Field methods for sampling tree height for tropical forest biomass estimation

Quantifying the relationship between tree diameter and height is a key component of efforts to estimate biomass and carbon stocks in tropical forests. Although substantial site‐to‐site variation in height–diameter allometries has been documented, the time consuming nature of measuring all tree heights in an inventory plot means that most studies do not include height, or else use generic pan‐tropical or regional allometric equations to estimate height. Using a pan‐tropical dataset of 73 plots where at least 150 trees had in‐field ground‐based height measurements, we examined how the number of trees sampled affects the performance of locally derived height–diameter allometries, and evaluated the performance of different methods for sampling trees for height measurement. Using cross‐validation, we found that allometries constructed with just 20 locally measured values could often predict tree height with lower error than regional or climate‐based allometries (mean reduction in prediction error = 0.46 m). The predictive performance of locally derived allometries improved with sample size, but with diminishing returns in performance gains when more than 40 trees were sampled. Estimates of stand‐level biomass produced using local allometries to estimate tree height show no over‐ or under‐estimation bias when compared with biomass estimates using field measured heights. We evaluated five strategies to sample trees for height measurement, and found that sampling strategies that included measuring the heights of the ten largest diameter trees in a plot outperformed (in terms of resulting in local height–diameter models with low height prediction error) entirely random or diameter size‐class stratified approaches. Our results indicate that even limited sampling of heights can be used to refine height–diameter allometries. We recommend aiming for a conservative threshold of sampling 50 trees per location for height measurement, and including the ten trees with the largest diameter in this sample.

[1]  Ariel E. Lugo,et al.  Biomass Estimation Methods for Tropical Forests with Applications to Forest Inventory Data , 1989, Forest Science.

[2]  Stephen P. Hubbell,et al.  Diameter, Height, Crown, and Age Relationship in Eight Neotropical Tree Species , 1995 .

[3]  M. G. Ryan,et al.  Hydraulic Limits to Tree Height and Tree Growth , 1997 .

[4]  S. T. Buckland,et al.  ANALYSIS OF POPULATION TRENDS FOR FARMLAND BIRDS USING GENERALIZED ADDITIVE MODELS , 2000 .

[5]  O. Phillips,et al.  Field Manual for plot establishment and remeasurement , 2002 .

[6]  O. Phillips,et al.  An international network to monitor the structure, composition and dynamics of Amazonian forests (RAINFOR) , 2002 .

[7]  J. L. Parra,et al.  Very high resolution interpolated climate surfaces for global land areas , 2005 .

[8]  J. Chambers,et al.  Tree allometry and improved estimation of carbon stocks and balance in tropical forests , 2005, Oecologia.

[9]  S. Wood.  Generalized Additive Models: An Introduction with R , 2006 .

[10]  Alan Y. Chiang,et al.  Generalized Additive Models: An Introduction With R , 2007, Technometrics.

[11]  J. Elith,et al.  Species Distribution Models: Ecological Explanation and Prediction Across Space and Time , 2009 .

[12]  J. Chave,et al.  Towards a Worldwide Wood Economics Spectrum 2 . L E a D I N G D I M E N S I O N S I N W O O D F U N C T I O N , 2022 .

[13]  D. A. King,et al.  Height-diameter allometry of tropical forest trees , 2010 .

[14]  R. B. Jackson,et al.  A Large and Persistent Carbon Sink in the World’s Forests , 2011, Science.

[15]  W. Salas,et al.  Benchmark map of forest carbon stocks in tropical regions across three continents , 2011, Proceedings of the National Academy of Sciences.

[16]  O. Phillips,et al.  ForestPlots.net: a web application and research tool to manage and analyse tropical forest plot data , 2011 .

[17]  S. Goetz,et al.  Estimated carbon dioxide emissions from tropical deforestation improved by carbon-density maps , 2012 .

[18]  J. Terborgh,et al.  Tree height integrated into pantropical forest biomass estimates , 2012 .

[19]  D. A. King,et al.  What controls tropical forest architecture: testing environmental, structural and floristic drivers , 2012 .

[20]  David Kenfack,et al.  Scale‐dependent relationships between tree species richness and ecosystem function in forests , 2013 .

[21]  F. Rovero,et al.  Large trees drive forest aboveground biomass variation in moist lowland forests across the tropics , 2013 .

[22]  J. Bogaert,et al.  Conventional tree height–diameter relationships significantly overestimate aboveground carbon stocks in the Central Congo Basin , 2013, Nature Communications.

[23]  Gregory P. Asner,et al.  Hydrological Networks and Associated Topographic Variation as Templates for the Spatial Organization of Tropical Forest Vegetation , 2013, PloS one.

[24]  Louis V. Verchot,et al.  Generic allometric models including height best estimate forest biomass and carbon stocks in Indonesia , 2013 .

[25]  Sean C. Thomas,et al.  Above-ground biomass and structure of 260 African tropical forests , 2013, Philosophical Transactions of the Royal Society B: Biological Sciences.

[26]  Helene C. Muller-Landau,et al.  Measuring tree height: a quantitative comparison of two common field methods in a moist tropical forest , 2013 .

[27]  B. Nelson,et al.  Improved allometric models to estimate the aboveground biomass of tropical trees , 2014, Global change biology.

[28]  O. Phillips,et al.  Tropical forest wood production: a cross‐continental comparison , 2014 .

[29]  R Core Team,et al.  R: A language and environment for statistical computing. , 2014 .

[30]  Jean-Jacques Boreux,et al.  Predicting tree heights for biomass estimates in tropical forests – a test from French Guiana , 2014 .

[31]  N. Laporte,et al.  Carbon stock corridors to mitigate climate change and promote biodiversity in the tropics , 2014 .

[32]  Adam R. Martin,et al.  Tropical trees in a wind‐exposed island ecosystem: height‐diameter allometry and size at onset of maturity , 2015 .

[33]  H. Beeckman,et al.  Seeing Central African forests through their largest trees , 2015, Scientific Reports.

[34]  R. Dubayah,et al.  Small Sample Sizes Yield Biased Allometric Equations in Temperate Forests , 2015, Scientific Reports.

[35]  J. Terborgh,et al.  Long-term decline of the Amazon carbon sink , 2015, Nature.

[36]  Andrej-Nikolai Spiess,et al.  Title R interface to the Levenberg-Marquardt nonlinear least-squares algorithm found in MINPACK, plus support for bounds , 2015 .

[37]  J. Doucet,et al.  Taller trees, denser stands and greater biomass in semi-deciduous than in evergreen lowland central African forests , 2016 .

[38]  N. Picard,et al.  Tree allometry for estimation of carbon stocks in African tropical forests , 2016 .

[39]  P. Pétronelli,et al.  Tree Height Reduction After Selective Logging in a Tropical Forest , 2016 .

[40]  Stephanie A. Bohlman,et al.  Dominance of the suppressed: Power-law size structure in tropical forests , 2016, Science.

[41]  J. Illian,et al.  Re-evaluation of individual diameter : height allometric models to improve biomass estimation of tropical trees. , 2016, Ecological applications : a publication of the Ecological Society of America.

[42]  Arief Wijaya,et al.  An integrated pan‐tropical biomass map using multiple reference datasets , 2016, Global change biology.

[43]  J. Chave,et al.  biomass: an r package for estimating above‐ground biomass and its uncertainty in tropical forests , 2017 .

[44]  Mark C. Vanderwel,et al.  Allometric equations for integrating remote sensing imagery into forest monitoring programmes , 2016, Global change biology.

[45]  Neil D. Burgess,et al.  New insights on above ground biomass and forest attributes in tropical montane forests , 2017 .

[46]  R. Primack,et al.  Long-term carbon sink in Borneo’s forests halted by drought and vulnerable to edge effects , 2017, Nature Communications.

[47]  J. Bauhus,et al.  Diversity and competition influence tree allometric relationships – developing functions for mixed‐species forests , 2017 .

[48]  J. Chave,et al.  Estimating the aboveground biomass in an old secondary forest on limestone in the Moluccas, Indonesia: Comparing locally developed versus existing allometric models , 2017 .