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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.

2025

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Abstract

A key property of the boreal forest is that it stores huge amounts of carbon (C), especially belowground in the soil. Amounts of C stored in the uppermost organic layer of boreal forest soils vary greatly in space due to an interplay between several variables facilitating or preventing C accumulation. In this study, we split C stocks into the organic layer and charcoal C due to their difference in origin, stability, and ecological properties. We compared organic layer C and charcoal C stocks in two regions of south-central Norway (Trillemarka and Varaldskogen), characterized by Scots pine and Norway spruce forests with varying fire histories. We used structural equation modeling to investigate how vegetation composition, hydrotopography, and soil properties interplay to shape organic layer C and charcoal C stocks. Pine forests consistently contained larger organic layer C stocks than spruce forests. Charcoal stocks, in contrast, were less consistent across both forest types and study regions as pine forests had higher charcoal C stocks than spruce forests in Trillemarka, while the two forest types contained equal charcoal C stocks in Varaldskogen. Charcoal and soil organic layer C stocks increased with higher fire frequencies (number of fire events over the last 600 years), but not with a shorter time since last fire (TSF). Additionally, vegetation composition, terrain slope, and soil moisture were the most important drivers of the organic layer C stocks, while charcoal C stocks were mainly controlled by the depth of the organic layer. Also, microtopography was of importance for organic layer C and charcoal C, since depressions in the forest floor had more charcoal C than well-drained minor hills.

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Abstract

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Abstract

The normalized difference vegetation index (NDVI) is a critical tool for studying Arctic vegetation patterns and changes, but more knowledge is needed about its links with plant biomass and disturbances, especially in sparsely vegetated habitats in the High Arctic. Here, we investigate the relationship between NDVI and vascular plant biomass, summer temperature, goose disturbance, and winter damage in Dryas ridge and moss tundra habitats on Svalbard, all recorded in the corresponding year across a 5-year time series. We test these relationships using mixed-effect models at two spatial resolutions (10 cm and 10 m) and two extents with data from drone and Sentinel-2 imagery. We found that in our plots, an increase in biomass of 100 g m−2 increased NDVI from drone imagery by 0.08 ± 0.03 (95% CI) for Dryas ridge and by 0.04 ± 0.03 for moss tundra. Despite record-warm summers, temperature of the same summer was not associated with NDVI in our time-series. In moss tundra, severe goose disturbance had a negative relationship with drone NDVI in plots, while in Dryas ridge habitat, winter damage had no clear correspondence with NDVI. Our study provides an example of context dependencies highlighted in remote-sensing literature in the Arctic, encouraging future studies to include effects of disturbance on NDVI and to establish habitat-specific relationships with NDVI.