Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2011
Forfattere
Md Hafizur Rahman Trine Lund Ian BrycesonSammendrag
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.
Forfattere
Frank Asche Kristin Helen Roll Ragnar TveteråsSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Ove BergersenSammendrag
Det er ikke registrert sammendrag
Forfattere
Theo RuissenSammendrag
Debattinnlegg forskningsmetodikk-forskningsetikk
Sammendrag
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.
Forfattere
Oskar PuschmannSammendrag
Det er ikke registrert sammendrag
Forfattere
Anita Land Anita LandSammendrag
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Forfattere
Venche TalgøSammendrag
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Forfattere
Venche TalgøSammendrag
Det er ikke registrert sammendrag