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

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Abstract

Although it is well known that insects are sensitive to temperature, how they will be affected by ongoing global warming remains uncertain because these responses are multifaceted and ecologically complex. We reviewed the effects of climate warming on 31 globally important phytophagous (plant‐eating) insect pests to determine whether general trends in their responses to warming were detectable. We included four response categories (range expansion, life history, population dynamics, and trophic interactions) in this assessment. For the majority of these species, we identified at least one response to warming that affects the severity of the threat they pose as pests. Among these insect species, 41% showed responses expected to lead to increased pest damage, whereas only 4% exhibited responses consistent with reduced effects; notably, most of these species (55%) demonstrated mixed responses. This means that the severity of a given insect pest may both increase and decrease with ongoing climate warming. Overall, our analysis indicated that anticipating the effects of climate warming on phytophagous insect pests is far from straightforward. Rather, efforts to mitigate the undesirable effects of warming on insect pests must include a better understanding of how individual species will respond, and the complex ecological mechanisms underlying their responses.

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Abstract

Aim: Distribution modelling is a useful approach to obtain knowledge about the spatial distribution of biodiversity, required for, for example, red-list assessments. While distribution modelling methods have been applied mostly to single species, modelling of communities and ecosystems (EDM; ecosystem-level distribution modelling) produces results that are more directly relevant for management and decision-making. Although the choice of predictors is a pivotal part of the modelling process, few studies have compared the suitability of different sets of predictors for EDM. In this study, we compare the performance of 50 single environmental variables with that of 11 composite landscape gradients (CLGs) for prediction of ecosystem types. The CLGs represent gradients in landscape element composition derived from multivariate analyses, for example “inner-outer coast” and “land use intensity.” Location: Norway. Methods: We used data from field-based ecosystem-type mapping of nine ecosystem types, and environmental variables with a resolution of 100 × 100 m. We built nine models for each ecosystem type with variables from different predictor sets. Logistic regression with forward selection of variables was used for EDM. Models were evaluated with independently collected data. Results: Most ecosystem types could be predicted reliably, although model performance differed among ecosystem types. We identified significant differences in predictive power and model parsimony across models built from different predictor sets. Climatic variables alone performed poorly, indicating that the current climate alone is not sufficient to predict the current distribution of ecosystems. Used alone, the CLGs resulted in parsimonious models with relatively high predictive power. Used together with other variables, they consistently improved the models. Main conclusions: Our study highlights the importance of variable selection in EDM. We argue that the use of composite variables as proxies for complex environmental gradients has the potential to improve predictions from EDMs and thus to inform conservation planning as well as improve the precision and credibility of red lists and global change assessments.conservation planning, distribution modelling, ecosystem classification, ecosystem types, IUCN Red List of Ecosystems, landscape gradients, spatial prediction, species response curves

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Abstract

Land-sea riverine carbon transfer (LSRCT) is one of the key processes in the global carbon cycle. Although natural factors (e.g. climate, soil) influence LSRCT, human water management strategies have also been identified as a critical component. However, few systematic approaches quantifying the contribution of coupled natural and anthropogenic factors on LSRCT have been published. This study presents an integrated framework coupling hydrological modeling, field sampling and stable isotope analysis for the quantitative assessment of the impact of human water management practices (e.g. irrigation, dam construction) on LSRCT under different hydrological conditions. By applying this approach to the case study of the Nandu River, China, we find that carbon (C) concentrations originating from different land-uses (e.g. forest, cropland) are relatively stable and outlet C variations are mainly dominated by controlled runoff volumes rather than by input C concentrations. These results indicate that human water management practices are responsible for a reduction of ∼60% of riverine C at seasonal timescales, with an even greater reduction during drought conditions. Annual C discharges have been significantly reduced (e.g. 77 ± 5% in 2015 and 39 ± 11% in 2016) due to changes in human water extraction coupled with climate variation. In addition, isotope analysis also shows that C fluxes influenced by human activities (e.g. agriculture, aquaculture) could contribute the dominant particulate organic carbon under typical climatic conditions, as well as drought conditions. This research demonstrates the substantial effect that human water management practices have on the seasonal and annual fluxes of LSRCT, especially in such small basins. This work also shows the applicability of this integrated approach, using multiple tools to quantify the contribution of coupled anthropogenic and natural factors on LSRCT, and the general framework is believed to be feasible with limited modifications for larger basins in future research.

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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

Denne rapporten er en litteratursammenstilling over tap av suspendert stoff, fosfor og nitrogen fra arealer med hhv. jordbruk og skog/utmark. I tillegg er det gjort en vurdering av tilsvarende tap i perioden der nydyrking gjennomføres. I de norske studiene som er gjennomgått er gjennomsnittlige tap av nitrogen 17 ganger høyere fra jordbruk enn fra skog. Tilsvarende er fosfortap 56 ganger høyere og tap av suspendert stoff 106 ganger høyere fra jordbruk enn fra skog.

Abstract

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