Usporedba procjene oštećenosti krošanja na analognim i digitalnim infracrvenim kolornim (ICK) aerosnimkama

Kolić, Jelena; Ančić, Mario; Samaržija, Mirna; Seletković, Ante; Pernar, Renata

doi:10.31298/sl.146.5-6.2

Cited by 1 publication

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“…The negative consequences of tree dieback are being mitigated by monitoring the status of trees, primarily by assessing tree and crown damage [11][12][13][14]. The primary task is to assess the degree of forest damage and spatial distribution of damaged trees, which can be performed by terrestrial-monitoring or by applying RS methods [15,16], most commonly by interpreting color infrared (CIR) aerial images [15,17,18]. CIR films register the visible and near-infrared (IR) radiation of the Sun reflected from the surface of vegetation, and the amount of this radiation depends on the type of tree and its physiological condition, i.e., health status [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

“…Multispectral images have also been successfully used for mapping individual forest stands [29,30], for crown reconstruction and individual tree phenotyping [31,32], for identification of tree species [33,34] and for determining the health status [15,18,[35][36][37][38][39][40][41][42].…”

Section: Introductionmentioning

confidence: 99%

“…The development of digital cameras has opened new possibilities for using digital CIR aerial photographs to assess damage to both single trees and stands on a digital photogrammetric station (DPS). However, this raises the problem of sample size; namely, in all previous research, a sample in the form of dot grids proved to be best because it is regularly distributed in space but interprets a much larger number of trees while achieving the same reliability in comparison to field assessments [46]. Thus, in order to apply the method in practice, it is necessary to determine the size of a sample that will ensure sufficient reliability in assessing the health status or tree damage in digital CIR aerial images.…”

Section: Introductionmentioning

confidence: 99%

“…For this reason, to define the most appropriate sample sizes that will ensure statistically sufficient reliability of tree health assessment, systematic samples with different dot grid densities-200 × 200 m, 300 × 300 m, 500 × 500 m and 1000 × 1000 m-were set up (Figure 3) with combinations of different numbers of interpreted trees per sample: 1 (A), 2 (AD) and 4 (ABCD) trees (Figure 4). Based on the results of digital aerial imagery photointerpretation, damage indicators (damage, D; mean damage, MD; damage index, DI; mean damage of significantly damaged trees, MD1) were calculated using Formulas ( 1)-( 4) [15,35,50,51] for single tree species and all the interpreted species together, both for individual survey strips and overall for the entire surveyed area (compartments and sub-compartments covered by surveying). Based on the results of digital aerial imagery photointerpretation, damage indicators (damage, D; mean damage, MD; damage index, DI; mean damage of significantly damaged trees, MD 1 ) were calculated using Formulas ( 1)-( 4) [15,35,50,51] for single tree species and all the interpreted species together, both for individual survey strips and overall for the entire surveyed area (compartments and sub-compartments covered by surveying).…”

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confidence: 99%

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Determining the Optimal Sample Size for Assessing Crown Damage on Color Infrared (CIR) Aerial Photographs

Kolić,

Pernar,

Seletković

et al. 2023

Sustainability

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One of the priorities in sustainable forest management is monitoring the health status of trees and stands. From the aspect of remote sensing (RS), the best way of doing this is by interpreting color infrared (CIR) aerial photographs; however, this raises the issue of sample size. For this reason, to apply this method in practice, it is indispensable to determine an appropriate sample size to ensure sufficient reliability of the health status assessment of trees in CIR aerial photographs. This research was conducted in lowland forests of pedunculate oak in Croatia. To determine damage in the photographs of the main tree species, a systematic sample with varying dot grid densities—100 × 100 m, 200 × 200 m, 300 × 300 m, 500 × 500 m, 1000 × 1000 m—was used with combinations of different numbers of interpreted trees per sample. Damage indicators were also calculated based on tree distributions obtained by interpreting four trees, two trees and one tree in different sample sizes. The results of the testing showed that there were no statistically significant differences between different sample densities and numbers of interpreted trees in relation to mean damage assessment. Regardless of the fact that there were no statistically significant differences during damage assessment, it was found that by lowering sample densities, starting with 200 × 200 m, the number of trees and the number of sample points per particular sub-compartment significantly decreased, and so did the desired accuracy. Consequently, the participation (distribution) of particular species and damage degrees in the sample were lost, which significantly affected the overall tree health assessment. In contrast, grid densities of 100 × 100 m with one interpreted tree at the raster point proved to be the optimal sample size. This confirms the fact found in earlier research, that is, that the selected sample should have several spatially well-distributed points with a smaller number of trees in the point, and samples with larger numbers of trees in a smaller number of points should be avoided.

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