Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2011
Abstract
Fungal hyphae in soil, although crucial in the C-dynamics, are difficult to quantify. Here we present a simple method for fungal biomass assessment and possibility for up-scaling. Originally we used root nets to quantify fine roots in drought-stressed Picea abies stand as described by Lukac and Godbold (2010).Root nets (7 cm wide, mesh size 1 mm) were inserted vertically to 20 cm depth, twice during the course of one year. When root nets were extracted from the soil, large amounts of hyphae were growing on and through the nets in the control plot, whereas little or no hyphae were growing in nets from the drought-stressed plot.This observation led us to consider root nets as a promising tool to quantify hyphae as well. The inert net material together with its regular geometric pattern is well suited for obtaining fungal biomass estimates and provide a material for further molecular analysis of fungal species. We will describe a proposal how to scan the hyphae, calculate the biomass and upscale to the soil volume unit.
Authors
John Marshall BrydenAbstract
No abstract has been registered
Authors
Karen Refsgaard Arild SpissøyAbstract
No abstract has been registered
Authors
Adam Paruch Trond Mæhlum Hanna Obarska-Pempkowiak Magdalena Gajewska Ewa Wojciechowska Arkadiusz OstojskiAbstract
This article describes Norwegian and Polish experiences concerning domestic wastewater treatment obtained during nearly 20 years of operation for constructed wetland (CW) systems in rural areas and scattered settlements. The Norwegian CW systems revealed a high performance with respect to the removal of organic matter, biogenic elements and faecal indicator bacteria. The performance of the Polish CW systems was unstable, and varied between unsatisfied and satisfied treatment efficiency provided by horizontal and vertical flow CWs, respectively. Therefore, three different concepts related to the improvement of CW technology have been developed and implemented in Poland. These concepts combined some innovative solutions originally designed in Norway (e.g. an additional treatment step in biofilters) with Polish inspiration for new CWs treating rural domestic wastewater. The implementation of full-scale systems will be evaluated with regard to treatment efficiency and innovative technology; based on this, a further selection of the most favourable CW for rural areas and scattered settlements will be performed.
Authors
Md Hafizur Rahman Trine Lund Ian BrycesonAbstract
Since shrimp farming started in Bangladesh in the 1970s, it has spread throughout the coastal region, increasing soil and water salinity levels. The water salinity in 2005 in the coastal districts of Khulna, Bagherat and Satkhira ranged from 0.3 to 20.7, 0.4 to 27.1 and 0.7 to 24.8 dS m(-1), respectively, whereby it was highly saline for several months of the year. Water salinity above 2.5 dS m(-1) is not suitable for irrigation, and may cause animal health problems. Irrigation with saline water may cause ion toxicity and osmotic stress, reducing plant growth and yield. Salinity has reduced the agro-biodiversity in the coastal regions of Bangladesh, and this paper investigates how these changes have impacted human food habits in the three coastal, rural villages Putia (Satkhira district), Srifaltala (Bagerhat district) and Hogolbunia (Khulna district). Fieldwork was conducted from July to December 2006 and Participatory Rural Appraisal methods including transect walks, key informant interviews, group discussions and personal interviews were carried out. In total, 121 respondents were interviewed and historical data from 1975 to 2006 were collected. For historical data, respondents aged above 50 years were sampled, but additional criteria such as socio-economic condition and farm location were applied to assure a sample representative for the population of the coastal areas. The sampled households had characteristics similar to the major part of Bangladeshi households (rural, agrarian based, regarding family size and food habits), and were thus representative of a broader cross-section of households in Bangladesh. As all sampled villages faced increasing salinity and spread of shrimp farming, they were representative of villages in the coastal areas. When salinity increased, the production of vegetables, seasonal fruits, animal species, eggs and milk declined. As the price of the mentioned animal commodities rose, cheaper commodities such as broilers, exotic and marine fish species and exotic oils were introduced. The decision on what to cultivate was also influenced by non-residents converting the farmers' land into shrimp ponds, increasing the salinity in the surroundings and killing the farmers' ducks. These agro-biodiversity changes caused reduced frequency of consumption of beef, goat, native chicken, egg, local freshwater fish, seasonal fruits, vegetables and milk, while broilers, exotic fish, exotic oils and marine fish species were increasingly consumed. Still, the total fish consumption declined. These changed food habits may lead to considerable negative health consequences for the rural, coastal populations.
Authors
Md Hafizur Rahman Trine Lund Ian BrycesonAbstract
Salinity increase has been one of the major problems for traditional agricultural practices in coastal Bangladesh for several decades, but very few studies have been conducted on effects of salinity on agrobiodiversity in this area. This study investigated the salinity effects on agro-biodiversity in rice (Oryza sativa L.), vegetables, and fruit trees in three coastal, rural villages; Putia (Satkhira district), Srifaltala (Bagerhat district) and Hogolbunia (Khulna district). Information was collected by participatory rural appraisal methods including transect walks, group discussions, key informant interviews, and 121 personal interviews from July to December 2006. The study revealed that increased salinity had significant negative impacts on the overall agro-biodiversity. From 1975 to 2006 the number of indigenous rice varieties declined from seventeen to zero in Putia, from twelve to nine in Hogolbunia and from fifteen to two in Srifaltala. The encroachment of shrimp ponds near the homestead, and cultivation of high yielding, salt-tolerant rice varieties contributed to the decline of indigenous rice varieties. The occurrence of vegetable and fruit tree species declined from 1975 to 1990. The farmers appeared generally unaware of the importance of conservation of seeds and local landraces. This paper highlights factors directly and indirectly influencing farmers’ agricultural practices, and contributes to the discussion as to how environmental changes influence agro-biodiversity conservation and food production. The large reduction in agro-biodiversity, largely induced by increasing salinity, is alarming and threatens the Bangladeshi farmers’ ability to continue crop cultivation and thus their livelihood.
Authors
Frank Asche Kristin Helen Roll Ragnar TveteråsAbstract
No abstract has been registered
Abstract
Aims Beech (Fagus sylvatica L.) is an important species in natural and managed forests in Europe. This drought-sensitive species dominates even-aged stands as well more natural stands composed of a mixture of tree species, age and size classes. This study evaluates the extent that heterogeneity in spacing and tree diameter affect the seasonal availability and use of water. Methods Two stands were evaluated: 1) a heterogeneous forest remnant (NAT) with trees up to ca. 300 years old, a mean top height of 28.4 m, and a total of 733 stems ha-1 with stem diameters averaging 18 cm and 2) an even-aged 80-year old stand (MAN), with a height of 25 m, and a total of 283 stems ha-1 with diameters averaging 38 cm. Stem sap flow, Js (g m-2 s-1), was continuously measured in 12 (MAN) and 13 (NAT) trees using 20 mm long heat dissipation sensors. Individual tree measures of sap flow were correlated using non-linear statistical methods with air vapour pressure deficit (D, hPa) and global radiation (Rg, J m-2 day-1), along with contraints imposed by reductions in soil water content (SWC). Soil water content was measured as volumetric % using time domain reflectometry. Important findings The daily integrated Js (Js-sum) for trees growing in the evenly spaced MAN stand and trees in canopy and closed forest positions in NAT stand decreased as the availability of soil moisture was reduced. In the heterogeneous NAT stand, SWC in a recently formed canopy gap remained high throughout the vegetation period. Based on regression models, the predicted relative decrease in Js-sum for dry relative to moist soil water conditions in the closed forest (at mean daily D = 10 hPa) was 7-11% for trees near the gap and 39-42% for trees in the closed forest. In MAN the reduction in Js-sum was 29% in dry relative to moist conditions. Js-sum in the outer 20 mm of the xylem in NAT was lower than that in MAN and the rate of decline in Js with xylem depth was less in NAT than in MAN. In MAN, Js-sum in deep and outer xylem was negatively affected at low soil moisture availability; in NAT this was the case for only the outer xylem indicating that deep roots could be important in supplying water at times of low soil moisture in the upper soil.
Abstract
odronia canker (Godronia cassandrae f. sp. vaccinii) is a severe disease in young plantings of highbush blueberry (Vaccinium corymbosum L.) in Norway. In Europe, only the imperfect stage (Topospora myrtillii) has been reported, and thus conidia produced in pycnidia are assumed to be important for dissemination of the fungus. The seasonal pattern of production of conidia was investigated in a commercial planting of ‘Jersey" in 1998 and a research planting of ‘Bluecrop" in 1998 to 2000. The disease became apparent in March on shoots infected the preceding growing season, and lesions started to form pycnidia containing conidia in April. Samples of stems with distinct lesions of Godronia canker were collected from the bushes every two to three weeks from early spring to autumn. Stem pieces with lesions were shaken in water to release conidia from the pycnidia, and the numbers of conidia were determined by microscopy. Conidia were present throughout the growing season, but the highest numbers occurred during May, with 106 to more than 107 conidia per lesion. The numbers generally decreased during July to 20 % or less of that found in May, and decreased further during September to around 4 %. Ability to germinate remained high throughout the period conidia were trapped, from April to November/December. Options to manage the disease are discussed.
Abstract
No abstract has been registered