Decision support approaches in adaptive forest management

Climate and social changes place strong demands on forest managers. Forest managers need powerful approaches and tools, which could help them to be able to react to the rapidly changing conditions. However, the complexity of quantifying forest ecosystems services as well as the complexity of current decision theories, technologies and operation research methods, complicate the creation of one general tool. The continuous research and development in this area is an indispensable part of the success of adaptive management as well as the sharing of knowledge and information between research teams around the world. The Community of Practice of Forest Management Decision Support Systems provides a platform for broad discussion among scientists, researchers as well as forest professionals. This special issue provides papers which resulted from a conference session of the International Union of Forest Research Organizations’ (IUFRO) 125th Anniversary Congress in Freiburg, Germany in 2017. The joint sessions and other meetings (and resulting publications) are appropriate opportunities for knowledge sharing on these important methods and systems for protecting and managing forest ecosystems in the future.This special issue was supported by the project “Advanced research supporting the forestry and wood-processing sector’s adaptation to global change and the 4th industrial revolution”, reg. No. CZ.02.1.01/0.0/0.0/16_019/0000803

Relationship between biodiversity indicators and its economic value – case study

Background and Purpose:Within the framework ofmulti-purpose forest management, biodiversity is usually considered as one of forest functions along with production, recreation and other functions of forests, while according to biodiversity definition and its partial components, these functions are integral elements of biodiversity. Forest inventory is an objective method for collecting information about biodiversity and forest functions. Materials and Methods: In the presented study, the data from forest inventory of the University Forest Enterprise Kostelec based on stratification sampling design (1,188 sample plots in 86 strata) were used for the analysis of the relationship between biodiversity indicators and its economic value. The area of the enterprise is characterised by heterogeneous site and landscape conditions. From the inventory data we quantified 171 partial diversity indicators. On the base of ANOVA andmultiple linear regression analysis, we selected the most suitable indicators most closely correlated to the sum of the values of individual social and economic forest functions. Results and Conclusion: We found that the relationship between the economic value of biodiversity and selected indicators is significant. Nevertheless, the derived models could explain not more than 25% of the total variability of the analysed relationship. Future research should search for objective indicators of biodiversity, and should aim at improving economic valuation of biodiversity

Input point distribution for regular stem form spline modeling

Aim of study: To optimize an interpolation method and distribution of measured diameters to represent regular stem form of coniferous trees using a set of discrete points.Area of study: Central-Bohemian highlands, Czech Republic; a region that represents average stand conditions of production forests of Norway spruce (Picea abies [L.] Karst.) in central Europe.Material and methods: The accuracy of stem curves modeled using natural cubic splines from a set of measured diameters was evaluated for 85 closely measured stems of Norway spruce  using five statistical indicators and compared to the accuracy of three additional models based on different spline types selected for their ability to represent stem curves. The optimal positions to measure diameters were identified using an aggregate objective function approach.Main results: The optimal positions of the input points vary depending on the properties of each spline type. If the optimal input points for each spline are used, then all spline types are able to give reasonable results with higher numbers of input points. The commonly used natural cubic spline was outperformed by other spline types. The lowest errors occur by interpolating the points using the Catmull-Rom spline, which gives accurate and unbiased volume estimates, even with only five input points.Research highlights: The study contributes to more accurate representation of stem form and therefore more accurate estimation of stem volume using data obtained from terrestrial imagery or other close-range remote sensing methods.Key words: spline; stem curve; taper model; diameter position; Norway spruce

Inventory of close-to-nature forest stands using terrestrial mobile laser scanning

In this work, we evaluated mobile laser scanning (MLS) technology for the acquisition of individual tree data in a close-to-natural forest structure. The data was collected during the leaf-on period in a single-tree selection forest stand. Individual tree positions and diameters at breast height (DBHs) were acquired in an automatic process. MLS data was collected on 1000 m2 circular inventory plots. We compared three trajectories consisting of the plot perimeter and 1), two perpendicular lines, 2) an additional concentric circle, and 3) four parallel lines. We compared two algorithms for tree segmentation: 1) a density-based approach and 2) a modified mean-shift algorithm. The diameters were estimated using a modified random sample consensus (RANSAC) algorithm. We tested a series of intensity thresholds for filtering returns from green vegetation. We achieved the best results with an intensity threshold of 0.7 quantile of point intensities, and mean-shift segmentation, resulting in the correct identification of trees representing 96.5 % of basal area and an overestimation of 6.8 % of the total basal area. The algorithm omitted mainly small trees and trees at close distances. False detections mainly comprised unvalidated detections of real trees that were not field-measured as their diameter did not exceed the registration limit, or were caused by point structures representing leaves and understory vegetation. Diameters were estimated with a mean error of 0.03 cm and a root mean square error of 3.5 cm. A joinpoint regression model demonstrated that for small trees (<9 cm) the diameters were generally overestimated. Diameters above 12 cm were underestimated consistently by 1 cm. The trajectory comprising two concentric circles was the most efficient

Importance of automatic threshold for image segmentation for accurate measurement of fine roots of woody plants

The fine roots are considered the key organs for plant survival, growth and productivity. Measurement of fine roots variables is easily and conveniently achieved by means of digital image. The descriptive variables like root area, surface, total length and diameter distribution may be obtained from the image. Analysis of digital image consists from several steps, each of them represents potential source of the error. In this article we want to evaluate the automatic thresholding and its impact on principal variables obtainable from digital scans of the fine roots. We compare 16 different thresholding methods and compare them with the human processed binary images of roots of cork oak (Quercus suber L.). We found some of the thresholding methods perform significantly better than others in the estimation of total projected area however the length estimation error points out a little different order of accuracy

Dynamic Young’s Modulus of Scarf- and Finger-Jointed Beams using Longitudinal Vibration Method

The elastic properties of oak wood (solid wood, scarf-jointed beams, and finger-jointed beams) and two different, independently applied adhesives (polyvinyl acetate and isocyanate) were investigated. Using a longitudinal vibration technique and comparing the elastic modulus of the solid wood and jointed beams, it was revealed that longer fingers (10 mm) in the finger joints and larger angle joints (70° and 75°) in the scarf-jointed beams enhanced the elastic properties of the beams. Based on these findings, it was concluded that these configurations result in elastic properties that are most similar to those of solid wood. The application of polyvinyl acetate rather than isocyanate significantly (P < 0.05) improved the elastic properties of the joints (both scarf- and finger-jointed beams)