FOREST HEALTH IN A CHANGING WORLD Sugden, Andrew; Fahrenkamp-Uppenbrink, Julia; Malakoff, David ...
Science (American Association for the Advancement of Science),
08/2015, Letnik:
349, Številka:
6250
Journal Article
•Intense drought increases bark beetle outbreaks in arid forests of the western US.•Drought does not have a large role in bark beetle outbreaks in the eastern US.•Defoliators exhibit no consistent ...response to drought.•Response to drought of sapfeeders is nonlinear.•Drought impacts differ between primary and secondary fungal pathogens.
Future anthropogenic-induced changes to the earth’s climate will likely include increases in temperature and changes in precipitation that will increase the frequency and severity of droughts. Insects and fungal diseases are important disturbances in forests, yet understanding of the role of drought in outbreaks of these agents is limited. Current knowledge concerning the effects of drought on herbivorous insect and pathogen outbreaks in U.S. forests is reviewed, and compared between the relatively mesic and structurally diverse forests of the eastern U.S. and the more xeric forests of the western U.S. Theory and limited evidence suggests a non-linear relationship between drought intensity and outbreaks of aggressive bark beetle species (i.e., those capable of causing extensive levels of tree mortality), where moderate droughts reduce bark beetle population performance and subsequent tree mortality, whereas intense droughts, which frequently occur in the western U.S., increase bark beetle performance and tree mortality. There is little evidence for a role of drought in outbreaks of the southern pine beetle (Dendroctonus frontalis), the only bark beetle species that causes large amounts of tree mortality in the eastern U.S. Defoliators do not show consistent responses to drought. The response of sapfeeders to drought appears non-linear, with the greatest performance and impacts at intermediate drought intensity or when drought is alleviated by wetter periods. Interactions between tree pathogens and drought are poorly understood, but available evidence suggests reduced pathogen performance and host impacts in response to drought for primary pathogens and pathogens whose lifecycle depends directly on moisture (humidity). In these cases, rates of reproduction, spread, and infection tend to be greater when conditions are moist. In contrast, secondary fungal pathogens (i.e., those that depend on stressed hosts for colonization) are anticipated to respond to drought with greater performance and host impacts. In the western U.S., drought increases stress on trees severely infected by mistletoes thereby predisposing mistletoe-infected trees to attack by insects, particularly bark beetles and wood borers. Research needed to advance understanding of drought impacts on forest insects and diseases, and the role of forest management in mitigation of infestations during drought are discussed.
Conservation forests must maintain the function and quality of their forests so that the preservation of the living natural resources therein is not damaged and the balance of the ecosystem is well ...ordered. The benefits of a conservation forest can be felt by the people who live around the forest such as carbon, water sources, non-timber forest products so that the community can prosper. Forest health monitoring is an activity designed to monitor the condition of forest health based on the results of measurable ecological indicators for forest management decision making. The purpose of this study is to determine the value of conservation forest health status and identify internal and external factors of conservation forest health. The method used is Forest Health Monitoring for assessing forest health status and Statistical Product and Service Solutions 20. software for determining the relationship of internal factors with external forest health. The results showed the health status of the conservation forest included in the management area of the Sustainable Peoples Forest System Farmer Group in the Teluk Pandan sub-district of Pesawaran District included in the medium category (3,20) . Internal factors that affect the health of conservation forests are biodiversity and tree damage while external factors that affect the health of conservation forests are the level of farmers' knowledge, farmer participation and farmer motivation.
•Correlation was found between canopy temperature depression (CTD) and disease level.•Inclusion of standard deviation of canopy temperature improved the relationship.•Change in environmental ...conditions altered the observed relationship.•The strongest relationship was obtained at the time of highest solar radiation.
Monoculture plantation woodlands are particularly vulnerable to disturbance events as species uniformity makes such stands highly susceptible to pests and diseases. Red band needle blight (caused by the fungus Dothistroma septosporum) is a disease which has a particularly significant economic impact on pine plantation forests worldwide, affecting diameter and height growth. However, monitoring its spread and intensity is complicated by the fact that the diseased trees are often only visible from aircraft in the advanced stages of the epidemic. Remote sensing could potentially aid in the detection of infected stands and in monitoring disease development and spread. Thermography is one of the techniques that can be used for monitoring changes in the physiological state of plants following infection. However, the use of thermography in forestry has so far been restricted by poor spatial resolution (satellite-based sensors) or high data acquirement costs (airborne sensors). This paper investigates the use of Unmanned Aerial Vehicle (UAV)-borne thermal systems for detecting disease-induced canopy temperature increase and explores the influence of the imaging time and weather conditions on the detected relationship. Furthermore, the potential of a number of airborne LiDAR-derived structural metrics for detection of changes in the canopy structure following the infection are investigated. The study was located in a diseased Scots pine (Pinus sylvestris) stand in Queen Elizabeth II Forest Park (central Scotland, UK), where 60 sample trees were surveyed. The thermal imagery was acquired at six different times of a day from an altitude of 60 m. Statistically significant correlation between canopy temperature depression (CTD) and disease levels was found for most of the flights (R2 between 0.27 and 0.41), which may be related to the needle damage symptoms caused by the disease, i.e. loss of cellular integrity, necrosis and eventual desiccation. Furthermore, the standard deviation of the crown temperature exhibited weak but statistically significant correlation (R2 between 0.11 and 0.13). The combination of CTD and standard deviation of crown temperature in a partial least squares regression (PLSR) further improved the observed relationship with the estimated disease level. Inclusion of LiDAR structural metrics was also investigated but only provided a slight improvement. A change in environmental conditions altered the magnitude of differences between canopy temperatures; no significant correlation with disease level was found in the morning flight, whilst the strongest relationship was obtained at the time of highest solar radiation, which coincides with the time of maximum photosynthetic activity.
Safe’I R, Latumahina FS, Dewi BS, Ardiansyah F. 2021. Short Communication: Assessing the state and change of forest health of the proposed arboretum in Wan Abdul Rachman Grand Forest Park, Lampung, ...Indonesia. Biodiversitas 22: 2072-2077. Forest health is the fundamental of sustainable forest management. As such, forest health needs to be continually monitored and maintained. This study assessed the state and change of forest health of the prospective arboretum in Wan Abdul Rachman Grand Forest Park (Tahura WAR), Lampung, Indonesia, aiming that the arboretum can serve for integrated conservation and education forest (Tahura War). This research used the Forest Health Monitoring (FHM) method by combining the parameters of vitality (i.e., tree damage and tree crown condition) and biodiversity (tree species diversity) across four Forest Health Monitoring plot clusters. The results showed there was a change in the state of forest health of the prospective arboretum in Tahura WAR. The first measurement showed that 50% of plot clusters had a status of bad, while 25% was moderate and 25% was good. The results of the second measurement showed that 50% of plot clusters had a status of moderate, while 25% was bad and 25% was good. This finding suggests that the prospective arboretum experienced changes toward better conditions in health status. Even so, it is still necessary to carry out regular forest health monitoring activities to determine trends.
In recent decades, increases in severe drought, heat extremes, and pest burden have contributed to increased global tree mortality. These risks are expected to be exacerbated under projected climate ...change. So far, observations of tree mortality are mainly based on manual field surveys with limited spatial coverage. The lack of accurate tree mortality data over large areas has limited the development and applications of tree mortality models. However, a combination of high-resolution remote sensing data, such as aerial imagery and automated imagery analysis, may provide a solution to this problem. In this study, we analysed the dynamics and drivers of forest canopy mortality in 117 366 ha of boreal forest in Southeast Finland, between 2017 and 2023. For this purpose, we first developed a fully convolutional semantic segmentation model to automatically segment forest canopy mortality from aerial imagery in 2017, 2020, and 2023 with a spatial resolution of 0.5 m. Secondly, we trained the model using a dataset consisting of 32555 canopy mortality segments manually delineated from aerial imagery from various geographic regions in Finland. The trained model showed high accuracy in detecting forest canopy mortality (with an F1 score of 0.86–0.93) when tested using an independent test set. To estimate standing deadwood volume, we combined the observed yearly forest canopy mortality with open forest resource information based on extensive field campaigns and airborne laser scanning. In our study area, forest canopy mortality increased from 23.4 ha (0.02 % of the study area) to 207.8 ha (0.18 %) between 2017 and 2023. Consequently, standing deadwood volume was estimated to increase from 5192 m3 (0.04 m3/ha) to 52800 m3 (0.45 m3/ha) during the study period. Both the volume of standing deadwood and the extent of forest canopy mortality increased exponentially. The majority of the forest canopy mortality occurred in Norway spruce-dominated forests (64.1–77.3 %) on relatively fertile soils (81.6–84.7 %) while 20–25 % of the forest canopy mortality occurred in Scots pine-dominated forests. The average age of stands where mortality was observed was between 60 and 70 years old (2017 = 69.7 years and 2023 = 62.6 years), indicating that mature forests were more susceptible to mortality than younger stands. Our findings highlight an exponential increase in forest canopy mortality over a relatively short time span (6 years). The increasing risk of tree mortality in boreal forests underlines the urgent need for large-scale and spatially accurate monitoring to keep up to date with fast-paced changes in boreal forest mortality. As climate change increases drought, extreme heat and bark beetle outbreaks, consistent canopy mortality mapping is essential for implementing timely risk management measures in forestry.
•Forest canopy mortality increased by 788 % between 2017 and 2023.•Distribution of canopy mortality shifted towards younger forest stands.•Forest canopy mortality detected with an F1-score of 0.86–0.93 from aerial imagery.
Ips bark beetles (Ips species; Coleoptera: Curculionidae: Scolytinae) play an important role in forest ecosystems by attacking injured, stressed, or dying pine (Pinus) trees. Management of Ips bark ...beetles has largely focused on prevention by maintaining tree health through silvicultural treatments including thinning to reduce basal area or prescribed fire. However, there is conflicting evidence of whether prescribed fire leads to increased bark beetle populations and, subsequently, increased tree mortality. Recent outbreaks of Ips bark beetles in the southeastern U.S. have caused renewed interest in the interactions between pine management and bark beetle populations. We monitored Ips populations following prescribed fire in intensively managed pine stands and quantified Ips damage. We captured over 361,000 Ips bark beetles with I. avulsus being the most abundant of the three species collected. While we found high variation among Ips populations across study sites and years, there was a significant increase in bark beetle populations after prescribed fire followed by a significant decline the next year. While Ips populations increased up to three-fold after prescribed burns, damage ratings in burned stands were no different than unburned stands which had significantly lower bark beetle populations. Unburned stands had higher basal area and a higher average tree damage rating, but the lowest number of Ips bark beetles. A total of 14,071 facultative (e.g., Monochamus = 9775) and obligate (e.g., Thanasimus dubius = 4296) predators were collected during the study across all sites and the ratio of predators:Ips also significantly increased following prescribed fire. These data suggest that while Ips are ubiquitous and abundant in pine forests being managed with prescribed fire, natural mechanisms such as predator activity mediate their overall damage and impact to southeastern pine stands.
•Ips bark beetles are ubiquitous in pine stands regardless of damage or mortality.•Prescribed fire results in significant increases in bark beetle trap collections.•Natural enemies also increase significantly in response to prescribed fire.•Two years after prescribed fire, Ips bark beetles decline, likely due to predators.
•A remote sensing approach was developed for identifying bark beetle infestation.•A low-cost hyperspectral camera was operated from UAV and aircraft platforms.•Spruces were classified as healthy, ...infested or dead using Support Vector Machine.•The method is feasible for assessing health of individual trees in urban forest.
Climate-related extended outbreaks and range shifts of destructive bark beetle species pose a serious threat to urban boreal forests in North America and Fennoscandia. Recent developments in low-cost remote sensing technologies offer an attractive means for early detection and management of environmental change. They are of great interest to the actors responsible for monitoring and managing forest health. The objective of this investigation was to develop, assess, and compare automated remote sensing procedures based on novel, low-cost hyperspectral imaging technology for the identification of bark beetle infestations at the individual tree level in urban forests. A hyperspectral camera based on a tunable Fabry-Pérot interferometer was operated from a small, unmanned airborne vehicle (UAV) platform and a small Cessna-type aircraft platform. This study compared aspects of using UAV datasets with a spatial extent of a few hectares (ha) and a ground sample distance (GSD) of 10–12 cm to the aircraft data covering areas of several km2 and having a GSD of 50 cm. An empirical assessment of the automated identification of mature Norway spruce (Picea abies L. Karst.) trees suffering from infestation (representing different colonization phases) by the European spruce bark beetle (Ips typographus L.) was carried out in the urban forests of Lahti, a city in southern Finland. Individual spruces were classified as healthy, infested, or dead. For the entire test area, the best aircraft data results for overall accuracy were 79% (Cohen’s kappa: 0.54) when using three crown color classes (green as healthy, yellow as infested, and gray as dead). For two color classes (healthy, dead) in the same area, the best overall accuracy was 93% (kappa: 0.77). The finer resolution UAV dataset provided better results, with an overall accuracy of 81% (kappa: 0.70), compared to the aircraft results of 73% (kappa: 0.56) in a smaller sub-area. The results showed that novel, low-cost remote sensing technologies based on individual tree analysis and calibrated remote sensing imagery offer great potential for affordable and timely assessments of the health condition of vulnerable urban forests.
PDF
