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.
2022
Abstract
Climate change is a serious and complex crisis that impacts humankind in different ways. It affects the availability of water resources, especially in the tropical regions of South Asia to a greater extent. However, the impact of climate change on water resources in Sri Lanka has been the least explored. Noteworthy, this is the first study in Sri Lanka that attempts to evaluate the impact of climate change in streamflow in a watershed located in the southern coastal belt of the island. The objective of this paper is to evaluate the climate change impact on streamflow of the Upper Nilwala River Basin (UNRB), Sri Lanka. In this study, the bias-corrected rainfall data from three Regional Climate Models (RCMs) under two Representative Concentration Pathways (RCPs): RCP4.5 and RCP8.5 were fed into the Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS) model to obtain future streamflow. Bias correction of future rainfall data in the Nilwala River Basin (NRB) was conducted using the Linear Scaling Method (LSM). Future precipitation was projected under three timelines: 2020s (2021–2047), 2050s (2048–2073), and 2080s (2074–2099) and was compared against the baseline period from 1980 to 2020. The ensemble mean annual precipitation in the NRB is expected to rise by 3.63%, 16.49%, and 12.82% under the RCP 4.5 emission scenario during the 2020s, 2050s, and 2080s, and 4.26%, 8.94%, and 18.04% under RCP 8.5 emission scenario during 2020s, 2050s and 2080s, respectively. The future annual streamflow of the UNRB is projected to increase by 59.30% and 65.79% under the ensemble RCP4.5 and RCP8.5 climate scenarios, respectively, when compared to the baseline scenario. In addition, the seasonal flows are also expected to increase for both RCPs for all seasons with an exception during the southwest monsoon season in the 2015–2042 period under the RCP4.5 emission scenario. In general, the results of the present study demonstrate that climate and streamflow of the NRB are expected to experience changes when compared to current climatic conditions. The results of the present study will be of major importance for river basin planners and government agencies to develop sustainable water management strategies and adaptation options to offset the negative impacts of future changes in climate.
Authors
Lars T. Havstad John Ingar Øverland Trygve S. Aamlid Trond Gunnarstorp Geir Kjølberg Knudsen Jon SælandAbstract
Desiccation with diquat about one week before seed harvest has been common practise in Norwegian clover seed production. However, after withdrawal of diquat in 2020, clover seed growers no longer have desiccators available. In 2019 and 2020, six field trials in red clover and two field trials in white clover were carried out to evaluate alternative chemical products at different rates and at two different spraying dates, either early at 50% mature seed heads and / or late at 65% mature seed heads. Products included, either for one or two years, was Spotlight Plus (carfentrazonethyl), Beloukha (pelargonic acid), Glypper (glyphosate), Gozai (Pyraflufen-ethyl), Harmonix LeafActive (acetic acid), Harmonix FoliaPlus (pelargonic acid), Flurostar (fluroxypyr) and Saltex (sodium chloride) and liquid urea-based fertilizers. In addition, swathing was examined as an alternative in two red clover trials in 2020. While none of the tested chemicals were superior to diquat, the most promising alternatives were Harmonix FoliaPlus and Harmonix LeafActive in red clover or Harmonix FoliaPlus in white clover. Although usually less effective than these products, Beloukha also had an acceptable desiccation effect, especially when sprayed early and late. Swathing before harvest, using finger bar cutters, was an effective drying method under favourable weather conditions.
Abstract
No abstract has been registered
Abstract
Lack of national soil property maps limits the studies of soil moisture (SM) dynamics in Norway. One alternative is to apply the global soil data as input for macro-scale hydrological modelling, but the quality of these data is still unknown. The objectives of this study are 1) to evaluate two recent global soil databases (Wise30sec and SoilGrids) in comparison with data from local soil profiles; 2) to evaluate which database supports better model performance in terms of river discharge and SM for three macro-scale catchments in Norway and 3) to suggest criteria for the selection of soil data for models with different complexity. The global soil databases were evaluated in three steps: 1) the global soil data are compared directly with the Norwegian forest soil profiles; 2) the simulated discharge based on the two global soil databases is compared with observations and 3) the simulated SM is compared with three global SM products. Two hydrological models were applied to simulate discharge and SM: the Soil and Water Integrated Model (SWIM) and the Variable Infiltration Capacity (VIC) model. The comparison with data from local soil profiles shows that SoilGrids has smaller mean errors than Wise30sec, especially for upper soil layers, but both soil databases have large root mean squared errors and poor correlations. SWIM generally performs better in terms of discharge using SoilGrids than using Wise30sec and the simulated SM has higher correlations with the SM products. In contrast, the VIC model is less sensitive to soil input data and the simulated SM using Wise30sec is higher correlated with the SM products than using SoilGrids. Based on the results, we conclude that the global soil databases can provide reasonable soil property information at coarse resolutions and large areas. The selection of soil input data should depend on the characteristics of both models and study areas.
Abstract
The success of Phasmarhabditis hermaphrodita (Schneider) Andrássy (Rhabditida: Rhabditidae) as a biological control agent of molluscs has led to a worldwide interest in phasmarhabditids. However, scant information is available on the lifecycle development of species within the genus. In the current study, the development of P. hermaphrodita, Phasmarhabditis papillosa, Phasmarhabditis bohemica and Phasmarhabditis kenyaensis were studied using ex vivo cultures, in order to improve our understanding of their biology. Infective juveniles (IJs) of each species were added to 1 g of defrosted homogenized slug cadavers of Deroceras invadens and the development monitored after inoculated IJ recovery, over a period of eight–ten days. The results demonstrated that P. bohemica had the shortest development cycle and that it was able to produce first-generation IJs after eight days, while P. hermaphrodita, P. papillosa and P. kenyaensis took ten days to form a new cohort of IJs. However, from the perspective of mass rearing, P. hermaphrodita has an advantage over the other species in that it is capable of forming self-fertilizing hermaphrodites, whereas both males and females are required for the reproduction of P. papillosa, P. bohemica and P. kenyaensis. The results of the study contribute to the knowledge of the biology of the genus and will help to establish the in vitro liquid cultures of different species of the genus.
Authors
Peter Annighöfer Martina Mund Dominik Seidel Christian Ammer Aitor Ameztegui Philippe Balandier Ieva Bebre Lluis Coll Catherine Collet Tobias Hamm Franka Huth Heike Schneider Christian Kuehne Magnus Löf Any Mary Petritan Ion Catalin Petritan Peter Schall Jürgen BauhusAbstract
Just as the aboveground tree organs represent the interface between trees and the atmosphere, roots act as the interface between trees and the soil. In this function, roots take-up water and nutrients, facilitate interactions with soil microflora, anchor trees, and also contribute to the gross primary production of forests. However, in comparison to aboveground plant organs, the biomass of roots is much more difficult to study. In this study, we analyzed 19 European datasets on above- and belowground biomass of juvenile trees of 14 species to identify generalizable estimators of root biomass based on tree sapling dimensions (e.g. height, diameter, aboveground biomass). Such estimations are essential growth and sequestration modelling. In addition, the intention was to study the effect of sapling dimension and light availability on biomass allocation to roots. All aboveground variables were significant predictors for root biomass. But, among aboveground predictors of root biomass plant height performed poorest. When comparing conifer and broadleaf species, the latter tended to have a higher root biomass at a given dimension. Also, with increasing size, the share of belowground biomass tended to increase for the sapling dimensions considered. In most species, there was a trend of increasing relative belowground biomass with increasing light availability. Finally, the height to diameter ratio (H/D) was negatively correlated to relative belowground biomass. This indicates that trees with a high H/D are not only more unstable owing to the unfavorable bending stress resistance, but also because they are comparatively less well anchored in the ground. Thus, single tree stability may be improved through increasing light availability to increase the share of belowground biomass.
Abstract
Using periodic measurements from permanent plots in non-thinned and thinned Norway spruce (Picea abies (L.) H. Karst.) stands in Norway, individual-tree growth models were developed to predict annual diameter increment, height increment, and height to crown base increment. Based on long-term data across a range of thinning regimes and stand conditions, alternative approaches for modeling response to treatment were assessed. Dynamic thinning response functions in the form of multiplicative modifiers that predict no effect at the time of thinning, a rapid increase followed by an early maximum before the effect gradually declines to zero could not be fitted to initially derived baseline models without thinning related predictors. However, alternative approaches were used and found to perform well. Specifically, indicator variables representing varying time periods after thinning were statistically significant and behaved in a robust manner as well as consistent with general expectations. In addition, they improved overall prediction accuracy when incorporated as fixed effects into the baseline models for diameter and height to crown base increment. Further, more simply, including exponentially decreasing multiplicative thinning response functions improved prediction accuracy for height increment and height to crown base increment. Irrespective of studied attribute and modelling approach, improvement in performance of these extended models was relatively limited when compared to the corresponding baseline models and more pronounced in trees from thinned stands. We conclude that the largely varying and often multi-year measurement intervals of the periodic data used in this study likely prevented the development of more sophisticated thinning response functions. However, based on the evaluation of the final models’ overall performance such complex response functions may not to be necessary to reliably predict individual tree growth after thinning for certain conditions or species, which should be further considered in future analyses of similar nature.
Authors
Britt Puidet Romain Mabon Michele Guibert Riinu Kiiker Liina Soonvald Vinh Hong Le Håvard Eikemo Pauline Dewaegeneire Guillaume Saubeau Catherine Chatot Frederique Aurousseau David E. L. Cooke Alison K. Lees Isaac K. Abuley Jens G. Hansen Roselyne Corbiere Melen Leclerc Didier AndrivonAbstract
Until recently, genotypes of Phytophthora infestans were regionally distributed in Europe, with populations in western Europe being dominated by clonal lineages and those in northern Europe being genetically diverse because of frequent sexual reproduction. However, since 2013 a new clonal lineage (EU_41_A2) has successfully established itself and expanded in the sexually recombining P. infestans populations of northern Europe. The objective of this study was to study phenotypic traits of the new clonal lineage of P. infestans, which may explain its successful establishment and expansion within sexually recombining populations. Fungicide sensitivity, aggressiveness, and virulence profiles of isolates of EU_41_A2 were analyzed and compared with those of the local sexual populations from Denmark, Norway, and Estonia. None of the phenotypic data obtained from the isolates collected from Denmark, Estonia, and Norway independently explained the invasive success of EU_41_A2 within sexual Nordic populations. Therefore, we hypothesize that the expansion of this new genotype could result from a combination of fitness traits and more favorable environmental conditions that have emerged in response to climate change.
Abstract
No abstract has been registered
Authors
Vibeke LindAbstract
No abstract has been registered