Resource Partitioning of Scots Pine (Pinus sylvestris L.) by Pine Shoot Beetles in Stands under Stress Conditions

The pine shoot beetles Tomicus piniperda L. and T. minor Hartwig are sympatric species that occur on Scots pine in two habitats. Feeding by the beetles in tree crowns causes significant losses in tree growth and disturbs the crown’s proper development. A review of the subject literature showed that there had been no previous studies of interspecific competition in stands with different degrees of crown damage. The aim of this work was to assess the resource partitioning of stems by the two species in stands with damaged and undamaged crowns. Data were collected in the years 1992–2008 in stands containing Scots pine located at different distances from timber yards. A total of 259 natural traps were laid, and measurements of height and diameter at breast height were made for 900 pines. The surface area of each stem was divided into 20 equal sections by making a division lengthwise (into units) and laterally (into an upper and lower part). In total, 90,501 egg galleries of pine shoot beetles were counted on 9560 stem sections. Feeding by pine shoot beetles in the crowns of pines reduces site productivity and the nutritional suitability of stems. The results of niche segregation indicate pine shoot beetles exhibited spatial specialization in the use of resources. prefers the thicker part of the stem, and T. minor the thinner part. The population of T. piniperda on the trap logs was described using a multiple linear regression model with three explanatory variables. As a result of regression modelling, from the set of variables representing characteristics of habitats, trees and trap logs and the parameters of infestation, the following explanatory variables were selected: range of colonisation of a trap log (rc), site quality class (sqc), and crown undamaged (cu). The explanatory variables included in the MLRM model explain to a significant degree (p < 0.05) the niche breadth of T. piniperda on trap logs. In all validated plots, the mean real and model values for the niche of T. piniperda on the trap logs are similar (p > 0.5), confirming the high accuracy of the developed model.

Emergence levels of pine shoot beetles from roundwood piles of Scots pine and the cascading damage in the surrounding forests

Bark beetles are amongst the most aggressive pest agents of coniferous forests. Due to this, many boreal countries have designated laws aiming to lower the risk of bark beetle epidemics. Finland’s forest legislation has pre-emptive measures targeted against bark beetles, and for Scots pine ( L.), the law concerns pine shoot beetles ( spp.). This study used data collected around 25 piles of Scots pine roundwood that were harvested in the winter but left in the forest until the following November. Thus, the pine shoot beetles were able to use the piles for breeding. We assessed the number of emerged insects from the piles and the cascading damage they caused in the surrounding forests. All roundwood piles, regardless of their volume, were used by the beetles for breeding. Highest densities of beetle exit holes were found from the parts of the log with thick and intact bark. If the bark of the log was damaged by the harvester head, the number of beetles decreased significantly. Depending on the volume of the roundwood pile, the cascading damage (fallen shoots) was noticeable up to ca. 40–60 m from the roundwood pile. Storing of piles smaller than 50 m did not cause excess damage. The number of fallen shoots per tree was generally below the known thresholds for when growth losses can occur. However, the study was conducted in mature forests, and it can be assumed that the recorded damage levels would severely affect the growth of young pines, raising the question of where to store the roundwood. As with other bark beetles, the role of beetles as damage agents may change in the future, but based on this as well as past studies, the species can be viewed as a notable damage agents only around long-term wood storage sites in the current northern conditions.Pinus sylvestrisTomicus3Tomicus

Detection of Shoot Beetle Stress on Yunnan Pine Forest Using a Coupled LIBERTY2-INFORM Simulation

Yunnan pine shoot beetles (PSB), Tomicus yunnanensis and Tomicus minor have spread through southwestern China in the last five years, leading to millions of hectares of forest being damaged. Thus, there is an urgent need to develop an effective approach for accurate early warning and damage assessment of PSB outbreaks. Remote sensing is one of the most efficient methods for this purpose. Despite many studies existing on the mountain pine beetle (MPB), very little work has been undertaken on assessing PSB stress using remote sensing. The objective of this paper was to develop a spectral linear mixing model aided by radiative transfer (RT) and a new Yellow Index (YI) to simulate the reflectance of heterogeneous canopies containing damaged needles and quantitatively inverse their PSB stress. The YI, the fraction of dead needles, is a physically-explicit stress indicator that represents the plot shoots damage ratio (plot SDR). The major steps of this methods include: (1) LIBERTY2 was developed to simulate the reflectance of damaged needles using YI to linearly mix the green needle spectra with the dead needle spectra; (2) LIBERTY2 was coupled with the INFORM model to scale the needle spectra to the canopy scale; and (3) a look-up table (LUT) was created against Sentinel 2 (S2) imagery and inversed leaf chlorophyll content (LCC), green leaf area index (LAI) and plot SDR. The results show that (1) LIBERTY2 effectively simulated the reflectance spectral values on infested needles (mean relative error (MRE) = 1.4–18%), and the YI can indicate the degrees of needles damage; (2) the coupled LIBERTY2-INFORM model is suitable to estimate LAI (R2 = 0.73, RMSE = 0.17 m m−2, NRMSE = 11.41% and the index of agreement (IOA) = 0.92) and LCC (R2 = 0.49, RMSE = 56.24 mg m−2, NRMSE = 25.22% and IOA = 0.72), and is better than the original LIBERTY model (LAI: R2 = 0.38, RMSE = 0.43 m m−2, NRMSE = 28.85% and IOA = 0.68; LCC: R2 = 0.34, RMSE = 76.44 mg m−2, NRMSE = 34.23% and IOA = 0.57); and (3) the inversed YI is positively correlated with the measured plot SDR (R2 = 0.40, RMSE = 0.15). We conclude that the LIBERTY2 model improved the reflectance simulation accuracy of both the needles and canopies, making it suitable for assessing PSB stress. The YI has the potential to assess PSB damage.

ENTOMOLOGIZES FACTORY IN THE PROCESS OF SPREADING COMMON PINE ROOT SPONGE UNDER THE CONDITIONS OF SHIP TIMBER FORESTRY OF STATE ENTERPRISE “ZHYTOMYR FORESTRY”

The article studies the species varieties of forest insects in the centers of attack with determination of the tree stocking degree. The major insect species are represented by such samilies as bark beetlesipidae capricon betles – Cerambycidae. The artice considers the effect of insect on common pipe decaying in the location of pine fungus. It has been substantiated that the formalion of forest insect attack centers depend on the age of trees. Concentration of larger and lasser pine – shoot beetles dominates in the forest of 40 years of age. They intensify the effect of pine fungus with further weakening the trees. Following the results of investigation it has been determined that such insects as larger pine-shoot beetle lesser pine-shoot beetle, black pine Capricorn beetle, blue pine char cool beetle, Curkulio glandium are the synergist of Heterobasidion annosum finvader.Обгрунтовано значення ентомологічного фактора у розповсюдженні кореневої губки сосни звичайної, а також видового складу стовбурових шкідників в осередках Heterobasidion annosum з визначенням ступеня заселеності дерев. Основні види стовбурових шкідників представлені родинами: короїди – Іріdае, вусачі – Сеrambycidае, златки – Вuprestidае, довгоносики – Сulculionida).Предметом роботи є збудник кореневої губки сосни звичайної в умовах Корабельного лісництва державного підприємства «Житомирське лісове господарство». Метою роботи є вивчення впливу стовбурових шкідників на всихання сосни звичайної в осередках кореневої губки. Встановлено, що формування осередків стовбурових шкідників залежить від віку насаджень – осередки великого і малого соснового лубоїдів переважають в насадженнях до 40 років, що призводить до підсилення шкідливої дії кореневої губки. Основними методами проведення робіт є фітопатологічна експертиза соснових насаджень, а також проведення обстежень соснових деревостанів з визначенням характеру всихання в залежності від ступеня ураження як збудником кореневої губки сосни звичайної, так і розповсюдження збудника ентомологічним шляхом в соснових деревостанах.За результатами роботи встановлено, що формування осередків стовбурових шкідників залежить від віку насаджень – осередки великого і малого соснового лубоїдів переважають в насадженнях до 40 років, призводячи до підсилення шкідливої дії кореневої губки і значного ослаблення насадження в подальшому. В результаті проведених досліджень було виявлено, що великий сосновий лубоїд, малий сосновий лубоїд, чорний сосновий вусач, синя соснова златка, соснова жерднякова смолівка є синергітами збудника Heterobasidion annosum.Сферою застосування результатів є лісогосподарські підприємства різних форм власності з метою збереження та захисту лісових насаджень від збудника кореневої губки в умовах зони Полісся України.Висновки досліджень полягають в тому, що для повноцінного відновлення лісів, з лісогосподарської точки зору найбільш ефективнішим вирішенням проблеми є проведення рубок догляду, тоді, коли приріст починає сповільнюватися, отже вдається зберегти максимальний приріст дерев що залишаються, а від реалізації заготовленої при рубках догляду деревини отримати прибуток не чекаючи, поки вони будуть знищені шкідниками. В перспективі є сенс в подальших дослідженнях штучно створених насаджень які ще довгий час не зможуть функціонувати без систематичного і регулярного лісогосподарського та лісосанітарного догляду, причому слід чітко розуміти, що цьому повинен передувати досить тривалий період трансформації штучних лісових фітоценозів до природного стану. Тому важливим завданням лісівників в ДП „Житомирське ЛГ” у цьому напрямку є підтримання стабільного фітосанітарного стану насаджень і всебічна стимуляція природних саморегуляційних процесів в лісових екоценозах.

Ethanol accumulation during severe drought may signal tree vulnerability to detection and attack by bark beetles

Tree mortality from temperature-driven drought is occurring in forests around the world, often in conjunction with bark beetle outbreaks when carbon allocation to tree defense declines. Physiological metrics for detecting stressed trees with enhanced vulnerability prior to bark beetle attacks remain elusive. Ethanol, water, monoterpene concentrations, and composition were examined in the phloem and sapwood of drought-stressed Aleppo pine (Pinus halepensis Mill.) freshly attacked by mature Mediterranean pine shoot beetles (Tomicus destruens (Wollaston, 1865)) and in neighboring unattacked trees. The attacked trees were more water-stressed and contained, on average, 2.1 and 2.4 times more ethanol in the phloem and sapwood, respectively, than the neighboring attack-free trees. This response is consistent with the known attraction of T. destruens to ethanol. Most monoterpene concentrations in the phloem, but not sapwood, were greater in tissues of attacked trees, whereas compositional differences were minor between the two tree groups for both tissues. Tissue water content explained much of the variation in phloem monoterpene concentrations, which increased as water in the phloem declined, suggesting that higher constitutive quantities existed in the more stressed trees prior to the attacks. Monoterpenes may have contributed to host tree selection by T. destruens, but their potential influence is considered less important than that of ethanol based on beetle responses to these compounds in previous trapping studies. This is the first report of elevated ethanol concentrations in tissues of trees experiencing natural drought stress and suggests that ethanol measurements in severely water-stressed trees may allow early detection of those most vulnerable to bark beetle attack.

Spatial distribution of losses in growth of trees caused by the feeding of pine shoot beetles Tomicus piniperda and T. minor (Col., Scolytidae) in Scots pine stands growing within range of the influence of a timber yard in southern Poland

This study deals with the assessment of increment losses in Scots pine trees caused by the maturation feeding of pine shoot beetles Tomicus piniperda (L.) and T. minor (Hart.) (Col., Scolytidae) in even-aged stands growing during their entire life span within range of the influence of a sawmill and its timber yard. In spring 2004, on three sample plots, 0.2 ha in size, situated 60, 200, and 500 m from the yard, height and dbh of all trees were measured and increment cores were taken from randomly selected sample trees. An agreement between the spatial distribution of losses in tree increments and the distribution of damage to crowns of investigated stands indicated that the losses resulted from the maturation feeding of pine shoot beetles migrating from the sawmill timber yard. Divergence of growth in the about 25-years-old stand indicated the beginning of intensive feeding of beetles in pine shoots with a high level of probability. In comparison with the control stand the basal area losses in stands growing 60 and 200 m from the beetle source amounted to 57% and 46%, respectively. The difference in the height of trees was as large as almost 100%.

Performance ofTomicus yunnanensisandTomicus minor(Col., Scolytinae) onPinus yunnanensisandPinus armandiiin Yunnan, Southwestern China

Pine shoot beetles,Tomicus yunnanensisKirkendall and Faccoli andTomicus minorHartig (Col., Scolytinae), have been causing substantial mortality to Yunnan pine (Pinus yunnanensisFranch) in Yunnan, southwestern China, whereas only a few Armand pine (Pinus armandiiFranch) were attacked by the beetles. In order to evaluate the suitability ofP. armandiias host material for the twoTomicus, adults of bothTomicuswere caged on living branches and felled logs of the two pines during shoot feeding and trunk attack phase, respectively. More beetles survived on the living branches ofP. yunnanensisthan onP. armandii.Tomicus yunnanensisandT. minorproduced similar progeny in the logs of the two pines. The sex ratio and developmental period were not affected by host species, but the brood beetles emerging from Armand pine weighed less than those from Yunnan pine, suggesting thatP. armandiiare less suitable to be host ofT. yunnanensisandT. minor.

Feeding ecology of pine shoot beetles (Tomicus spp.) in tree crowns of Scots pine (Pinus sylvestris L.) stands under one-year outbreak

Studies were carried out in southern Poland during 2002–2006 in Scots pine stands under the effect of an outbreak of pine shoot beetles. The qualitative aspects of beetle feeding in tree crowns, studied on the basis of fallen shoots collected on experimental plots, are presented in this paper. The beetle numbers affected the age distribution of damaged shoots and the proportion of multiple attacks. The proportions of one-year-old shoots and the numbers of shoots with more than two attacks increased in the marginal part of the stand in the year of intensive feeding of beetles and in the subsequent year. A similar proportion of shoots with two attacks in both stands under investigations in individual study periods, with no relation to beetle numbers, does not permit to use this characteristic for forecasting purposes. The average length of tunnels in shoots attacked once reached 20 mm at maximum. The average length of tunnels (measured from the place of shoot disruption) was greater in shoots with two attacks than in shoots with a single one (<i>P</I> < 0.0001). The difference was not significant (<I>P</I> = 0.3429) only in stand B during the study season 2004–2005. The majority of the tunnels made in apical portions of shoots with two attacks damaged the tissue of apical shoots. The distance between the base of the second tunnel and the shoot apex in shoots with two attacks, and its significant (<I>P</I> < 0.01) linear relationship with the length of beetle tunnels, indicated a high nutritional quality of apical portions of shoots.