Einfluß langjähriger Gülledüngung auf den Nährstoffhaushalt des Bodens. 1. Mitteilung: N-Akkumulation und N-Nachlieferungsvermögen

Influence of long-term slurry application on soil nutrients. 1. N accumulation and N mineralization potential The influence of longterm slurry applications on the total N content, N fractions and N mobilization potential of the soil was investigated. The following results were obtained:

• – Application of high amounts of slurry over a long period of time resulted in higher total N contents not only in the upper soil layers but also in the layer 60–90 cm.
• – In two sites the higher total N contents are mainly resulting from higher contents of hydrolyzable organic N compounds and in one site of higher contents of non hydrolyzable organic N compounds.
• – The influence of the slurry application on the content of non exchangeable NH₄⁺ is depending on the K saturation of the clay minerals.
• – In incubation experiments N mobilization of the soils supplied with slurry was higher as compared to soils supplied with mineral fertilizer.
• – A highly significant correlation is existing between N mobilization and the content of hydrolyzable organic N compounds and the N_org fraction, determined by means of EUF, respectively.
• – The N_min content of the soils supplied with slurry was higher during the whole growing season.

     

Diversity patterns in butterfly communities of the Greek nature reserve Dadia

Traditionally, nature reserves have been centered mainly around areas that are important for vertebrate diversity. This practice has not gone unchallenged and may be a suboptimal choice for overall conservation planning. To investigate this problem, we sampled butterfly species richness in a nature reserve in north eastern Greece that was originally established for the protection of birds of prey. Patterns of butterfly species richness and abundance were investigated by means of transect walks across a range of the seven predominant habitat types (wet and dry meadow, pine, oak and mixed forest, grazed, and agricultural land). Data analysis, including ANOVA and DCA (detrended correspondence analysis), revealed that the main gradients in butterfly species richness (low to high) were from sites dominated by the pine forest matrix of the core areas of the reserve, to peripheral sites in landscapes of mixed or oak forest, and from sites with little human impact to more disturbed areas with high grazing pressure. Species of conservation interest were concentrated at sites of low human impact. Ten of them are endemic to Europe and/or threatened in Europe. In this respect, the most important species are Lycaena ottomanus, Thymelicus acteon, and Pseudophilotes vicrama which are declining all over Europe. Our results suggest that (1) traditional agricultural practices in areas surrounded by forest can be considered as important management tools in butterfly conservation, (2) highest butterfly species richness is found in the periphery of the reserve rather than in the core areas, and (3) for butterfly conservation the zones surrounding the strictly protected areas are equally important as the core areas.     

Influence of ethylene inhibition by 1-methylcyclopropene on apricot quality,volatile production,and glycosidase activity of low- and high-aroma varieties of apricots

Apricots of two varieties, Ceccona with strong aroma and San Castrese with low aroma but good firmness, were treated with 1 microL L(-)(1) 1-methylcyclopropene (1-MCP) for 12 h at 20 degrees C and then kept for shelf life at 20 degrees C and 85% relative humidity. 1-MCP treatment strongly inhibited ethylene production in apricots of both varieties, and softening was delayed. Fruit softening started before the rise of ethylene in air-treated apricots, which softened even when the rise of ethylene production was inhibited by 1-MCP. The softening reduction was more significant in Ceccona apricots than in San Castrese. Pectinmethylesterase (PME) activity declined in Ceccona fruit regardless of the treatment; in San Castrese, PME of air-treated fruit slightly increased, whereas in 1-MCP-treated apricots the activity declined. alpha-d-Galactosidase (alpha-gal) and beta-d-galactosidase (beta-gal) activities in Ceccona apricot were significantly reduced by 1-MCP treatment, whereas in San Castrese apricot no difference in activities was observed between air- and 1-MCP-treated fruit. The pattern of beta-d-xylosidase (xyl) activity in San Castrese apricot was similar to that of beta-gal, showing a peak on day 4 without difference between treatments. alpha-d-Mannosidase (alpha-man) activity of air-treated apricots of both varieties rose slightly, and 1-MCP treatment decreased the enzyme activity in both varieties. alpha-d-Glucosidase (alpha-glu) decreased in air-treated apricots in both varieties, and 1-MCP maintained higher activity in Ceccona fruit but not in San Castrese. Acidity decreased during postharvest ripening regardless of the treatment, whereas soluble solids content (SSC) increased in Ceccona apricot and slightly diminished in San Castrese ones without any effect by 1-MCP treatment. 1-MCP did not show any effect on apricot color; in contrast, it affected the volatiles profile, especially in Ceccona apricot, reducing the synthesis of lactones and promoting the rise of terpenols.     

Nitrogen Deposition and Nitrate Leaching at Forest Edges Exposed to High Ammonia Emissions in Southern Bavaria

The atmospheric deposition of air pollutants was studied by means of monitoring canopy throughfall at six forest stands. The investigation was carried out in Norway spruce (Picea abies L. Karst.) forests in Southern Bavaria with high ambient ammonia concentrations due to either adjacent intensive agriculture or poultry housing. Five monitoring plots transected the forest edges and forest interior from the edge, at 50, 150, about 400 m and about 800m to the interior. Additionally, nutrient concentration in soil solution was sampled with suction cups at each plot, and C/N ratio of the humus layer was also determined. The variation of ambient ammonia concentration between three of the six investigated sites was estimated using diffusive samplers. In order to compare the effects of atmospheric deposition on European beech (Fagus sylvatica L.) and Norway spruce additional monitoring plotswere installed under each of these species in a mixed beech and spruce stand. Bulk deposition and soil water samples were analysed for major ions (NO₃ ^-, NH₄ ⁺, SO₄ ^2-, Cl^-, Na⁺, K⁺, Mg²⁺, Ca^2+M).The results show a substantial increase of deposition towards the forest edges for all ions. This so called 'edge effect' continued in most cases until a distance from 50 to 150 m from edge. For both ambient ammonia concentrations and nitrogen deposition, it can be concluded that increased dry deposition is the main reason for the edge effect. Over 76% of the nitrogen ratios in throughfall deposition between the edge and 50 m distance into the spruce forest exceed 1.0. Except for potassium, beech generally showed lower ratios than spruce.Due to high nitrogen deposition the forest floor, C/N ratios were lower at stand edges when compared to their interior. In contrast to the increase of nitrogen deposition at the edge, nitrate export below the main rooting zone was lower at the edge. Nitrate export was generally lower under beech than spruce. Nitrogen budgets of some plots were negative, indicating a reduction of total ecosystem nitrogen stock.The results show that forest edges, especially in areas with high air pollution, receive much more atmospheric deposition than the interior parts of closed forest stands. As many deposition studies in forests were conducted at field stations in the central parts of forests the estimated deposition for the whole forest may be underestimated. This may be important to consider in geo-statistical studies and models aiming to estimate spatial critical deposition values, especially with an increasing fragmentation of the forest cover.     

Isolation of a new natural product and cytotoxic and antimicrobial activities of extracts from fungi of Indonesian marine habitats

In the search for bioactive compounds, 11 fungal strains were isolated from Indonesian marine habitats. Ethyl acetate extracts of their culture broth were tested for cytotoxic activity against a urinary bladder carcinoma cell line and for antifungal and antibacterial activities against fish and human pathogenic bacteria as well as against plant and human pathogenic fungi. The crude extract of a sterile algicolous fungus (KT31), isolated from the red seaweed Kappaphycus alvarezii (Doty) Doty ex P.C. Silva exhibited potent cytotoxic activity with an IC₅₀ value of 1.5 μg/mL. Another fungal strain (KT29) displayed fungicidal properties against the plant pathogenic fungus Cladosporium cucumerinum Ell. et Arth. at 50 μg/spot. 2-Carboxy-8-methoxy-naphthalene-1-ol (1) could be isolated as a new natural product.     

A whole-genome association study of major determinants for host control of HIV-1

Understanding why some people establish and maintain effective control of HIV-1 and others do not is a priority in the effort to develop new treatments for HIV/AIDS. Using a whole-genome association strategy, we identified polymorphisms that explain nearly 15% of the variation among individuals in viral load during the asymptomatic set-point period of infection. One of these is found within an endogenous retroviral element and is associated with major histocompatibility allele human leukocyte antigen (HLA)-B*5701, whereas a second is located near the HLA-C gene. An additional analysis of the time to HIV disease progression implicated two genes, one of which encodes an RNA polymerase I subunit. These findings emphasize the importance of studying human genetic variation as a guide to combating infectious agents.     

Beef with environmental and quality attributes: Preferences of environmental group and general population consumers in Saskatchewan, Canada

We attempt to quantify and qualify the preferences of consumers for beef with a number of environmental and food quality attributes. Our goal is to evaluate the viability of a proposed food co-operative based in the Wood River watershed of southern Saskatchewan, Canada. The food co-operative was designed to provide a price premium to producers who adopted alternative management practices. In addition, the study evaluated the acceptance of a proposed food co-operative by consumer that had environmental interests as compared to the general population. Conjoint analysis was used to determine the trade-off and relative value of beef with the following production and purchasing characteristics: (a) use of hormones, antibiotics and vaccination in production; (b) method of obtaining the beef including monthly or yearly purchase contracts or a local market; (c) price relative to beef purchased from the local grocery store; and (d) impact on the river ecosystem. Consumers from environmental groups had stronger environmental and food quality preferences than individuals from the general population. However, consumers from both groups expressed a willingness to pay higher prices for food that had these attributes. It was uncertain whether the magnitude of the premium, in combination with a desire not to enter a long-term purchasing commitment, would be large enough to encourage farmers to adopt the alternative management. Ken W. Belcher is an Associate Professor in the Department of Agricultural Economics at the University of Saskatchewan. His research has focused on ecological economics and environmental policy with a particular interest in environmental conservation in agricultural landscapes. Andrea E. Germann was a Research Assistant with the Centre for Studies in Agriculture, Law and the Environment at the University of Saskatchewan. Josef K. Schmutz is a Research Fellow with the Centre for Studies in Agriculture, Law and the Environment. Joe has expanded his research interest on prairie raptors by fostering strategic design for alternative, local economies that include the conservation of birds and their ecosystems.