Comparative assessment of food web structure and fisheries productivity of three reservoirs in Ghana

Three Ghanaian reservoirs (Tono, Bontanga and Golinga) were compared through a food web modelling approach (Ecopath with Ecosim) to assess production characteristics and food web structures. The lakes differ in size and morphology, generating specific conditions for fish growth and production. While the two top fishery target species were Sarotherodon galilaeus (L.) and Oreochromis niloticus (L.) in all reservoirs, the mean trophic level of the catch was lowest in the largest and deepest reservoir (Tono) due to higher trophic level species occupying less accessible deep “refuge” habitats. The smallest lake had the highest fish production under optimal conditions of water supply (17.1 compared with 15.5 and 10.1 t/km²/year for lakes Bontanga and Tono), but it appears to be most vulnerable under conditions of drought. For the planning and construction of adequately sized reservoirs used for fishery and irrigation purposes, the water budget (ratio of inflow and evaporation) needs to be estimated.     

Contribution of methylated exudate flavonoids to the anti-inflammatory activity of Grindelia robusta

The flavonoid pattern of an acetonic extract of Grindelia robusta Nutt. was investigated in detail. The flavonoids were enriched by CC. In addition to twelve known methylated exudate flavonols four compounds were identified for the first time in G. robusta. Several substances of the flavonoid complex, among them the main compounds quercetin-3-methylether and 6-OH-kaempferol-3,6-dimethylether, were tested for their activity to inhibit neutrophil elastase. Quercetin-3-methylether was shown to be most active with an IC₅₀ of 19 µM, thus obviously contributing to the anti-inflammatory activity of the drug.     

Analyses of the impact of changes in atmospheric deposition and climate on forest growth in European monitoring plots: A stand growth approach

During the last 15 years a number of studies have shown increasing forest growth in central Europe, rather than a decline as was expected due to negative effects of air pollution. We have here used data from intensive monitoring plots spread over Europe for a five year period in order to examine the influence of environmental factors on forest growth. Evaluations focussed on the influence of nitrogen, sulphur and acid deposition, temperatures, precipitation and on a drought index calculated as deviation from the long-term mean. The study included the main tree species Norway spruce, Scots pine, common beech as well as European and sessile oak and was based on data from 363 plots. As many other factors besides nitrogen and temperature influence tree growth, expected stem volume increments were modelled using site productivity, stand age and a stand density index. Relative volume increment was then calculated as actual increment in % of expected increment. The site productivity, assumed to be given by site conditions and past environmental conditions, was either taken from expert estimates or computed from site index curves from northern, central and southern Europe. The model explained between 18% and 39% of the variance with site productivity being positively related and age negatively related to actual increment. The various models and statistical approaches were fairly consistent, and indicated a fertilizing effect of nitrogen deposition, with slightly above one percent increase in volume increment per kg of nitrogen deposition per ha and year. This was most clear for spruce and pine, and most pronounced for plots having soil C/N ratios above 25. Also, we found a positive relationship between relative increment and summer temperature, i.e. May–August mean temperature deviation from the 1961–1990 means. The cause–effect relationship here is, however, less certain. Other influences were uncertain. Possibly, sulphur and acid deposition have effects on growth, but these effects are obscured by, and outweighed by the positive effect of nitrogen deposition, because of collinearity between these variables. Drought effects were uncertain also, and one reason for this might be large uncertainties in the precipitation data: precipitation measured on some 50% of the plots correlated poorly with the precipitation data obtained from Europe-wide databases. The major finding of this study was a positive relationship between higher than normal volume increment on one hand and nitrogen deposition on the other hand.     

Impacts of increased fire frequency and aridity on eucalypt forest structure,biomass and composition in southwest Australia

Water stress and fire disturbance can directly impact stand structure, biomass and composition by causing mortality and influencing competitive interactions among trees. However, open eucalypt forests of southwest Australia are highly resilient to fire and drought and may respond differently to increased fire frequency and aridity than forests dominated by non-eucalypt species. We measured the variation in stem density, basal area, stand biomass, sapwood area, leaf area and litterfall across 16 mixed jarrah (Eucalyptus marginata) and marri (Corymbia calophylla) forest stands along an aridity gradient in southwest Australia that had variable fire histories. Fire frequency was defined as the total number of fires over a ∼30-year period and aridity as the ratio of potential evapotranspiration to annual precipitation. Total stand biomass and sapwood area were predicted from diameter at breast height of individual jarrah and marri trees using allometric equations. Leaf area was estimated using digital cover photography. More arid and frequently burnt stands had higher stem density, especially of smaller trees, which were mainly jarrah. Overall, both standing biomass and leaf area decreased at more arid sites, while sapwood area was largely unaffected by aridity, suggesting that these stands respond to increased water limitation by decreasing their leaf area relative to their sapwood area. Biomass of marri was reduced at more arid and, to a lesser extent, at more frequently burnt stands. However, total stand biomass (jarrah and marri) and leaf area index did not vary with fire frequency, suggesting that less marri biomass (due to slower growth rates, higher mortality or less recruitment) was compensated by an increase in the density of jarrah trees (regeneration). We conclude that increased fire and drought shift tree species composition towards more fire-resistant species and result in denser stands of smaller trees. In contrast, total stand biomass declines with increasing aridity, but has no association with fire frequency.     

Analysis of trade in illegally harvested timber: Accounting for trade via third party countries

The paper presents a model to analyse trade in illegally harvested timber with a particular focus on trade via third party countries. The model is deduced from the conventional input–output-analysis. In contrast to this type of analysis, inverse export coefficients are introduced to analyse the effect of a certain amount of country-specific supply, e.g., of illegally harvested timber, to the use of wood and wood products of all other countries, based on trade relationships. A database has been compiled especially for application of the model. It comprises data on industrial round-wood production in terms of industrial wood harvested and removed from the forest; recovered wood fibre in the form of recovered paper and waste wood; bilateral trade of 272 wood-based commodities in m³ raw wood equivalent (rwe), and domestic use of those commodities. Two scenarios expressing high and low estimates of illegal harvesting for all countries have been employed in the model. The model reveals the trade linkages between all countries of the world and allows quantification of the global supply and use arising from illegal harvesting. Furthermore it allows calculation of the import of illegally harvested timber for each country of the world. And finally, the model likewise allows the quantification of domestic use of illegally harvested timber for each country of the world.The results show that international trade increases the global domestic supply of illegally harvested timber by more than 70% in each scenario. In particular industrial round-wood from Papua New Guinea, Malaysia, Indonesia and Myanmar passes through many countries until it ends in form of finished wood products in the country of final destination. Not only due to suggested illegally harvested timber in the own country, but also due to strongly developed trade relationships, China holds the lead in total supply and use of illegally harvested timber. However this result must be seen against the background of the large population in China. This aspect also helps to explain the predominant position of China, Brazil and Russia with regard to the domestic use of illegally harvested timber. A comparison of import of illegally harvested timber on the basis of “simple” (covering only bilateral trade) and inverse export coefficients demonstrates the model's merit. The hitherto usually simple approach underestimates the “real” trade by a third up to a half.     

Slurry injection with nitrification inhibitor in maize: Plant phosphorus,zinc, and manganese status

Slurry injection below the maize (Zea mays L.) row may substitute a mineral nitrogen (N) phosphorus (P) starter fertilizer (MSF) and thus reduce nutrient surpluses in regions with intensive livestock husbandry. We investigated the plant P, zinc (Zn), and manganese (Mn) status compared to the current farm practice. In 2014 and 2015 field trials were conducted to evaluate plant nutrient status at different growth stages. Besides an unfertilized control, two slurry injection treatments (±nitrification inhibitor (NI)) were compared to slurry broadcast application plus MSF. In both experiments NI addition significantly increased nutrient concentrations during early growth (6-leaf 2015: +33% P, +25% Zn, +39% Mn). Under P deficiency due to cold weather conditions broadcast application showed higher P uptake until 6-leaf (36–58%), while it was lower at 8- (32%) and 10-leaf (19%) stage compared to slurry injection (+NI). Zn availability was enhanced for slurry injection (+NI) during early growth and Zn and Mn uptakes were higher at harvest. Slurry injection decreased P balances by 10–14 kg P ha^?1, while Zn and Mn balances were excessive independent of treatments. Slurry injection (+NI) can substitute a MSF without affecting early growth and enhances the Zn and Mn status. This new fertilizing strategy enables farmers to reduce P surpluses.     

Insecticidal efficacy of botanical food by-products against selected stored-grain beetles by the combined action with modified diatomaceous earth

Journal of Plant Diseases and Protection - Farmers in Africa in general have repeatedly prioritized the urgent need for improved methods of storage pest control. Laboratory studies were evaluated...     

Antibacterial compounds from marine Vibrionaceae isolated on a global expedition

On a global research expedition, over 500 bacterial strains inhibitory towards pathogenic bacteria were isolated. Three hundred of the antibacterial strains were assigned to the Vibrionaceae family. The purpose of the present study was to investigate the phylogeny and bioactivity of five Vibrionaceae strains with pronounced antibacterial activity. These were identified as Vibrio coralliilyticus (two strains), V. neptunius (two strains), and Photobacterium halotolerans (one strain) on the basis of housekeeping gene sequences. The two related V. coralliilyticus and V. neptunius strains were isolated from distant oceanic regions. Chemotyping by LC-UV/MS underlined genetic relationships by showing highly similar metabolite profiles for each of the two V. coralliilyticus and V. neptunius strains, respectively, but a unique profile for P. halotolerans. Bioassay-guided fractionation identified two known antibiotics as being responsible for the antibacterial activity; andrimid (from V. coralliilyticus) and holomycin (from P. halotolerans). Despite the isolation of already known antibiotics, our findings show that marine Vibrionaceae are a resource of antibacterial compounds and may have potential for future natural product discovery.     

Statistical methods for detecting and comparing periodic data and their application to the nycthemeral rhythm of bodily harm: A population based study

Background  

Animals, including humans, exhibit a variety of biological rhythms. This article describes a method for the detection and simultaneous comparison of multiple nycthemeral rhythms.     

Mikro- und makroskopische Untersuchungen an Straßenbaumveredelungen im Hinblick auf die Beeinflussung ihrer Bruchsicherheit

Aim of the study was to identify changes within xylem structure of grafted trees which could possibly lead to a higher risk of breakage. Therefore, 83 trees from the genera Prunus, Sorbus, Carpinus, Quercus, Robinia and Crateagus were examined at the macro- and microscopic level. All wood samples showed changes in their xylem structure in the areas at or around the contact zone of stock and scion. Cells were deviated in different angles from the stem axis in the tangential direction. Furthermore, whirled grain areas were found adjacent to the contact zone. Abnormal xylem structures could be found in various quantum's. Despite the observed changes in the xylem structure, the risk of breakage is not significantly increased. An e-mail based survey among 496 administrations of rural districts in Germany and bigger towns all over Germany including 64 botanical gardens and arboretum, revealed only nine cases of stem breakage at the contact zone of grafted trees. These breaks were found in the genera Tilia, Fagus and Robinia. Further studies are recommended to gain more knowledge about how xylem structure develops during the lifespan of a tree under stress conditions, especially in urban environments.