Age-independent site index mapping with repeated single-tree airborne laser scanning. Issue 8 (17th November 2019)

• Record Type: Journal Article
• Authors: Solberg, Svein; Kvaalen, Harald; Puliti, Stefano
• Is Part Of: Scandinavian journal of forest research. Volume 34:Issue 8(2019)
• Page Start: 763
• Page End: 770
• Publication Date: 2019-11-17
• Subjects: Site index -- airborne laser scanning -- productivity; Forests and forestry -- Scandinavia -- Periodicals; Forests and forestry -- Periodicals; Forests and forestry -- Research -- Scandinavia -- Periodicals; 634.90948
• DOI: 10.1080/02827581.2019.1616814
• Languages: English
• ISSNs: 0282-7581

Abstract

ABSTRACT: A novel method for age-independent site index estimation is demonstrated using repeated single-tree airborne laser scanning (ALS) data. A spruce-dominated study area of 114 km 2 in southern Norway was covered by single-tree ALS twice, i.e. in 2008 and 2014. We identified top height trees wall-to-wall, and for each of them we derived based on the two heights and the 6-year period length. We reconstructed past, annual height growth in a field campaign on 31 sample trees, and this showed good correspondence with ALS based heights. We found a considerable increase in site index, i.e. about 5 m in the H40 system, from the old site index values. This increase corresponded to a productivity increase of 62%. This increase appeared to mainly represent a real temporal trend caused by changing growing conditions. In addition, the increase could partly result from underestimation in old site index values. The method has the advantages of not requiring tree-age data, of representing current growing conditions, and as well that it is a cost-effective method with wall-to-wall coverage. In slow-growing forests and short time periods, the method is least reliable due to possible systematic differences in canopy penetration between repeated ALS scans.