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.
2010
Sammendrag
Determining the feedbacks between terrestrial biosphere processes and the meteorological drivers (here precipitation and temperature) is crucial to ecosystem research. In this context, the continuous monitoring of the earth surface provides an invaluable basis for investigating the spatiotemporal dynamics in the activity of vegetation in relation to environmental conditions. Here, we seek to identify which patterns of variability in the meteorological drivers dominate the terrestrial photosynthetic activity from monthly to interannual time scales (resp. fluctuation frequencies). We investigate the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) using SeaWiFS observations from 1998 to 2005 and ancillary meteorological variables. A spectralanalysis leads to a global `classification` of the terrestrial biosphere according to prevalent scale dependent dynamics of fAPAR and its relation to the meteorology. A combined subsignal extraction and dimensionality reduction reveals a series of dominant geographical gradients on specific time scales. E.g. we uncover spatially coherent patterns at low frequencies and show where these are induced by precipitation or temperature fluctuations. We also show where high frequency variations (relative to the annual cycle) in fAPAR coincide with corresponding precipitation dynamics. However, we can also identify regions where the variability of fAPAR on specific time scales cannot be traced back to climate and is apparently shaped by other geoecological or anthropogenic drivers. http://www.terrabites.net/fileadmin/user_upload/terrabites/PDFs/Programme_Book_TERRABITES.pdf
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
The utilization history of the Lange Bramke catchment and the northern Harz mountains is dominated by ore mining. Historical documents were used to provide ample evidence that forestry and water utilization were managed according to administrative goals in a largely centralized manner. However, the perception of the landscape and its function and purpose have changed significantly over the centuries. In particular, the distinction between renewable (such as forests) and non-renewable resources (such as ore deposits) is a rather modern one, as is the principle of sustainability. This change in perception is apparent from the type of maps used, the different conflicts on property and exploitation rights, and the request for quantitative inventories of resources, appearing only quite late in the mining history. The remnants of smelters and charcoal production still demonstrate the importance of historical land use for proper interpretation of monitoring data.
Sammendrag
The Lange Bramke catchment has been investigated as a monitored catchment for 60 years. However, its utilization history even dates back to medieval times, and is well documented in part. The intense interplay between ore mining, forestry, and water resources exploitation left remains such as scoriae piles and modified forest growth, e.g. due to local pollution at smelter locations. It is demonstrated that considering local land use history is important for a proper understanding and interpretation of modern monitoring data. A theoretical framework is proposed for the integration of the two data sources. This requires a joint approach combining two modelling paradigms, the functional one dominating in current ecosystem research, and an interactive one which best characterizes the human–environment relationship in historic times.
Forfattere
Tuula Kantola Mikko Vastaranta Xiaowei Yu Paivi Lyytikainen-Saarenmaa Markus Holopainen Mervi Talvitie Sanna Kaasalainen Svein Solberg Juha HyyppäSammendrag
Climate change has been observed to be related to the increase of forest insect damages in the boreal zone. The prediction of the changes in the distribution of insect-caused forest damages has become a topical issue in the field of forest research. The common pine sawfly (Diprion pini L.) (Hymenoptera, Diprionidae) is regarded as a significant threat to boreal pine forests. Defoliation by D. pini caused severe growth losses and tree mortality of Scots pine (Pinus sylvestris L.) (Pinaceae). Logistic regression is commonly used in modelling the probability of occurrence of an event. In this study the logistic regression was investigated for predicting the needle loss of individual Scots pines (pine) using the features derived from airborne laser scanning (ALS) data. The defoliation level of 164 trees was determined subjectively in the field. Statistical ALS features were extracted for single trees and used as independent variables in logistic regression models. Classification accuracy of defoliation was 87.8% as respective kappa-value was 0.82. For comparison, only penetration features were selected and classification accuracy of 78.0% was achieved (kappa=0.56). Based on the results, it is concluded that ALS based prediction of needle losses is capable to provide accurate estimates for individual trees.
Sammendrag
Le gel printanier peut etre dommageable pour les semis de Picea abies (L.) Karst. nouvellement plantes si leur rythme de croissance n'est pas suffisamment adapte aux conditions climatiques de la station forestiere. Les objectifs de cette etude consistaient a determiner de quelle facon le debourrement et la resistance au gel printanier sont influences par un traitement de jours courts (JC) appliques a differents moments et avec differents regimes de temperature durant la periode de formation des bourgeons. A la suite d'un entreposage hivernal, la resistance au gel a ete evaluee apres une, trois et cinq semaines dans des conditions de forcage. Le traitement JC a avance le debourrement comparativement aux semis temoins. Par comparaison, le moment du traitement et les differentes temperatures ont eu peu d'effet sur le debourrement. Le traitement JC a augmente la resistance au gel des aiguilles d'un an pendant la periode de desendurcissement. Applique tot, le traitement JC a augmente la resistance au gel des aiguilles d'un an et le diametre au collet comparativement a une application plus tardive. Il est important que la periode de noirceur atteigne une duree critique lorsque le traitement JC prend fin pour eviter une deuxieme eclosion des bourgeons. Des temperatures basses a la suite du traitement JC ont augmente la resistance au gel des aiguilles et diminue celle de la tige. Les effets contraires de la temperature sur differents tissus vegetaux demontrent l'importance d'examiner differents tissus apres des essais de gel-degel. Spring frost may result in detrimental damage in newly planted Picea abies (L.) Karst. seedlings if their growth rhythm is not sufficiently adapted to the climatic conditions on the forest site. The aims of this study were to evaluate how bud break and spring frost hardiness were influenced by short-day (SD) treatments with different timing and different temperature regimes during bud formation. Following winter storage, frost hardiness was tested after 1, 3 and 5 weeks in forcing conditions. The SD treatment advanced bud break compared with the control seedlings. In comparison, the effects of timing and the different temperatures on bud break were small. The SD treatment improved frost hardiness in first-year needles during dehardening. The early SD treatment resulted in improved frost hardiness in first-year needles and greater root collar diameter compared with later SD treatment. To avoid a second bud flush, it is important that a critical night length is attained when the SD treatment terminates. Low temperatures following the SD treatment resulted in increased hardiness of the needles and decreased hardiness of the stems. The contrasting effect of temperature in different plant tissues demonstrates the importance of examining different tissues following freezing tests.
Sammendrag
Denne rapporten presenterer resultatene fra en taksering av naturlig foryngelse i 99 bestand på bonitet G14 i Romedal og Stange allmenninger. Arealene ble markberedt i perioden 2001–2006, og var avvirket ved flatehogst der målet var naturlig foryngelse av gran basert på frø fra bestandskant. Takseringen ble gjennomført i juni – oktober 2008. Arealene fordelte seg med 29 bestand i bærlyngskog, 52 bestand i blåbærskog, og 18 bestand i småbregneskog. Granplanter som hadde spirt våren 2007 (toårig gran) utgjorde det største bidraget til foryngelsen i de fleste bestandene....
Sammendrag
I denne rapporten presenteres resultatene fra resultatkontrollen i 2009, som omfatter foryngelseskontroll, kontroll av skogsveger og kontroll av skogbruksplaner. Resultatene fra foryngelseskontrollen er basert på kontroll av 967 foryngelsesfelt som er avvirket i løpet av 2007. Andelen av arealet der foryngelsesmetoden er planting var i 2009 på 55,6 %, og har økt vesentlig siden kontrollåret 2008 da andelen var 40,1%. Andelen som forynges ved en kombinasjon av planting og naturlig foryngelse har endret seg relativt lite siden 2008, mens det er registrert nedgang i andelen av arealet som er tilrettelagt for naturlig foryngelse, og andelen der det ikke er gjennomført tiltak for å legge til rette for foryngelse. Til sammen 72,0 % av foryngelsesarealet har en tetthet i foryngelsene i henhold til anbefalingene eller høyere der foryngelsesmetoden er planting. Innen arealene som forynges ved en kombinasjon av planting og naturlig foryngelse er andelen 67,6 %, mens 43,9 % av arealet som er tilrettelagt for naturlig foryngelse har et planteantall på nivå med anbefalingene eller høyere på kontrolltidspunktet. Der det ikke var tilrettelagt for foryngelse hadde det meste av arealet (71,3 %) et planteantall per dekar under bærekraftforskriftens minstekrav. Resultatene viser videre at om lag fire femtedeler av foryngelseshogstene (% av areal) gjennomføres før skogen når hogstklasse V. Omfanget av tidlig hogst var vesentlig høyere i granskog (21,9%) enn i furuskog (10,4%), og økte med økende bonitet uansett treslagsammensetning i det forrige bestandet. Det er kontrollert 296 skogsbilveganlegg i 2009 som gir en kontrollprosent på 36 %. Antallet kontrollerte anlegg er omtrent det samme som i 2008. Resultatkontrollen viser at det i selve godkjenningsprosessen blir gjort få endringer av vegplanene. Dette indikerer at planene er godt gjennomarbeidet før de kommer til formell behandling. Den tekniske og landskapsmessige standarden på ferdigstilte anlegg har over lang tid vært god, og dette er også tilfellet i 2009. Kontroll av skogbruksplanprosjekter omfatter 20 godkjente takstprosjekter totalt. Takstene representerer 1,87 millioner dekar fordelt på 3 158 eiendommer med en gjennomsnittskostnad på 11,3 kroner per dekar. Dette er en økning på om lag fire kroner per dekar i forhold til 2008. Til sammen utgjør miljøfigurer fra MiS-registreringer et areal på 35 391 dekar.
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Svein Solberg Rasmus Astrup Dan Johan Weydahl Erik Næsset Terje Gobakken Ole Martin BollandsåsSammendrag
There is an increasing need for forest resource monitoring methods, as more attention is paid to deforestation, bio-energy and forests as habitats. Most national forest inventories are based on networks of field inventory plots, sometimes together with satellite data, and airborne laser scanning (ALS) is increasingly used for local forest mapping. These methods are expensive to establish or carry out, and many countries, including some severely affected by deforestation, do not apply such methods.Satellite based remote sensing methods in use today are hampered by problems caused by clouds and saturation at moderate biomass levels. Satellite SAR is not hampered by cloud problems, and monitoring of canopy surface elevation, which is correlated to key forest resource variables, might be a future method in forest monitoring.We here present the main findings of three studies (Solberg et al. 2010, a, b, c) investigating the potential of interferometric SAR (InSAR) for forest monitoring, by describing the relationship between InSAR height above ground and key forest variables. We based this study on InSAR data from the Shuttle Radar Topographic Mission (SRTM) with its acquisition in February 2000. We obtained SRTM InSAR DEM data from DLR for two forest areas in Norway, and built a ground-truth from the combination of field inventory and ALS.The forest areas were dominated by Norway spruce and Scots pine. In each forest area we laid out a number of field inventory plots, where we recorded standard forest variables such as Dbh and tree height, and from this derived plot aggregated variables of top height, mean height, stand density (mean tree height divided by the mean tree spacing), volume and biomass. We used this to calibrate and validate ALS based models, from which we derived estimates of the same variables for each SRTM pixel. This served as reference data for the SRTM data.From the X-band SRTM digital surface model (DSM) image we subtracted a high quality digital terrain model (DTM) derived from the ALS data. This was based on an extraction of ground echoes from the data provider, and the elevations of these echoes were interpolated into a grid fitting the SRTM grid.This produced data on the RADAR echo height above ground (InSAR height), which we related to the forest variables. With digital stand maps we aggregated the variables to the stand level. The X-band microwaves penetrate a little into the canopy, and the InSAR height was on average about 1.2 m below the mean tree height. InSAR height was strongly related to all forest variables, most strongly to top height.Particularly valuable was that stem volume and biomass, ranging up to 400 m3/ha and 200 t/ha, respectively, were linearly related to InSAR height with an accuracy, RMSE, of 19% at the stand level. However, these relationships had an intercept, which represents the microwave penetration into the vegetation, and due to this the relationships were non-linear for forest stands having heights and biomass values close to zero.With a lower quality DTM derived from topographic maps, the relationships were weaker. However, as long as a forest variable is within the ranges of the linear relationship, any change in InSAR elevation would be proportional to a change in forest height, volume or biomass. And, any logging should be detectable as a sudden decrease in InSAR elevation.Hence, a forest monitoring based on X-band InSAR might be suitable even without a DTM. An application of space borne InSAR for forest monitoring would be feasible for large areas at low cost, whereas an ALS acquisition for a part of the area would serve as reference data for calibration.