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.
2020
Abstract
1. Ecological network theory hypothesizes that the structuring of species interactions can convey stability to the system. Investigating how these structures react to species loss is fundamental for understanding network disassembly or their robustness. However, this topic has mainly been studied in‐silico so far. 2. Here, in an experimental manipulation, we sequentially removed four generalist plants from real plant–pollinator networks. We explored the effects on, and drivers of, species and interaction disappearance, network structure and interaction rewiring. First, we compared both the local extinctions of species and interactions and the observed network indices with those expected from three co‐extinction models. Second, we investigated the trends in network indices and rewiring rate after plant removal and the pollinator tendency at establishing novel links in relation to their proportional visitation to the removed plants. Furthermore, we explored the underlying drivers of network assembly with probability matrices based on ecological traits. 3. Our results indicate that the cumulative local extinctions of species and interactions increased faster with generalist plant loss than what was expected by co‐extinction models, which predicted the survival or disappearance of many species incorrectly, and the observed network indices were lowly correlated to those predicted by co‐extinction models. Furthermore, the real networks reacted in complex ways to plant removal. First, network nestedness decreased and modularity increased. Second, although species abundance was a main assembly rule, opportunistic random interactions and structural unpredictability emerged as plants were removed. Both these reactions could indicate network instability and fragility. Other results showed network reorganization, as rewiring rate was high and asymmetries between network levels emerged as plants increased their centrality. Moreover, the generalist pollinators that had frequently visited both the plants targeted of removal and the non‐target plants tended to establish novel links more than who either had only visited the removal plants or avoided to do so. 4. With the experimental manipulation of real networks, our study shows that despite their reorganizational ability, plant–pollinator networks changed towards a more fragile state when generalist plants are lost.
Authors
Kjetil Hindar Lars Robert Hole Kyrre Linné Kausrud Martin Malmstrøm Espen Rimstad Lucy Robertson Odd Terje Sandlund Eva Bonsak Thorstad Knut Vollset Hugo de Boer Katrine Eldegard Johanna Järnegren Lawrence Richard Kirkendall Inger Elisabeth Måren Erlend Birkeland Nilsen Eli Knispel Rueness Anders Nielsen Gaute VelleAbstract
Key words: VKM, risk assessment, Norwegian Scientific Committee for Food and Environment, Norwegian Environment Agency, Norwegian Food Safety Authority Introduction: The Norwegian Environment Agency and the Norwegian Food Safety Authority asked the Norwegian Scientific Committee for Food and Environment to assess the risk to Norwegian biodiversity, to the productivity of native salmonid populations, and to aquaculture, from the spread and establishment of pink salmon in Norwegian rivers, and to assess mitigation measures to prevent the spread and establishment of this alien species. Pink salmon is native to rivers around the northern Pacific Ocean. The species usually has a strict two-year life cycle, with populations spawning in even and odd years being genetically isolated. Fertilized eggs of pink salmon were transferred from Sakhalin Island to Northwest Russia in the late 1950s, and fry were released in rivers draining to the White Sea. The first abundant return to rivers in Northwest Russia, as well as to Norway and other countries in northwestern Europe, was recorded in 1960. Stocking with fish from Sakhalin was terminated in 1979. By then, no self-sustaining populations had been established. From 1985 onwards, stocking in White Sea rivers was resumed with fish from rivers in the more northerly Magadan oblast on the Russian Pacific, resulting in the establishment of reproducing populations. Stocking was continued until 1999, when the last batch of evenyear fertilized eggs was imported, and the fry released in spring 2000. Thus, all pink salmon caught after 2001 in the Northeast Atlantic and the Atlantic side of the Arctic Ocean including the Barents Sea, as well as in rivers draining into these seas, are the result of reproduction in the wild. Pink salmon is now established with abundant and increasing stocks in Northwest Russia and regular occurrence in rivers in eastern Finnmark. Catches of odd-year adult pink salmon in Northwest Russia were usually below 100 tonnes before 2001 and increased to an annual average of 220.5 tonnes during the period 2001-2017. Even-year returns are smaller than odd-year returns both in Northwest Russia and in Norway. The number of pink salmon recorded in Norwegian rivers peaked in 2017, with a high number of fish in eastern Finnmark, and substantial numbers recorded in rivers all along the coast of Norway and in other European countries. In 2019, the area with abundant returns expanded in comparison with 2017, to include rivers in western Finnmark and Troms. The recorded numbers were perhaps lower in southern Norway in 2017 than in 2019 (full statistics not available when this report was finalised), but also in southern Norway there were more pink salmon in 2019 than in any year before 2017. The large numbers of pink salmon in western Finnmark and Troms in 2019 may indicate an expansion of the area in Norway with abundant odd-year pink salmon returns. In some small rivers in eastern Finnmark, between 1000 and 1500 pink salmon were fished out by local people in 2019, demonstrating the magnitude of the potential impact in terms of numbers of pink salmon. We cannot rule out that this will not happen over larger parts of Norway in the coming years. The even-year strain of pink salmon only occurs in low numbers in Russian rivers, as well as Norwegian, rivers. Adult pink salmon enter the rivers from early July, and spawning occurs in AugustSeptember. Spawning habitat requirements are like those of native salmonids: Atlantic salmon, brown trout, and Arctic charr. Spawning of pink salmon occurs earlier than the native salmonids, but observations in 2019 indicate a possible overlap with native salmonids in September in northern Norway. . Pink salmon eggs hatch in late winter or spring, and the alevins remain in the gravel until most of the yolk sac has been resorbed. Emerging fry are approximately 30 mm in length. ...................
Abstract
Global economic value of agriculture production resulting from animal pollination services has been estimated to be $235–$577 billion. This estimate is based on quantification of crops that are available at the global markets, and mainly originates from countries with precise information about quantities of agriculture production, exports, and imports. In contrast, knowledge about the contribution of pollinators to household food and income in small-scale farming at local and regional scales is still lacking, especially for developing countries where the availability of agricultural statistics is limited. Although the global decline in pollinator diversity and abundance has received much attention, relatively little effort has been directed towards understanding the role of pollinators in small-scale farming systems, which feed a substantial part of the world’s population. Here, we have assessed how local farmers in northern Tanzania depend on insect-pollinated crops for household food and income, and to what extent farmers are aware of the importance of insect pollinators and how they can conserve them. Our results show that local farmers in northern Tanzania derived their food and income from a wide range of crop plants, and that 67% of these crops depend on animal pollination to a moderate to essential degree. We also found that watermelon—for which pollination by insects is essential for yield—on average contributed nearly 25% of household income, and that watermelons were grown by 63% of the farmers. Our findings indicate that local farmers can increase their yields from animal pollinated crops by adopting more pollinator-friendly farming practices. Yet, we found that local farmers’ awareness of pollinators, and the ecosystem service they provide, was extremely low, and intentional actions to conserve or manage them were generally lacking. We therefore urge agriculture authorities in Tanzania to act to ensure that local farmers become aware of insect pollinators and their important role in agriculture production.
Abstract
Agricultural practices to improve yields in small‐scale farms in Africa usually focus on improving growing conditions for the crops by applying fertilizers, irrigation, and/or pesticides. This may, however, have limited effect on yield if the availability of effective pollinators is too low. In this study, we established an experiment to test whether soil fertility, soil moisture, and/or pollination was limiting watermelon (Citrullus lanatus) yields in Northern Tanzania. We subjected the experimental field to common farming practices while we treated selected plants with extrafertilizer applications, increased irrigation and/or extra pollination in a three‐way factorial experiment. One week before harvest, we assessed yield from each plant, quantified as the number of mature fruits and their weights. We also assessed fruit shape since this may affect the market price. For the first fruit ripening on each plant, we also assessed sugar content (brix) and flesh color as measures of fruit quality for human consumption. Extra pollination significantly increased the probability of a plant producing a second fruit of a size the farmer could sell at the market, and also the fruit sugar content, whereas additional fertilizer applications or increased irrigation did not improve yields. In addition, we did not find significant effects of increased fertilizer or watering on fruit sugar, weight, or color. We concluded that, insufficient pollination is limiting watermelon yields in our experiment and we suggest that this may be a common situation in sub‐Saharan Africa. It is therefore critically important that small‐scale farmers understand the role of pollinators and understand their importance for agricultural production. Agricultural policies to improve yields in developing countries should therefore also include measures to improve pollination services by giving education and advisory services to farmers on how to develop pollinator‐friendly habitats in agricultural landscapes.
Authors
Eli Knispel Rueness Maria Gulbrandsen Asmyhr Hugo de Boer Katrine Eldegard Kjetil Hindar Lars Robert Hole Johanna Järnegren Kyrre Linné Kausrud Lawrence Richard Kirkendall Inger Elisabeth Måren Erlend Birkeland Nilsen Eva Bonsak Thorstad Gaute Velle Anders NielsenAbstract
Key words: Psittaciformes, CITES, Appendix I parrots, Status and trade assessment, Norwegian Scientific Committee for Food and Environment, Norwegian Environment Agency, VKM Background: Parrots are one of the most species-rich groups of birds of which the majority inhabits tropical and subtropical forests. Nearly one-third of parrots are threatened with extinction (IUCN categories CR, EN or VU) and more than half of the world’s parrot species are assumed to be decreasing in numbers. Parrots are popular pets on all continents, mainly due to their colourful feathers, their capacity to mimic the human voice, and their tolerance to life in captivity. More than 250 species have been traded internationally. Since the inception of CITES in 1975, trade of about 12 million live wild-sourced parrots has been registered. Currently, 55 parrot species are listed on CITES Appendix I (Norwegian CITES regulation list A) that includes the most endangered among CITES-listed animals and plants. In compliance with CITES, Norway only permits import for commercial purposes of Appendix I listed parrots bred in captivity in operations included in the Secretariat's Register (Resolution Conf. 12.10 (Rev. CoP15). Presently, 9 of the Appendix I parrot species are bred in such facilities. Import of Appendix I species to Norway requires permits both from the exporter’s CITES authority and the Norwegian Environment Agency (Norwegian CITES Management Authority). All legal transactions of CITES Appendix I listed species should be recorded in the UNEP World Conservation Monitoring Centre (UNEP-WCMC) Trade Database. However, discrepancies are common, demonstrating that the trade monitoring is not accurate. Moreover, several studies suggest that regardless of efforts to regulate trade, the global conservation situation for parrots may be worse than estimated by the IUCN species statuses. Even though habitat loss is the main threat to most parrot species, it has been suggested that priority should be given to conservation actions aimed at reducing the illegal capture of wild parrots for the pet trade. As Norway’s CITES Scientific Authority, the Norwegian Scientific Committee for Food and Environment (VKM) was assigned by the Norwegian Environment Agency to assess the status of populations and trade for Appendix I parrot species. Methods: As different trade patterns are typical for different geographic regions, the species were initially divided into three groups: Africa, Australasia and Central and South America. For species with commercial trade registered in the UNEP-WCMC trade database after year 2010 a full assessment was made. In addition, two species for which negative impact from illegal trade is suspected were also fully assessed. The assessments are based on the Norwegian Cites Regulation and Article III of the Convention and Resolution 16.7(Rev.CoP17). Information on the parrot species assessed in this report were gathered from the text accounts published by BirdLife International and Birds of the World as well as literature cited in the text. Results: VKM undertook full assessments of the population status and trade for 26 of the 55 CITES Appendix I species. The species assessments are presented as fact sheets. They each contain a brief summary of the species’ biology (name, taxonomy, distribution, life history, habitat and role in ecosystem), populations and trends, threats and conservation status, population surveillance and regulations, evaluation of legal/illegal trapping and trade, overall assessment of data quality and references. We found that the quantity, as well as quality, of the information available for the Appendix I parrot species varied much. This was the case for data on general biology, population size and trends and levels of illegal trade. For all of the 23 of species for which commercial trade was registered since 2010 in the UNEP-WCMC trade database discrepancies ........
Abstract
Within the last decade, implementing eight key principles of Integrated Pest Management (IPM) has become mandatory for all professional users of pesticides in the European Union (EU) and European Economic Area (EEA). Meanwhile, evidence of the level of implementation is lacking. In this study, the adoption of IPM principles among Norwegian grain farmers was measured using a novel IPM index based on self-reported levels of performing IPM practices. Three IPM experts weighted the principles and practices included in the index. They found prevention and suppression to be the most important principle, followed by monitoring and decisionmaking, while pesticide selection and evaluation were deemed least important. A survey of 1250 farmers showed that the principles with the highest adoption rates were evaluation and anti-resistance strategies, while non-chemical methods and reduced pesticide use had the lowest adoption rates. The results support previous suggestions that more complex principles, requiring a larger set of practices, are less readily adopted than those that are less complex. Nevertheless, the index scores showed that most Norwegian grain farmers are extensively practicing IPM; 75% of the respondents obtained scores between 60 and 80 on a 100-point scale, with an average score of 68. In the Norwegian context, it is more relevant to discuss the varying use of IPM rather than how to increase adoption in general.
Abstract
This paper analyses two strategies to reduce the use of pesticides in grain production. We study Norwegian farmers’ willingness to voluntarily forego income by reducing pesticide use as well as their responses to a doubling of the pesticide price (through increased pesticide taxes). We use mixed methods including an experiment, a survey and focus group discussions. The experiment shows that most farmers are willing to sacrifice some income to reduce environmental risks by using less pesticide. According to the survey, they are, at the same time, relatively insensitive to a 100% price increase on herbicides and fungicides. While the response to the price increase probably would have been stronger if differentiated between chemicals, our research indicates potential benefits from supporting voluntary action. Value orientations and agronomic conditions influence the stated responses in both circumstances. Respondents emphasizing environmental values are more willing to voluntarily reduce pesticide use and show a greater response to the economic incentive than farmers emphasizing economic outcome and issues such as clean fields. A hypothesized willingness to reduce pesticide use voluntarily to strengthen the reputation of the sector was, however, rejected. Farmers appear to have few alternatives to pesticides, but increased knowledge about the alternatives that do exist, seems able to promote some change. Our findings suggest that the extension service should put greater emphasis on these options, even if they may have negative effects on income.
Authors
Valborg KvakkestadAbstract
No abstract has been registered
Authors
Habtamu AlemAbstract
The study aimed to extend the static concepts of multiproduct technical efficiency and determinants into a dynamic setting within the input distance function framework. The existing literature in performance analysis of the dairy farms in Norway based on static modelling and thus ignores the inter-temporal nature of production decisions. The empirical application focused on the farm-level analysis of the Norwegian dairy sector for 2000- 2018. The dynamic efficiency allows analysing the performance of dairy farms in regards of inter-temporal optimization of the investment behaviour. The analysis shows that the static model efficiency study in the previous studies underestimate the performance of the dairy farms. The marginal effects experience positively correlated with dairy farm technical efficiency whereas copped subsidy and asset debt ratio negatively correlated to the performance of the dairy farm.
Authors
Habtamu AlemAbstract
The objective of this paper is to examine the economic performance of crop-producing farms accounting for unobserved heterogeneity,environmental variables, and regions. The empirical analysis was based on a translog cost function and unbalanced farm-level panel data for 1991–2013 from the 455 crop-producing farms with 3,885 observations (1,004observations from the central region and 2,881 observations from the eastern region). We found that the mean minimum costs were about 93% and 92% of the actual costs for crop farms in the central and eastern regions, respectively.The marginal effects of crop rotation, land tenure, off-farm activity, direct government support, and experience were positively associated with crop farm economic performance. The marginal contribution of these variables on economic performance increased in the years 2000–2013 compared with the years 1991–1999 in both regions.