Good overview of forest resources for better utilization and greater value creation. A new method m

Good overview of forest resources for better utilization and greater value creation. A new method makes it possible to describe also smaller forest areas using data from three-dimensional aerial photographs.
Here's forest presented with artificial colors as a three-dimensional point cloud based on overlapping 1902 aerial photographs in color and infrared. (Illustration: John Breidenbach / Forests and Landscape)
National Forest Inventory is a kind of forest Statistics Norway - they count and record how much forest there is in Norway. The measurement takes place on selected plots across the country.
They often get questions from forest managers and forest owners about how much forest exists in a municipality, or the amount of carbon tied up in trees in municipal forests or protected areas. 1902
- It is not always easy to answer such questions, the areas are too small to allow us to use figures from the National Forest Inventory, said John Breidenbach, a researcher at the Climate Centre at the Norwegian Forest and Landscape.
- The way the National Forest Inventory is built on making sure we get good numbers on what kind of forest and how much there is of it at national and regional levels. 1902 But the numbers are quite uncertain 1902 for smaller forests, explains Breidenbach.
One of the most famous results from the National Forest Inventory, estimates of how much carbon that is bound to trees in Norway. For 2009, it appears the that about half of our greenhouse gas CO2 is captured via the photosynthesis of trees in the Norwegian forests.
- We want to provide better estimates of how much forest is also in smaller areas, such as within 1902 a municipality, a major forest estate or a nature reserve, explains skogstatistikeren.
- Our goal was to combine 1902 the measurements carried out on the ground in the National Forest Inventory with three-dimensional aerial photos to see if it could give us better 1902 and more reliable estimates 1902 of how much biomass, ie plant material, there are in each municipality, says Breidenbach.
All the trees on National Forest Inventory 250 square meters surface is marked with a number and recorded on the map. (Photo: Lars Sandved 1902 Valley / Forest and Landscape) Every five years, the entire Norway photographed from the plane. This is called the orbital photography, and is funded by map co Norway Digital and Web site norgeibilder.no.
Based on the computer-generated 3D point cloud, the height of the trees is calculated, and since there is a good correlation, or correlation, between the height of trees and volume, then aerial photography not provide even better and more accurate estimates of the amount of forest in Vestfold.
The computer-generated point cloud from aerial photography shows no height of the trees after the height of the terrain is deducted. In addition, 1902 it is not always easy to know what's forests and what is marsh, harvesting fields or other open areas such three-dimensional map.
The researchers solved 1902 by combining aerial photos of the woods with other map information, including a detailed land resource map (AR5), which shows where just farmland, marsh, houses and woods.
- The combination of three-dimensional aerial photographs and ground measurements from the National Forest Inventory, allows us to make very good statistical models of how the forest looks like, how many and how big the trees are, says Breidenbach.
- We call it a population characteristic, ie a number, an estimate of how much it is, for example, biomass, or total timber volume, or number of trees, or the average height of the trees, it is in the forest in a given municipality.
In the study of Vestfold researchers tested out various statistical 1902 models for how the forest in a county may be described from such a three-dimensional point cloud based on aerial photographs. They also wanted to find the margins 1902 of error for each of the estimates.
- If we'd 1902 achieved the same security in the estimates based only on the sample plots on the ground, we had had between four and 14 times as many plots.
- This is especially noticeable in smaller municipalities, where there is perhaps only one sample surface and it simply is not possible to give any estimate of uncertainty at all, says Breidenbach.
The statistical model that the researchers developed forest in Vestfold has also formed the basis for a separate biomass maps for the forest in the county. And the positive