Fearscapes: Mapping Functional Properties of Cover for Prey with Terrestrial LiDAR

Heterogeneous vegetation structure can create a variable landscape of predation risk—a fearscape—that influences the use and selection of habitat by animals. Mapping the functional properties of vegetation that influence predation risk (e.g., concealment and visibility) across landscapes can be challenging. Traditional ground-based measures of predation risk are location specific and limited in spatial resolution. We demonstrate the benefits of terrestrial laser scanning (TLS) to map the properties of vegetation structure that shape fearscapes. We used TLS data to estimate the concealment of prey from multiple vantage points, representing predator sightlines, as well as the visibility of potential predators from the locations of prey. TLS provides a comprehensive data set that allows an exploration of how habitat changes may affect prey and predators. Together with other remotely sensed imagery, TLS could facilitate the scaling up of fearscape analyses to promote the management and restoration of landscapes

TERRESTRIAL LASER SCANNER FOR METRIC EXTRACTION IN EUCALYPTUS UNDER DIFFERENT IMPLANTATION SYSTEMS

This study evaluates the influence of the cropping system in the extraction of Eucalyptus benthamii metrics by terrestrial laser scanner (TLS) and by traditional inventory. The hypothesis is that the extraction methods do not differ significantly from each other. The study area consists of a conventional planting system under 3 x 2 m spacing, and a CFI (crop-forest integration) system under 14 x 2 m spacing. To obtain the variables DBH (diameter at 1.3 m aboveground) and total height (H), we used a traditional inventory and collected data with TLS. For point cloud processing, we manually extracted the metrics DBH and H by simple scanning. We estimated total volume (V) by a fitted equation that matches the characteristics of the study area. To estimate above-ground biomass (AGB), we fitted models based on AGB data provided by the NITA project and by BIOFIX. Better visualization of trees in the CFI system facilitated metric extraction, leading to less data variability. In addition, DBH, V, and AGB values were higher in the CFI system compared to the conventional system. However, when including the number of trees per hectare, the conventional system is more productive. The initial hypothesis was confirmed. Therefore, metric extraction using the traditional inventory and TLS methods did not differ significantly for the two cropping systems considered

Estimating residual biomass of olive tree crops using terrestrial laser scanning

[EN] Agricultural residues have gained increasing interest as a source of renewable energy. The development of methods and techniques that allow to inventory residual biomass needs to be explored further. In this study, the residual biomass of olive trees was estimated based on parameters derived from using a Terrestrial Laser Scanning System (TLS). To this end, 32 olive trees in 2 orchards in the municipality of Viver, Central Eastern Spain, were selected and measured using a TLS system. The residual biomass of these trees was pruned and weighed. Several algorithms were applied to the TLS data to compute the main parameters of the trees: total height, crown height, crown diameter and crown volume. Regarding the last parameter, 4 methods were tested: the global convex hull volume, the convex hull by slice volume, the section volume, and the volume measured by voxels. In addition, several statistics were computed from the crown points for each tree. Regression models were calculated to predict residual biomass using 3 sets of potential explicative variables: firstly, the height statistics retrieved from 3D cloud data for each crown tree, secondly, the parameters of the trees derived from TLS data and finally, the combination of both sets of variables. Strong relationships between residual biomass and TLS parameters (crown volume parameters) were found (R2 = 0.86, RMSE = 2.78 kg). The pruning biomass pre- diction fraction was improved by 6%, in terms of R2, when the variance of the crown-point elevations was selected (R2 = 0.92, RMSE = 2.01 kg). The study offers some important insights into the quantification of residual biomass, which is essential information for the production of biofuel.Fernández-Sarría, A.; López- Cortés, I.; Estornell Cremades, J.; Velázquez Martí, B.; Salazar Hernández, DM. (2019). Estimating residual biomass of olive tree crops using terrestrial laser scanning. International Journal of Applied Earth Observation and Geoinformation. 75:163-170. https://doi.org/https://doi.org/10.1016/j.jag.2018.10.019S1631707

Detecting changes in forest structure over time with bi-temporal terrestrial laser scanning data

Peer reviewe

Application of handheld laser scanning technology for forest inventory purposes in the NE Turkey

Forest inventory (FI) is the most challenging stage of forest management and planning process. Therefore, in situ surveys are often reinforced by modern remote sensing (RS) methods for collecting forestry-related data more efficiently. This study tests a state-of-the-art data collection method for practical use in the Turkish FI system for the first time. To this end, forest sampling plots were conventionally measured to collect dendrometric data from 437 trees in Artvin and Saçınka Forest Enterprises. Then, each plot was scanned using a handheld mobile laser scanning (HMLS) instrument. Finally, HMLS data were compared against ground measurements via basic FI measures. Based on statistical tests, no apparent differences were found between the two datasets at the plot level (P 0.97; P < 0.01). Residual analysis showed that both positive and negative errors had a homogeneous distribution, except for plot 8 where tree stems were in irregular shapes due to anthropogenic pressures. When all plots’ data were aggregated, average values for the number of trees, basal area, and timber volume were estimated as 535 trees/ha–1, 49.6 m2/ha–1, and 499.7 m3/ha–1, respectively. Furthermore, secondary measures such as the number of saplings and slope were successfully retrieved using HMLS method. The highest overestimation was in timber volume with less than 10% difference at the landscape level. The differences were attributed to poor data quality of conventional measurements, as well as marginal site conditions in some plots. We concluded that the HMLS method met the accuracy standards for most FI measures, except for stand height. Thus, the Turkish FI system could benefit from this novel technology, which in turn supports the implementation of sound forest management and planning

Urban-Tree-Attribute Update Using Multisource Single-Tree Inventory

Peer reviewe

Aplicação da varredura laser terrestre em plantios clonais de Eucalyptus spp para determinação do número de árvores e estudos diamétricos

Orientador : Profª. Drª. Christel LingnauCoorientadores : Prof. Dr. Alvaro Muriel Lima Machado e Prof. Dr. Afonso Figueiredo FilhoTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Agrárias, Programa de Pós-Graduação em Engenharia Florestal. Defesa: Curitiba, 28/05/2015Inclui referências : f. 79-85Área de concentração : Manejo florestalResumo: O objetivo desta pesquisa foi avaliar a aplicação da varredura laser terrestre simples e múltipla na detecção de árvores e na determinação do DAP em plantios clonais de Eucalyptus spp, considerando diferentes posicionamentos do equipamento e tamanho de unidades amostrais. O equipamento Trimble TX5 foi posicionado no centro e em quatro pontos externos à unidade amostral circular formando um quadrilátero. A varredura simples foi testada apenas com a posição do equipamento no centro da unidade amostral. Para varreduras múltiplas foram avaliadas dois e três arranjos de varredura, as quais levam em consideração a posição do equipamento em relação às linhas de plantio. A detecção automática de árvores foi realizada a partir do algoritmo baseado em uma malha de projeção de pontos 2D, onde unidades amostrais circulares de 200, 300 e 400 m² foram avaliadas. A determinação do DAP foi realizada pelo algoritmo de distância máxima, considerando os diferentes tamanhos das unidades amostrais para varreduras simples e múltiplas. A varredura simples, para a idade de 2 anos sem desrama, apresentou ótimos resultados, sendo que 100% das árvores em unidades amostrais de 200 e 300 m² foram detectadas. Para as idades de 2, 4,5 e 5,5 anos em unidades amostrais de 300 e 400 m², não foi possível a detecção de 100% das árvores com varredura simples, pois à medida que aumenta o diâmetro a acurácia diminui. A análise sobre varreduras múltiplas com dois posicionamentos do equipamento laser possibilitou a detecção de 100% das árvores nos três tamanhos de unidades amostrais até a idade de 4,5 anos. Para a idade de 5,5 anos, verificou-se a necessidade de empregar três varreduras para detecção de todas as árvores devido aos maiores diâmetros. A determinação do diâmetro médio para todas as idades não apresentou diferença estatística no nível de 95% de probabilidade, com erros variando entre -5,3% a 4,7%. Os resultados indicam que o número de varreduras com o intuito de detectar 100% das arvores está relacionado principalmente com o DAP médio, considerando o espaçamento de plantio neste estudo de caso.Abstract: The objective of this research was to evaluate the use of single and multiple terrestrial laser scanning in detecting trees and in determining DBH in clonal plantations of Eucalyptus spp at varying equipment locations and in varying sample unit sizes. Trimble TX5 units were positioned in the center and at four locations external to the circular sample unit in the form of a quadrilateral. A simple scan was tested only at the center location of each sample unit. For multiple scans two and three scanning arrangements were assessed, taking into account the position of the equipment with respect to the plantation rows. Automatic detection was performed on trees using an algorithm based on grid of 2D projection points where circular sampling units of 200, 300 and 400 m² were evaluated. DBH was determined using the maximum distance algorithm, considering both the various sample unit sizes and single or multiple scan regime. A simple scan of a 2-year-old unpruned trees yielded excellent results, with 100% detection of the trees in sampling units within 200 and 300 meters. Meanwhile 100% of 2, 4.5 and 5.5-year-old trees in sample units of 300 and 400 m², could not be detected with a simple scan, because as diameter increases accuracy decreases. The analysis of multiple scans using laser equipment placed at two locations enabled detection of 100% of the trees in three sample unit sizes in trees up to 4.5 years old. At age 5.5 years, three scans were required to detect all trees because of their larger diameters. There was no statistical difference (at 95% probability) between mean diameters of an age group, with errors ranging from -5.3% to 4.7%. Results indicate that in order to detect 100% of the trees, the number of scans depends largely on the average DBH, given the plant spacing in this case study

Terrestrial Laser Scanning data processing: development of a new methodology applied to mixed forests.

El poder conocer variables dendrométricas para los inventarios forestales de forma rápida y con el mínimo error posible es hoy en día posible gracias al uso de Láser Escáner Terrestre (TLS) con el que se obtienen nubes de puntos 3D con gran cantidad de detalle de la que podemos extraer prácticamente cualquier variable del árbol. Sin embargo el procesado de los datos es largo y en muchos de los caso, complicado. El objetivo de este estudio ha sido desarrollar una metodología combinando varios programas informáticos que nos permita obtener datos de una manera semiautomática, y de forma objetiva en una masa de mixta de Pinus sylvestris y Quercus pyrenaica del norte de España. Nuestros datos han sido evaluados en 15 árboles de cada especie ajustando modelos predictivos básicos y expandidos para evaluar el efecto de la mezcla sobre las variables dendrométricas. Los resultados muestran que la metodología seguida permite obtener medidas fiables de los árboles y podrá ser aplicable a nivel masa en futuros estudios.Departamento de Producción Vegetal y Recursos ForestalesMáster en Investigación en Ingeniería para la Conservación y Uso Sostenible de Sistemas ForestalesPremio San Isidro otorgado por la Escuela Técnica Superior de Ingenierías Agrarias (Palencia