Current issue: 55(5)

Under compilation: 56(1)

Scopus CiteScore 2019: 3.1
Scopus ranking of open access forestry journals: 6th
PlanS compliant
Silva Fennica 1926-1997
1990-1997
1980-1989
1970-1979
1960-1969
Acta Forestalia Fennica
1953-1968
1933-1952
1913-1932

Silva Fennica vol. 56 | 2022

Category: Research article

article id 10608, category Research article
Lennart Noordermeer, Erik Næsset, Terje Gobakken. (2022). Effects of harvester positioning errors on merchantable timber volume predicted and estimated from airborne laser scanner data in mature Norway spruce forests. Silva Fennica vol. 56 no. 1 article id 10608. https://doi.org/10.14214/sf.10608
Highlights: Timber volume was estimated using harvester and airborne laser scanner (ALS) data acquired with different scanners over eight years; The year of ALS acquisition did not have a significant effect on errors in timber volume estimates; Accuracies of timber volume estimates decreased significantly with increasing levels of positioning error; When using inaccurately positioned harvester data, larger grid cells are beneficial.

Newly developed positioning systems in cut-to-length harvesters enable georeferencing of individual trees with submeter accuracy. Together with detailed tree measurements recorded during processing of the tree, georeferenced harvester data are emerging as a valuable tool for forest inventory. Previous studies have shown that harvester data can be linked to airborne laser scanner (ALS) data to estimate a range of forest attributes. However, there is little empirical evidence of the benefits of improved positioning accuracy of harvester data. The two objectives of this study were to (1) assess the accuracy of timber volume estimation using harvester data and ALS data acquired with different scanners over multiple years and (2) assess how harvester positioning errors affect merchantable timber volume predicted and estimated from ALS data. We used harvester data from 33 commercial logging operations, comprising 93 731 harvested stems georeferenced with sub-meter accuracy, as plot-level training data in an enhanced area-based inventory approach. By randomly altering the tree positions in Monte Carlo simulations, we assessed how prediction and estimation errors were influenced by different combinations of simulated positioning errors and grid cell sizes. We simulated positioning errors of 1, 2, …, 15 m and used grid cells of 100, 200, 300 and 400 m2. Values of root mean square errors obtained for cell-level predictions of timber volume differed significantly for the different grid cell sizes. The use of larger grid cells resulted in a greater accuracy of timber volume predictions, which were also less affected by positioning errors. Accuracies of timber volume estimates at logging operation level decreased significantly with increasing levels of positioning error. The results highlight the benefit of accurate positioning of harvester data in forest inventory applications. Further, the results indicate that when estimating timber volume from ALS data and inaccurately positioned harvester data, larger grid cells are beneficial.

  • Noordermeer, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, NMBU, P.O. Box 5003, NO-1432 Ås, Norway ORCID ID:E-mail: lennart.noordermeer@nmbu.no (email)
  • Næsset, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, NMBU, P.O. Box 5003, NO-1432 Ås, Norway ORCID ID:E-mail: erik.naesset@nmbu.no
  • Gobakken, Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, NMBU, P.O. Box 5003, NO-1432 Ås, Norway ORCID ID:E-mail: terje.gobakken@nmbu.no
article id 10520, category Research article
Shaoqin Yang, Lita Yi, Nuonan Ye, Mengyuan Wu, Meihua Liu. (2022). Spatial pattern dynamics of Cyclobalanopsis myrsinifolia in mixed broad-leaved forests on Tianmu Mountain, eastern China, 1996–2012. Silva Fennica vol. 56 no. 1 article id 10520. https://doi.org/10.14214/sf.10520
Highlights: Spatial distribution pattern monitoring of Cyclobalanopsis myrsinifolia was performed over 16 years in a 1 ha plot; The importance value of C. myrsinifolia decreased between 1996 and 2012; The spatial distribution pattern changed at a spatial scale of 0–25 m; The drivers of the variation in spatial distribution were intra- and interspecific mutual relationships.

Studies of the spatial patterns of dominant plant species may provide significant insights into processes and mechanisms that maintain stand stability. This study was performed in a permanent 1 ha plot in evergreen and deciduous broad-leaved mixed forests on Tianmu Mountain. Based on two surveys (1996 and 2012), the dynamics of the spatial distribution pattern of the dominant population (Cyclobalanopsis myrsinifolia (Blume) Oersted) and the intra- and interspecific relationships between C. myrsinifolia and other dominant species populations were analyzed using Ripley’s K(r) function. We identified the importance value of a species in a community, which is the sum of the relative density, relative frequency, and relative dominance. The drivers of spatial distribution variation and the maintenance mechanisms of the forest were discussed. The results showed that the importance value of C. myrsinifolia within the community decreased over the past 16 years. The C. myrsinifolia population exhibited a significantly aggregated distribution within a spatial scale of 0–25 m in 1996 whereas it changed to a random distribution at scales larger than 5.5 m in 2012. From 1996 to 2012, the spatial distribution patterns between C. myrsinifolia and Cyclocarya paliurus (Batal.) Iljinsk. and between C. myrsinifolia and Cunninghamia lanceolata (Lamb.) Hook did not change significantly. In 1996, C. myrsinifolia and Daphniphyllum macropodum Miq. were positively associated at the scale of 0–25 m; this relationship was strongly significant at the scale of 6–10 m. However, there was no association between the populations of two species in terms of the spatial distribution at the scale of 0–25 m in 2012. Our findings indicate that the drivers of variation in the spatial distribution of the C. myrsinifolia population were intra- and interspecific mutual relationships as well the seed-spreading mechanism of this species.

  • Yang, Zhejiang Forest Resources Monitoring Center, Hangzhou 310020, China ORCID ID:E-mail: 20080095@zafu.edu.cn
  • Yi, School of Forestry and Biotechnology, Zhejiang A & F University, Lin’an 311300, China ORCID ID:E-mail: yilita@zafu.edu.cn
  • Ye, School of Forestry and Biotechnology, Zhejiang A & F University, Lin’an 311300, China ORCID ID:E-mail: 542243187@qq.com
  • Wu, School of Forestry and Biotechnology, Zhejiang A & F University, Lin’an 311300, China ORCID ID:E-mail: 326585523@qq.com
  • Liu, School of Forestry and Biotechnology, Zhejiang A & F University, Lin’an 311300, China ORCID ID:E-mail: mhliu@zafu.edu.cn (email)

Register
Click this link to register for Silva Fennica submission and tracking system.
Log in
If you are a registered user, log in to save your selected articles for later access.
Contents alert
Sign up to receive alerts of new content
Your selected articles

Committee on Publication Ethics A Trusted Community-Governed Archive