Contents lists available at ScienceDirect Journal of Environmental Management journal homepage: www.elsevier.com/locate/jenvman Research article Factors influencing the accuracy of ground-based tree-height measurements for major European tree species Krzysztof Stereńczak a,* , Miłosz Mielcarek a , Bogdan Wertz b , Karol Bronisz c , Grzegorz Zajączkowski a , Andrzej M. Jagodziński d , Wojciech Ochał b , Maciej Skorupski e a Forest Research Institute, Sękocin Stary, Braci Leśnej 3, PL-05-090, Raszyn, Poland b Department of Biometry and Forest Productivity, Faculty of Forestry, University of Agriculture in Krakow, Al. 29 Listopada 46, PL-31-425, Krakow, Poland c Laboratory of Dendrometry and Forest Productivity, Faculty of Forestry, Warsaw University of Life Sciences - SGGW, Nowoursynowska 159, PL-02-787, Warsaw, Poland d Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, PL-62-035, Kórnik, Poland e Department of Game Management and Forest Protection, Faculty of Forestry, Poznań University of Life Sciences, Wojska Polskiego 71c, PL-60-625, Poznań, Poland ARTICLE INFO Keywords: Tree height Absolute error Relative error Ecological study Measurement device ABSTRACT Tree height is one of the most important forest characteristics and is one of the crucial measurements taken for either practical or scientific reasons. However, the accuracy of a tree-height measurement may vary in relation to many factors. The work described here thus sought to evaluate the accuracy of ground-based tree-height mea- surements for major forest-forming tree species of the temperate and boreal zones. The focus was on the im- portance of factors affecting accuracy of the measurements in question at larger geographical scales. In line with the above research goals, data were gathered from 299 stands throughout Poland and heights of 2388 sample trees of eight species, growing in different stands and site conditions, were measured; heights were then com- pared with measured lengths of felled trees as a reference. In total, 10 variables to determine factors that may influence ground-based tree-height measurement accuracy were used. We merged them into 4 groups: mea- surements, topography, stand and biometric-related factors. Results showed that biometric and topographic factors had the greatest relative influence on the accuracy of measurements of tree height. Tree length and species, followed by the slope of the terrain, tree age, and height above sea level were the most important factors found to affect accuracy. In most of the cases studied the terrestrial tree-height measurements were under- estimated when set against definitive measurements of length. This was true for all species studied except oak, for which height measurements were typically overestimated. Notwithstanding the broad geographical scope of the work, the particular device used and the team factor were only found to have a marginal influence on measurement accuracy. 1. Introduction The total height of a tree is defined as the “vertical distance from ground level to its uppermost point” (Schreuder et al., 1993). While it clearly represents a component of fundamental significance to the ecological strategy of any plant species, this plant trait capable of being measured relatively easily has not been the subject of much research in the broader sense. Especially little is known about global patterns characterizing plant height or its variability (Falster and Westoby, 2003; Moles et al., 2009). Height is obviously one of the most important functional traits de- termining response to different environmental factors as well as po- tential influence on ecosystem properties (Cornelissen et al., 2003; Pérez-Harguindeguy et al., 2013). Above all, height could be assumed to be a major determinant of the ability of individuals of any given species to compete for light, and could therefore offer information about an individual's position within the vertical light gradient of a given forest. The benefit of greater height in both intra- and inter- specific competition is access to and potential capture of light (Koch et al., 2004). Given that light is one of the key abiotic resources un- derpinning tree growth and development, competition for it determines the course of further investment in stem-growth (in terms of diameter as well as height), with the consequence that standing biomass pro- duction and allocation change (e.g. Jagodziński and Oleksyn, 2009a, 2009b; Poorter et al., 2015). Moreover, changes in the heights of trees are also used in ecological studies investigating the life histories of https://doi.org/10.1016/j.jenvman.2018.09.100 Received 1 June 2018; Received in revised form 26 September 2018; Accepted 28 September 2018 * Corresponding author. E-mail address: k.sterenczak@ibles.waw.pl (K. Stereńczak). Journal of Environmental Management xxx (xxxx) xxx–xxx 0301-4797/ © 2018 Elsevier Ltd. All rights reserved. Please cite this article as: Stereńczak, K., Journal of Environmental Management, https://doi.org/10.1016/j.jenvman.2018.09.100