Application of LIDAR to forest inventory for tree count in stands of Eucalyptus sp

Luciano Teixeira De Oliveira,Thomaz Chaves De Andrade Oliveira,Luis Marcelo Tavares De Carvalho,Fausto Weimar Acerbi Junior,Maria Zélia Ferreira

doi:10.1590/s0104-77602012000200001

Luciano Teixeira De Oliveira, Thomaz Chaves De Andrade Oliveira + Show 3 more

Open Access

https://doi.org/10.1590/s0104-77602012000200001

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Abstract

Light Detection and Ranging, or LIDAR, has become an effective ancillary tool to extract forest inventory data and for use in other forest studies. This work was aimed at establishing an effective methodology for using LIDAR for tree count in a stand of Eucalyptus sp. located in southern Bahia state. Information provided includes in-flight gross data processing to final tree count. Intermediate processing steps are of critical importance to the quality of results and include the following stages: organizing point clouds, creating a canopy surface model (CSM) through TIN and IDW interpolation and final automated tree count with a local maximum algorithm with 5 x 5 and 3 x 3 windows. Results were checked against manual tree count using Quickbird images, for verification of accuracy. Tree count using IDW interpolation with a 5x5 window for the count algorithm was found to be accurate to 97.36%. This result demonstrates the effectiveness of the methodology and its use potential for future applications.

Highlights

With the expansion of the forestry sector and with timber increasingly becoming a scarce commodity, it becomes vital that long, medium- and short-term planning be more and more accurate to ensure timber availability over time, maximizing timber yield and reducing production costs.Bearing this in mind, forest planners are more and more in search of tools from which to derive accurate information on current forest stock, looking to model future forest yield
Data obtained with the local maximum algorithm using 3 x 3 filtering (Tables 2 and 3) were not as effective if compared with results obtained using 5 x 5 filtering (Tables 4 and 5), since all results found with 3 x 3 filtering tended to overestimate the number of individuals in the stand, generating a higher error of commission
This result contrasted with the result obtained with 5 x 5 filtering, which tended to underestimate the population in both stands and detected values closer to reality, with a minor error of omission. This result relates to the spacing being used in the plantation (4 x 3), suggesting that if spacing is reduced in the study site, the 3 x 3 filter may have better performance while the 5 x 5 filter, worse

Summary

Introduction

With the expansion of the forestry sector and with timber increasingly becoming a scarce commodity, it becomes vital that long-, medium- and short-term planning be more and more accurate to ensure timber availability over time, maximizing timber yield and reducing production costs.Bearing this in mind, forest planners are more and more in search of tools from which to derive accurate information on current forest stock, looking to model future forest yield. This type of inventory, permanent plots are installed when stands reach age two or three years, being systematically remeasured at intervals of one to two years (KANEGAE JUNIOR et al, 2006; OLIVEIRA, 2006) It has been observed, that some inconsistencies may be associated with conventional inventories, including bias in diameter and height mensurations, error in data handling, error in plot area measurements and, especially, errors associated with the sampling procedure, which may vary depending on the dendrometric variable being analyzed, being high for the variable ‘number of trees per hectare’. Sampling errors can only be resolved if a census is conducted in the relevant area

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