Tree Damage Research Articles

Current status of the distribution of European mistletoe (Viscum album L.) in Zhytomyr Polissia

Background. European mistletoe (Viscum album L.) is a hemiparasitic, autotrophic plant, which is an integral part of natural and urbanized ecosystems of Ukraine, in particular Zhytomyr Polissia. V. album is considered to be an aboriginal species which is largely responsible for the deterioration of the sanitary condition of woody plants. In particular, it causes their premature drying, a sharp decrease in the intensity of growth and yield of fruit. This study pursues the following goals: 1) to identify the species of trees affected by V. album and which ones it prefers in the conditions of Zhytomyr Polissia; 2) to study the biology of the development of V. album in the conditions of the region; 3) analysis of the degree of damage to trees by V. album using the coefficient of complex assessment. Materials and Methods. The reconnaissance method was used to determine the distribution of V. album, the type of damage and the intensity of damage to tree plantations and the degree of tree damage by mistletoe was determined using the coefficient of comprehensive damage assessment (Ccda). Results and Discussion. It was found that out of the total number of affected trees, B. pendula (27.13 %), R. pseudoacacia (17.04 %) and P. tremula (11.13 %) were the most commonly infested by V. album in the region. At the same time, 46 % of the trees are slightly damaged, 31 % are moderately damaged and 23 % are insignificantly dama­ged. It was found that without human intervention, the number of populations and the number of V. album tend to increase. Conclusions. On the territory of Zhytomyr Polissia, V. album has entered the cate­gory of invasive plants. V. album was detected on 20 tree species, of which the number of trees affected by V. album reached 41.54 % of the total number of the examined trees. The vast majority of V. album populations (61 %) are growing. The largest numbers of V. album shrubs were recorded on trees aged 60–80 and 80–100 years, accounting for 23 % and 25.13 % of the total number of trees infested by V. album, respectively.

Recent increase in tree damage and mortality and their spatial dependence on drought intensity in Mediterranean forests

ContextGlobal change is leading to more frequent and intense tree damage and mortality events. Drought-induced tree mortality is occurring worldwide leading to broad-scale events, but the spatial patterns of tree damage and mortality, their underlying drivers and their variation over time is largely unknown.ObjectivesWe investigated the spatial patterns of tree damage and mortality across Mediterranean forests of the Iberian Peninsula, the underlying effects of stand structure and climate, and how the spatial patterns and relationships with underlying drivers changed over time.MethodsWe used the Spanish Forest Inventory to analyse the autocorrelation in tree damage and mortality across forest types, hurdle-gamma models to quantify the effect of stand structure and climate on tree damage and mortality, and cross-correlograms to assess their spatial dependence and its change over time.ResultsWe observed a greater magnitude and a stronger autocorrelation in tree damage than mortality, with positive aggregation up to 20 kms. There was a spatial dependence between tree damage and mortality with their drivers, with spatial aggregation increasing with water availability, drought intensity and stand structure. The spatial dependence of tree damage and mortality with the underlying drivers increased over time, particularly for drought intensity.ConclusionsOur results suggest that the combined effect of intense competition and drought could favour more extensive die-off and tree mortality events, providing key information for identifying vulnerable areas and the planning of adaptation measures.

Experimental investigation of freeze injury temperatures in trees and their contributing factors based on electrical impedance spectroscopy.

In trees, injuries resulting from subfreezing temperatures can cause damage to the cellular biofilm system, metabolic functions, and fibrous reticulum, and even cell death. Investigating the occurrence of freezing damage and its contributing factors could help understand the mechanisms underlying freezing injury and prevent the subsequent damage in trees. To achieve this, a laboratory experiment was conducted using cut wood samples from Korean pine (Pinus koraiensis Siebold & Zucc) and Simon poplar (Populus simonii Carr.), and the effects of environmental freezing factors, including freezing temperatures, freezing duration, and cooling rate, on the temperature at which freezing injuries occur were examined using the electrical impedance spectroscopy (EIS) method. The semi-lethal temperature (LT50), as an indicator of freezing injury in wood tissue, was theoretically deduced based on the measured extracellular resistance (r e) using EIS. The contributory factors to changes in LT50 were determined and their relationship was established. The results revealed that all freezing factors exhibited significant effects on electrical impedance characteristics (r e, r i, and τ), significantly influencing the LT50 of the wood. Random forest (RF) and support vector machine (SVM) models were used to assess the contribution of the freezing factors and moisture content (MC). Among the factors examined, freezing duration had the greatest impact on LT50, followed by the MC, whereas the contribution of the cooling rate was minimal. The model accuracies were 0.89 and 0.86 for Korean pine and Simon poplar, respectively. The findings of our study illustrate that the occurrence of freezing injury in trees is primarily influenced by the duration of freezing at specific subzero temperatures. Slow cooling combined with prolonged freezing at low subzero temperatures leads to earlier and more severe freezing damage.

Evaluating Different Deep Learning Approaches for Tree Health Classification Using High-Resolution Multispectral UAV Data in the Black Forest, Harz Region, and Göttinger Forest

We present an evaluation of different deep learning and machine learning approaches for tree health classification in the Black Forest, the Harz Mountains, and the Göttinger Forest on a unique, highly accurate tree-level dataset. The multispectral UAV data were collected from eight forest plots with diverse tree species, mostly conifers. As ground truth data (GTD), nearly 1500 tree polygons with related attribute information on the health status of the trees were used. This data were collected during extensive fieldwork using a mobile application and subsequent individual tree segmentation. Extensive preprocessing included normalization, NDVI calculations, data augmentation to deal with the underrepresented classes, and splitting the data into training, validation, and test sets. We conducted several experiments using a classical machine learning approach (random forests), as well as different convolutional neural networks (CNNs)—ResNet50, ResNet101, VGG16, and Inception-v3—on different datasets and classes to evaluate the potential of these algorithms for tree health classification. Our first experiment was a binary classifier of healthy and damaged trees, which did not consider the degree of damage or tree species. The best results of a 0.99 test accuracy and an F1 score of 0.99 were obtained with ResNet50 on four band composites using the red, green, blue, and infrared bands (RGBI images), while VGG16 had the worst performance, with an F1 score of only 0.78. In a second experiment, we also distinguished between coniferous and deciduous trees. The F1 scores ranged from 0.62 to 0.99, with the highest results obtained using ResNet101 on derived vegetation indices using the red edge band of the camera (NDVIre images). Finally, in a third experiment, we aimed at evaluating the degree of damage: healthy, slightly damaged, and medium or heavily damaged trees. Again, ResNet101 had the best performance, this time on RGBI images with a test accuracy of 0.98 and an average F1 score of 0.97. These results highlight the potential of CNNs to handle high-resolution multispectral UAV data for the early detection of damaged trees when good training data are available.

Is mowing effective in reducing rodent damage to forest plantations?

Forest trees, particularly at a young age in afforestation, are susceptible to bark gnawing by herbivorous rodents such as voles. Few preventive measures for vole damage exist, although mowing to control herbaceous vegetation is often suggested. However, no empirical evidence supports the claim that mowing prevents or inhibits rodent damage to seedlings in a forest ecosystem. We examined the effects of single mowing applications on rodent population dynamics and the amount of damage they cause. The study was conducted at 34 randomly selected European beech forest plantations in Poland, with half manually mowed in late summer. In each plantation, we monitored the population dynamics of small rodents every 2 months from December 2019 to April 2021, and/or measured the level of damage to tree saplings monthly. The amount of damage followed a clear seasonal pattern with peaks in late autumn ranging from 0 to 40% of saplings per plantation. Mowing did not alter the pattern of population dynamics of small rodents (including voles and mice) on the plantations, nor did it reduce sapling damage caused by rodents. Additionally, herbaceous vegetation cover had no significant effect on the damage intensity. Our results indicate that mowing is ineffective in preventing tree damage by small rodents in forest plantations; therefore, we do not recommend it as a forestry practice. © 2023 Society of Chemical Industry.

Comparing perceptions of barriers to tree planting in domestic and public spaces of low-income neighbourhoods in small to medium-sized South African towns

Neighbourhood greenness is one of the indicators for residential satisfaction in urban areas. However, residents in low-income urban communities often express dissatisfaction with their neighbourhoods because of limited urban green infrastructure (UGI) and trees in comparison to relatively affluent neighbourhoods. Low-income neighbourhoods in South Africa, known as low-cost housing areas (LCHAs) face a myriad of systemic and institutional dynamics that may exacerbate the limitations to successful greening. In this context, this study investigated household perceptions on barriers to new and continued urban tree planting in domestic and public spaces such as parks and streets in low-income neighbourhoods in eight South African towns. Questionnaires were administered to 800 households across 16 old (n = 400) and newer (n = 400) LCHAs. Inadequate space (58 %), insufficient funds (37 %), lack of equipment (35 %), tree damage (34 %), limited knowledge (25 %), and municipal restrictions (12 %) were the most frequently mentioned limitations to tree planting in domestic spaces. By contrast, residents identified municipal incompetence (55 %), inadequate space (40 %); insufficient funds (28 %), tree damage (27 %), risk of crime (21 %), and politics (20 %) as some of the factors hindering institutions from planting trees in public parks and along streets. Understanding these barriers is an important step towards the design of sustainable urban greening initiatives for low-income communities in Global South contexts.

HLB Progress and Yield Sustainability in Mature Sweet Orange Orchards Treated with Nutritional and Elicitor Products

Although the implementation of area-wide inoculum reduction and Asian citrus psyllid control are decisive in controlling Huanglongbing (HLB) epidemics, growers continue looking for enhanced nutritional and/or resistance inducer (ENRI) treatments to mitigate yield damage in HLB-affected trees. Therefore, an experiment was set up in an 8-year-old sweet orange orchard to evaluate the effects of the foliar application of nutrients, phosphite, and salicylate sprayed four to five times per year during flushing periods. The trial had eight treatments in four randomized blocks. HLB incidence and yield were assessed from December 2010 to January 2017. HLB-symptomatic trees with less than 5% HLB severity were selected from each plot in the first (Group 1), second (Group 2), and third years (Group 3) after the beginning of treatments to assess the frequency of trees with different HLB symptoms and micronutrient deficiencies, HLB severity, and fruit yield until January 2017. Twenty asymptomatic trees from each plot were also harvested for comparison each year. ENRI treatments did not reduce the progress of HLB incidence in the plots or the HLB severity progress or frequency of HLB symptoms in the selected trees. ENRI treatments did not improve the yield of symptomatic trees compared with asymptomatic trees. Hence, in a scenario without HLB-symptomatic tree removal in mature orchards, disease severity progress and yield reduction in HLB-affected trees remained regardless of ENRI treatment. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Population and conservation status of the endangered Dracaena ombet tree in dry Afromontane forests

Dracaena ombet, a flagship tree species in arid ecosystems, holds a significant ecological, economic, and socio-cultural value. However, its persistence is currently under threat from both anthropogenic and natural factors. Consequently, the species has been listed as an endangered tree species on the IUCN Red List, requiring urgent conservation actions for its continued existence. To develop effective conservation actions, it is necessary to have information on the population dynamics of the species. A study was conducted in the lowland and midland agroecological zones (sites) within the Desa'a dry Afromontane forest, northern Ethiopia to analyze the population status of D. ombet and identify its site-specific threats. At each site, abundance, health status, diameter, height and threats of the species were collected using 60 sample plots (20 m × 20 m) distributed over six transects (500 m × 20 m) spaced one km apart. The study showed that the D. ombet population was characterized by low abundance and unstable structure. It was further characterized by a substantial number of unhealthy damaged and dead trees. The low abundance of the species with unstable age structure in the dry Afromontane forests can be attributed to various factors such as stem cutting and debarking, leaf defoliation, overgrazing, soil erosion, and competition from expansive shrubs. Alternative livelihood options for the local inhabitants should be introduced to minimize the overexploitation of D. ombet for subsistence use in the dry Afromontane forests. The impacts of overgrazing and soil erosion on D. ombet and its Desa'a habitats should also be addressed through the introduction of community-based exclosures and in-situ soil and water conservation practices, respectively.

Perceptions of Tree Diseases in Indigenous Communities: Native Alaskan and Hawaiian Insights

Abstract Concern for tree mortality and damage, and preferences for management interventions, reflect people’s values and cultures. We examine perceptions of tree diseases in two Indigenous communities to provide examples of the types of distress and attitudes that arise when tree diseases significantly damage cultural values. Summaries of yellow-cedar decline as perceived by Tlingit and Haida Alaska Natives and rapid ʻōhiʻa death (ROD) and Native Hawaiian culture underscore the interconnections between local people and local forests and the ways forest diseases can impart a loss of culture and connections to ancestors. The complex relationships between Indigenous people, ecosystems, and tree diseases highlight the importance of the inclusion of diverse viewpoints to inform natural resource planning and management so that it may be conducted equitably and ethically. Study Implications: Consideration of cultural and social impacts as criteria for prioritization of forest disease management requires knowledge of the types and intensity of impacts that forest diseases have on Indigenous and Western culture. A greater understanding of the diversity of perspectives toward forest diseases is needed to inform natural resource planning and management so that it may be conducted in an ecologically sound and inclusive manner.

Self-Healing Properties of Water Tree Damage in Multilayered Shell-Core-Structured Microcapsules/Cross-Linked Polyethylene Composites.

To investigate the effect of the structure of microcapsules on the properties of cross-linked polyethylene (XLPE) composites, three XLPE specimens filled with multilayered shell-core-structured microcapsules are designed. In this paper, the microcapsules are first analyzed morphologically and chemically. In addition, the effect of the microcapsule structure on the typical electrical properties of the composites is explored. Finally, the self-healing ability of XLPE specimens filled with microcapsules is verified. The results show that the SiO2 on the surface of the trilayer shell-core microcapsules can make the microcapsules and the XLPE matrix have a better mechanical interlocking ability, which makes the typical properties of the trilayer shell-core microcapsules slightly better than those of the bilayer shell-core microcapsules. Moreover, when the bilayer shell-core or trilayer shell-core microcapsules rupture under the action of an electric field, the repair material reacts with the water tree under capillary action to consume the residual water while generating organic matter to fill in the cavity, thus repairing the damaged area of the water tree and ultimately achieving the self-healing of the composite water tree.

Neighborhood effects on tree growth in a Fagus sylvatica - Abies alba forest following an ice storm

Ice storms can cause substantial damage to tree crowns and lead to growth reduction. However, in uneven-aged stands, the growth of an individual tree may also increase due to crown release caused by the damage or mortality of neighboring trees. Three years after the devastating ice storm in 2014 in mixed uneven-aged Dinaric forests (Croatia), we cored 156 European beech (Fagus sylvatica) and 85 silver fir (Abies alba) trees across 20 permanent sample plots to study the post-storm growth response as a function of tree, stand, site, spatial arrangement and local competition factors. The ice storm damaged over 84% of trees on the sampled plots. Among the cored trees, 52.7% exhibited growth reduction, which on average amounted to −3.1% relative to the pre-disturbance average. Trees with less than 40% crown damage maintained their pre-disturbance growth rates or experienced only minor growth suppression. While 60% of beech trees suffered a growth reduction at an average rate of −7.2%, the average radial increment of fir after the storm was 14.0% higher compared to the pre-storm rate. A linear mixed-effects model suggests that the growth response can largely be explained by the focal and neighboring tree species identity, tree competition pressure, focal and neighboring tree damage, crown size, slenderness index and stoniness. Growth release was positively associated with fir, inverse distance-weighted crown damage of the nearest neighbor, shorter crowns, slenderness, less stony sites and less damaged trees. The analysis suggests that at the same level of local competition load, trees with a broadleaved and damaged nearest neighbor are more likely to experience growth release than those with a coniferous or undamaged nearest neighbor. This implies that uneven-aged stands with a substantial presence and mingling of both conifers and broadleaves are expected to be more resilient to ice storms and are less likely to suffer growth reduction.

Functionally Assembled Terrestrial Ecosystem Simulator (FATES) for Hurricane Disturbance and Recovery

AbstractTropical cyclones are an important cause of forest disturbance, and major storms caused severe structural damage and elevated tree mortality in coastal tropical forests. Model capabilities that can be used to understand post‐hurricane forest recovery are still limited. We use a vegetation demography model, the Functionally Assembled Terrestrial Ecosystem Simulator, coupled with the Energy Exascale Earth System Model Land Model (ELM‐FATES) to study the processes and the key factors regulating post‐hurricane forest recovery. We implemented hurricane‐induced forest damage, including defoliation, structural biomass reduction, and tree mortality, performed ensemble model simulations, and used random forest feature importance. For the simulation in the Luquillo Experimental Forest, Puerto Rico, we identified factors controlling the post‐hurricane forest recovery, and quantified the sensitivity of key model parameters to the post‐hurricane forest recovery. The results indicate a tendency for the Bisley forests to shift toward the light demanding plant functional type (PFT) when the pre‐hurricane biomass between the light demanding and shade tolerant PFTs is nearly equal and forests experience hurricane disturbance with mortality >60% for both the two PFTs. Under more realistic conditions where the shade tolerant PFT is initially dominant, mortality >80% is required for a shift toward dominance of the light demanding PFT at Bisley. Hurricane mortality and background mortality are the two major factors regulating post‐hurricane forest recovery in simulations. This research improves understanding of the ELM‐FATES model behavior associated with hurricane disturbance and provides guidance for dynamic vegetation model development in representing hurricane induced forest damage with varied intensities.

Automated Large-Scale Tornado Treefall Detection and Directional Analysis Using Machine Learning

Abstract In many regions of the world, tornadoes travel through forested areas with low population densities, making downed trees the only observable damage indicator. Current methods in the EF scale for analyzing tree damage may not reflect the true intensity of some tornadoes. However, new methods have been developed that use the number of trees downed or treefall directions from high-resolution aerial imagery to provide an estimate of maximum wind speed. Treefall Identification and Direction Analysis (TrIDA) maps are used to identify areas of treefall damage and treefall directions along the damage path. Currently, TrIDA maps are generated manually, but this is labor-intensive, often taking several days or weeks. To solve this, this paper describes a machine learning– and image-processing-based model that automatically extracts fallen trees from large-scale aerial imagery, assesses their fall directions, and produces an area-averaged treefall vector map with minimal initial human interaction. The automated model achieves a median tree direction difference of 13.3° when compared to the manual tree directions from the Alonsa, Manitoba, tornado, demonstrating the viability of the automated model compared to manual assessment. Overall, the automated production of treefall vector maps from large-scale aerial imagery significantly speeds up and reduces the labor required to create a Treefall Identification and Direction Analysis map from a matter of days or weeks to a matter of hours. Significance Statement The automation of treefall detection and direction is significant to the analyses of tornado paths and intensities. Previously, it would have taken a researcher multiple days to weeks to manually count and assess the directions of fallen trees in large-scale aerial photography of tornado damage. Through automation, analysis takes a matter of hours, with minimal initial human interaction. Tornado researchers will be able to use this automated process to help analyze and assess tornadoes and their enhanced Fujita–scale rating around the world.

Self-healing of water tree damage of double-shell microcapsules/XLPE insulation composite material Insulation

Self-healing of water tree damage of double-shell microcapsules/XLPE insulation composite material Insulation

Utilization of Convolutional Neural Network on Deep Learning in Predicting Digital Image to Tree Damage Type

Utilization of Convolutional Neural Network on Deep Learning in Predicting Digital Image to Tree Damage Type

Thinning reduces late-spring frost impact on stem radial growth in a beech forest stand

Resistance and resilience to multiple stresses depend on competition among trees, thus they can be improved by means of silvicultural practices reducing stand density. However, we often ignore whether thinning is an appropriate practice to increase the resistance and resilience to late-spring frosts. These climatic events can damage tree species, especially when leaf emergence is advanced by warmer springs. Here, we compared the effect of a late-spring frost on crown damage and stem radial growth in beech trees (Fagus sylvatica) from areas thinned and not thinned. The study area is a mixed forest of F. sylvatica, Quercus petraea and Q. pyrenaica, and is located in central Spain, near the southern limit of beech distribution. The proportion of trees damaged by frost was not significantly different in thinned vs non-thinned areas. However, severely damaged trees in non-thinned areas showed higher growth reductions and a longer legacy effect than severely damaged trees in thinned plots. Severely damaged trees were those with earlier leaf and stem growth phenology in the frost year. These trees, compared to slightly damaged trees, delayed growth cessation and had a longer growth period in the frost year, and the year afterwards in non-thinned areas. Growth recovery was size-dependent in non-thinned areas, in which bigger trees recovered growth faster. The positive effect of thinning in attenuating frost impact on growth and accelerating growth recovery adds up to other beneficial effects of thinning for stress tolerance. Similar results could occur in other deciduous species highly sensitive to spring temperatures, which are likely to increase with global warming.

Healthy Index Level of Mangrove Forests around Sylvo-Ecotourism in Tanjungpiayu and Kabil, Batam Island

The existence of mangrove forests in several coastal areas of Batam Island is threatened by the development of settlements and ports as well as industrial activities. Environmental changes due to land clearing have an impact on the health of the surrounding mangrove forests. In fact, several mangrove forest areas in Batam City have the potential to be developed as mangrove sylvo-ecotourism areas. The decline in the health of mangrove forests around land conversion areas can be seen from the level of tree damage. Mangrove tree sampling was carried out in Tanjungpiayu Village and Kabil Village in Batam, Riau Islands Province. Sampling of tree stands using cluster plots. The tree health index is observed based on the percentage of damage locations, type and severity of tree damage. The research results showed that the mangroves around the sampling location were considered healthy even though there was light and moderate damage. The worst damage locations are on the leaves, roots and lower stem. The most types of damage were in other categories (submerged in red mud), damaged and discoloured leaves, termites, broken or dead roots and stems. The most severe levels occur around 10-20%, 30% and 90%. The health of the mangroves in the Tanjungpiayu and Kabil mangrove sylvo-ecotourism areas is still relatively good.

Extracellular Self- and Non-Self DNA Involved in Damage Recognition in the Mistletoe Parasitism of Mesquite Trees.

Psittacanthus calyculatus parasitizes mesquite trees through a specialized structure called a haustorium, which, in the intrusive process, can cause cellular damage in the host tree and release DAMPs, such as ATP, sugars, RNA, and DNA. These are highly conserved molecules that primarily function as signals that trigger and activate the defense responses. In the present study, we generate extracellular DNA (exDNA) from mesquite (P. laevigata) tree leaves (self-exDNA) and P. calyculatus (non-self exDNA) mistletoe as DAMP sources to examine mesquite trees' capacity to identify specific self or non-self exDNA. We determined that mesquite trees perceive self- and non-self exDNA with the synthesis of O2•-, H2O2, flavonoids, ROS-enzymes system, MAPKs activation, spatial concentrations of JA, SA, ABA, and CKs, and auxins. Our data indicate that self and non-self exDNA application differs in oxidative burst, JA signaling, MAPK gene expression, and scavenger systems. This is the first study to examine the molecular biochemistry effects in a host tree using exDNA sources derived from a mistletoe.

Responses at the stand and tree level to ice storm injuries in beech forests in eastern Serbia

The paper presents the study on the condition and structural stability of European beech (Fagus sylvatica L.) stands after the 2014 ice storm disturbance. The research was conducted in three pure beech stands on the Rtanj mountain in eastern Serbia. The stand condition after the ice storm was analyzed using changes in taxation elements. The assessment of tree damage was done according to the ICP Forests methodology, while the structural stability of the stands and individual trees was analyzed using the slenderness coefficient. The obtained results indicate very heterogeneous responses of beech stands to the negative impact of the ice storm. Heterogeneity is not only expressed between stands but also within individual stands. The stands after the ice storm are characterized by significantly reduced values of production indicators, but also by satisfactory stability, considering that the trees from the understory suffered the most. Statistically significant differences in the stability of trees of different dimensions expressed through the slenderness coefficient were determined. Consequently, the stands have maintained an appropriate level of stability thanks to the survival and resistance of the dominant trees that are the bearers of functions in these stands (trees with dbh > 40 cm). This indicates the great potential of silvicultural treatments that can increase the stability and resistance of stands in areas with a high risk of such phenomena. In addition, repressive action in the form of salvage logging has a very important role with the aim of ensuring the continuity of stands after damage has occurred.

Damage of trees by forest Elephants (Elephas maximus) in Cauvery Wildlife Sanctuary, Western Ghats, Karnataka: Are they sustainable?

Damage of trees by forest Elephants (Elephas maximus) in Cauvery Wildlife Sanctuary, Western Ghats, Karnataka: Are they sustainable?