threatened native species.