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.
2021
Sammendrag
Increasing atmospheric nitrogen deposition and climate change are considered the main factors accelerating the long-term growth of forests. Quantification of changes in growth rate can be extremely useful in monitoring and assessing the impact of climate change on site productivity. In this study, we carried out a country-wide analysis of long-term (100 years) dynamics and changes in the height growth rate and site index (SI) of Scots pine in Poland. To ensure representativeness we used a large sample of stem analysis trees collected on 312 plots selected using stratified sampling. To control the effect of site fertility and thus avoid the over-representation of older stands on infertile sites, we measured a range of soil properties that, together with environmental indicators characterising climatic conditions and topography, were used in growth trend modelling as explanatory variables. We found that trees planted in successive years have grown faster. The SI calculated for individual trees is linearly dependent on the year of germination and with increasing age of germination, the SI at the base age of 100 years has increased by 8.4 cm per year. Despite the differences in the growth dynamics of pines planted in different germination years, tree growth follows the same growth pattern. The observed continuous changes in site productivity correspond to an increase in the SI by over 29% between 1900 and 2000. A consequence of continuous changes in site conditions and height growth rate is ambiguity in derived SI values. Under changing site conditions, SI values calculated based on stand height and age depend not only on site productivity but also the year of germination. As a consequence, stands growing under identical site conditions show different SIs, which should be acknowledged if the SI is to be used in forest management. Therefore, determining the SI of newly established stands based on the SI of older generations requires the application of an amendment to account for stand age. Continuously improving our understanding of potential climate change impacts on forest ecosystems is essential and provide information to support forest managers seeking to develop effective adaptation measures and determine sustainable forestry production. As such, our results provide valuable support when making long-term decisions and developing effective adaptation strategies in forest management.
Forfattere
Sigitas Girdziušas Magnus Löf Kjersti Holt Hanssen Dagnija Lazdiņa Palle Madsen Timo Saksa Kaspars Liepiņš Inger Sundheim Fløistad Marek MetslaidSammendrag
Since the beginning of the twentieth century, forest regeneration management and policy in the Nordic–Baltic region (Denmark, Sweden, Norway, Finland, Estonia, Latvia and Lithuania) have gone through significant changes. For decades forest as a key natural resource was managed with main focus on timber production. However, several factors influenced shifting forest management, including forest regeneration to meet a wide range of society needs. This review study aims to reveal the historical development of forest regeneration identifying knowledge gaps and supporting decisions that promote sustainable regeneration of future forests. The development of forest regeneration management and policy in the Nordic–Baltic countries is analyzed through reforestation and afforestation practices as well as legislation aspects using a narrative review approach. Trends in forest regeneration practices within the region are identified and explored over a timeframe spanning from 1900 until today. Despite diverse forestry management structures and differing political, social situations, the study shows that forest regeneration development has followed similar patterns over time in all Nordic–Baltic region countries: extensive forestry, clear-cut forestry, retention forestry and currently evolving climate-adaptive forestry. Nevertheless, regional differences among the Nordic–Baltic countries, especially in forest regeneration-related legislation, were identified due to a mixture of international and local driving forces.
Sammendrag
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Sammendrag
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Forfattere
Jon Andreas Ask Jon Lasse Bratli Kjersti Holt Hanssen Baro Moslet Sina Jenhaug Ringlund Jakob Sandven Odd-Kristian Selboe Gunnhild Søgaard Torleif Terum Fredrik Vaadal Runa AanerødSammendrag
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Sammendrag
In a young Norway spruce stand (planted in 2012) at Hoxmark, Southeast Norway, Net Ecosystem Exchange (NEE) was measured using Eddy Covariance. The data were carefully processed with time-dependent stand parameters (i.e. canopy height), a detailed footprint analysis and calculated at 30 min temporal resolution. Photosynthetic Active Radiation (PAR) as the primary driver for carbon uptake was also available at the site. Despite its young age, the plantation already acted as a net carbon sink according to the annual NEE budget, e.g. by ca. 300 g C m-2 in 2019. However, the response of the system depended strongly on hydrometeorological conditions. We demonstrate this by investigating the relationship between NEE and PAR for this system in a temporally local fashion (30 days moving windows), using a Michaelis-Menten approach involving three parameters. Although the regression captured up to ca. 80% of the variance, the parameter estimates differed substantially throughout the season, and were contrasting between the very dry year 2018 and the close to normal year 2019. Comparison with other EC-equipped sites in a future study will clarify whether this variable sensitivity is due to the young age or is a pattern pertaining also to mature spruce stands. https://doi.org/10.5194/egusphere-egu21-5028
Sammendrag
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Sammendrag
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Sammendrag
There is a need for mapping of forest areas with young stands under regeneration in Norway, as a basis for conducting tending, or precommercial thinning (PCT), whenever necessary. The main objective of this article is to show the potential of multitemporal Sentinel-1 (S-1) and Sentinel-2 (S-2) data for characterization and detection of forest stands under regeneration. We identify the most powerful radar and optical features for discrimination of forest stands under regeneration versus other forest stands. A number of optical and radar features derived from multitemporal S-1 and S-2 data were used for the class separability and cross-correlation analysis. The analysis was performed on forest resource maps consisting of the forest development classes and age in two study sites from south-eastern Norway. Important features were used to train the classical random forest (RF) classification algorithm. A comparative study of performance of the algorithm was used in three cases: I) using only S-1 features, II) using only S-2 optical bands, and III) using combination of S-1 and S-2 features. RF classification results pointed to increased class discrimination when using S-1 and S-2 data in relation to S-1 or S-2 data only. The study shows that forest stands under regeneration in the height interval for PCT can be detected with a detection rate of 91% and F-1 score of 73.2% in case III as most accurate, while tree density and broadleaf fraction could be estimated with coefficient of determination ( R2 ) of about 0.70 and 0.80, respectively.
Sammendrag
Statskog eier om lag 8% av Norges produktive skogareal. Skogen er dominert av en stor andel hogstmoden skog og en overvekt av skog på lavere boniteter. Tilveksten i skogen er svakt avtagende noe som sannsynligvis skyldes skjev aldersklasse fordeling med mye eldre skog. Hogsten i skogen er kun om lag en tredjedel av tilveksten og fører til en sterk oppbygging av det stående volum på Statskog sine eiendommer. Når tilveksten er høyere enn avvirking vil man vanligvis forvente et opptak av karbon i skogen. Dette er også tilfellet for Statskog hvor det er estimert et karbonopptak på om lag 1,5 mill. ton CO2 per år. Karbon opptaket er litt mindre nå enn det var tidligere ettersom tilveksten er fallende og hogsten har vært svakt økende. Når man driver hogst er det fossile utslipp knyttet til hogst, terrengtransport, og tømmerbil transport. Mellom 2010 og 2019 har utslippene fra hogst og transport variert mellom 1 600 tonn CO2 og 4 900 tonn CO2 avhengig av hogstkvantum. Det er viktig å fremheve at utslippene fra transport og hogst er minimale sammenlignet med opptaket av CO2 i skogen til Statskog. Når man avvirker skog produseres det materialer som kan erstatte fossil intensive materialer til andre sektorer slik som bygg og energi. Det er vanskelig å direkte kvantifisere substitusjonen av fossil intensive materialer da effekten er avhengig av de spesifikke materialene som erstattes og effektiviteten i hele verdikjeden. På den andre siden er substitusjon en viktig del av klimaeffekten ved hogst og bør inkluderes når man vurderer klimaeffekter av skogsdrift. Hvis vi antar at skurlast produsert fra avvirkningen til Statskog benyttes til å erstatte stål er det estimert at substitusjonen mellom 2010 og 2019 har variert mellom 32 000 og 99 000 tonn CO2 per år. Substitusjonseffekten er dermed mye høyere enn utslippene fra hogst og transport, men likevel små i forhold til opptaket av karbon i skogen til Statskog. Gjennom skogbehandlingen kan man kraftig påvirke opptaket av karbon i skogen. På lang sikt, er det muligheter for å øke opptaket av karbon gjennom økt plantetetthet og økt bruk av foredlet plantemateriale. Ved å gjødsle skogen kan man oppnå raskt økende opptak av karbon, men den samlede effekten er ikke nødvendigvis så stor da det er begrenset med arealer som er egnet til økt gjødslingsintensitet. Andre tiltak slik som forlenget omløpstid kan også vurderes, men må ses i sammenheng med skogens helsetilstand og effekter på det tilgjengelige hogstkvantum.