49 research outputs found
Mapping forest age using National Forest Inventory, airborne laser scanning, and Sentinel-2 data
The age of forest stands is critical information for many aspects of forest
management and conservation but area-wide information about forest stand age
often does not exist. In this study, we developed regression models for
large-scale area-wide prediction of age in Norwegian forests. For model
development we used more than 4800 plots of the Norwegian National Forest
Inventory (NFI) distributed over Norway between 58{\deg} and 65{\deg} northern
latitude in a 181,773 km2 study area. Predictor variables were based on
airborne laser scanning (ALS), Sentinel-2, and existing public map data. We
performed model validation on an independent data set consisting of 63 spruce
stands with known age. The best modelling strategy was to fit independent
linear regression models to each observed site index (SI) level and using a SI
prediction map in the application of the models. The most important predictor
variable was an upper percentile of the ALS heights, and
root-mean-squared-errors (RMSE) ranged between 3 and 31 years (6% to 26%) for
SI-specific models, and 21 years (25%) on average. Mean deviance (MD) ranged
between -1 and 3 years. The models improved with increasing SI and the RMSE
were largest for low SI stands older than 100 years. Using a mapped SI, which
is required for practical applications, RMSE and MD on plot-level ranged from
19 to 56 years (29% to 53%), and 5 to 37 years (5% to 31%), respectively. For
the validation stands, the RMSE and MD were 12 (22%) and 2 years (3%). Tree
height estimated from airborne laser scanning and predicted site index were the
most important variables in the models describing age. Overall, we obtained
good results, especially for stands with high SI, that could be considered for
practical applications but see considerable potential for improvements, if
better SI maps were available
Building a high-resolution site index map using boosted regression trees: The Norwegian case
Accurate estimation of site productivity is essential for forest projections and scenario modelling. We present and evaluate models to predict site index (SI) and whether a site is productive (potential total stem volume production â„ 1 m3·haâ1·yearâ1) in a wall-to-wall high-resolution (16 m Ă 16 m) SI map for Norway. We investigate whether remotely sensed data improve predictions. We also study the advantages and disadvantages of using boosted regression trees (BRT), a machine-learning algorithm, to create high-accuracy SI maps. We use climatic and topographical data, soil parent material, a land resource map, and depth to water, together with Sentinel-2 satellite images and airborne laser scanning metrics, as predictor variables. We use the SI observed at more than 10â000 National Forest Inventory (NFI) sample plots throughout Norway to fit BRT models and validate the models using 5822 independent temporary plots from the NFI. We benchmark our results against SI estimates from forest monitoring inventories. We find that the SI from BRT has root mean squared error (RMSE) ranging from 2.3 m (hardwoods) to 3.6 m (spruce) when tested against independent validation data from the NFI temporary plots. These RMSEs are similar or marginally better than an evaluation of SI estimates from operational forest management plans where SI normally stems from manual photo interpretation.publishedVersio
Anvendelse av aldersfri bonitet for skog i Norge
Aldersfri bonitering er en metode for estimering av bonitet uten bruk av alder pÄ skogen. Metoden er utviklet ved NIBIO i seinere Är, og omtalt i tidligere publikasjoner. Vi gÄr her videre i arbeidet med Ä kvalitetssikre metoden, og vurderer hvilken potensiell anvendelse den kan ha i skogbruket. Samlet sett viser resultatene at aldersfri bonitet har et potensial for Ä brukes i skogbruk i Norge. Det kan brukes for det fÞrste som et alternativ til konvensjonell bonitering i skogbruksplanlegging og pÄ det landsdekkende skogressurskartet SR16, og for det andre som et supplement til konvensjonell bonitet pÄ Landsskogtakseringens felt for Ä overvÄke endringer forÄrsaket av klimaendringer. I det fÞrste tilfellet er fordelen at metoden ikke krever alder som input. En generell fordel er at metoden kan fange opp endringer i bonitet som skyldes endringer i vekstvilkÄr grunnet for eksempel klimaendringer, og dermed i stÞrre grad enn konvensjonell bonitet representere dagens bonitet. Metoden har ogsÄ den fordelen at den er velegnet for bruk med fjernmÄling, og resultatene viser at bÄde enkelttre- og areal-baserte metoder fungerer, og at bÄde laserskanning og stereo flybilder kan brukes.publishedVersio
Ressursoversikt og prognoser for framtidig virkestilgang fra SR16
SR16 er et skogressurskart utviklet og publisert av NIBIO. Det er tenkt som et supplement til allerede eksisterende ressurskart i skogbruket med kvalitet og romlig opplÞsning mellom tradisjonelle takster og regionale oversikter fra Landskogtakseringen. SR16 byr pÄ noen interessante muligheter for aktÞrer i skogbruket. FormÄlet med denne rapporten er Ä vurdere SR16s kvalitet og innhold opp mot skogbrukets Þnskede bruk av SR16. Alle aktÞrene som har uttalt seg om SR16 fremhever behovet for Ä «fylle hull» der det mangler informasjon om skogtilstanden. Videre er det sterke Þnsker om ressursanalyser med tanke pÄ tilgjengelighet, for eksempel skogressurs sett opp mot veinett, bÄde nÄ og fremover (prognoser). Private aktÞrer er i tillegg opptatt av om SR16 kan utnyttes i forbindelse med forenklet registrering av miljÞelementer (MiS), mens det offentlige Þnsker Ä koble ressurskart med kartlegging og stedfesting av (alle) tiltak som gjennomfÞres i skogbruket. Det er Þnskelig at kvaliteten pÄ SR16 er pÄ hÞyde med dagens skogbruksplaner.....publishedVersio
Detection and segmentation of small trees in the forest-tundra ecotone using airborne laser scanning
Use of remote sensing for mapping of non-native conifer species
Serien het tidligere INA fagrapportNon-native species are by many considered a threat to local biodiversity. In Norway, conifer species have been introduced in order to find species with better timber production than the native species. Several of these introduced species have been considered to be invasive, and put on an official âblacklistâ. Thus, from a management perspective, more information about the extent, occurrences and potential dispersal are important information. To gather such information solely based on field surveys are time-consuming and costly, and it has therefore been suggested to develop methods based on remote sensing. In this report we review different types of remote sensing data and how these can be used to map and monitor non-native species.
Natural species distributions of Norway spruce and Scots pine were created based on available literature and existing remote sensing-based forest maps. The same maps were used to create a non-native species map, i.e. a map of areas where spruce occur outside its natural distribution. We evaluated the accuracy of the map by photo-interpretation, and assessed the consistency with other occurrence data. We further estimated the area of non-native species on a county and national level in Norway. The area covered by non-native species outside the natural distribution of spruce was estimated to be 1200 km2, with a standard error of 275 km2.
A specific challenge when using remote sensing for mapping of non-native species in Norway is to separate species of the same genera. We therefore conducted a study in Fusa and Tysnes municipalities where we evaluated the ability to discriminate between Norway spruce and Sitka spruce using different types of remote sensing data. Data from Landsat 8 satellite images, aerial imagery and airborne laser scanning were tested. Slight to moderate ability to separate between the two species were found, with a best overall accuracy of 78%. The results suggest that Landsat 8 imagery can be used to discriminate between stands dominated by Norway spruce and Sitka spruce. Additional data from airborne sensors contributed not substantially in this case.
Based on our own analyses and a review of relevant literature we discuss a possible establishment of a national mapping and monitoring programme for non-native tree species.Fremmede arter blir av mange betraktet som en trussel mot det biologiske mangfoldet. I Norge har flere bartrearter blitt innfÞrt med tanke pÄ Ä bedre produksjonspotensialet i skogen, og flere av disse artene finnes nÄ pÄ den offisielle «svartelista». For forvaltningen er det derfor et Þkende behov for kunnskap om utbredelse og potensiell spredning av disse artene. Det er bÄde tidkrevende og kostbart Ä samle denne informasjonen utelukkende basert pÄ feltundersÞkelser, og det er derfor foreslÄtt Ä utvikle metoder basert pÄ fjernmÄling for kartlegging og overvÄkning. I denne rapporten har vi gjennomgÄtt ulike typer fjernmÄlingsdata med hensyn pÄ potensiale for kartlegging og overvÄking av fremmede bartrÊr.
Vi har videre etablert utbredelsekart for vanlig gran og furu basert pÄ gjennomgang av eksisterende litteratur samt nasjonale skogkart fra fjernmÄlingsdata. De eksisterende skogkartene ble ogsÄ bruk til Ä etablere et kart over fremmede bartrÊr, dvs. grantrÊr utenfor sin naturlige utbredelse. NÞyaktigheten av utbredelseskartet ble evaluert ved hjelp av fototolkning. Videre undersÞkte vi hvordan kartet stemte overens med andre tilgjengelige kilder om lokaliteter av fremmede treslag, og estimerte arealet med fremmede bartrÊr pÄ fylkes- og landsnivÄ. Arealet av fremmede bartrÊr utenfor den naturlige utbredelsen til gran i Norge ble estimert til 1200 km2, med en standardfeil pÄ 275 km2.
En spesifikk utfordring i fjernmÄling av fremmede bartrÊr er Ä skille mellom arter av samme slekt. Vi etablerte en test i Fusa og Tysnes dere vi vurderte potensialet for Ä skille mellom vanlig gran og sitkagran med ulike typer fjernmÄlingdata. FjernmÄlingsdata som ble testet var satellittbilder fra Landsat 8, flyfoto fra omlÞpsfotograferingen og flybÄren laserskanning. Vi fant en svak til moderat evne til skille mellom de to artene. Den beste totale nÞyaktigheten var pÄ 78%, dvs. at 78% av lokalitetene var riktig bestemt. Testen indikerer at Landsat 8 bilder kan brukes til Ä skille mellom bestand med vanlig gran og sitkagran og at resultatene ikke bedres vesentlig ved bruk av flybÄrne sensorer.
Basert pÄ en litteraturgjennomgangen og vÄre analyser diskuterer vi en mulig etablering av et kartleggings- og overvÄkingopplegg for fremmede treslag
Discriminating between Native Norway Spruce and Invasive Sitka SpruceâA Comparison of Multitemporal Landsat 8 Imagery, Aerial Images and Airborne Laser Scanner Data
Invasive species can be considered a threat to biodiversity, and remote sensing has been proposed as a tool for detection and monitoring of invasive species. In this study, we test the ability to discriminate between two tree species of the same genera, using data from Landsat 8 satellite imagery, aerial images, and airborne laser scanning. Ground observations from forest stands dominated by either Norway spruce (Picea abies) or Sitka spruce (Picea sitchensis) were coupled with variables derived from each of the three sets of remote sensing data. Random forest, support vector machine, and logistic regression classification models were fit to the data, and the classification accuracy tested by performing a cross-validation. Classification accuracies were compared for different combinations of remote sensing data and classification methods. The overall classification accuracy varied from 0.53 to 0.79, with the highest accuracy obtained using logistic regression with a combination of data derived from Landsat imagery and aerial images. The corresponding kappa value was 0.58. The contribution to the classification accuracy from using airborne data in addition to Landsat imagery was not substantial in this study. The classification accuracy varied between models using data from individual Landsat images