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.
2018
Sammendrag
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Forfattere
Eva BrodSammendrag
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Sammendrag
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Forfattere
Daniel RasseSammendrag
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Forfattere
Daniel RasseSammendrag
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Forfattere
Frans-Jan W. Parmentier Daniel Rasse Magnus Lund Jarle W. Bjerke Bert G. Drake Simon Weldon Hans Tømmervik Georg Heinrich HansenSammendrag
Extreme winter events that damage vegetation are considered an important climatic cause of arctic browning—a reversal of the greening trend of the region—and possibly reduce the carbon uptake of northern ecosystems. Confirmation of a reduction in CO2 uptake due to winter damage, however, remains elusive due to a lack of flux measurements from affected ecosystems. In this study, we report eddy covariance fluxes of CO2 from a peatland in northern Norway and show that vegetation CO2 uptake was delayed and reduced in the summer of 2014 following an extreme winter event earlier that year. Strong frost in the absence of a protective snow cover—its combined intensity unprecedented in the local climate record—caused severe dieback of the dwarf shrub species Calluna vulgaris and Empetrum nigrum. Similar vegetation damage was reported at the time along ~1000 km of coastal Norway, showing the widespread impact of this event. Our results indicate that gross primary production (GPP) exhibited a delayed response to temperature following snowmelt. From snowmelt up to the peak of summer, this reduced carbon uptake by 14 (0–24) g C m−2 (~12% of GPP in that period)—similar to the effect of interannual variations in summer weather. Concurrently, remotely-sensed NDVI dropped to the lowest level in more than a decade. However, bulk photosynthesis was eventually stimulated by the warm and sunny summer, raising total GPP. Species other than the vulnerable shrubs were probably resilient to the extreme winter event. The warm summer also increased ecosystem respiration, which limited net carbon uptake. This study shows that damage from a single extreme winter event can have an ecosystem-wide impact on CO2 uptake, and highlights the importance of including winter-induced shrub damage in terrestrial ecosystem models to accurately predict trends in vegetation productivity and carbon sequestration in the Arctic and sub-Arctic.
Sammendrag
Norway is strongly committed to the Paris Climate Agreement with an ambitious goal of 40% reduction in greenhouse gas emission by 2030. The land sector, including agriculture and forestry, must critically contribute to this national target. Beyond emission reduction, the land sector has the unique capacity to actively removing CO2 from the atmosphere through biological carbon storage in biomass and in soils. Soils are the largest reservoir of terrestrial carbon, and relatively small changes in soil carbon content can have an amplified mitigation effect on the Earth’s climate. Therefore, improved management of soils for carbon storage is receiving a lot of attention, for example through international political initiatives such as the “4-permill” initiative. However, in Norway, many mitigation measures targeting soil carbon might negatively impact food production and economic activity. For example, soil carbon storage can be increased by shifting from cereal crop production to grasslands, but Norway already has abundant grassland and a comparatively small area dedicated to cereals. Another such issue is cultivation on drained peatland, where food is produced at the expense of large losses of soil carbon as CO2 to the atmosphere. Therefore, there is a need to look for win-win solutions for soil carbon storage, which benefit both food production and climate mitigation. Large-scale conversion of agricultural and forest waste biomass to biochar is such an option, and is considered the activity with the largest potential for soil carbon sequestration in Norway. Biochar has been demonstrated to have a mean residence time exceeding 100 years in Norwegian field conditions (Rasse et al, 2017), and no negative effects on plant and soils has been observed. However, despite the convincing benefits of biochar as a climate mitigation solution, it has not yet advanced much beyond the research stage, notably because its effect on yield are too modest. Here, we will first present the comparative advantage of biochar technology as compared to traditional agronomy methods for large-scale C storage in Norwegian agricultural soils. We will further discuss the need for developing innovations in pyrolysis and nutrient-rich waste recycling leading to biochar-fertilizer products as win-win solution for carbon storage and food production.
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