Livestock grazing practices in rangelands are being recognized as management tool for environmental protection and increased livestock productivity. Continuous grazing has been largely reported to reduce pasture productivity and increase environmental degradation. Rotational grazing is an alternative to continuous grazing and is considered to reduce negative environmental effects and provide qu...

The Fisher-Kolmogorov-Petrovskii-Piskunov equation with a variable growth rate and advection by an incompressible velocity field is considered as a model for plankton dispersed by ocean currents. If the average growth rate is negative then the model has a survival-extinction transition; the location of this transition in the parameter space is constrained using variational arguments and delimit...

The effect of environmental factors on cell-lipid content, on the growth rate and on the overall productivity ofNannochloropsis salina was tested in the laboratory and in outdoor cultures. Under optimum conditions in the laboratory, the maximum growth rate (#max.) was 0"030 h -1, which corresponds to a doubling time of 23 h. Cellular lipid content was affected by the phase of growth and the tem...

Monotonic, hump-shaped and zero-correlation productivity-diversity relationships have been found to date in many ecosystems. This diversity of responses has puzzled ecologists in their search for general principles on ecosystem functioning. Some state that the scale of observation is crucial in defining this relationship. We have developed a spatial model of tallgrass prairies where biomass and...

Abbreviations: Conversion (%): [(g consumed glucose/g feeding glucose) x 100], dilution of medium glucose by NaOH feeding was considered in the calculations mp: Specific gluconic acid productivity, [g gluconic acid/(g biomass x h)], Rj [g/(l x h)]/biomass concentration (g/l), g/(g x h) Rj: Formation rate of the generic product (volumetric productivity), g gluconic acid/(l x h), gluconic acid co...

Commercial production of renewable energy feedstocks from microalgae will require reliable and scalable growth systems. Two and one half years of biomass and lipid productivity data were obtained with an industrial-scale outdoor photobioreactor operated in Fort Collins, Colorado (USA). The annualized volumetric growth rates for Nannochloropsis oculata (CCMP 525) and Nannochloropsis salina (CCMP...

Pleurotus species are recognized for producing beta-glucans with important medicinal properties as a constituent of the cellular wall of the fruiting body or of the mycelium. The aims of this work were to select a culture medium that maximized the production of biomass and polysaccharides produced by Pleurotus ostreatus DSM 1833 and to evaluate the selected medium in two values of initial oxyge...

The mangrove forest that fringes the Bon Accord Lagoon measures 0.8 km(2) and is dominated by red mangrove (Rhizophora mangle). This forest forms the landward boundary of the Buccoo Reef Marine Park in Southwest Tobago, and is part of a mangrove-seagrass-coral reef continuum. Biomass and productivity, as indicated by litterfall rates, were measured in seven 0.01 ha monospecific plots from Febru...

The dynamics of aquatic macrophytes in intermittent rivers is generally related to the characteristics of the resistance and resilience of plants to hydrologic disturbances of flood and drought. In the semi-arid region of Brazil, intermittent rivers and streams are affected by disturbances with variable intensity, frequency, and duration throughout their hydrologic cycles. The aim of the presen...

Trade-offs in sex resource allocation are commonly inferred from a negative correlation between male and female reproduction. We found that for three California oak species, aboveground annual net productivity (ANP) differences among individuals were primarily correlated with water availability and soil fertility. Reproductive biomass increased with ANP, but the relative allocation to reproduct...