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.
2012
Abstract
This study investigates the relationship between Leaf Area Index (LAI) reduction in pine stands caused by pine sawfly (Neodiprion sertifier) larva and reflectance change measured using multitemporal optical satellite data. The study was carried out in 552 Scots Pine (Pinus sylvestris)-dominated stands in southern Norway (60° 41′ N, 12° 18′ E). Post-damage Satellite Pour l'Observation de la Terre (SPOT) satellite data were calibrated to surface reflectance using reflectance products of the moderate-resolution imaging spectroradiometer (MODIS). Standwise reflectance change was then computed by subtracting a pre-damage SPOT image that had been relative calibrated to the post-damage image using histogram matching. The reflectance changes were related to changes in LAI obtained from multitemporal lidar data calibrated with field measurements made with a LiCOR LAI-2000 plant canopy analyser. The reduced needle biomass growth due to the insect damage caused an increase in reflectance on the order of 0.002–0.015 in the visible and short-wave infrared SPOT bands and a decrease of 0.01 in the near infrared (NIR) band compared with a large reference data set with normally developed stands. A cross-validated discriminant analysis showed that 79% of the damaged stands could be separated from the undamaged stands by using the SPOT data.
Authors
Juha Heikkinen Erkki Tomppo Alexandra Freudenschuss Peter Weiss Gro Hylen Gal Kusar Ronald McRoberts Gerald Kändler Emil Cienciala Hans Petersson Göran StahlAbstract
National forest inventories (NFIs) are an important source of data for reporting greenhouse gas emissions and removals for the Land Use, Land-Use Change, and Forestry sector as required by the United Nations Framework Convention on Climate Change and its Kyoto Protocol. A major limitation is that NFI resources are generally not sufficient for producing reliable information on year-to-year variation. Interpolation, extrapolation, smoothing, and/or aggregation of data from several years are therefore needed to comply with the reporting requirements for a specific year. Various methods for accomplishing this task are illustrated and evaluated based on data and experiences from the NFIs of six countries, concentrating on the estimation of the stem volume of living trees as a surrogate for tree biomass. Six main conclusions were drawn: (1) NFI data from the target years only were not sufficient for reliable estimation of annual stock change; (2) changes between whole inventory cycles (typically 5 years) could be estimated with reasonable precision; (3) simple moving average estimators of stock are problematic in the estimation of changes; (4) interpenetrating panel designs with permanent sample plots are desirable from the point of view of inter/extrapolating and change estimation; (5) data on annual growth variation and harvests are important and can be used directly in the default method, which is based on differences between increment and drain; and (6) time gaps between NFI surveys may lead to significant errors in the estimation of stock changes.
Authors
Signe Kynding Borgen Arne Grønlund Olof Andrén Thomas Kätterer Ole Einar Tveito Lars Bakken K PaustianAbstract
No abstract has been registered
Abstract
The study describes the development of surface mould and blue stain fungi on painted wooden claddings exposed to outdoor weathering. The materials consisted of Norway spruce (Picea abies) claddings that were processed from inner boards, outer boards, and edge-grained boards with known origin. Heartwood proportion, density, annual ring width, knot diameters and relative knot area were measured, and all boards were coated with the same water-borne alkyd modified acrylic paint system. Most of the tangentially sawn boards were coated on the side facing the pith, but a sub-sample was coated on the opposite side for comparison. The specimens were exposed with a 45° angle of inclination facing south in a field trial in Oslo from 2007 to 2011, and mould growth was evaluated visually according to EN 927-3. The development of mould rating was described with an ordinal logistic regression model. The model predicts expected mould rating to follow a sigmoid curve with some deviation in the first part. Neither wood properties nor manufacturing characteristics had any significant effect on the model, and this may in part be due to the use of a high performance coating system.
Abstract
The genera Leiopus Audinet-Serville, 1835 and Acanthocinus Dejean, 1821 are redescribed. New morphological differences at the generic level are described, and the importance of genitalia characters in taxonomy at both species and generic level is emphasized. Carinopus subgen. nov. in Leiopus is described from mainland China and Taiwan. Acanthobatesianus subgen. nov. in Acanthocinus is described from China, the Korean peninsula and Japan. Leiopus (Carinopus) campbelli (Gressitt, 1937) comb. nov. is transferred from Acanthocinus, and Acanthocinus (Acanthobatesianus) guttatus (Bates, 1873) comb. nov. from Leiopus. Six new species of Leiopus from China are diagnosed, described, and illustrated: L. nigropunctatus sp. nov., L. flavomaculatus sp. nov., L. ocellatus sp. nov., L. nigrofasciculosus sp. nov., L. holzschuhi sp. nov. and L. multipunctellus sp. nov. Redescriptions of L. kharazii Holzschuh, 1974, L. albivittis albivittis Kraatz, 1879, L. stillatus (Bates, 1884), L. (Carinopus) shibatai Hayashi, 1974, L. (Carinopus) fallaciosus Holzschuh, 1993, L. (Carinopus) campbelli (Gressitt, 1937) comb. nov. and Acanthocinus (Acanthobatesianus) guttatus (Bates, 1873) comb. nov. are added. A key to the generic and subgeneric levels of Leiopus and Acanthocinus, and a dichotomous key to all six new species of Carinopus subgen. nov. (Leiopus str.) from China, are provided.
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
Springs are characterized by consistent thermal and hydrologic conditions, which enable use of spring-inhabiting organisms as sensitive indicators of biogeochemical changes in their catchments. We hypothesized that bryophytes would show a stronger response than vascular plants to changes in spring water quality because submerged bryophytes do not take up compounds from the soil. We analyzed species responses to interannual changes in spring water quality (discharge, water temperature, electrical conductivity, and pH) in 57 forest springs over 4 consecutive years. We calculated interannual turnover in species composition for bryophytes and vascular plants with the Bray–Curtis dissimilarity index. We applied regression analysis to test interannual changes in species composition of the taxonomic groups over time, and we used 2-sided t-tests to compare year-to-year changes in species composition between bryophytes and vascular plants. We used boosted regression tree (BRT) models to quantify the relative importance of different physicochemical variables and Pearson linear correlation to quantify short-term changes in vegetation relative to changes in spring-water pH. For both groups, interannual changes in species composition were significantly positively related to time scale. Bryophytes did not show a significantly stronger response than vascular plants to interannual changes in the environment. Alterations in pH and conductivity explained most of the observed interannual changes in species composition of both groups, whereas changes in water temperature and discharge were less important. However, responses of single species to environmental change may be delayed, resulting in inertia at the community and ecosystem scales. Hence, longer time periods need to be considered for a better understanding of response times of the vegetation of European forest springs to changes in spring water quality.
Abstract
No abstract has been registered
Abstract
No abstract has been registered