Tree Damage Research Articles

Self-healing of electrical tree damage of polyethylene/microcapsules insulation composite material

During the use of polyethylene (PE) cable in power systems, electrical tree damages can inevitably occur inside the insulation materials, causing partial discharges and threatening the safety of the power supply. It is difficult to detect the micro damages inside the materials by existing technology, and replacing cables creates a lot of solid waste. The microcapsule self-healing technology derived from bionics can automatically detect and heal micro damages inside the material in time, avoiding accidents and saving resources. In this paper, the self-healing abilities and mechanism of the PE/microcapsule composite materials to the electrical tree damage are studied by means of experiments and simulation. PE/microcapsule composite materials are prepared, and the composite material with 1 wt% microcapsule is demonstrated to have better insulation strength. Microcapsules can attract the development of electric trees and limit their size, while the electrical tree can trigger the self-healing behavior of microcapsules in time. The self-healing behavior can effectively heal the electrical tree branch channel, restore breakdown strength and polarization current, and reverse the deterioration process of the material. Molecular dynamics (MD) simulation confirms that there is good chemical compatibility between the healing product and PE matrix, ensuring a good self-healing effect.

Growth and formation of Scots pine stands in Eastern Polissia of Ukraine

Abstract The purpose of the research is to study the current state, features of growth and formation of Scots pine (Pinus sylvestris L.) stands in Eastern Polissia of Ukraine. The structure of pine stands by origin, age, the density of stocking, site indices, forest types and health condition was analysed. Features of the formation of stands were studied at the permanent sample plots. Visual assessment of health condition, as well as signs of pest and disease damage of trees, other defects and external signs that caused stem defects was carried out. The age structure of pine stands was not optimal: there was an excess of mature stands and a lack of young stands. The health condition of mixed pine stands was relatively better than that of pure pine stands. Mixed pine stands were characterised by high biological resistance and accumulated significant wood stock under regular sylvicultural maintenance. The dynamics of forestry and evaluation indicators of reference pine stands were evaluated and comparison of their growth with stocked pine stands was performed.

Termite diversity and damage assessment in urban trees from different parks of Lahore, Punjab, Pakistan.

Termite infestation is one of the fundamental problems associated with the loss of urban trees and ecological services. However, no such study has been performed in Pakistan to investigate the termite occurrence and assess such damages to urban trees caused by termites. For Lahore, research and comparable data on urban tree damages are rare or missing. This study surveyed six different microhabitats, including Bagh-e-Jinnah, canal vegetation, Model Town Park, Jallo Forestry, Race-Course Park, and FC College Vegetation employing the three belt transects (100 × 5m) method. We geo-referenced termite-infested trees to investigate the termite occurrence on living and dead standing trees, termite diversity, and the assessment of tree damage by termites' attack. We recorded four termite species (Odontotermes obesus Rambur, Coptotermes heimi Wasmann, Heterotermes indicola Wasmann, and Microtermes obesi Holmgren) representing two families (Rhinotermitidae and Termitidae). However, the diversity indices revealed that O. obesus (higher termite) and C. heimi (lower termite) were dominant with 46.60 and 36% of occurrence among observed trees, respectively. Kernel density function indicated that the Lahore Canal and Bagh-e-Jinnah plantation shared all four termites' infestation evenly compared to other study sites. We observed the maximum number of damaged trees by termites in canal vegetation with the most damaged exotic tree species Populus euramericana along the canal green belt. Additionally, we observed significant (P < 0.05) termite-tree interactions with exotic, living, and dead standing tree species and found termite colony size positively (R = 0.985) correlated with the tree trunk diameter up to breast height (DBH). The average population of termites per unit volume of deadwood log was (0.39/cm3) within all plantation sites. In conclusion, this study provides simple, reckless, and inexpensive knowledge about the assessment of termite damage to trees, which may give a better idea in making decisions on tree selection and management in urban ecosystems.

Environmental Impacts of Boom-Corridor and Selectively Thinned Small-Diameter-Tree Forests

European forest stands of small-diameter trees can provide industries with biomass as an alternative to fossil use. Small-tree harvesting is costly using conventional methods but using accumulating felling heads (AFH) in combination with a novel boom-corridor thinning (BCT) technique can increase harvester productivity and supply cost efficiency. This method has great potential to reduce costs, but its environmental impact compared with selective thinning (ST) needs to be determined. The objectives of this study were therefore to quantify and compare tree and soil damage as well as air, water and soil emissions for both BCT and ST in various European small-diameter-tree forests. Trials were performed in 84 study units (42 replications per thinning technique) across four countries. Damaged trees (with a diameter at breast height ≥ 7 cm) were measured after thinning and after forwarding. Harvesting emissions were calculated from a life cycle assessment. The percentage of remaining trees that had been damaged by the harvesting processes was 13% and 19% for BCT and ST, respectively, and the difference was significant. BCT exhibited the lowest emissions in all environmental impact categories considered, in all countries. Greenhouse gas emissions were on average 17% lower for BCT. BCT in small-diameter-tree stands therefore reduces the environmental impact of thinning operations compared with conventional methods, and results in less damage to the remaining trees.

Fire severity assessment on peatland vegetation diversity

Forest fires have a significant impact on peatland ecosystem, including its vegetation diversity. Several approaches applied for forest fire severity assessment are available in the literature. This study aimed to implement field-based and spatial-aware fire severity assessments and to compare both approaches. Peat swamp forests of Ogan Komering Ilir, South Sumatera Province, for field assessment and Siak, Riau Province, for spatial assessment were selected in this research. Field-based fire severity assessment used indicators of vegetation analyses (individual tree damages, burned vegetation severity, and diversity index), which were measured and analyzed from sample plots in both burned and unburned areas. Spatial analyses of fires severity assessment employed Sentinel-2 satellite imagery with Normalized Burn Ratio (NBR) approach. The research revealed a significant change in tree species diversity, indicating a lower diversity in burned areas than the ones in pristine fields. Magnitude of changes in diversity was influenced by fire severity levels in burned areas and pre-fire condition of burned areas. Spatial analyses indicated low to high fire severity with burned area estimation for each fire severity class. Both approaches have their own benefits and challenges. Field-based severity assessment is beneficial for a detailed assessment of fire damages and losses, whereas spatial analyses would be considered for a broader estimation of fire severity. Both assessments are mutually implemented. Field-based assessment can serve as a verification tool for spatial assessment.

An Integration of Linear Model and ‘Random Forest’ Techniques for Prediction of Norway Spruce Vitality: A Case Study of the Hemiboreal Forest, Latvia

The increasing extreme weather and climate events have a significant impact on the resistance and resilience of Norway spruce trees. The responses and adaptation of individual trees to certain factors can be assessed through the tree breeding programmes. Tree breeding programmes combined with multispectral unmanned aircraft vehicle (UAV) platforms may assist in acquiring regular information of individual traits from large areas of progeny trials. Therefore, the aim of this study was to investigate the vegetation indices (VI) to detect the early stages of tree stress in Norway spruce stands under prolonged drought and summer heatwave. Eight plots within four stands throughout the vegetation season of 2021 were monitored by assessing spectral differences of tree health classes (Healthy, Crown damage, New crown damage, Dead trees, Stem damage, Root rot). From all tested VI, our models showed a moderate marginal R2 and total explanatory power—for Normalized Difference Red-edge Index (NDRE), marginal R2 was 0.26, and conditional R2 was 0.49 (p &lt; 0.001); for Normalized Difference Vegetation Index (NDVI), marginal R2 was 0.34, and conditional R2 was 0.60 (p &lt; 0.001); for Red Green Index (RGI), marginal R2 was 0.36, and conditional R2 was 0.55 (p &lt; 0.001); while for Chlorophyll Index (CI), marginal R2 was 0.27, and conditional R2 was 0.49 (p &lt; 0.001). The reliability of the identification of tree health classes for selected VI was weak to fair (overall classification accuracy ranged from 34.4% to 56.8%, kappa coefficients ranged from 0.09 to 0.34) if six classes were assessed, and moderate to substantial (overall classification accuracy ranged from 71.1% to 89.6% and kappa coefficient from 0.39 to 0.71) if two classes (Crown damage and Healthy trees) were tested.

Effects of heat and drought stress on the health status of six urban street tree species in Leipzig, Germany

Trees are one of the most important elements of green infrastructure in cities. Climate change is specifically affecting trees in many European cities. Trees are experiencing negative impacts from the increase in heat waves and droughts, both of which begin, in some cases, early in the year and continue through the growing season. Current studies on the regionalization of climate change indicate that important water reservoirs such as soil and tree canopies have been drying out for years/decades, and these impacts can be observed in various parts of Europe. Trees react to stress as they age through mechanisms such as crown defoliation, early wilting, shedding of branches and, ultimately, lowered resistance to pests. As a result, massive tree death, both in park trees and street trees, can be observed in many cities. The present study provides a current inventory of street tree damage caused by heat and drought in the city of Leipzig, Germany, in 2020, the third extreme dry year after 2018 and 2019. The field maps focus on different age groups of Quercus, Tilia, Aesculus, Platanus, Fraxinus and Acer along a periurban-urban gradient. The results are clear: significant damage was found in all tree species. Older trees and newly planted trees are most likely to die as a result of extreme conditions, while younger trees with narrow trunks and crowns that have not yet expanded cope better with both heat and drought. Four out of five mapped street trees showed recognizable damage, indicating severe impacts of climate change on important elements of green infrastructure in cities.

Noninvasive Sonic Tomography for Detecting Internal Defects in Old, Large Oriental White Oak in Cultural Heritage Areas

Incidence rates of tree damage are increasing because of the increased intensity and frequency of abnormal climate events such as strong winds and heavy rains. Structural defects inside trees are difficult to detect by visual inspection; therefore, it is difficult to respond to them in advance based on prediction. Noninvasive sonic tomography (SoT) is a method that estimates internal defects while minimizing physical damage to trees; however, its accuracy differs depending on the species. Therefore, in this study, we aimed to compare the performance of noninvasive SoT and invasive resistance micro-drilling (RM) in detecting tree damage in oriental white oak (Quercus aliena Blume) distributed in East Asia and performed wood section analysis to verify the accuracy of noninvasive SoT. Linear regression analysis showed that defects in tomograms tended to increase with an increase in the number of defects in the RM profile, but the value of R2 was 0.405, which is lower than that of other tree species. The results from the wood section analysis and SoT were compared; the SoT tomograms appropriately reflected the location and size of the defects with a tendency to overestimate the defects when cracks were present, while the electric resistance tomography was effective for detecting incipient decay.

Estimating Tree Defects with Point Clouds Developed from Active and Passive Sensors

Traditional inventories require large investments of resources and a trained workforce to measure tree sizes and characteristics that affect wood quality and value, such as the presence of defects and damages. Handheld light detection and ranging (LiDAR) and photogrammetric point clouds developed using Structure from Motion (SfM) algorithms achieved promising results in tree detection and dimensional measurements. However, few studies have utilized handheld LiDAR or SfM to assess tree defects or damages. We used a Samsung Galaxy S7 smartphone camera to photograph trees and create digital models using SfM, and a handheld GeoSLAM Zeb Horizon to create LiDAR point cloud models of some of the main tree species from the Pacific Northwest. We compared measurements of damage count and damage length obtained from handheld LiDAR, SfM photogrammetry, and traditional field methods using linear mixed-effects models. The field method recorded nearly twice as many damages per tree as the handheld LiDAR and SfM methods, but there was no evidence that damage length measurements varied between the three survey methods. Lower damage counts derived from LiDAR and SfM were likely driven by the limited point cloud reconstructions of the upper stems, as usable tree heights were achieved, on average, at 13.6 m for LiDAR and 9.3 m for SfM, even though mean field-measured tree heights was 31.2 m. Our results suggest that handheld LiDAR and SfM approaches show potential for detection and measurement of tree damages, at least on the lower stem.

The slow invasion of England by the non-native Edible Dormouse (Glis glis): where and how many after 120 years?

Since the Edible Dormouse (Glis glis) was introduced to England in 1902, it very slowly invaded a wider area west of London. A recent and more rapid increase in both numbers and distribution is reported. Regular population monitoring for 23 years by volunteers at a woodland study site using nestboxes, and microchipping individuals, confirmed consistently increasing numbers. Independent reports of culling in buildings (under Licence) also indicates an increasing level of conflict. As part of a formal assessment of all British mammals published in 2018, the Glis population size was unfortunately based on estimated density data from two decades ago, indicating &amp;lt;1/ha. This was in a non-breeding year, when evidence indicates many marked adult Glis are not available to be counted, but re-appear the next year. We compare more recent information using a variety of different methods of density estimation which each indicate the total population to be at least an order of magnitude greater at 10-20 adults/ha. Our interpretation of these analyses discounts the suggestion that nestbox presence alone has directly caused the population increase, as happens with some bird species. Additionally, evidence from culls in woodland match our live capture population estimates. The principal aim of the national Invasive Species Strategy is to minimise the risk and negative impacts of invasive non-native species in Great Britain. Edible Dormice damage trees, predate nests of woodland birds and cause problems in the built environment. Our updated estimates affect the seriousness with which this slowly invading species should be regarded.

An Approach to Estimate Individual Tree Ages Based on Time Series Diameter Data—A Test Case for Three Subtropical Tree Species in China

Accurate knowledge of individual tree ages is critical for forestry and ecological research. However, previous methods suffer from flaws such as tree damage, low efficiency, or ignoring autocorrelation among residuals. In this paper, an approach for estimating the ages of individual trees is proposed based on the diameter series of Cinnamomum camphora (Cinnamomum camphora (L.) Presl), Schima superba (Schima superba Gardn. et Champ.), and Liquidambar formosana (Liquidambar formosana Hance). Diameter series were obtained by stem analysis. Panel data contains more information, more variability, and more efficiency than pure time series data or cross-sectional data, which is why diameter series at stump and breast heights were chosen to form the panel data. After choosing a base growth equation, a constraint was added to the equation to improve stability. The difference method was used to reduce autocorrelation and the parameter classification method was used to improve model suitability. Finally, the diameter increment equation of parameter a-classification was developed. The mean errors of estimated ages based on the panel data at breast height for C. camphora, S. superba, and L. formosana were 0.47, 2.46, and −0.56 years and the root mean square errors were 2.04, 3.15 and 2.47 years, respectively. For C. camphora and L. formosana, the estimated accuracy based on the panel data was higher at breast height than at stump height. This approach to estimating individual tree ages is highly accurate and reliable, and provides a feasible way to obtain tree ages by field measurement.

PENILAIAN KERUSAKAN POHON AKIBAT AKTIVITAS WISATA DI BUMI PERKEMAHAN KUBU PERAHU TAMAN NASIONAL BUKIT BARISAN SELATAN (TNBBS)

Kubu Perahu Camp Ground is the tourist destinations in the Bukit Barisan Selatan National Park (TNBBS), located in Pekon Kubu Perahu, Balik Bukit District, West Lampung Regency. This area is an intensive utilization zone as a tourist location. The number of tourist activities in Kubu Perahu area, can cause various impacts, one of the impacts that can be observed is damage to trees. The purpose of this study is to determine the status of damage to trees in Kubu Perahu Camp Ground. The study was conducted using the Forest Health Monitoring (FHM) method. The results showed there were three tree damage locations with the most damage locations, namely 29 trunk locations (code 3); type of damage to trees with the type of damage that is open wounds caused by stabbing and cutting sharp objects; with an average tree damage level of 20%. Based on the data analysis, it is known range value 2.9-4.4 belongs to Good category, there are 13 species of trees, range value 4.5-6.0 belonging to Medium category, there are no trees in this category, and range value 6.1-7.7 are classified as Bad category, there are 5 species of trees. The status of damage to trees in Kubu Perahu Camp Ground is in the category of 290 Good trees (97%), 0 medium trees (0%), and 8 trees bad (3%).

Scots pine (Pinus sylvestris L.) demonstrates a high resistance against bark stripping damage

Bark stripping damage reduces timber quality due to fungal infection and structural defects. Weakened stems may break and induce the death of trees, which strongly affects forest stability. Some tree species, such as Norway spruce (Picea abies [L.] Karst.), are highly susceptible to bark stripping, but Scots pine (Pinus sylvestris L.) has been studied to a lesser extent. The objective of this study was to predict the effect of the degree of bark stripping damage and rot on the production parameters of Scots pine and to determine the influence of climatic factors on various damaged trees. The research was conducted on 15 pine forest stands aged 40–42 years with a numerous sika deer (Cervusnippon nippon) population in the western part of the Czech Republic (425–492 m a.s.l.). The results showed significant differences in tree diameter and volume (but not height) between healthy and extensively damaged trees according to 417 pines measured. However, no differences were found between lightly damaged trees. Similarly, circumference damage did not significantly affect mean tree stem volume, in contrast to previously reported results for Norway spruce. The trees were first damaged by deer at the age of 18.5 years on average. According to the prediction model based on 40 felled and sampled trees, rot did not reach a distance > 50 cm from the site of the bark stripping on the stem, with a mean speed of vertical spreading of 0.9 cm yr−1. Concerning the effect of climatic factors on radial growth (60 core samples taken), the difference between healthy and minor to extensively damaged trees was negligible. However, healthy trees responded more to the effects of temperature, and damaged trees were more sensitive to the precipitation amounts. Scots pine appears to be a suitable tree species for afforestation in areas with high game pressure during continuing climate change.

The effect of insects on elephant‐induced tree damage within a small, fenced reserve in South Africa

AbstractAfrican savanna elephants (Loxodonta africana) have been recognised as ecosystem engineers, where their feeding habits have been shown to alter landscapes. Within small, fenced reserves, studies exploring elephant damage on trees and their recovery have overlooked secondary damages that could be contributing to tree mortality. The aim of this study is to assess the significance of both elephant damage and secondary damage, and the subsequent tree recovery. We identified secondary damage as insects and considered wood borers and termites in this study. This was conducted in in the small fenced Karongwe Private Game Reserve, South Africa. We analysed the level of damage, recovery and insect presence using vegetation transects, where all trees ≥2 m in height were surveyed (n = 1278 trees). Forty tree species were recorded, with 5 species accounting for 77% of the data set and used for further analysis. Termites were found to be more likely to colonise damaged trees without signs of recovery. However, wood borers were more likely to colonise damaged trees showing signs of recovery. Termites and wood borer presence on damaged trees was not dependent on tree height. We suggest carefully considering management approaches for elephant‐induced termite and wood borer damage on trees.

Tree damage arising from the effects of Storm Arwen

WeatherVolume 77, Issue 4 p. E3-E3 Inside Cover Photograph Tree damage arising from the effects of Storm Arwen First published: 28 March 2022 https://doi.org/10.1002/wea.4190Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume77, Issue4April 2022Pages E3-E3 RelatedInformation

Hurricane‐associated population decrease in a critically endangered long‐lived reptile

AbstractCatastrophic events, like hurricanes, bring lethal conditions that can have population‐altering effects. The threatened Caribbean dry forest occurs in a region known for its high‐intensity hurricane seasons and high species endemism, highlighting the need to better understand hurricane impacts in combination with habitat fragmentation and loss. However, such studies remain rare and for reptiles are mostly restricted to Anolis. Here, we used single‐season occupancy modeling to infer the impact of the intense 2017 Atlantic hurricane season on the critically endangered Lesser Antillean Iguana, Iguana delicatissima. We surveyed 30 transects across eight habitats on St. Eustatius during 2017–2019, which resulted in 344 individual surveys and 98 iguana observations. Analyses of abundance and site occupancy indicated both measures for 2018 and 2019 were strongly reduced compared to the pre‐hurricane 2017 state. Iguanas at higher elevations were affected more profoundly, likely due to higher wind speeds, tree damage, and extensive defoliation. Overall, our results indicate a decrease in population estimates (23.3%–26.5%) and abundance (22%–23.8%) for 2018 and 2019, and a 75% reduction in opportunistic sightings of tagged iguanas between 2017 and 2018. As only small and isolated I. delicatissima populations remain, our study further demonstrates their vulnerability to stochastic events. Considering the frequency and intensity of hurricanes are projected to increase, our results stress the urgent need for population‐increasing conservation actions in order to secure the long‐term survival of I. delicatissima throughout its range. Given the projected increase and poleward shift of hurricanes, our study provides important insights from a non‐model species.

Dynamic pressure evolution within the 18 May 1980 Mount St. Helens pyroclastic density current: evidence from tree damage

The effects of pyroclastic density currents (PDCs) can be devastating, so understanding their internal dynamics and evolution is important for hazard assessment. We use damaged trees located around Mount St. Helens (USA) as proxy for the dynamic pressure (Pdyn) of the PDC erupted on 18 May 1980. We recorded the location, distribution, and foliage preservation of damaged trees within the medial and distal parts of the devastated forest. Sub-meter resolution aerial photographs from a month after the eruption allow distinction between standing trees that retained foliage from those that were stripped. Heights of standing trees were estimated from the measured lengths of their shadows. The number of standing trees was counted within defined areas along the propagation paths of PDCs. From the measured tree heights, we estimated tree toppling stresses from Pdyn. Overall, Pdyn of the PDC head within the medial to distal portions of the blowdown zone ranged from 10 to 35 kPa. Pdyn likely waned with distance, as shown by the increased number of standing trees in the outer parts of the devastated area. In addition, we find clusters of standing trees on the lee sides of some hills. We propose that these clusters survived because they were primarily impacted by lower dynamic pressures extant within the PDC body, with foliage retention or stripping as a function of the Pdyn evolution in the PDC body. We estimate that Pdyn of the body was less than the estimated maximum Pdyn of the PDC head by 12 ± 4 kPa.

An integrated damage modeling and assessment framework for overhead power distribution systems considering tree-failure risks

The overhead power distribution system (OPDS) is vulnerable to strong winds, such as hurricanes. Due to the challenges of including tree damage risks to the OPDS, tree failures are usually ignored in the risk assessment of the OPDS against strong winds. In the present study, an integrated damage modeling and assessment framework for the OPDS is proposed considering tree failure risks. The geographical information of trees surrounding the OPDS is extracted from satellite images using computer vision techniques, including CNN-based (convolutional neural network) image classifier and sliding window approach. The tree failure risk models are developed using tree geographical information in conjunction with tree height data, tree allometry and finite element analysis. With further integration of the conditional probability failure of poles under fallen tree impacts, the pole’s failure probability considering the combined wind and fallen trees is obtained using series system reliability analysis. The failure probability of the pole is obtained using physics-based modeling facilitated by Bayesian regularisation neural network (BRNN) algorithm. The poles and wires are connected for system reliability assessment using connectivity-based theory. When the wind direction is counterclockwise from the east and the wind speed is 57 m/s, tree-failure can introduce 68.6% differences in OPDS’ failure probabilities compared with that without consideration of fallen trees.

Tree dynamic response and survival in a category-5 tropical cyclone: The case of super typhoon Trami.

In the future with climate change, we expect more forest and tree damage due to the increasing strength and changing trajectories of tropical cyclones (TCs). However, to date, we have limited information to estimate likely damage levels, and nobody has ever measured exactly how forest trees behave mechanically during a TC. In 2018, a category-5 TC destroyed trees in our ongoing research plots, in which we were measuring tree movement and wind speed in two different tree spacing plots. We found damaged trees in only the wider spaced plot. Here, we present how trees dynamically respond to strong winds during a TC. Sustained strong winds obviously trigger the damage to trees and forests but inter-tree spacing is also a key factor because the level of support from neighboring trees modifies the effective “stiffness” against the wind both at the single tree and whole forest stand level.

Determination of an optimum sampling unit of Ricania shantungensis (Hemiptera: Ricaniidae) eggs in persimmons

Even though the optimum sampling methods for invasive pests are very important in newly invaded areas, the standard sampling unit of Ricania shantungensis is still undeveloped in persimmons. Among all developmental stages of R. shantungensis, the egg has close relationship between its density and subsequent tree damage. Thus, this study was conducted to suggest an optimum sampling unit for R. shantungensis eggs in persimmons based on characteristics of its within-tree distribution pattern. The within-tree distribution pattern was characterized with 60 persimmon trees by cutting 12 branches at three vertical levels (low, middle, and high) in four horizontal criteria (east, west, south, and north) per tree. The sampling units were determined based on coefficient of variation (CV) and coefficient of determination (r2) calculated from egg mass numbers per 10 cm from the tip within a branch. In numbers of R. shantungensis egg masses, there was no significant difference (P > 0.05) horizontally, but significant (P < 0.05) difference vertically. More R. shantungensis eggs were found on terminal branches of each trunk. The 60 cm from the tip of branches in the terminal positions of each trunk was selected as the optimum sampling unit for R. shantungensis in persimmons because this unit has the lowest CV value and more than 0.9 of r2 value. Even though the optimum sample number per tree should be determined field-specifically, it would be acceptable to sample two or three branches by considering this pests’ recognizable damage level. This small sampling unit could make the sampling of R. shantungensis become more economical, precise, and consistent in persimmon fields.