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The European spruce bark beetle (Ips typographus L.) is a major disturbance agent in Norway spruce (Picea abies (L.) Karst) forests in Europe and it is estimated that a changing climate will result in more severe outbreaks in the future. To reduce the risk of large outbreaks it is important to have methods that enable early detection of bark beetle attacks to help forest managers to prevent population build-up, e.g by sanitary cutting. Several studies have been devoted to early detection of bark beetle attacks with Sentinel-2 data with a focus on spectral properties and vegetation indices for early detection with pixel-based methods. In this study we explore the potential to use changes in variability between pixels in windows of different sizes (3×3, 4×4 and 5×5 pixels). We compute the coefficient of variation for four vegetation indices (NDVI, NDWI, CCI and NDRS) in a time-series of Sentinel-2 data during a bark beetle outbreak in Sweden that was triggered by a drought in 2018. The results indicate that CCI is the most promising index for early detection and that the variability between pixels increase in windows with attacked trees from late July when the main swarming was the second week of May.

Growing interest is awarded to the digitalization of the building permitting use case and many works are developed about the topic. However, the subject is very complex and many aspects are usually tackled separately, making it very hard for traditional literature reviews to grasp the actual progress in the overall topic. This paper unveils the detailed state of the art in Digital Building Permitting (DBP) by critically analysing the literature by means of a set of coding tags (research progress, implementation, affected DBP workflow steps, ambitions addressed) assigned by a multidisciplinary team. The executed research shows that the mainly addressed aspects of the digitalization of building permit process are the technologies to check the compliance of design proposals against regulations, followed by the digitalization of regulations. Improvable aspects identified in the entire building permit system are instead e.g. the involvement of officers, scalability of solutions and interoperability of data, intended both as data validation and as integration of geospatial data with building models.

The Artic is exposed to faster temperature changes than most other areas on Earth. Constantly increasing temperature will lead to thawing permafrost and changes in the CH4 emissions from wetlands. One of the places exposed to those changes is the Abisko-Stordalen Mire in northern Sweden, where climate and vegetation studies have been conducted from the 1970s.In our study, we analyzed field-scale methane emissions measured by the eddy covariance method at Abisko-Stordalen Mire for three years (2014–2016). The site is a subarctic mire mosaic of palsas, thawing palsas, fully thawed fens, and open water bodies. A bimodal wind pattern prevalent at the site provides an ideal opportunity to measure mire patches with different permafrost statuses with one flux measurement system. The flux footprint for westerly winds is dominated by elevated palsa plateaus, while the footprint is almost equally distributed between palsas and thawing bog-like areas for easterly winds. As these patches are exposed to the same climatic conditions, we analyzed the differences in the responses of their methane emission for environmental parameters.The methane fluxes followed a similar annual cycle over the three study years, with a gentle rise during spring and a decrease during autumn and with no emission burst at either end of the ice-free season. The peak emission during the ice-free season differed significantly for the mire with two permafrost statuses: the palsa mire emitted 24 mg-CH4 m−2 d−1 and the thawing wet sector 56 mg-CH4 m−2 d−1. Factors controlling the methane emission were analyzed using generalized linear models. The main driver for methane fluxes was peat temperature for both wind sectors. Soil water content above the water table emerged as an explanatory variable for the three years for western sectors and the year 2016 in the eastern sector. Water table level showed a significant correlation with methane emission for the year 2016 as well. Gross primary production, however, did not show a significant correlation with methane emissions. Annual methane emissions were estimated based on four different gap-filing methods. The different methods generally resulted in very similar annual emissions. The mean annual emission based on all models was 4.2 ± 0.4 g-CH4 m−2 a−1 for western sector and 7.3 ± 0.7 g-CH4 m−2 a−1 for the eastern sector. The average annual emissions, derived from this data and a footprint climatology, were 3.6 ± 0.7 g-CH4 m−2 a−1 and 11 ± 2 g-CH4 m−2 a−1 for the palsa and thawing surfaces, respectively. Winter fluxes were relatively high, contributing 27–45 % to the annual emissions.

The Arctic is exposed to even faster temperature changes than most other areas on Earth. Constantly increasing temperature will lead to thawing permafrost and changes in the methane (CH4) emissions from wetlands. One of the places exposed to those changes is the Abisko–Stordalen Mire in northern Sweden, where climate and vegetation studies have been conducted since the 1970s. In our study, we analyzed field-scale methane emissions measured by the eddy covariance method at Abisko–Stordalen Mire for 3 years (2014–2016). The site is a subarctic mire mosaic of palsas, thawing palsas, fully thawed fens, and open water bodies. A bimodal wind pattern prevalent at the site provides an ideal opportunity to measure mire patches with different permafrost status with one flux measurement system. The flux footprint for westerly winds was dominated by elevated palsa plateaus, while the footprint was almost equally distributed between palsas and thawing bog-like areas for easterly winds. As these patches are exposed to the same climatic and weather conditions, we analyzed the differences in the responses of their methane emission for environmental parameters. The methane fluxes followed a similar annual cycle over the 3 study years, with a gentle rise during spring and a decrease during autumn, without emission bursts at either end of the ice-free season. The peak emission during the ice-free season differed significantly for the two mire areas with different permafrost status: the palsa mire emitted 19 mg-C m−2 d−1 and the thawing wet sector 40 mg-C m−2 d−1. Factors controlling the methane emission were analyzed using generalized linear models. The main driver for methane fluxes was peat temperature for both wind sectors. Soil water content above the water table emerged as an explanatory variable for the 3 years for western sectors and the year 2016 in the eastern sector. The water table level showed a significant correlation with methane emission for the year 2016 as well. Gross primary production, however, did not show a significant correlation with methane emissions. Annual methane emissions were estimated based on four different gap-filing methods. The different methods generally resulted in very similar annual emissions. The mean annual emission based on all models was 3.1 ± 0.3 g-C m−2 a−1 for the western sector and 5.5 ± 0.5 g-C m−2 a−1 for the eastern sector. The average annual emissions, derived from these data and a footprint climatology, were 2.7 ± 0.5 and 8.2 ± 1.5 g-C m−2 a−1 for the palsa and thawing surfaces, respectively. Winter fluxes were relatively high, contributing 27 %–45 % to the annual emissions.

Forests are of major importance to climate change mitigation due to their strong capacity to sequester carbon. Nearly half of the terrestrial carbon is stored in forests, and forests contribute to half of the terrestrial primary productivity, with forests in the mid- and high latitude ecosystems as major contributors. These high latitude forests are, however, projected to be strongly influenced by climate change. A warmer climate is likely to have a positive effect on forest productivity and increase the ability to absorb CO2 from the atmosphere. At the same time it is projected that a warmer climate will increase the impact of forest disturbances, such as insect outbreaks. Insect outbreaks are, however, generally excluded in large scale carbon modeling. In addition, there are large uncertainties in the quantitative effects of insect outbreaks on the carbon balance. Hence, it is important to develop methods to monitor insect disturbances and to quantify the impact of these disturbances on the carbon balance. The general aim of this thesis was to develop methods for mapping of insect outbreaks with satellite data, and to quantify the impact of these outbreaks on primary productivity. The results demonstrated that time-series of satellite data could be applied to find what year an outbreak by the invasive Hungarian spruce scale in southern Sweden started, and showed the potential of developing an early warning system. An early warning system would most likely have detected the outbreak the year before it was detected in field; for invasive species early detection is important to enable rapid counter-measures to decrease the risk that new species establish populations. The results also showed that coarse spatial resolution satellite data (MODIS 250x250 m pixels size) can be used for near real-time monitoring of insect induced defoliation with the aid of Kalman filtering and cumulative sums (CUSUM). Of the defoliated MODIS pixels in mountain birch forests in northern Sweden 74–100% were detected with a misclassification of undisturbed pixels of 39–56%, depending on threshold settings. In addition, the developed method facilitates studies of the intra-seasonal dynamics of an insect outbreak as well as mapping of potential refoliation; these are major advantages compared to methods that classify a pixel into defoliated or undisturbed for an entire season. The coarse spatial resolution of MODIS is, however, a limitation in fragmented forests. A method based on z-scores of seasonal maximum values of a vegetation index showed that detection accuracies were low in fragmented and heavily managed pine forests in eastern Finland compared to the more homogenous mountain birch forests in northern Sweden. The thesis also demonstrated that satellite data and meteorological data can be used to map the impact of insect outbreaks on gross primary productivity (GPP) with the aid of a light use efficiency (LUE) model. The LUE model was calibrated with eddy covariance measurements, and the near real-time monitoring method was applied to monitor defoliation. An extensive set-back to the carbon uptake in deciduous semi-arctic forests due to insect defoliation was recorded. These results demonstrated the potential to develop methods to both monitor insect disturbances and to quantify the impact of these disturbances on primary productivity. Such methods would be important to decrease the uncertainties in estimates of insect outbreaks impact on the carbon balance. Skogar är av stor betydelse ur klimatsynpunkt på grund av deras stora förmåga att binda kol. Skogar på de nordligare breddgraderna spelar en viktig roll med sitt stora kolupptag, men eftersom dessa nordliga skogar troligen kommer att påverkas av klimatförändringarna i hög grad är det osäkert hur framtida kolupptag kommer att utvecklas. Ett varmare klimat kommer sannolikt att öka tillväxten och därmed öka skogarnas upptag av koldioxid från atmosfären. Samtidigt beräknas det att ett varmare klimat kommer att öka mängden skogsskador, såsom insektsangrepp, vilket kan resultera i stora förluster av koldioxid till atmosfären. Insektangrepp är i allmänhet inte inkluderade i kolbudgetar vilket kan resultera i överskattningar av mängden kol som binds i skogar. Därför är det viktigt att utveckla metoder för att kartera insektsangrepp samt att beräkna hur dessa angrepp påverkar kolbalansen. Det övergripande syftet med avhandlingen var att utveckla metoder för kartläggning av insektsangrepp med satellitdata samt att beräkna effekterna av dessa angrepp på skogens kolupptag. Studien visade att tidsserieanalyser av satellitdata kunde användas för att bestämma vilket år ett utbrott av den invasiva ungerska gransköldlusen i sydvästra Skåne startade. Resultaten visade också på möjligheten att utveckla system för övervakning av skogsskador med hjälp av satellitdata. Om ett sådant övervakningssystem hade varit aktivt hade sannolikt angreppen av gransköldlusen upptäckts redan samma år som de startade, vilket var ett år tidigare än det upptäcktes i fält. För invasiva insektsarter är en tidig upptäckt viktig för att minska risken för vidare spridning. Studien visade också att satellitdata med låg rumslig upplösning (pixelstorlek 250x250 m) kan användas för nära realtidsövervakning av insektsskador. 74 100% av pixlarna med björkmätarangrepp i fjällbjörkskog i norra Sverige detekterades med en felklassning av ostörd björkskog på 39 56%, beroende på tröskelvärden i detekteringsmetoden. Metoden kan även användas för att studera hur ett insektsangrepp utvecklas över tid och kartera björkskog som återhämtar sig senare under samma växtsäsong som insektsangreppen. Detta är stora fördelar jämfört med metoder som klassificerar pixlar som angripna eller ostörda för en hel växtsäsong. Den låga rumsliga upplösningen är emellertid en begränsning i fragmenterade skogar som är uppsplittrade i många mindre skogsbestånd av varierande storlek och ålder. En metod för kartering av insektsangrepp baserad på säsongsmax av ett vegetationsindex visade att detektionsgraden för tallstekelskador i fragmenterade tallskogar med intensivt skogsbruk i östra Finland var låg i jämförelse med de mer homogena fjällbjörkskogarna i norra Sverige. Studien visade också att satellitdata i kombination med meteorologiska data kan användas för att kartera effekterna av insektsangrepp på skogens kolupptag med hjälp av en s.k. light use efficience (LUE) modell. LUE modellen kalibrerades med fluxmätningar av skogens kolupptag och metoden för nära realtidsövervakning användas för att kartera angreppen. Dessa resultat visade på stora effekter på kolupptaget orsakade av insektsangrepp samt att det är möjligt att utveckla metoder för att övervaka och kartera insektsangrepp samt att kvantifiera effekterna av dessa angrepp på kolupptaget med satellitdata. Sådana metoder är viktiga för att minska osäkerheten i hur insektsangrepp påverkar skogarnas kolupptag.