Estimating Changes in Leaf Area, Leaf Area Density, and Vertical Leaf Area Profile for Mango, Avocado, and Macadamia Tree Crowns Using Terrestrial Laser Scanning

Vegetation metrics, such as leaf area (LA), leaf area density (LAD), and vertical leaf area profile, are essential measures of tree-scale biophysical processes associated with photosynthetic capacity, and canopy geometry. However, there are limited published investigations of their use for horticultural tree crops. This study evaluated the ability of light detection and ranging (LiDAR) for measuring LA, LAD, and vertical leaf area profile across two mango, macadamia and avocado trees using discrete return data from a RIEGL VZ-400 Terrestrial Laser Scanning (TLS) system. These data were collected multiple times for individual trees to align with key growth stages, essential management practices, and following a severe storm. The first return of each laser pulse was extracted for each individual tree and classified as foliage or wood based on TLS point cloud geometry. LAD at a side length of 25 cm voxels, LA at the canopy level and vertical leaf area profile were calculated to analyse tree crown changes. These changes included: (1) pre-pruning vs. post-pruning for mango trees; (2) pre-pruning vs. post-pruning for macadamia trees; (3) pre-storm vs. post-storm for macadamia trees; and (4) tree leaf growth over a year for two young avocado trees. Decreases of 34.13 m2 and 8.34 m2 in LA of mango tree crowns occurred due to pruning. Pruning for the high vigour mango tree was mostly identified between 1.25 m and 3 m. Decreases of 38.03 m2 and 16.91 m2 in LA of a healthy and unhealthy macadamia tree occurred due to pruning. After flowering and spring flush of the same macadamia trees, storm effects caused a 9.65 m2 decrease in LA for the unhealthy tree, while an increase of 34.19 m2 occurred for the healthy tree. The tree height increased from 11.13 m to 11.66 m, and leaf loss was mainly observed between 1.5 m and 4.5 m for the unhealthy macadamia tree. Annual increases in LA of 82.59 m2 and 59.97 m2 were observed for two three-year-old avocado trees. Our results show that TLS is a useful tool to quantify changes in the LA, LAD, and vertical leaf area profiles of horticultural trees over time, which can be used as a general indicator of tree health, as well as assist growers with improved pruning, irrigation, and fertilisation application decisions.

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Suitability of Airborne and Terrestrial Laser Scanning for Mapping Tree Crop Structural Metrics for Improved Orchard Management

Remote Sensing ◽

10.3390/rs12101647 ◽

2020 ◽

Vol 12 (10) ◽

pp. 1647 ◽

Cited By ~ 2

Author(s):

Dan Wu ◽

Kasper Johansen ◽

Stuart Phinn ◽

Andrew Robson

Keyword(s):

Leaf Area ◽

Laser Scanning ◽

Terrestrial Laser Scanning ◽

Tree Structure ◽

Crown Height ◽

Crown Area ◽

Vertical Leaf ◽

Fractional Cover ◽

Crown Volume ◽

Crown Structure

Airborne Laser Scanning (ALS) and Terrestrial Laser Scanning (TLS) systems are useful tools for deriving horticultural tree structure estimates. However, there are limited studies to guide growers and agronomists on different applications of the two technologies for horticultural tree crops, despite the importance of measuring tree structure for pruning practices, yield forecasting, tree condition assessment, irrigation and fertilization optimization. Here, we evaluated ALS data against near coincident TLS data in avocado, macadamia and mango orchards to demonstrate and assess their accuracies and potential application for mapping crown area, fractional cover, maximum crown height, and crown volume. ALS and TLS measurements were similar for crown area, fractional cover and maximum crown height (coefficient of determination (R2) ≥ 0.94, relative root mean square error (rRMSE) ≤ 4.47%). Due to the limited ability of ALS data to measure lower branches and within crown structure, crown volume estimates from ALS and TLS data were less correlated (R2 = 0.81, rRMSE = 42.66%) with the ALS data found to consistently underestimate crown volume. To illustrate the effects of different spatial resolution, capacity and coverage of ALS and TLS data, we also calculated leaf area, leaf area density and vertical leaf area profile from the TLS data, while canopy height, tree row dimensions and tree counts) at the orchard level were calculated from ALS data. Our results showed that ALS data have the ability to accurately measure horticultural crown structural parameters, which mainly rely on top of crown information, and measurements of hedgerow width, length and tree counts at the orchard scale is also achievable. While the use of TLS data to map crown structure can only cover a limited number of trees, the assessment of all crown strata is achievable, allowing measurements of crown volume, leaf area density and vertical leaf area profile to be derived for individual trees. This study provides information for growers and horticultural industries on the capacities and achievable mapping accuracies of standard ALS data for calculating crown structural attributes of horticultural tree crops.

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Beitrag des terrestrischen Laserscannings zur Erfassung der Struktur von Baumkronen | Application of terrestrial laser scanning for measuring tree crown structures

Schweizerische Zeitschrift fur Forstwesen ◽

10.3188/szf.2011.0186 ◽

2011 ◽

Vol 162 (6) ◽

pp. 186-194 ◽

Cited By ~ 5

Author(s):

Hans Pretzsch ◽

Stefan Seifert ◽

Peng Huang

Keyword(s):

Laser Scanning ◽

Terrestrial Laser Scanning ◽

Tree Crown ◽

Mixed Stands ◽

Individual Tree ◽

Area Index ◽

Tree Crowns ◽

Crown Structure ◽

The Individual ◽

Tree Leaf

This paper addresses the potential of terrestrial laser scanning (TLS) for describing and modelling of tree crown structure and dynamics. We first present a general approach for the metabolic and structural scaling of tree crowns. Out of this approach we emphasize those normalization and scaling parameters which become accessible by TLS. For example we show how the individual tree leaf area index, convex hull, and its space-filling by leaves can be extracted out of laser scan data. This contributes to a theoretical and empirical substantiation of crown structure models which were missing so far for e.g. quantification of structural and species diversity in forest stands, inventory of crown biomass, species detection by remote sensing, and understanding of self- and alien-thinning in pure and mixed stands. Up to now works on this topic delivered a rather scattered empirical knowledge mainly by single inventories of trees and stands. In contrast, we recommend to start with a model approach, and to complete existing data with repeated TLS inventories in order to come to a consistent and theoretically based model of tree crowns.

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Functional Crown Architecture of Five Temperate Broadleaf Tree Species: Vertical Gradients in Leaf Morphology, Leaf Angle, and Leaf Area Density

Forests ◽

10.3390/f10030265 ◽

2019 ◽

Vol 10 (3) ◽

pp. 265 ◽

Cited By ~ 7

Author(s):

Marc Hagemeier ◽

Christoph Leuschner

Keyword(s):

Spatial Distribution ◽

Leaf Area ◽

Tree Species ◽

Leaf Morphology ◽

Leaf Size ◽

Leaf Angle ◽

Area Density ◽

Tree Crowns ◽

Leaf Area Density ◽

Total Leaf

The morphology, inclination, and spatial distribution of leaves in different parts of tree crowns are important determinants of the radiation, momentum, and gas exchange between the canopy and the atmosphere. However, it is not well known how these foliage-related traits vary among species differing in successional status. We measured leaf size, leaf mass area (LMA), leaf inclination (angle to the horizontal), leaf area density (LAD), total leaf area (leaf area index, LAI), and leaf area distribution across the crown in adult trees of five common, early to late-successional tree species (Betula pendula Roth, Quercus petraea (Matt.) Liebl., Carpinus betulus L., Tilia cordata Mill., and Fagus sylvatica L.) using different canopy access techniques and the harvest of foliated trees (29 trees in total). Leaf size increased continuously with crown depth in B. pendula and T. cordata but peaked at mid-crown in Q. petraea, C. betulus, and F. sylvatica to decrease toward the shade crown. By contrast, LMA and leaf angle decreased continuously with crown depth in all species, but the pattern of vertical change varied. The mid/late- and late-successional species had higher LAI, lower shade-leaf LMA, lower leaf angles (shade and sun crown), and higher LAD in the uppermost sun crown in comparison to early successional B. pendula. We assume that the most peripheral sun leaf layer is partly acting as a shield against excess radiation, with foliage properties depending on the structure of the shade crown. We conclude that the vertical change in leaf morphology, inclination, and spatial distribution in tree crowns is highly species specific, with partial dependence on the species’ position in succession.

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Estimation of Pinus massoniana Leaf Area USING Terrestrial Laser Scanning

Forests ◽

10.3390/f10080660 ◽

2019 ◽

Vol 10 (8) ◽

pp. 660 ◽

Cited By ~ 3

Author(s):

Yangbo Deng ◽

Kunyong Yu ◽

Xiong Yao ◽

Qiaoya Xie ◽

Yita Hsieh ◽

...

Keyword(s):

Leaf Area ◽

Point Cloud ◽

Laser Scanning ◽

Terrestrial Laser Scanning ◽

Pinus Massoniana ◽

Accurate Estimation ◽

Point Cloud Data ◽

Individual Tree ◽

Cloud Data ◽

Non Destructive

The accurate estimation of leaf area is of great importance for the acquisition of information on the forest canopy structure. Currently, direct harvesting is used to obtain leaf area; however, it is difficult to quickly and effectively extract the leaf area of a forest. Although remote sensing technology can obtain leaf area by using a wide range of leaf area estimates, such technology cannot accurately estimate leaf area at small spatial scales. The purpose of this study is to examine the use of terrestrial laser scanning data to achieve a fast, accurate, and non-destructive estimation of individual tree leaf area. We use terrestrial laser scanning data to obtain 3D point cloud data for individual tree canopies of Pinus massoniana. Using voxel conversion, we develop a model for the number of voxels and canopy leaf area and then apply it to the 3D data. The results show significant positive correlations between reference leaf area and mass (R2 = 0.8603; p < 0.01). Our findings demonstrate that using terrestrial laser point cloud data with a layer thickness of 0.1 m and voxel size of 0.05 m can effectively improve leaf area estimations. We verify the suitability of the voxel-based method for estimating the leaf area of P. massoniana and confirmed the effectiveness of this non-destructive method.

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Detecting seasonal change of broad-leaved woody canopy leaf area density profile using 3D portable LIDAR imaging

Functional Plant Biology ◽

10.1071/fp09113 ◽

2009 ◽

Vol 36 (11) ◽

pp. 998 ◽

Cited By ~ 19

Author(s):

Fumiki Hosoi ◽

Kenji Omasa

Keyword(s):

Leaf Area ◽

Seasonal Change ◽

Lidar Data ◽

Area Density ◽

Cloud Data ◽

Vertical Leaf ◽

Leaf Area Density ◽

Different Seasons ◽

Lad Estimation ◽

Autumn And Winter

Seasonal change of vertical leaf area density (LAD) profiles of woody canopy broad-leaved trees (Zelkova serrata [Thunberg] Makino) was estimated using 3D portable scanning light detection and ranging (LIDAR) imaging. First, 3D point cloud data for the canopy were collected using a portable LIDAR in spring, summer, autumn and winter. For data collection, the canopy was evenly scanned by the LIDAR from three positions 10 m above the ground. Next, the vertical LAD profile in each season was computed from the LIDAR data using the voxel-based canopy profiling (VCP) method. For the computation, non-photosynthetic tissues were eliminated using the LIDAR data obtained during winter. Influence of leaf inclination angle (LIA) on LAD estimation was corrected by LIA data measured by a high-resolution portable scanning LIDAR. The resultant profiles showed that LAD values tended to increase at the upper canopy from spring to summer and decrease at the middle and lower canopy from summer to autumn. Moreover, LIDAR-derived LIA distributions were compared among different seasons. LIA showed an even distribution in spring but changed to a planophile distribution in summer. In autumn, the angles in the <30° class decreased and those between the 30 and 40°classes increased.

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Retrieval of effective leaf area index (LAIe) and leaf area density (LAD) profile at individual tree level using high density multi-return airborne LiDAR

International Journal of Applied Earth Observation and Geoinformation ◽

10.1016/j.jag.2016.03.014 ◽

2016 ◽

Vol 50 ◽

pp. 150-158 ◽

Cited By ~ 15

Author(s):

Yi Lin ◽

Geoff West

Keyword(s):

Leaf Area Index ◽

Leaf Area ◽

High Density ◽

Airborne Lidar ◽

Tree Level ◽

Individual Tree ◽

Area Index ◽

Area Density ◽

Leaf Area Density ◽

Effective Leaf Area Index

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Estimating cover fraction from TLS return intensity in coniferous and broadleaved tree shoots

Silva Fennica ◽

10.14214/sf.10533 ◽

2021 ◽

Vol 55 (4) ◽

Author(s):

Daniel Schraik ◽

Aarne Hovi ◽

Miina Rautiainen

Keyword(s):

Leaf Area ◽

Laser Scanning ◽

Forest Canopy ◽

Point Clouds ◽

Laser Beams ◽

Experimental Calibration ◽

Area Density ◽

Leaf Area Density ◽

Calibration Measurement ◽

Lidar Return

Terrestrial laser scanning (TLS) provides a unique opportunity to study forest canopy structure and its spatial patterns such as foliage quantity and dispersal. Using TLS point clouds for estimating leaf area density with voxel-based methods is biased by the physical dimensions of laser beams, which violates the common assumption of beams being infinitely thin. Real laser beams have a footprint size larger than several millimeters. This leads to difficulties in estimating leaf area density from light detection and ranging (LiDAR) in vegetation, where the target objects can be of similar or even smaller size than the beam footprint. To compensate for this bias, we propose a method to estimate the per-pulse cover fraction, defined as the fraction of laser beamsâ footprint area that is covered by vegetation targets, using the LiDAR return intensity and an experimental calibration measurement. We applied this method to a Leica P40 single-return instrument, and report our experimental results. We found that conifer foliage had a lower average per-pulse cover fraction than broadleaved foliage, indicating an increased number of partial hits in conifer foliage. We further discuss limitations of our method that stem from unknown target properties that influence the LiDAR return intensity and highlight potential ways to overcome the limitations and manage the remaining uncertainty. Our methodâs output, the per-beam cover fraction, may be useful in a weight function for methods that estimate leaf area density from LiDAR point clouds.

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