Windthrow Damage Research Articles

Identifying Areas Prone to Windthrow Damage and Generating Susceptibility Maps Utilizing a Novel Vegetation Index Extracted from Sentinel-2A Imagery

Identifying Areas Prone to Windthrow Damage and Generating Susceptibility Maps Utilizing a Novel Vegetation Index Extracted from Sentinel-2A Imagery

Windthrow damage detection in Nordic forests by 3D reconstruction of very high-resolution stereo optical satellite imagery

ABSTRACT We tested whether windthrow damage to Nordic conifer forest stands could be reliably detected as canopy height decrease between a pre-storm LiDAR (Light Detection and Ranging) digital surface model (DSM) and a photogrammetric DSM derived from a post-storm WorldView-3 stereo pair. The post-storm ground reference data consisted of field and unmanned aerial vehicle (UAV) observations of windthrow combined with no-damage areas collected by visual interpretation of the available very high resolution (VHR) satellite imagery. We trained and tested a thresholding model using canopy height change as the sole predictor. We undertook a two-step accuracy assessment by (1) running k-fold cross-validation on the ground reference dataset and examining the effect of the potential imperfections in the ground reference data, and (2) conducting rigorous accuracy assessment of the classified map of the study area using an extended set of VHR imagery. The thresholding model produced accurate windthrow maps in dense, productive forest stands with a sensitivity of 96%, specificity of 71%, and Matthews correlation coefficient (MCC) over 0.7. However, in sparse and high elevation stands, the classification accuracy was poor. Despite certain collection challenges during the winter months in the Nordic region, we consider VHR stereo satellite imagery to be a viable source of forest canopy height information and sufficiently accurate to map windthrow disturbance in forest stands of high to moderate density.

Long‐term dynamics of species diversity in natural secondary forest stands after severe windthrow damage

AbstractSpecies diversity encompasses both richness and evenness, but the interrelationship between these two aspects remains poorly understood. The long‐term dynamics of species diversity were examined in three natural secondary forests in Hokkaido, northern Japan, using permanent plot data gathered over 65–66 years after severe windthrow damage. The relationships among species diversity, species richness, and evenness were analyzed in the context of stand dynamics. Temporal trends in species diversity were unimodal‐shaped in three permanent plots, consistent with the pattern predicted by the intermediate disturbance hypothesis. Species richness and evenness increased following the windthrow, but decreased 27–37 years later in all three plots. In two plots, species diversity was closely associated with species richness and evenness at the early and late successional stages, respectively; in the other plot, species diversity was significantly related to both species richness and evenness in the later stage. The former two plots and the latter one plots differed markedly in terms of the extents of fatal tree damage caused by windthrow. Thus, windthrow severity affected the relationships among diversity, richness, and evenness as succession proceeded in these secondary forests. The tree density, species richness, evenness, and species diversity in all three plots decreased when the basal areas exceeded 18–24 m2/ha, indicating that increased competition among trees affected the temporal trends in these metrics. In conclusion, after a severe disturbance, the relationships among species diversity, richness, and evenness in secondary forests change with succession.

Harvesting wind damaged trees: a study of prediction of windthrow damage in mixed-broadleaf stands via a machine learning model

ABSTRACT Due to climate change, windstorms are becoming increasingly common resulting in the destruction not only of extensive forest areas but, quite often, of small-sized and scattered forest lands, thereby adversely affecting both the productivity and the safety of workers employed in the harvest of windblown trees. In the present study, an attempt is made to identify and record areas in the northeastern forests of Greece covered by mixed stands of conifers and broadleaves that experienced massive windthrow following local storms. Our results reveal that where Pinus sylvestris was mixed either with Quercus sp. or with Fagus sylvatica, it had been substantially protected, while in plots where it stood on its own it had been extensively uprooted. On the other hand, Picea abies, even if it was mixed with Fagus sylvatica and Pinus sylvestris, had been blown down to a large extent. Based on tree-level data, local topographic features, forest characteristics, and the mechanical properties of green wood, a reliable model, to be used for the prediction of similar disturbances in the future, has been selected after a thorough comparative study of the most well-known intelligent Machine Learning (ML) algorithms. Specifically, Random Forest Classifier, k-Neighbors Classifier, Decision Tree Classifier, Light Gradient Boosting Machine, Gradient Boosting Classifier, Ada Boost Classifier, Ridge Classifier, Linear Discriminant Analysis, Logistic Regression, Naive Bayes, SVM – Linear Kernel, and Quadratic Discriminant Analysis were evaluated and compared using six performance measures (confusion matrix, accuracy, precision, recall, F1-score, and ROC).

A Sentinel-2 Based Multi-Temporal Monitoring Framework for Wind and Bark Beetle Detection and Damage Mapping

The occurrence of extreme windstorms and increasing heat and drought events induced by climate change leads to severe damage and stress in coniferous forests, making trees more vulnerable to spruce bark beetle infestations. The combination of abiotic and biotic disturbances in forests can cause drastic environmental and economic losses. The first step to containing such damage is establishing a monitoring framework for the early detection of vulnerable plots and distinguishing the cause of forest damage at scales from the management unit to the region. To develop and evaluate the functionality of such a monitoring framework, we first selected an area of interest affected by windthrow damage and bark beetles at the border between Italy and Austria in the Friulian Dolomites, Carnic and Julian Alps and the Carinthian Gailtal. Secondly, we implemented a framework for time-series analysis with open-access Sentinel-2 data over four years (2017–2020) by quantifying single-band sensitivity to disturbances. Additionally, we enhanced the framework by deploying vegetation indices to monitor spectral changes and perform supervised image classification for change detection. A mean overall accuracy of 89% was achieved; thus, Sentinel-2 imagery proved to be suitable for distinguishing stressed stands, bark-beetle-attacked canopies and wind-felled patches. The advantages of our methodology are its large-scale applicability to monitoring forest health and forest-cover changes and its usability to support the development of forest management strategies for dealing with massive bark beetle outbreaks.

Modeling Tree Recovery in Wind-Disturbed Forests with Dense Understory Species under Climate Change

Future climate conditions will alter the frequency and intensity of typhoons. Thus, post-windthrow management, which can enhance tree recovery in wind-disturbed forests with dense understory species, is essential for sustainable forest management to adapt to climate change. This study explores management options that can recover the above-ground biomass (AGB) and tree species composition after windthrow damage even under climate change. A case study area was established in the Oshima–Hiyama National Forest in southern Hokkaido, northern Japan, which were damaged by typhoons in late August 2016. We incorporated the understory species Sasa kurilensis as understory vegetation into the LANDIS-II Net Ecosystem Carbon and Nitrogen Succession extension v6.3 model to simulate the outcome of tree establishment under climate change. AGB recovery up to the year 2100 at 1,753 damaged grid cells was simulated for the Intergovernmental Panel on Climate Change representative concentration pathway (RCP) 2.6 and 8.5 scenarios. Different post-windthrow management cases were designed by varying the treatment of fallen trees and the types of trees planted. The results demonstrated that salvage logging and planting successfully recovered the AGB by 2050 at the landscape scale regardless of the climate change scenario, whereas leaving fallen trees in the damaged site or salvage logging only did not facilitate the recovery of AGB. Leaving fallen trees in damaged grid cells as ecological legacies recovered the AGB only in damaged grid cells with a sufficient number of advanced seedlings of adequate types of species irrespective of the climate change scenario. The decreasing water equivalent of snowpack in the RCP scenarios caused Sasa kurilensis mortality and promoted the recovery of AGB of trees. The dominant species recovered in natural forests, which experienced either salvage logging or leaving trees in the damaged site, varied among climate change scenarios. The warmer climate condition facilitated the recovery of Fagus crenata by 2100. These results can help designing a robust forest recovery even in uncertain future climate.

Likelihood of Failure of Trees Along Electrical Utility Rights-of-Way: A Literature Review

Utility vegetation managers need tools to predict tree-related risks and knowledge of the necessary management prescriptions to reduce the risk of windthrow damage to utilities’ electrical infrastructure. This review focuses on key studies involving the likelihood of failure of trees, beginning with a description and discussion of failure in trees, followed by an examination of methodologies that have been used to assess tree failure, before concluding with a review of factors which have been found to influence tree failure. Ultimately, a better understanding of the likelihood of failure of individual trees and the relationships governing tree failure and vegetation-related outages may allow for significant advances in the risk management of utility infrastructure.

A Robust Method for Detecting Wind-Fallen Stems from Aerial RGB Images Using a Line Segment Detection Algorithm

Increased frequencies and windspeeds of storms may cause disproportionately high increases in windthrow damage. Storm-felled trees provide a surplus of breeding material for bark beetles, often resulting in calamities in the subsequent years. Thus, the timely removal of fallen trees is regarded as a good management practice that requires strategic planning of salvage harvesting. Precise information on the number of stems and their location and orientation are needed for the efficient planning of strip roads and/or cable yarding lines. An accurate assessment of these data using conventional field-based methods is very difficult and time-consuming; remote sensing techniques may be a cost-efficient alternative. In this research, a methodology for the automatic detection of fallen stems from aerial RGB images is presented. The presented methodology was based on a line segment detection algorithm and proved to be robust regarding image quality. It was shown that the method can detect frequency, position, spatial distribution and orientation of fallen stems with high accuracy, while stem lengths were systematically underestimated. The methodology can be used for the optimized planning of salvage harvesting in the future and may thus help to reduce consequential bark beetle calamities after storm events.

The Effects of Windthrow Damage on Soil Properties in Scots Pine, Black Pine and Kazdağı Fir Stands in the Northwest Turkey

Aim of study: The short-term effects of windthrow damage on soil properties were investigated in Kazdağı fir (Abies nordmanniana subsp. equi-trojani), Scots pine (Pinus sylvestris L.) and black pine (Pinus nigra Arnold.) stand in northwest Turkey. Area of study: The study was carried out in Kastamonu and Sinop regions. Material and methods: In order to understand the effects of windthrow damage occurred in 2013, soil samples were collected at a depth of 0-30 cm from the disturbed and undisturbed sites in 2018 (5 year later), and analyzed for soil physical and chemical properties. Main results: The increases in temperature, wind speed and heavy rainfall in the study sites seemed to result in the windthrows. There were significant differences in soil physical and chemical properties among the three tree species, and also between the disturbed and the undisturbed sites. Highlights: After the windthrows, increased SOC and TN stocks, P and K could be related to the accumulation of organic matter. However, we were not able to identify a single mechanism to explain this observed relationship. Thus, the root-soil interactions of the three tree species should be conclusively examined in future studies in order to define the relationships between soil chemical properties and root features.

Long‐term stand‐level resilience in natural secondary forest stands recovering from severe windthrow damage

AbstractLong‐term stand‐level resilience in three natural secondary forests after a stand‐replacing windthrow damage event was examined by analyzing stand composition, structure, and function using repetitive measurement data collected in permanent plots over 60 yr. The secondary forests differed among pre‐disturbance forest types. For the purposes of this study, stand resilience comprised resistance to and recovery from windthrow damage. To analyze composition, the dynamics of species numbers in the permanent plots were tracked and temporal trends in similarity between pre‐ and post‐disturbance compositions were examined. To investigate stand structure, the dynamics of tree density, mean diameter at breast height (DBH), and temporal trends in similarity between pre‐ and post‐disturbance DBH frequency distributions were analyzed. To investigate stand function, the dynamics of stand basal area were analyzed. The calculations showed that tree density, basal area, species composition, and DBH frequency distribution were associated with low resistance to windthrow damage. By contrast, the number of species and mean DBH were resistant to windthrow damage. Basal areas recovered quickly in the 60 yr post‐windthrow damage, but recovery of the pre‐damage mean DBH and DBH frequency distribution was slow. Tree density and the number of species recovered to levels that exceeded those in the stands prior to the windthrow event. The recovery of species composition varied by pre‐disturbance forest type. Among the stands analyzed, the hardwood forest that existed prior to disturbance was resistant to and recovered well from windthrow damage in comparison with other types of pre‐disturbance forests. In conclusion, stand‐replacing windthrow damage can have a long‐lasting influence on secondary forests, especially in terms of stand composition and structure.

Slenderness coefficient models for tree species in Omo biosphere reserve, South-western Nigeria

This study was carried out to aid the prediction of tree slenderness coefficient using non-linear regression models for tree species in Omo Biosphere Reserve, Southwestern Nigeria. Systematic line transect design was adopted for the study. Three transects were laid with four plots on each transect at alternate positions which made a total of 12 sample plots (50 m × 50 m) in the study area. Diameter at breast height (DBH), diameter at the top, diameter at the middle and diameter at the base as well as total height and merchantable height of all trees were measured. Descriptive statistics, Pearson’s correlation and regression analysis were adopted for the study. The study showed that about 23.5% of the trees in the study area are susceptible to wind-throw damage. Correlation analysis revealed that DBH is a better predictor of Slenderness coefficient than other tree growth characteristics. Six non-linear models were adopted for the tree slenderness coefficient prediction. The best models were selected based on the highest Adj.R2, lowest AIC and SEE values. Normal logarithmic equation SLC = 30.72 + (-41.21) In(D) was selected as the candidate model for the pooled data. The same candidate model (Natural logarithm) was selected for both the Desplatsia lutea and Strombosia pustulata species with the equation SLC = -0.04 + (-63.82) In(D) and SLC = 22.12 + (-51.40) In(D) respectively while exponential model with equation SLC = 170.94e(-1.93) was selected for Sterculia rhinopetala. These equations were recommended for predicting slenderness coefficient for each of the tree species in Omo Biosphere with apparently valid potentials for enhancing reasonable quantification of the stands’ stability.

Polypores, Agrobacterium and ivy damage on Hungarian ancient trees

Ancient trees are important habitats, confer vital ecological roles and function as cultural legacies. Old trees with large girth are keystone structures in various ecosystems. We aim to present which species amongst the greatest Hungarian trees (and some other phanerophyte plants) are damaged by polypores (the most important agents of wood decay), Agrobacterium tumefaciens (usually causing root tumour) or ivy (competing against the native vegetation and causing windthrow damage) and at what extent and frequency; and whether there is a relationship between these types of damage and the origin of the species (native or adventive) or its situation (solitary or surrounded by other trees). We measured 2,000 trees, belonging to 29 native and 43 non-native species. Polypore infection could be detected in 12.2% of the observed 531 settlements, 22.8% are damaged by Agrobacterium and 29.6% by ivy, while 51.2% by other types of pests and diseases. Altogether, one third of the observed 2000 ancient or veteran trees suffered from one or more types of damage. A total of 33.5% of the native species (519 specimens out of 1550) and 28.7% of the adventives (129 trees out of 450) are damaged by any (or more than one) of the mentioned infections or ivy. Mostly, damage occurred to those old trees that stand in a park or forest, while the single (solitary) trees were usually healthy. The most infected regions are the western and south-western counties, while the Northern Hungarian Mountain Range is much less affected, despite its great sample size. Low damage was detected in the Great Hungarian Plain, but the number of sample areas and veteran trees was also low here. The damage to old trees remains without any management or healing in Hungary, since the only effective solution would be prevention.

The Influence of Local Habitat and Microclimate on the Levels of Secondary Metabolites in Slovak Bilberry (Vaccinium myrtillus L.) Fruits

The berries of Vaccinium myrtillus L. are usually collected in the wild for the purpose of being a food source. They are naturally high in phenolic compounds, which possess antioxidative properties, so the berries are therefore often labeled as “functional foods”. This study evaluated seven samples of bilberry fruits from different locations in Slovakia for the content of the main phenolic compounds (anthocyanins, flavonoids and tannins) using European Pharmacopoeia 9 spectrophotometric methods. A thorough analysis of environmental factors showed that several phenolic constituents are closely corresponding with their respective environments, as well as with each other. The environmental factors with statistically significant correlations in this study are altitude, habitat type, sunlight exposure, and soil carbon content. Our findings suggest that the berries collected at sunny sites with no topsoil damage contain more phenolic compounds. The lowest amounts of phenolic compounds were found in samples from dense forests or with visible soil erosion and windthrow damage. The negative effect of windthrow damage on the levels of secondary metabolites in bilberry fruits has been described for the first time. This study observed no relationship between the amount of phenolic compounds and soil pH, soil nitrogen levels, or slope exposition.

Stand-level windthrow patterns and long-term dynamics of surviving trees in natural secondary stands after a stand-replacing windthrow event

Abstract We examined typhoon windthrow patterns in stand-scale permanent plots within three natural forests and the long-term dynamics of surviving trees in two of these plots. The aim was to verify whether pre-disturbance composition and structure affected windthrow damage and stand recovery. The stands, which were in Hokkaido, the northernmost main island of Japan, differed in pre-disturbance composition (coniferous, mixed and broadleaved stands) and structure, and the basal area losses by the windthrow event were 81–93 per cent. Tree mortality was significantly related to tree size (diameter at breast height) and species. The windthrow patterns differed among the three stands; and, windthrow severity was affected by the pre-disturbance composition and structure. The mortality of trees that survived the windthrow event was ~60 per cent in the two plots. The surviving trees comprised a majority of the canopy layer in the secondary stands. The relative basal area of surviving trees decreased rapidly with increasing tree density in the stand initiation stage but differed between plots. Consequently, the pre-disturbance composition and structure influenced windthrow severity, stand recovery and secondary succession in the recovered stands.

The role of topography, canopy gaps, and forest edges in the distribution of windthrow damage in the Western Tatra Mountains, Poland

The role of topography, canopy gaps, and forest edges in the distribution of windthrow damage in the Western Tatra Mountains, Poland

A multiscale analysis of the effects of alternative silvicultural treatments on windthrow within balsam fir dominated stands

Boreal ecosystem functioning is largely controlled by disturbance dynamics. There have been efforts at adapting forest management approaches to emulate natural disturbance effects, as this is expected to maintain ecosystem resilience. In many instances, this involves resorting to partial cutting strategies that are likely to increase windthrow losses. The objective of this study was to determine the effects of alternative silvicultural practices on windthrow damage and how these effects vary with the scale of treatment. The study was conducted in the Quebec North Shore region (Canada), an area dominated by balsam fir (Abies balsamea (L.) Mill.) and accompanied by black spruce (Picea mariana (Mill) B.S.P.). Four different silvicultural treatments (overstory removal, heavy partial cutting, and two patterns of selection cutting) and control areas were implemented in 2004 and 2005. The experiment used a nested approach where treatment at the plot level was independent and yet nested within the block-level treatment. At the block level, treatments were applied over 10–20 ha units, leaving a small portion of the block for a smaller application of each treatment (plot scale, 2500 m2). Inventory was carried out before harvesting and monitoring was done yearly after harvesting, with the aim to better understand the plot- and block-level factors that drive windthrow damage levels and the effects of alternative silvicultural treatments. Results after 6–7 years show that basal area proportion windthrown differs substantially between treatments, as well as between treated sites and control sites. Windthrow levels were higher under heavy cuts relative to selection cuts and also increased with balsam fir proportion. Windthrow proportions were better correlated to block-level treatment than plot-level treatment, showing that the environment surrounding the treated plot can have an important effect on windthrow losses. Overall, the selection cutting system, particularly SC2, retains the most green-tree basal area and thus best meets the management objective of retaining old-growth attributes. A simple empirical model was calibrated that could aid in hazard rating.

Identifying the determinants of windthrow damage in wildlife tree patches in the Boreal White and Black Spruce biogeoclimatic zone of northeastern British Columbia

Leaving wildlife tree patches (WTPs) has become a common strategy employed to maintain biodiversity among managed forest ecosystems in British Columbia. High levels of wind damage have been observed in many of these reserves owing to the increased wind loading after harvesting. The ensuing damage disrupts forest management plans and reduces the value of WTPs. The objective of this study was to identify the primary determinants of windthrow in WTPs in the boreal forest of northeastern British Columbia andto suggest management strategies to minimize wind-related damage. Line transects oriented parallel and perpendicular to prevailing and dominant winds across 13 WTP reserves were used to quantify wind-related damage and factors that may contribute to windthrow incidence. The occurrence of windthrow corresponded with the exposure of WTP edges to high velocity winds; common, but lower-velocity winds resulted in little windthrow damage. Edaphic, site, and forest-stand factors appeared to have little influence on the incidence of windthrow in this study as compared to exposure to strong winds. The study suggests that forest managers can reduce the incidence of windthrow in WTPs in the boreal forests of northeastern British Columbia by:(1) creating patches that are elliptically shaped with the long axis in the direction of the dominant winds;(2) reducing wind exposure of susceptible edges; and (3) increasing the size of WTPs.

Windwurf und Borkenkäferepidemien im Alptal nach Vivian und Lothar | Windthrow and bark beetle attacks in the Alptal after the wind storms Vivian and Lothar

After the strong winter storms Vivian (1990) and Lothar (1999), many Swiss forests have been severely infested by bark beetles. Based on detailed forest management information from 28 forest compartments this study tested a set of potential explanatory variables as predictors for the occurrence of bark beetle damage in the Alptal valley (northern Swiss Prealps). For each storm we developed a separate multiple linear regression model. Bark beetle occurrence was measured as the sum of insect-damaged wood within five years after the winter storms. Two predictors (wind-damaged wood during a winter storm and occurrence of adult spruce) explained more than 50% of the variance of bark beetle occurrence. Our results support the idea that windthrow damage is highly conducive to subsequent bark beetle attack of the surrounding forests. Additionally, the occurrence of larger spruce trees (diameter at breast height > 40 cm) explains a significant fraction of the remaining variance of bark beetle occurrence, which underpins the importance of forest age structure for windthrow and insect damage as causes of tree death. Methodologically, our study highlights the value of historical forest management data in the context of ecological modeling.

Evaluation of drag coefficients of poplar-tree crowns by a field test method

To estimate the wind force that causes windthrow damage to a tree, the drag coefficients of actual-sized trees were evaluated by a field test method. In this method, wind velocity and stem deflection were monitored simultaneously. The wind force acting on a tree crown was calculated from stem deflection; stem stiffness was evaluated by conducting tree-bending tests. The results of tests conducted on three poplar trees showed that drag coefficient decreased with an increase in wind velocity. Although the variation in the drag coefficient was large at low wind velocity because of the vibrating behavior of the stem subjected to variable wind force, the variation at wind velocities above 10 m/s was small. The average drag coefficient at a wind velocity of 30 m/s was estimated by the curve-fitting of a power function to the wind velocity-drag coefficient relationship to be 0.102, which was smaller than that of actual-sized conifers studied in previous wind tunnel experiments. The drag coefficients of these crown areas in the defoliation season were smaller than those measured in the leafy season.

Identifying the determinants of windthrow damage in wildlife tree patches in the Boreal White and Black Spruce biogeoclimatic zone of northeastern British Columbia

Leaving wildlife tree patches (WTPs) has become a common strategy employed to maintain biodiversity among managed forest ecosystems in British Columbia. High levels of wind damage have been observed in many of these reserves owing to the increased wind loading after harvesting. The ensuing damage disrupts forest management plans and reduces the value of WTPs. The objective of this study was to identify the primary determinants of windthrow in WTPs in the boreal forest of northeastern British Columbia and to suggest management strategies to minimize wind-related damage. Line transects oriented parallel and perpendicular to prevailing and dominant winds across 13 WTP reserves were used to quantify wind-related damage and factors that may contribute to windthrow incidence. The occurrence of windthrow corresponded with the exposure of WTP edges to high velocity winds; common, but lower-velocity winds resulted in little windthrow damage. Edaphic, site, and forest-stand factors appeared to have little influence on the incidence of windthrow in this study as compared to exposure to strong winds. The study suggests that forest managers can reduce the incidence of windthrow in WTPs in the boreal forests of northeastern British Columbia by: (1) creating patches that are elliptically shaped with the long axis in the direction of the dominant winds; (2) reducing wind exposure of susceptible edges; and (3) increasing the size of WTPs.