Thin Bark Research Articles

Bark thickness and related parameters of tree species along an elevation transect leading to treeline in Central Himalaya.

Since treelines are generally fire-free, the trees growing there are expected to have thin bark, unless adaptation to other factors than fire results in the selection of a thick bark. Related to this is also higher proportional investment in inner bark in such an environment of infrequent fire. This study has considered stem bark thickness both in absolute and relative terms and also in the frame of the composition of outer and inner bark components of 20 tree species along an elevation transect (2100-3300m) in high ranges of the Central Himalaya leading to treelines. The study species varied from 2.1 to 16.2mm for total bark thickness and from 1.2 to 18.85% for relative bark thickness. The average absolute total bark thickness across the tree species decreased with elevation from forest to treeline, both when trees of all diameters (10.2 ± 0.84mm for forest and 6.9 ± 1.79mm for treeline) and those of the same stem diameter range (18-20m) were compared (9.10 ± 1.30mm for forest species and 6.38 ± 1.31mm for treeline species). Nevertheless, the treeline bark thickness was similar to those of several forest communities considered to have comparatively thick bark. Like many other biological structures, bark carries out multiple functions; therefore, its thickness could be affected by more than one environmental factor. We suggest that the requirement of mechanical resistance to the snowfall, rainstorms, wind and adaptation to a high sunlight and UV radiations or storage of water, and non-structural carbohydrates could affect total, outer and inner bark thickness. Studies on these aspects in similar ecosystems may help understand the multi-functional attributes of the bark. For trees of comparable sizes (trees with 18-20cm diameter at breast height) treeline species also had lower relative bark thickness (< 6%) than trees of forest below it (> 7%). The median proportion of inner bark of the total bark (70.5%) for our 20 species was more than that for savannas (~ 50%), exposed to frequent fire regime and similar to those of in cool sclerophyllous forests and temperate rain forests where fire return time is > 100years. However, it was lower than the inner bark proportion reported for tropical rain forests. To conclude, in spite of a fire-free environment, the Himalayan treeline and adjoining forest species show mixed bark characters.

Legacies of multiple disturbances on fruit and seed patterns in Amazonia: Implications for forest functional traits

AbstractForest disturbances associated with edge effects, wildfires, and windthrow events have impacted large swaths of the tropics. Defining the levels of forest disturbance that cause ecologically relevant reductions in fruit and seed (FS) production is key to understanding forest resilience to current and future global changes. Here, we tested the hypotheses that: (1) low‐intensity experimental fires alone would cause minor changes in FS production and diversity in a tropical forest, whereas synergistic disturbance effects resulting from edge effects, wildfires, droughts, and blowdowns would drive long‐term reductions in FS diversity and production; and (2) the functional composition of FS in disturbed forests would shift toward tree species with acquisitive strategies. To test these hypotheses, we quantified FS production between 2005 and 2018 in a large‐scale fire experiment in southeast Amazonia. The experimental treatments consisted of three 50‐ha plots: a Control plot, a plot burned annually (B1yr) and a plot burned every three years (B3yr) between 2004 and 2010. These plots were impacted by edge effects, two droughts (2007 and 2010), and a blowdown event in 2012. Our results show that FS production remained relatively high following low‐intensity fires, but declined where fires were most severe (i.e., forest edge of B3yr). The number of species‐producing FS declined sharply when fires co‐occurred with droughts and a windthrow event, and species composition shifted throughout the experiment. Along the edge of both burned plots, the forest community became dominated by species with faster relative growth, thinner leaves, thinner bark, and lower height. We conclude that compounding disturbances changed FS patterns, with a strong effect on species composition and potentially large effects on the next generation of trees. This is largely due to reductions in the diversity of species‐producing FS where fires are severe, causing a shift toward functional traits typically associated with pioneer and generalist species.

Wood Material Properties of Forest Fire-Damaged Norway Spruce and Scots Pine for Mechanical Wood Processing in Finland

Due to climate change, the risk of forest fires has increased in Europe, resulting in challenges in the allocation of salvaged wood. We studied the raw material potential for wood products of Norway spruce and Scots pine sawn log trees that remained standing after a large forest fire in Kalajoki, Finland, in July 2021. Eight burned trees, with four reference trees per species, were sampled as standard specimens, and measurements were analyzed with linear mixed models. The effects of fire on the modulus of elasticity and rupture, Brinell hardness, moisture gradient, and color were measured on clear wood specimens of sapwood and heartwood. The wood density, level of fire damage, and height location of a tree were used as additional predictors. The results show some changes in the sapwood material. Spruce wood underwent stronger changes after the fire than pine wood, probably due to spruce wood having a thinner bark and a longer crown. The moisture content decreased in spruce, and the color darkened in both spruce and pine. Changes in the mechanical properties were mostly negligible, but a small increase in the Brinell hardness in spruce and a small decrease in the modulus of rupture in pine were observed. Fresh salvaged wood can be a suitable material for middle-quality and lower-quality wood products. The spread of char and soot into wood and wood processing machinery still limits its usage, especially for spruce.

Life after fire - Long-term responses of 20 timber species in semi-deciduous forests of West Africa

Understanding the response of commercial timber species to fire is fundamental to designing sustainable forest management strategies in West Africa. In this area of high deforestation for agriculture, semi-deciduous tropical forests have been reduced to a trickle in 50 years and are now subject not only to logging but also to increasingly frequent fires. This paper aims to study the long-term (37 years) demographic and growth responses of 20 timber species after a spatially heterogeneous fire in a West African semi-deciduous forest. We (i) inventoried, in 2020, 100 hectares of plots already established before the 1983 fire, (ii) built demographic and growth models, in a Bayesian framework, to estimate the vulnerability to fire of each species and (iii) linked this vulnerability to functional traits: wood density (WD) and bark thickness (BT). Our results show that most species have lower current abundances but higher growths in burnt areas than in fire-preserved areas. We identified three categories of vulnerability to fire: 1 non-vulnerable species, 16 species with vulnerable demography, and 3 highly vulnerable species. Species with high wood density or thin bark show higher demographic vulnerability to fire. Our results show that fire management is a top priority in West African semi-deciduous forests to maintain long-term populations of timber species and ultimately the forest industry. The differences in vulnerability observed, and the strong predictive power of the functional traits studied, should make it possible to (i) better define harvesting rates and adapt them to fire risk and (ii) better select commercial species to be promoted for reforestation or natural (assisted) regeneration.

From mallees to mountain ash, specific leaf area is coordinated with eucalypt tree stature, resprouting, stem construction, and fruit size

Context The radiation of eucalypts into almost every Australian environment offers valuable insights to plant ecological strategies. Aims We aimed to assess the degree to which functional traits across different organs are independent or reflect coordinated strategies in southern eucalypts. Methods We applied ordinary and phylogenetic generalised least squares regressions to 164 southern Australian taxa, examining the network of pairwise relationships between 10 functional traits representing aspects of stature, leaf economics, reproduction and post-fire regeneration. We examined coordination and modularity in this network and estimated how phylogeny affects observed trait correlations. Results Stem and stature traits were generally independent of reproductive traits, with Specific Leaf Area the most connected trait, being correlated with traits from all organs. Resprouting ability was also connected to several traits. Species able to resprout basally, but not epicormically, were on average shorter, stouter, with higher stem sapwood density, thinner bark, smaller leaves and lower Specific Leaf Area than those able to resprout using both methods. Taxa resembled their relatives; phylogenetic signal was significant for all continuous traits except Relative Height, ranging from Pagel’s Lambda λ = 0.37 (Relative Bark Thickness) to λ = 0.82 (Specific Leaf Area). Phylogenetic analyses showed weakened correlations for most (but not all) trait pairs. However, most moderate relationships on the trait correlation network also displayed correlated evolution. Conclusions Stature, stem, leaf and reproductive traits and fire response of eucalypts are somewhat coordinated, principally through leaf economics. Trait combinations that confer ecological competence on eucalypt taxa in present-day conditions are likely to have been similarly favoured throughout their evolutionary history. Implications This supports theory of coordinated plant strategies.

Functional Diversity in Woody Organs of Tropical Dry Forests and Implications for Restoration

Tropical dry forests (TDFs) represent one of the most diverse and, at the same time, most threatened ecosystems on earth. Restoration of TDFs is thus crucial but is hindered by a limited understanding of the functional diversity (FD) of original communities. We examine the FD of TDFs based on wood (vessel diameter and wood density) and bark traits (total, inner, and outer bark thicknesses) measured on ~500 species from 24 plant communities and compare this diversity with that of seven other major vegetation types. Along with other seasonally dry sites, TDFs had the highest FD, as indicated by the widest ranges, highest variances, and largest trait hypervolumes. Warm temperatures and seasonal drought seem to drive diverse ecological strategies in these ecosystems, which include a continuum from deciduous species with low-density wood, thick bark, and wide vessels to evergreen species with high-density wood, thin bark, and narrow vessels. The very high FD of TDFs represents a challenge to restoring the likely widest trait ranges of any habitat on earth. Understanding this diversity is essential for monitoring successional changes in minimal intervention restoration and guiding species selection for resilient restoration plantings in the context of climate change.

ИЗМЕНЧИВОСТЬ ТВЕРДОСТИ ДРЕВЕСИНЫ СОСНЫ, ПОВРЕЖДЕННОЙ СИЛЬНЫМ НИЗОВЫМ И ПОВАЛЬНЫМ ВЕРХОВЫМ ПОЖАРОМ

Fires cause huge damage to forests. The degree of damage to plantings depends on the type of fire, which is largely determined by climatic conditions, terrain, age of plantings, etc. The greatest damage to plantings is caused by a strong grassroots and rampant riding fire. The commodity value of such wood is minimal. Resin formation processes occur in wood damaged by fire. The degree of tarring of the wood depends on the viability of the cambium. The thin bark of young trees does not provide sufficient protection of cambium from heat exposure and trees die quickly. A thick layer of bark partially protects the cambium and the resin formation processes are activated in the wood, which can take a long period of time. The effect of high temperature, including its tarring, has a significant impact on the physical and mechanical properties of wood. Information about the quality of wood damaged by fire and their variability during long-term storage or during operation is of great practical importance. The aim of the study is to establish the static end hardness of pine wood damaged by a strong grassroots and rampant riding fire, after long-term storage in room conditions. It was found that during storage for 10 years, the static end hardness of tarred pine wood increased by 1.9-2.2 times, compared with the indicators at the time of cutting wood after a fire and exceeds the indicators of intact pine wood in trees with a trunk diameter of 22-26 cm by 42.5% and a diameter of 50-56 cm by 67.7%. The degree of tarring and the strength of wood are higher in trees with thicker bark

Variation in eucalypt bark allometry across Australia

Positive bark allometry (hyperallometry), characterised by rapid early bark growth, is expected where fire selects for thicker bark to resist cambial damage and topkill. We examine this prediction for 52 Australian eucalypt species. An effective bark allometric coefficient (α) was estimated from the first segment of breakpoint regression, which included fire-affected young trees. Eucalypts presented a negative–positive bark allometry continuum. Contrary to expectation, 73% of species (n = 38) displayed negative effective bark allometry. Early rapid bark growth was observed (α = 0.92 ± 0.04, x ± s.e., n = 168 sites), but was slower than isometry and bark was thinner overall than expected. Fire type (crown-fire propensity) and net primary productivity (resource availability) most influenced bark allometry. Productive ecosystems experienced crown-fire and bark was thicker at standardised diameter (x ± s.e. = 2.04 ± 0.20 cm) than in less productive ecosystems under surface fire (x ± s.e. = 1.68 ± 0.18 cm). Bark morphology types did not differ in their stem diameter (x ± s.e. = 21.47 ± 1.06 cm) or bark thickness (x ± s.e. = 1.88 ± 0.08 cm) thresholds, representing putative stable alternative evolutionary solutions. Fundamentally, many eucalypts possess negative bark allometry with a relatively thin bark compared to non-eucalypts, because unique bark bud traces sustain post-fire resilience through epicormic resprouting. The resource allocation trade-off to thin bark v. height growth, selected by fire and resource limitation, accounts for eucalypt persistence and domination of Australia’s flammable ecosystems.

The Latent Dirichlet Allocation model with covariates (LDAcov): A case study on the effect of fire on species composition in Amazonian forests.

Understanding and predicting the effect of global change phenomena on biodiversity is challenging given that biodiversity data are highly multivariate, containing information from tens to hundreds of species in any given location and time. The Latent Dirichlet Allocation (LDA) model has been recently proposed to decompose biodiversity data into latent communities. While LDA is a very useful exploratory tool and overcomes several limitations of earlier methods, it has limited inferential and predictive skill given that covariates cannot be included in the model. We introduce a modified LDA model (called LDAcov) which allows the incorporation of covariates, enabling inference on the drivers of change of latent communities, spatial interpolation of results, and prediction based on future environmental change scenarios. We show with simulated data that our approach to fitting LDAcov is able to estimate well the number of groups and all model parameters. We illustrate LDAcov using data from two experimental studies on the long‐term effects of fire on southeastern Amazonian forests in Brazil. Our results reveal that repeated fires can have a strong impact on plant assemblages, particularly if fuel is allowed to build up between consecutive fires. The effect of fire is exacerbated as distance to the edge of the forest decreases, with small‐sized species and species with thin bark being impacted the most. These results highlight the compounding impacts of multiple fire events and fragmentation, a scenario commonly found across the southern edge of Amazon. We believe that LDAcov will be of wide interest to scientists studying the effect of global change phenomena on biodiversity using high‐dimensional datasets. Thus, we developed the R package LDAcov to enable the straightforward use of this model.

Thick bark can protect trees from a severe ambrosia beetle attack.

Thick bark has been shown to protect trees from wildfires, but can it protect trees from an ambrosia beetle attack? We addressed this question by examining the distribution of holes of the invasive Kuroshio Shot Hole Borer (KSHB, Euwallacea kuroshio; Coleoptera: Scolytinae) in the bark of Goodding’s black willow (Salix gooddingii), one of the KSHB’s most-preferred hosts. The study was conducted in the Tijuana River Valley, California, in 2016–17, during the peak of the KSHB infestation there. Using detailed measurements of bark samples cut from 27 infested trees, we tested and found support for two related hypotheses: (1) bark thickness influences KSHB attack densities and attack locations, i.e., the KSHB bores abundantly through thin bark and avoids boring through thick bark; and (2) bark thickness influences KSHB impacts, i.e., the KSHB causes more damage to thinner-barked trees than to thicker-barked trees. Our results indicate that thick bark protects trees because it limits the density of KSHB entry points and thereby limits internal structural damage to low, survivable levels. This is the first study to identify bark thickness as a factor that influences the density of KSHB—or any ambrosia beetle—in its host tree, and the first to link bark thickness to rates of host tree mortality.

Fungal succession in decomposing woody debris across a tropical forest disturbance gradient

Fungi decompose woody debris, an important carbon pool in forests. Fungal community structure is expected to vary according to the wood species, habitats and extent of abiotic disturbance, which have consequences for carbon cycling in tropical forests. Here we examined the effects of fungal diversity and composition on woody debris decomposition rates and sought potential mechanisms to explain an observed lack of difference in decomposition rates across a disturbance gradient in a tropical montane rainforest in Xishuangbanna, SW China. We measured wood specific gravity (WSG) loss from 280 logs of Litsea cubeba and Castanopsis mekongensis over 3 years and monitored fungal communities from 418 samples using next-generation sequencing after 0, 18 and 36 months field exposure. Wood species and termite presence determined changes in fungal diversity through time. Overall there was a peak in fungal diversity at 18 mo, suggesting an initial period of colonization followed by a period of increasingly competitive interactions leading to decreased diversity. Litsea logs, which had relatively low initial WSG and thinner bark, harbored higher fungal diversity. Shared fungal OTUs between wood species peaked at 18 mo (~50%). However, fungal diversity was not a significant predictor of WSG loss. An effect of habitat on fungal community composition suggests that functional replacement explains the similar decay rates across the disturbance gradient. In addition, the proportions of saprotroph and white-rot fungi increased through time regardless of wood species. Termite presence reduced WSG loss, but the effect was mediated via the abundance of soft rot fungi. Our results suggest that changes in functional traits, rather than fungal species diversity, may better explain variation in WSG loss. Future studies should investigate roles of fungal functional traits and rot types, particularly those of Ascomycete fungi, whose roles in wood decay are still poorly characterized.

Caracterização de compostos voláteis e compostos bioativos da polpa e geleia de cagaita por microextração em fase sólida no modo headspace e espectrometria de massa por paper spray

A cagaiteira (Eugenia dysenterica) pertencente à família Myrtaceae, é uma árvore nativa do Cerrado brasileiro, o seu fruto é muito frágil, apresentando casca fina e polpa suculenta, é consumido na forma processada como geleia para prolongar a vida útil. O presente trabalho teve como objetivo elaborar geleia de cagaita e avaliar a alteração de compostos bioativos e compostos voláteis em relação à polpa in natura. A análise de espectrometria de massa por paper spray nos modos positivos e negativos permitiu a identificação de 27 compostos, dentre elas, ácidos orgânicos, açúcares, antocianinas, ácidos hidroxicinâmicos, ácidos hidroxibenzóicos e flavonoides, indicando que a produção de geleia pode ser uma técnica para conservação de compostos fenólicos com suas respectivas qualidades sensoriais como cor e sabor. Na análise de voláteis por microextração em fase sólida no modo headspace, foram detectados no total de 33 compostos, principalmente das classes de monoterpenos, de sesquiterpenos e de ésteresindicando que a produção da geleia pode conservar o aroma característico do fruto. Na caracterização dos compostos voláteis da polpa de cagaita, o 3-careno foi o monoterpeno majoritário encontrado. Enquanto no processamento da geleia houve produção do furaldeído, produto obtido como consequência natural do aquecimento.

SIMPLE OSSEOUS CYST OF THE CALCANEUS: A CASE REPORT.

Bone tumors are pathologies resulting from modifications in the bone structure and its content, they can present as benign or malignant, primitive or metastatic tumor lesions, depending on various factors: age of presentation, location, growth rate, periosteal reaction and infiltration to neighboring structures. The publications show that small, asymptomatic and small bone cysts do not require treatment, up to 25% are spontaneous resolution after a pathological fracture; while larger cysts with thin bark require some type of intervention.The case of a 17-year-old female patient is presented, who presents for presenting moderate intensity pain in the left heel that intensifies on ambulation, with a time of 2 months of evolution, after a blunt trauma in this region. On physical examination, pain from the pressure digit and active-passive mobilization maneuvers were evidenced on the external lateral aspect at the calcaneus level of the left foot. A simple lateral radiograph of the left calcaneus was performed, showing a 3 by 3 cm circular lytic lesion involving the anteroinferior region of the calcaneus.In conclusion, simple or solitary bone cyst is a benign pathology that, although it does not endanger the person’s life, can seriously affect the functionality of the foot. Currently, there is no standardized treatment for the management of this pathology, current surgical techniques, especially curettage and bone autograft are very promising.

Ecology and Distribution of Collemiform Lichens in the Southern Part of the Russian Far East

Environmentally related patterns of the occurrence of 14 collemiform lichen species (Collema s. l. sensu Degel.: C. (Rostania) callibotrys var. callibotrys Tuck., C. complanatum Hue, С. (Enchylium) conglomeratum var. conglomeratum Hoffm., C. (Arctomia) fasciculare var. fasciculare (L.) Weber ex F. H. Wigg., C. japonicum (Mull. Arg.) Hue, C. leptaleum var. leptaleum Tuck., С. (Enchylium) ligerinum (Hy) Harm., C. nepalense Degel., C. pulcellum var. pulcelllum Ach., С. (Enchylium) pycnocarpum Nyl. (=C. conglomeratum var. crassiusculum (Malme) Degel.), C. shiroumanum var. shiroumanum Rasanen, C. subconveniens Nyl., C. subflaccidum Degel., and C. substipitatum var. substipitatum Zahlbr.) on the trunks of various tree species in different forest types have been analyzed, as has their distribution in the southern part of the Russian Far East. The maximum species diversity of collemiform lichens is observed on the oak (Quercus mongolica Fisch. ex Ledeb.) and linden (Tilia mandshurica Rupr. et Maxim., T. amerensis Rupr.) trees (10 and 9 species, respectively), while the minimum diversity is observed on broadleaved trees with a smooth and thin bark. The oak–broadleaved and coniferous–broadleaved (with Pinus koraiensis Siebold et Zucc.) forests meet the ecological requirements of collemiform lichens in the best way; in these forests, 8 and 11 lichen species have been registered, respectively. The three most thermophilic oceanic species, C. complanatum, C. japonicum, and C. subconveniens, have been found only on the coast of the Sea of Japan in the narrow zone of the direct monsoon influence.

Long-term effects of white-tailed deer overabundance, hybrid poplar genotype and planting stock type on tree growth and ecosystem services provision in bioenergy buffers

Populus hybrids are increasingly planted in multifunctional bioenergy buffers bordering crop fields. However, such small agroforestry systems are vulnerable to damage caused by overabundant deer populations. We measured after 8 years the effects of white-tailed deer (Odocoileus virginianus), genotype and planting stock type on tree growth and ecosystem services provision (biomass production; energy, nutrient and carbon storage; and phytoaccumulation of soil nitrate and phosphorus) in 15-m wide buffers located downslopes of hayfields in southern Québec (Canada). Two deer protection treatments (fenced and unfenced), two genotypes (P. deltoides × P. nigra, genotype D×N-3570 and P. maximowiczii × P. balsamifera, genotype M×B-915311) and two stock types (bare-root stocks: ±1.8 m in height and whips: 2.5 m in height) were studied. In unfenced plots, deer heavily browsed poplars (increase in the height of the first branch by 59 cm), repeatedly rubbed tree bark (36% of trees with rubs for genotype D×N-3570, and 59% for genotype M×B-915311), slightly decreased survival (by 2.9%), which reduced tree-level and stand-level productivity. Proportion of trees with rubs, first branch height and survival were correlated (p < 0.001) with woody biomass yields. Fenced poplars increased wood volume, biomass and energetic content by 20–21%, and C, N and P stocks in aboveground biomass by 13–20%. Higher soil phosphorus bioavailability was also found in unfenced plots. Genotype D×N-3570, which allocates less biomass to branches, grows its first branches farther from the ground and rapidly develops a rough and thick bark, was the least affected by deer, despite its high palatability. Genotype M×B-915311, which had higher biomass allocation to branches, a smooth and thin bark, but low palatability, was the most affected by deer. Soils in plots of genotype M×B-915311 had the lowest macronutrients availability, except for nitrate. Biomass feedstock quality (i.e. low nutrient concentrations and high heating value of woody biomass) was highest for genotype M×B-915311. In both fenced and unfenced plots, whips were more productive than bare-root stocks, especially for genotype D×N-3570. Optimizing ecosystem services provision in bioenergy buffers can be achieved by fencing, and by genotype and stock type selection.

Bark attributes determine variation in fire resistance in resprouting tree species

Predicting the impact of wildfires on ecosystem services and habitat values requires quantifying rates of post-fire tree mortality and topkill. For those species that resprout epicormically (i.e. from above-ground buds), rates of post-fire topkill (death of aboveground biomass) can vary considerably. Laboratory studies indicate that bark attributes are key determinants of post-fire topkill in these resprouting species. Specifically, bark thickness and bark density influence the capacity of bark to insulate the cambium from the lethal temperatures generated during wildfires. Field studies are generally consistent with these laboratory studies and demonstrate that smaller trees, with thinner bark, are more vulnerable to post-fire topkill. However, comparatively few studies model topkill explicitly as a function of bark thickness, and fewer still model topkill as a function of bark density. In this study we measured post-fire mortality and topkill across eight tree species with varying bark types. We also estimated pre-fire bark thickness (from relationships between stem diameter and bark thickness derived from unburnt forest) and measured bark density. We undertook our study at two dry sclerophyll eucalypt forests located in eastern Australia. The two study areas were subject to wildfire 18 months prior to measurements, with one site characterised by a semi-arid climate, and the second site (located 400 km south-east) characterised by a humid climate. We found that species with thick bark and a low bark density were most resistant to topkill. We defined vulnerability to topkill as the stem diameter associated with a 50% probability of topkill, estimated from logistic regressions. Multiple linear regression indicated that bark thickness and density accounted for 65% of the variation in vulnerability to topkill among species. This regression excluded one species; Eucalyptus crebra, which was identified as an outlier. This species was the most vulnerable to topkill and was located at the semi-arid study site. This study site had been subject to a more severe pre-fire drought than the mesic site, suggesting that drought may also have influenced post-fire topkill. However, it is not possible to exclude other species-specific factors or site factors such as climate or fire intensity, which may also have impacted the probability of topkill. Our results demonstrate that bark thickness and density are critically important in developing predictive models of post-fire topkill in resprouting forests.

Роль метеорологічних чинників у зменшенні продукції верхівкового короїда в соснових деревостанах Східного Полісся

Інтенсивне поширення групових і куртинних осередків усихання в соснових насадженнях Східного Полісся розпочалося після дуже посушливої другої половини вегетаційного періоду 2016 р. та тривало протягом 2017–2018 рр., які вирізнялися екстремально посушливими умовами на початку вегетаційних періодів, коли гідротермічний коефіцієнт за Г. Т. Селяніновим становив 0,1–0,5, а дефіцит атмосферних опадів – 10–30 % у різні місяці. Після сприятливого для росту дерев початку вегетаційного періоду 2019 р. з гідротермічним коефіцієнтом 1,7 у результаті надлишку атмосферних опадів за пониженої температури поширення патологічного всихання сосняків у Східному Поліссі істотно знизилося та стабілізувалося з переважанням поодинокого та групового типів. Відновлення водозабезпечення дерев активізувало процеси смоловиділення, що інтенсивно перешкоджало спробам заселення дерев верхівковим короїдом на відносній висоті стовбура 0,51–0,75 і меншій. Середні значення продукції вздовж стовбурів заселених дерев становили від 29 до 33 шт.∙дм-2 молодих імаго.

Основні показники вогнестійкості сосни звичайної в умовах Лівобережного Лісостепу

Метою дослідження є визначення основних морфометричних показників вогнестійкості дерев сосни звичайної в умовах свіжого субору Лівобережного Лісостепу та їхніх вікових змін. На відміну від пожежостійкості, вогнестійкість визначає ступінь потенційної спроможності дерева зберігати свою життєдіяльність на індивідуальному рівні після пірогенних пошкоджень. Виявлено, що верхня межа розташування грубої кори найбільше залежить від діаметра (r = 0,97) та віку дерев (Ff = 83,2, Fst = 1,8). Визначено, що товщина кори на всіх висотах заміру зазвичай є більшою в дерев із більшою висотою верхньої межі розташування грубої кори, в зоні переходу грубої кори в тонку вона становить 0,1–0,9 мм. Товщина кори в окоренковій частині дерев сосни звичайної в 10–15 разів перевищує товщину кори в тріщинах, де вона становить 1,5–5,8 мм, тому під час низових пожеж є ризик локального ураження камбію вздовж тріщин. Враховуючи отримані результати, було розроблено статистично-математичну модель, за якою можна оцінювати висоту верхньої межі розташування грубої кори дерев у сосняках.

Biogeography of fire regimes in western U.S. conifer forests: A trait‐based approach

AbstractAimFunctional traits are a crucial link between species distributions and the ecosystem processes that structure those species’ niches. Concurrent increases in the availability of functional trait data and our ability to model species distributions present an opportunity to develop functional trait biogeography (i.e., the mapping of functional traits across space). Functional trait biogeography can improve process‐based predictions about the resistance of certain species assemblages to changing environmental conditions across landscape scales. We illustrate this concept by developing the first trait‐based, quantitative ranking of fire resistance (adult tree survival) in North American conifer species and mapping that fire resistance across space.Location and time periodWestern continental USA, present day.Major taxa studiedTwenty‐nine common conifer tree species.MethodsWe compiled six traits for each species: three relating to tree morphology and three relating to litter flammability. We combined these traits into a single fire resistance score and used community‐weighted averaging to estimate the fire resistance scores of different forest communities, using interpolated species distribution and relative abundance data.ResultsSpecies associated historically with frequent fire have high fire resistance scores (e.g.,Pinus ponderosa), reflected by thick bark, tall crowns and flammable litter. Species associated with subalpine or arid conditions have low fire resistance scores (e.g.,Picea engelmanniiandPinus edulis), reflected by thin bark, short stature, poor self‐pruning and low litter flammability. A map of forest community fire resistance across the western USA reveals agreement with independent assessments of historical fire regimes, while also identifying areas where community‐wide species traits might be mismatched with historical fire regimes.Main conclusionsQuantifying the functional traits that confer resistance to tree‐killing fire provides a direct link between ecosystem disturbance and community resistance. Understanding this link is crucial to evaluation of the long‐term resilience of different forest types under dynamic fire regimes. Our work represents the first known spatial representation of fire resistance traits at a regional scale and, as such, provides a link between functional traits and biogeography relevant to a critical ecosystem process.

Beetles and nematodes associated with wither Scots pines

Abstract This study focused on the occurrence of xylophagous beetles and nematodes in the different parts of Pinus sylvestris L. trees of different health condition in the pure stands in Zhytomyr region (Central Polissya). Stem fragments with thin, thick and transitional bark, branches and twigs were examined in each of 12 model trees. Xylophagous beetles were identified by adults or by galleries. Nematodes were isolated from wood samples in the laboratory using the Baermann method and identified by morphometric characteristics. Among 10 species of xylophagous beetles, Ips acuminatus (frequency 16.7%; dominance 17.9%) and I. sexdentatus (frequency 11.1%, dominance 54.6%) dominated, which prefer the fragments with thin and thick bark respectively. No xylophagous beetle was found in the healthy and slightly weakened trees. Among 15 nematode species, 40% were saproxylic, 33.3% entomophilic, 13.3% phytophagous, and by 6.7% predators and species associated with fungi. An entomophilic nematodes Cryptaphelenchus macrogaster f. acuminati was common in all parts of stem and branches (frequency of occurrence 25–33.3%). An entomophilic nematodes Parasitorhabditis acuminati and a predator Fuchsia buetschlii acuminati had the highest frequency of occurrence (41.7%) under the thin bark and in the branches. The frequency of these species in colonized with xylophagous insects stem fragments with thin bark was significantly higher than in respective not colonized fragments.