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.
2021
Sammendrag
Macrocystis pyrifera is a major habitat forming kelp in coastal ecosystems of temperate regions of the northern and southern hemispheres. We investigated the seasonal occurrence of adult sporophytes, morphological characteristics, and reproductive phenology at two sites within a wave-protected harbour and two wave-exposed sites in southern New Zealand every 3–4 months between 2012 and 2013. Seasonality in reproduction was assessed via the number of sporophylls, the occurrence of sori on sporophylls, and non-sporophyllous laminae (fertile pneumatocyst-bearing blades and fertile apical scimitars), meiospore release, and germination. We found that M. pyrifera was present and reproductive year-round in three of the four sites, and patterns were similar for the wave-exposure conditions. Sori were found on pneumatocyst-bearing blades and apical scimitars in addition to the sporophylls, and viable meiospores were released from all three types of laminae. Morphological variations between sites with different wave exposure indicate that sporophytes from wave-protected sites have bigger blades and holdfasts and are longer than those from wave-exposed sites. We discuss the implications of these biological variables for the ecology of M. pyrifera inhabiting different wave exposure environments in southern New Zealand.
Forfattere
Kemeng Xiao Karin Juul Hesselsøe Christer Magnusson Tatsiana Espevig Trond Olav Pettersen Trygve S. AamlidSammendrag
In 2018–2019, establishment problems were encountered, after reseeding creeping bentgrass (Agrostis stolonifera) on a sand-based putting green after ice encasement at the NIBIO Turfgrass Research Center, Norway. Seeds germinated, but the seedlings attained a purple color and died in large patches. Replacement of the top 3 cm layer with new sand amended with Sphagnum peat or garden compost did not solve the problem. To explain this phenomenon, we (1) analyzed the original substrate for nematodes in patches with and without reestablishment failure; and (2) conducted a factorial pot trial with creeping bentgrass and Chewings fescue (Festuca rubra ssp. commutata) seeded on different substrates, some of them in layers, and with and without phosphorus (P) fertilization. The nematode counts showed six times more stubby-root nematodes and two times more spiral nematodes and needle nematodes in the patches with dead seedlings than in the patches with healthy seedings. In the pot trial, the fastest and slowest reestablishment was observed with new sand amended with garden compost and in the two treatments that included the original substrate, respectively. Replacement of the top 3 cm of the old substrate with new garden compost resulted in stagnation of bentgrass seedlings from four weeks after seeding, while fescue seedlings were unaffected. We conclude that the failure to reestablish creeping bentgrass was primarily due to nematodes, which are likely to be more critical for seedlings than for established turf. The green was later reestablished successfully with a 100 % red fescue seed blend.
Forfattere
Peter Horvath Hui Tang Rune Halvorsen Frode Stordal Lena M. Tallaksen Terje Koren Berntsen Anders BrynSammendrag
Vegetation is an important component in global ecosystems, affecting the physical, hydrological and biogeochemical properties of the land surface. Accordingly, the way vegetation is parameterized strongly influences predictions of future climate by Earth system models. To capture future spatial and temporal changes in vegetation cover and its feedbacks to the climate system, dynamic global vegetation models (DGVMs) are included as important components of land surface models. Variation in the predicted vegetation cover from DGVMs therefore has large impacts on modelled radiative and non-radiative properties, especially over high-latitude regions. DGVMs are mostly evaluated by remotely sensed products and less often by other vegetation products or by in situ field observations. In this study, we evaluate the performance of three methods for spatial representation of present-day vegetation cover with respect to prediction of plant functional type (PFT) profiles – one based upon distribution models (DMs), one that uses a remote sensing (RS) dataset and a DGVM (CLM4.5BGCDV; Community Land Model 4.5 Bio-Geo-Chemical cycles and Dynamical Vegetation). While DGVMs predict PFT profiles based on physiological and ecological processes, a DM relies on statistical correlations between a set of predictors and the modelled target, and the RS dataset is based on classification of spectral reflectance patterns of satellite images. PFT profiles obtained from an independently collected field-based vegetation dataset from Norway were used for the evaluation. We found that RS-based PFT profiles matched the reference dataset best, closely followed by DM, whereas predictions from DGVMs often deviated strongly from the reference. DGVM predictions overestimated the area covered by boreal needleleaf evergreen trees and bare ground at the expense of boreal broadleaf deciduous trees and shrubs. Based on environmental predictors identified by DM as important, three new environmental variables (e.g. minimum temperature in May, snow water equivalent in October and precipitation seasonality) were selected as the threshold for the establishment of these high-latitude PFTs. We performed a series of sensitivity experiments to investigate if these thresholds improve the performance of the DGVM method. Based on our results, we suggest implementation of one of these novel PFT-specific thresholds (i.e. precipitation seasonality) in the DGVM method. The results highlight the potential of using PFT-specific thresholds obtained by DM in development of DGVMs in broader regions. Also, we emphasize the potential of establishing DMs as a reliable method for providing PFT distributions for evaluation of DGVMs alongside RS.
Sammendrag
Distribution modeling methods are used to provide occurrence probability surfaces for modeled targets. While most often used for modeling species, distribution modeling methods can also be applied to vegetation types. However, surfaces provided by distribution modeling need to be transformed into classified wall-to-wall maps of vegetation types to be useful for practical purposes, such as nature management and environmental planning. The paper compares the performance of three methods for assembling predictions for multiple vegetation types, modeled individually, into a wall-to-wall map. The authors used grid-cell based probability surfaces from distribution models of 31 vegetation types to test the three assembly methods. The first, a probability-based method, selected for each grid cell the vegetation type with the highest predicted probability of occurrence in that cell. The second, a performance-based method, assigned the vegetation types, ordered from high to low model performance, to a fraction of the grid cells given by the vegetation type’s prevalence in the study area. The third, a prevalence-based method, differed from the performance-based method by assigning vegetation types in the order from low to high prevalence. Thus the assembly methods worked in two principally different ways: the probability-based method assigned vegetation types to grid cells in a cell-by-cell manner, and both the performance-based method and prevalence-based method assigned them in a type-by-type manner. All methods were evaluated by use of reference data collected in the field, more or less independently of the data used to parameterize the vegetation-type models. Quantity, allocation, and total disagreement, as well as proportional dissimilarity metrics, were used for evaluation of assembly methods. Overlay analysis showed 38.1% agreement between all three assembly methods. The probability-based method had the lowest total disagreement with, and proportional dissimilarity from, the reference datasets, but the differences between the three methods were small. The three assembly methods differed strongly with respect to the distribution of the total disagreement on its quantity and allocation components: the cell-by-cell assignment method strongly favored allocation disagreement and the type-by-type methods strongly favored quantity disagreement. The probability-based method best reproduced the general pattern of variation across the study area, but at the cost of many rare vegetation types, which were left out of the assembled map. By contrast, the prevalence-based and performance-based methods represented vegetation types in accordance with nationwide area statistics. The results show that maps of vegetation types with wall-to-wall coverage can be assembled from individual distribution models with a quality acceptable for indicative purposes, but all the three tested methods currently also have shortcomings. The results also indicate specific points in the methodology for map assembly that may be improved. area frame survey, assembly strategies, distribution modeling, spatial probabilities, vegetation mapping, vegetation types
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Abdelhameed Elameen Svein Stueland Ralf Kristensen Rosa Ferreira Fristad Trude Vrålstad Ida SkaarSammendrag
Det er ikke registrert sammendrag
Forfattere
Sigitas Girdziušas Magnus Löf Kjersti Holt Hanssen Dagnija Lazdiņa Palle Madsen Timo Saksa Kaspars Liepiņš Inger Sundheim Fløistad Marek MetslaidSammendrag
Since the beginning of the twentieth century, forest regeneration management and policy in the Nordic–Baltic region (Denmark, Sweden, Norway, Finland, Estonia, Latvia and Lithuania) have gone through significant changes. For decades forest as a key natural resource was managed with main focus on timber production. However, several factors influenced shifting forest management, including forest regeneration to meet a wide range of society needs. This review study aims to reveal the historical development of forest regeneration identifying knowledge gaps and supporting decisions that promote sustainable regeneration of future forests. The development of forest regeneration management and policy in the Nordic–Baltic countries is analyzed through reforestation and afforestation practices as well as legislation aspects using a narrative review approach. Trends in forest regeneration practices within the region are identified and explored over a timeframe spanning from 1900 until today. Despite diverse forestry management structures and differing political, social situations, the study shows that forest regeneration development has followed similar patterns over time in all Nordic–Baltic region countries: extensive forestry, clear-cut forestry, retention forestry and currently evolving climate-adaptive forestry. Nevertheless, regional differences among the Nordic–Baltic countries, especially in forest regeneration-related legislation, were identified due to a mixture of international and local driving forces.
Forfattere
Yuying Jing Martin Krauss Simon Zschieschang Anja Miltner Andrii Butkovskyi Trine Eggen Matthias Kästner Karolina M. NowakSammendrag
Surface water runoff can export pesticides from agricultural fields into adjacent aquatic ecosystems, where they may pose adverse effects to organisms. Constructed wetlands (CWs) are widely used to treat agricultural runoff contaminated by pesticides, but the removal of hydrophilic pesticides is usually low. In this study, we suggest superabsorbent polymer (SAP), a cross-linked hydrophilic polymer, as a supplement to substrates of CWs and tested the hypothesis that SAP results in an enhanced removal of hydrophilic pesticides. Therefore, batch experiments were conducted to study the retention capacity of water-saturated SAP (w-SAP) for several hydrophilic pesticides. Retention of the pesticides on w-SAP was related to the ionization state and water solubility of the pesticides. The retention of neutral pesticides, imidacloprid, metalaxyl and propiconazole, was about 20% higher than that measured for anionic pesticides, bentazone, glyphosate and MCPA. The retention of the pesticides by w-SAP mainly resulted from their distribution in the gel-water phase of w-SAP, while less water soluble pesticides might have also been adsorbed on the molecular backbone of SAP. Furthermore, we tested the efficacy of w-SAP for treatment of runoff water contaminated by pesticides in lab-scale horizontal subsurface flow CWs. SAP in CWs improved the removal of the pesticides, including the recalcitrant ones. The removal enhancement was owing to the increase of hydraulic retention time and improvement of biodegradation. The removal of the pesticides in SAP containing CWs was > 93% for MCPA, glyphosate, and propiconazole, 62 – 99% for imidacloprid, 50 – 84% for metalaxyl, and 38 – 73% for bentazone. In the control gravel CWs, the removal was > 98% for glyphosate, generally > 83% for MCPA and propiconazole, 46 – 98% for imidacloprid, 32 – 97% for metalaxyl, and 9 – 96% for bentazone.
Forfattere
Juliana D. Klein Tamaryn A. Asbury Charlene da Silva Kelvin L. Hull Matthew L. Dicken Enrico Gennari Simo Maduna Aletta E Bester-van der MerweSammendrag
The common smooth-hound shark, Mustelus mustelus, is a widely distributed demersal shark under heavy exploitation from various fisheries throughout its distribution range. To assist in the development of appropriate management strategies, the authors evaluate stock structure, site fidelity and movement patterns along the species’ distribution in southern Africa based on a combination of molecular and long-term tag-recapture data. Eight species-specific microsatellite markers (N = 73) and two mitochondrial genes, nicotinamide adenine dehydrogenase subunit 4 and control region (N = 45), did not reveal any significant genetic structure among neighbouring sites. Nonetheless, tagging data demonstrate a remarkable degree of site fidelity with 76% of sharks recaptured within 50 km of the original tagging location. On a larger geographic scale, dispersal is governed by oceanographic features as demonstrated by the lack of movements across the Benguela-Agulhas transition zone separating the South-East Atlantic Ocean (SEAO) and South-West Indian Ocean (SWIO) populations. Microsatellite data supported very shallow ocean-based structure (SEAO and SWIO) and historical southward gene flow following the Agulhas Current, corroborating the influence of this dynamic oceanographic system on gene flow. Moreover, no movements between Namibia and South Africa were observed, indicating that the Lüderitz upwelling formation off the Namibian coast acts as another barrier to dispersal and gene flow. Overall, these results show that dispersal and stock structure of M. mustelus are governed by a combination of behavioural traits and oceanographic features such as steep temperature gradients, currents and upwelling systems.