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Platforms mounted in rope parks cause injuries to trees. A new method for mounting platforms uses clamps, which are theoretically less damaging to trees. The aim of the study was to determine changes in the vitality of Scots pine (Pinus sylvestris L.) and European beech (Fagus sylvatica L.) in response to both old and new platform mounting systems. In the old system, wooden brackets are embedded in the cut fragments of tree trunks. The new system utilizes clamps that hug the trunks. A vitality assessment was carried out for control trees and trees with platforms on the basis of changes in the assimilation apparatus and the degree of thinning of the outer parts of the tree crowns. The visual assessments differentiated between four classes 0–3. We conducted the visual assessment of tree vitality four years after the installation of the platforms. The level of trunk circumference damaged at the platform attachment point was determined using photogrammetric measurements and laser scanning technology. The obtained results were compared to the vitality recorded for the control trees. Trees that initially had better vitality showed a clear decrease in vitality of ~0.5 class. Trees that initially had worse vitality showed a clear increase in vitality, ranging from 0.25 class for pines to 1 class for beeches. Pine and beech trees reacted differently to injuries caused by platform installations. Pine trees responded with a slight increase in vitality, while beech trees experienced a decrease of over a hundred percent. The reactions were more pronounced for the new type of platform. Although the new method of platform installation caused more damage to the surface of tree trunks, its impact on tree vitality was not significantly greater than that of the old system. Since the new system allows, in the long term, to change the position on the tree and adjust the clamping force to the trunk, it can be recommended for use in practice despite the overall slightly worse state of the trees when compared to trees with the old mounting system. [ABSTRACT FROM AUTHOR]

It is important to have reliable information on the presence/absence, population structure, and density of animals across their natural range. Detecting small organisms, however, such as the Nearctic tree trunk sheetweaver spider Drapetisca alteranda Chamberlin 1909 (Araneae: Linyphiidae), presents challenges due to its diminutive size and cryptic nature. We used a capture/recapture study to determine the detection and recapture probabilities of this spider using a standard beat sheet technique adopted for surveying tree trunks. Spiders were released on 3 different tree species that provided a range of microhabitats, including variable bark surface area and furrow depth/width. Microhabitat features played a small role in the timing of spider recapture (i.e. slower rate of recapture as furrowing increased). However, our results demonstrated 100% detection across replicate experiments and individual recapture probabilities exceeding 90% in most situations, with no significant differences in recapture observed among tree species and with respect to tree circumference. Furthermore, we show that most spiders could be recaptured within 2 sampling revolutions around the tree trunk, and there was no difference in the probability of collecting male and female spiders (although they differ markedly in size). Finally, we found no difference among brushers, supporting the idea that this method is replicable across collectors and studies. Collectively, we establish confidence in the ecological knowledge obtained with this technique and encourage its application with similar species and systems. [ABSTRACT FROM AUTHOR]

With the advent of affordable and more accurate third-generation sequencing technologies, and the associated bioinformatic tools, it is now possible to sequence, assemble, and annotate more species of conservation concern than ever before. Juglans cinerea , commonly known as butternut or white walnut, is a member of the walnut family, native to the Eastern United States and Southeastern Canada. The species is currently listed as Endangered on the IUCN Red List due to decline from an invasive fungus known as Ophiognomonia clavigignenti-juglandacearum (Oc-j) that causes butternut canker. Oc-j creates visible sores on the trunks of the tree which essentially starves and slowly kills the tree. Natural resistance to this pathogen is rare. Conserving butternut is of utmost priority due to its critical ecosystem role and cultural significance. As part of an integrated undergraduate and graduate student training program in biodiversity and conservation genomics, the first reference genome for Juglans cinerea is described here. This chromosome-scale 539 Mb assembly was generated from over 100 × coverage of Oxford Nanopore long reads and scaffolded with the Juglans mandshurica genome. Scaffolding with a closely related species oriented and ordered the sequences in a manner more representative of the structure of the genome without altering the sequence. Comparisons with sequenced Juglandaceae revealed high levels of synteny and further supported J. cinerea's recent phylogenetic placement. Comparative assessment of gene family evolution revealed a significant number of contracting families, including several associated with biotic stress response. [ABSTRACT FROM AUTHOR]

Water stored in trunk sapwood is vital for the canopy to maintain its physiological function under high transpiration demands. Little is known regarding the anatomical properties that contribute to the hydraulic capacitance of tree trunks and whether trunk capacitance is correlated with the hydraulic and gas exchange traits of canopy branches. We examined sapwood capacitance, xylem anatomical characteristics of tree trunks, embolism resistance, the minimal xylem water potential of canopy branches, leaf photosynthesis and stomatal conductance in 22 species from a tropical seasonal rainforest and savanna. The results showed that the mean trunk sapwood capacitance did not differ between the two biomes. Capacitance was closely related to the fiber lumen fraction and fiber wall reinforcement and not to the axial and ray parenchyma fractions. Additionally, it was positively correlated with the theoretical hydraulic conductivity of a trunk and the specific hydraulic conductivity of branches, and showed a trade-off with branch embolism resistance. Species with a high trunk sapwood capacitance maintained less negative canopy water potentials in the dry season, but higher leaf photosynthetic rates and stomatal conductance in the wet season. This study provides a functional link among trunk sapwood capacitance, xylem anatomy, canopy hydraulics and photosynthesis in tropical trees. [ABSTRACT FROM AUTHOR]

Lianas employ a variety of searching mechanisms to find support; however, it is not clear to what extent environmental signals are used to help direct the search. Several adventitious root climbers have been shown to bend away from light and grow toward darker areas or objects, in one case including actual tree trunks. In the literature, this negative phototropism (NP) has also been informally and inconsistently reported from a temperate root climber Hedera helix L. (common ivy). In this study, rigorous laboratory tests have confirmed the occurrence of NP in both seedlings and prostrate shoots of H. helix. Furthermore, a field experiment with potted ivy seedlings placed around tree trunks demonstrated their ability to remotely locate trees. This finding was corroborated by a survey of growth directions in wild-growing prostrate ivy shoots in two woodland habitats. An additional outdoor experiment showed that the ability to locate support is expressed in shade but supressed by full sun conditions. These results show that H. helix uses NP to locate support and indicate that this ability is a component of the species' shade escape strategy. [ABSTRACT FROM AUTHOR]

Deadwood decomposition and other environmental processes mediated by microbial communities are generally studied with composite sampling strategies, where deadwood is collected from multiple locations in a large volume, that produce an average microbial community. In this study, we used amplicon sequencing to compare fungal and bacterial communities sampled with either traditional, composite samples, or small, 1 cm3 cylinders from a discrete location within decomposing European beech (Fagus sylvatica L.) tree trunks. We found that bacterial richness and evenness is lower in small samples when compared to composite samples. There was no significant difference in fungal alpha diversity between different sampling scales, suggesting that visually defined fungal domains are not restricted to a single species. Additionally, we found that composite sampling may obscure variation in community composition and this affects the understanding of microbial associations that are detected. For future experiments in environmental microbiology, we recommend that scale is explicitly considered as a factor and properly selected to correspond with the questions asked. Studies of microbial functions or associations may require samples to be collected at a finer scale than is currently practised. [ABSTRACT FROM AUTHOR]

The spotted lanternfly, Lycorma delicatula (White) (Hemiptera: Fulgoridae), is an invasive planthopper that was first detected in the United States in Berks County, PA, in 2014, and has since spread to 13 states in the Eastern United States. This phloem-feeding pest has a broad host range, including economically important crops such as grapevine, Vitis spp. Monitoring presence and relative abundance of L. delicatula is essential to develop pest management tools. Here, we compared deployment strategies to optimize use of L. delicatula monitoring traps. Standard circle traps, sticky bands, and circle traps with replaceable bag tops were deployed at sites with either high or low populations present. Trap deployment at different heights and on different host tree species and trap sampling intervals were evaluated for standard circle traps only. Circle traps captured significantly more L. delicatula adults at low-density sites compared with other trap types in 2021, and no differences were detected at high-density sights. Traps deployed 1 m from the ground captured significantly more adults than those deployed at 0.5 m; no differences were detected for nymphs. While no significant differences in captures were found among intervals, weekly or biweekly sampling prevented specimen degradation. Although traps deployed on Ailanthus altissima (Mill.) Swingle (Sapindales: Simaroubaceae) captured significantly or numerically more L. delicatula at most sites, traps deployed on other hosts also yielded consistent captures. We were also able to alter the construction of circle trap skirts to allow for deployment on different sized tree trunks. [ABSTRACT FROM AUTHOR]

This scientific commentary discusses the shade-response strategy of lianas, specifically the common ivy (Hedera helix). Unlike shade-avoiding plants that grow away from shaded areas, lianas exhibit negative phototropism, growing towards structures such as tree trunks to ascend towards light-exposed canopy zones. The study conducted experiments to confirm the existence of negative phototropism in common ivy and found that the majority of seedlings reached and climbed the focal tree trunk. However, further research is needed to determine if negative phototropism is widespread among lianas and to understand the molecular mechanisms behind this growth response. [Extracted from the article]

When I remember that unmade clay feelingI want to say I I am she i but pressing her to me, I feel a space, like something it feels good to squish,a space pressed closer in and never getting, like a kiss. POETRY Birds, we've cleared away your space. One time, you opened the moon roof for me to better seea mountain I pretended was above usas our car ascended an actual, modest mountain. [Extracted from the article]

Background and Aims The defensive role of spines has previously been related to leaves, young shoots and reproductive organs. However, some woody species harbour spines on their trunks where none of those organs are present. Several explanations are plausible: they could be (1) climbing aids, (2) remnants from defence of leaves or reproductive organs during an earlier development phase, or (3) an as-yet undescribed defence. Here we investigate whether they could play a role against either bark feeding or preventing climbing animals accessing food resources in the tree canopy. Methods We described 31 woody species with spines on their trunk, growing in a botanical garden, to test whether morphological strategies could be identified and suggest what could be their most likely function. As testing their function is difficult experimentally for large pools of species, we performed virtual experiments to evaluate the potential roles of trunk spines against bark removal and climbing animals of different sizes. We then compared for each species and their confamilial non-spiny species the nutritional profiles of leaf, bark and reproductive organs to test whether trunk spines were associated with a nutritious organ (more likely targeted by herbivores). Key Results We identified four morphological syndromes of trunk spines. Two corresponded to already known functions (anchorage for lianas and crown defence against large ground mammals), and two strategies are newly described trait syndromes with traits suggesting a defence against bark feeding and climbing mammals. By simulation, we show how each strategy could translate into defence against debarking and prevent herbivores from climbing. Conclusions We identified trunk spine strategies and the criteria to classify them, their most likely function and the likely feeding mode and size of animal against which different trunk spine strategies may be effective. We discuss further perspectives for testing their function and their ecological significance. [ABSTRACT FROM AUTHOR]

The use of size-controlling rootstocks is central to modern high-density fruit production systems. While biological mechanisms responsible for vigor control are not fully understood, differences in water relations and carbohydrate storage ability have been suggested as two potential factors. To better understand the processes that control growth vigor, we analyzed the trunk radial variation at seasonal and diurnal timescales and measured the midday leaf water potential (ΨMD), leaf gas exchange and concentrations of non-structural carbohydrates (NSC) in apple trees of variety 'Jonagold' grafted on two rootstocks of contrasting growth vigor (dwarfing J-TE-G vs invigorating J-TE-H). The measurements were conducted during an exceptionally hot and dry summer. We found that smaller annual trunk radial increments in dwarfed trees were primarily due to an earlier cessation of trunk secondary growth. The interdiurnal trunk circumference changes (Δ C) were slightly lower in dwarfed trees, and these trees also had fewer days with positive Δ C values, particularly during the driest summer months. The trunks of dwarfed trees shrank gradually during the drought, showed less pronounced diurnal variation of trunk circumference and the maximum trunk daily shrinkage was only weakly responsive to the vapor pressure deficit. These results indicated that lower turgidity in the cambial region may have limited the trunk radial expansion in dwarfed trees during the hot and dry days. Dwarfed trees also maintained lower ΨMD and leaf gas exchange rates during the summer drought. These parameters decreased in parallel for both rootstock combinations, suggesting their similar drought sensitivity. Similar concentrations and seasonal dynamics of NSC in both rootstock combinations, together with their similar spring growth rates, suggest that NSC reserves were not directly limiting for growth. Our results support the prominent role of water relations in rootstock-induced size-controlling mechanisms and highlight the complexity of this topic. [ABSTRACT FROM AUTHOR]

The evolution of key innovations—unique features that enable a lineage to interact with the environment in a novel way—may drive broad patterns of adaptive diversity. However, traditional tests of the key innovation hypothesis, those which attempt to identify the evolutionary effect of a purported key innovation by comparing patterns of diversity between lineages with and without the key trait, have been challenged on both conceptual and statistical grounds. Here, we explore alternative, untested hypotheses of the key innovation framework. In lizards, adhesive toepad structures increase grip strength on vertical and smooth surfaces such as tree trunks and leaves and have independently evolved multiple times. As such, toepads have been posited as a key innovation for the evolution of arboreality. Leveraging a habitat use data set applied to a global phylogeny of 2692 lizard species, we estimated multiple origins of toepads in three major clades and more than 100 origins of arboreality widely across the phylogeny. Our results suggest that toepads arise adaptively in arboreal lineages and are subsequently rarely lost while maintaining arboreal ecologies. Padless lineages transition away from arboreality at a higher rate than those with toepads, and high rates of invasion of arboreal niches by nonarboreal padbearing lineages provide further evidence that toepads may be a key to unlocking evolutionary access to the arboreal zone. Our results and analytical framework provide novel insights to understand and evaluate the ecological and evolutionary consequences of key innovations.[Arboreality; ecological transition; key innovation; macroevolution; phylogenetic comparative methods.] [ABSTRACT FROM AUTHOR]

Instantaneous electrical responses in plants have been widely studied, but the mechanism of spontaneous, periodic electric potential alternations in the xylem of tree trunks remains controversial. The generation of the electric potential can be explained by the electrode potential, which depends on ion concentrations near electrodes. However, several different hypotheses about its periodic variations have been proposed, including streaming potential, ion diffusion, charge transport, and oxygen turnover. Here, we performed long-term measurements on the electric potential and water content in the xylem of trees, and observed changes in the electric potential and transpiration rate in response to varied numbers of leaves, light radiation, temperature, and relative air humidity. The electric potential showed a distinct seasonal trend, combined with daily rhythms, and could be affected by environmental changes. Rapid changes in the electric potential routinely lagged behind those of the transpiration rate, but their ranges of change were proportional. Both annual and diurnal patterns of the electric potential were synchronous with the trees' water content. Moreover, we found potential function relationships between the electric potential and water content. Accordingly, we propose a new perspective, that the variations of the electric potential in tree xylem could be associated with water content rhythms. [ABSTRACT FROM AUTHOR]

The Asian longhorned beetle (Anoplophora glabripennis [Motschulsky]) is an invasive wood-boring beetle that threatens urban trees and forests in North America and Europe. The entomopathogenic fungus Metarhizium brunneum Petch strain F52 can infect and kill A. glabripennis adults. Products containing this fungus were available for commercial use in the United States but not registered for Asian longhorned beetle. This study tested different formulations and application rates of M. brunneum F52 microsclerotial granules for their potential development for management of A. glabripennis adults. Three application rates of M. brunneum microsclerotial granules relative to a 1× formulation from previous experiments (0.03 g/cm2; 2× = 0.06 g/cm2 and 3× = 0.09 g/cm2) were exposed on tree trunks for 4-wk periods during May–September. Increased application rates had better retention (% of initial g applied) than the 1× rate, rather than greater weathering loss. Microsclerotia at the 2× application produced 5.05 × 106 conidia/cm2, which was 18 times more conidia than the 1× application. Since A. glabripennis is under active eradication, bioassays with adult beetles were carried out in a quarantine laboratory, using the formulation samples from field exposures. The 2× application resulted in faster beetle mortality. The 3× and 2× rates were not significantly different in retention of the formulation, conidial production, or mortality, but 2× produced the most conidia per gram applied (3.92 × 109 conidia/g). An augmented formulation containing 70% M. brunneum by weight, rather than 50%, produced significantly more conidia and faster beetle mortality than the 50% formulation. [ABSTRACT FROM AUTHOR]

Lightning is a common agent of disturbance in many forest ecosystems. Lightning-damaged trees are a potentially important resource for beetles, but most evidence for this association is limited to temperate pine forests. Here, we evaluated the relationship between lightning damage and beetle colonization of tropical trees. We recorded the number of beetle holes on the trunks of trees from 10 strike sites (n = 173 lightning-damaged trees) and 10 matching control sites (n = 137 control trees) in Panama. The trunks of lightning-struck trees had 370% more beetle holes than control trees. The abundance of beetle holes increased with increasing total crown dieback among both control and lightning-damaged trees, and with larger tree diameter among lightning-struck trees. Beetle holes also were more abundant in trunk sections of lightning-damaged trees located directly below a damaged section of the crown. The results of this study suggest that lightning damage facilitates beetle colonization in tropical forest trees and provide a basis for investigations of the effects of lightning-caused disturbance on beetle population dynamics and assemblage structure. [ABSTRACT FROM AUTHOR]

Animals clinging to natural surfaces have to generate attachment across a range of surface roughnesses in both dry and wet conditions. Plethodontid salamanders can be aquatic, semi-aquatic, terrestrial, arboreal, troglodytic, saxicolous, and fossorial and therefore may need to climb on and over rocks, tree trunks, plant leaves, and stems, as well as move through soil and water. Sixteen species of salamanders were tested to determine the effects of substrate roughness and wetness on maximum cling angle. Substrate roughness had a significant effect on maximum cling angle, an effect that varied among species. Substrates of intermediate roughness (asperity size 100–350 µm) resulted in the poorest attachment performance for all species. Small species performed best on smooth substrates, while large species showed significant improvement on the roughest substrates (asperity size 1000–4000 µm), possibly switching from mucus adhesion on a smooth substrate to an interlocking attachment on rough substrates. Water, in the form of a misted substrate coating and a flowing stream, decreased cling performance in salamanders on smooth substrates. However, small salamanders significantly increased maximum cling angle on wetted substrates of intermediate roughness, compared with the dry condition. Study of cling performance and its relationship to surface properties may cast light onto how this group of salamanders has radiated into the most speciose family of salamanders that occupies diverse habitats across an enormous geographical range. [ABSTRACT FROM AUTHOR]

The spotted lanternfly, Lycorma delicatula White, is an invasive planthopper (Hemiptera: Fulgoridae) that was first detected in the United States in Berks County, PA, in 2014, and has since spread in the mid-Atlantic region. This phloem-feeding pest has a broad host range, including economically important crops such as grape where their feeding causes dieback of infested plants. Monitoring the presence and abundance of L. delicatula is of utmost importance to develop pest management approaches. Current monitoring practices include sticky bands deployed on tree trunks, sometimes paired with commercially available methyl salicylate lures. A drawback associated with sticky bands is the high numbers of nontarget captures. Here, we developed traps for L. delicatula based on a circle trap originally designed for weevils. These traps are comprised of a screen funnel that wraps around the trunk of a tree and guides individuals walking up the trunk into a collection device. In 2018 and 2019, we compared circle trap designs with sticky bands in Pennsylvania and Virginia. In both years, circle trap designs yielded captures that were equivalent to or exceeded captures of L. delicatula on sticky bands. Nontarget captures were significantly lower for circle traps compared with sticky bands. Presence of a methyl salicylate lure in association with traps deployed on host trees or vertical tree-mimicking posts did not increase L. delicatula captures compared with unbaited traps. Circle traps, modified using vinyl screen and a larger collection device, present an alternative to the current approach with reduced nontarget capture for monitoring L. delicatula. [ABSTRACT FROM AUTHOR]

Adult ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) bore into ornamental nursery trees resulting in trunk vascular tissue damage, which can potentially kill trees. Ambrosia beetle exposure to surface-applied insecticides is minimal after internal trunk galleries are formed, so effective management requires insecticide treatments to be applied near the time of infestation or to have residual activity on the bark. Tree trunk sections (bolts) were used to determine the effect of field aging or irrigation (i.e. simulated rainfall weathering) on permethrin residual activity against ambrosia beetles. In all experiments, 30-cm-long bolts from Liriodendron tulipifera L. (Magnoliales: Magnoliaceae) were hollowed and filled with 70% ethanol at field deployment to induce ambrosia beetle attacks over a 2-wk period. To evaluate insecticide residual activity, permethrin was sprayed onto tree bolts at 0, 8, 17, or 24 d before ethanol addition, and then bolts were deployed along a wooded border in fall 2017 and spring 2018. Tree bolts with permethrin residues ≤17 d old had significantly fewer ambrosia beetle attacks than bolts with 24-d-old residues or the non-permethrin-treated control bolts. To evaluate simulated rainfall weathering, permethrin was applied to tree bolts 8 or 22 d before ethanol (spring 2018) or 10 or 24 d before ethanol (fall 2018) with half of the bolts receiving regular irrigation events. Irrigation had no significant effect on permethrin residual activity against ambrosia beetles during either test. This study determined ambrosia beetle control was affected by permethrin residue age more than simulated rainfall weathering, and a reapplication interval of ≤17 d maximized beetle control. [ABSTRACT FROM AUTHOR]

Predation risk is important in influencing animal behaviour. We investigated how the choice of nocturnal sleeping and diurnal resting sites by two species of primates was influenced by the most likely forms of attack (diurnal raptors and nocturnal felids). We recorded vertical and horizontal patterns of occupancy for 47 sleeping and 31 resting sites, as well as the presence of lianas or vines on trees. We compared the heights of trees used as resting or sleeping sites by the monkeys with those of 200 forest trees that the monkeys did not use. Trees used as nocturnal sleeping sites were taller than those used as diurnal resting sites, and taller than trees that the monkeys did not use. However, while trees used as diurnal resting sites were not significantly taller than non-used trees, diurnal resting sites were located on branches closer to the ground, closer to the main trunk of the tree and in trees with more lianas/vines than nocturnal sleeping sites. The differences in site location can be explained by the type of predator most likely to attack at a particular time: raptors in the day and felids at night. [ABSTRACT FROM AUTHOR]

By completely censusing a 1 ha forest dynamics plot it was possible to identify the variables (spider mass, size, sex and tree species, size, and bark roughness) that influenced the spatial distribution of adult Drapetisca alteranda Chamberlin 1909 (Araneae: Linyphiidae), a sheet web spider that specializes in lower tree trunks in North American forests. To account for spatial autocorrelation, a conditional autoregressive random effect was included in the zero-inflated Poisson generalized linear mixed model. Parameters estimated were produced by Bayesian inference with vague prior probability distributions and the best of 16 models were selected using Watanabe-Akaike Information Criterion. The best model showed that larger diameter trees located at higher plot elevations were more likely to have D. alteranda present. Smooth bark tree species such as paper birch and American basswood tended to have the most spiders while rough bark species had the least. The relationship between tree diameter and D. alteranda abundance also varied by tree species. Paper birch and quaking aspen tend to produce a greater slope compared to the other species, indicating that as these trees get larger, the abundance of D. alteranda increases at a higher rate than on other tree species. Spider sex and size were not associated with height on the trunk or tree species selection, nor were they associated with microhabitats such as bark furrow depth. Landscape-level factors largely predict D. alteranda abundance and distribution, suggesting that spatial autocorrelation should be considered when modeling the abundance of even small organisms, such as spiders. [ABSTRACT FROM AUTHOR]

The spotted lanternfly, Lycorma delicatula (White), an invasive, phloem-feeding fulgorid generalist, was recently discovered in the United States. Current trapping methods include placing glue-covered sticky bands around trunks of host trees to exploit the lanternfly's behavior of climbing up tree trunks. These bands are messy and need to be replaced often as they become covered in both target and nontarget insects and debris. Fourth instar nymphs and adults have also shown an ability to escape from traditional tree bands or avoid capture. A promising commercially available tree band (BugBarrier) design that faces inward to the trunk and targets larger developmental stages was tested. A modified pecan weevil trap (circle trunk trap) was also compared with tree bands. This design does not require the use of insect-trapping adhesive. Circle trunk traps caught more third and fourth instar and adult L. delicatula than BugBarrier bands. Flight intercept traps caught fewer adult L. delicatula than trunk-based tree bands. In a separate comparison, more spotted lanternflies were caught on adhesive-coated 'tree mimicking' traps placed along the edges of Ailanthus altissima Swingle (Sapindales: Simaroubaceae) stands than away from hosts in an open field. Circle trunk traps are recommended for their effectiveness at capturing L. delicatula as well as their relative ease-of-use and reusability. [ABSTRACT FROM AUTHOR]

Urban tardigrades are studied little worldwide. In Salta (Argentina), two studies have evaluated their diversity in an urban–native gradient. Vehicular traffic in Salta city has increased over the last decade, increasing environmental pollution. Our aim is to determine whether biotic homogenization occurs in this city. Sampling sites were selected considering different vehicular traffic intensities (high, medium and low). Tardigrades were sampled from bryophytes growing on tree trunks. Specimens were treated according to the usual study methodology. Different biotic and environmental abiotic variables of the microhabitat were considered. A total of 3049 specimens of 16 species of heterotardigrades and eutardigrades were reported. The low vehicular transit habitat was more diverse than the others. Ordination analyses evidenced a nested pattern in the studied urban habitats. Milnesium sp. nov. 3 and Minibiotus sp. nov. 1 were reported as detector species for habitats with medium vehicular traffic. The partition of the β diversity showed that the species turnover was higher among low and high vehicular traffic communities than medium, whereas a loss of species was evidenced between high and medium habitats. The high diversity of tardigrades in Salta city and their assemblages are partly dependent on several factors, including vehicular traffic. [ABSTRACT FROM AUTHOR]

Background and Aims Through careful field examination of the growth habit of the gametophytes and sporophytes of Hymenasplenium volubile across an ontogenetic series, we aim to understand better the evolution of epiphytism in this poorly understood group of ferns Methods We made field observations of H. volubile sporophytes and gametophytes, and brought specimens back to the lab for microscopic analysis. In the field, sporophytes at each ontogenetic stage were photographed to document the species' growth habit. We used an existing phylogeny to optimize growth form of New World Hymenasplenium. Key Results Young sporophytes were at first fully epiphytic and produced one or two long feeding roots that extend to the soil where they branch profusely. The feeding roots remain in contact with the soil throughout the life of the plant. Thus, H. volubile is a hemiepiphyte. While immature, gametophytes are appressed to the tree trunk, but, as their gametangia mature, their lower margin lifts upward, imparting a shelf-like appearance to the thallus. The thallus attaches to the substrate by branched rhizoids produced along the margin of the thallus in contact with the substrate. Conclusions Hemiepiphytes are a key link in the evolution of epiphytic ferns and may act as a bridge between the forest floor and the canopy. Our finding is the first report of hemiepiphytism in Aspleniaceae, a large lineage with many epiphytic and terrestrial taxa. This work serves as an important model to understand the evolution of epiphytism in this group specifically and in ferns in general. The majority of our understanding of fern gametophyte biology is derived from laboratory studies. Our efforts represent a fundamental contribution to understanding fern gametophyte ecology in a field setting. [ABSTRACT FROM AUTHOR]

Pest abundance on urban trees often increases with surrounding impervious surface. Gloomy scale (Melanaspis tenebricosa Comstock; Hemiptera: Diaspididae), a pest of red maples (Acer rubrum L.; Sapindales: Sapindaceae) in the southeast United States, reaches injurious levels in cities and reduces tree condition. Here, we use a chronosequence field study in Raleigh, NC, to investigate patterns in gloomy scale densities over time from the nursery to 13 yr after tree planting, with a goal of informing more efficient management of gloomy scale on urban trees. We examine how impervious surfaces affect the progression of infestations and how infestations affect tree condition. We find that gloomy scale densities remain low on trees until at least seven seasons after tree planting, providing a key timepoint for starting scouting efforts. Scouting should focus on tree branches, not tree trunks. Scale density on tree branches increases with impervious surface across the entire studied tree age range and increases faster on individual trees that are planted in areas with high impervious surface cover. There is a lag between the onset of pest infestations and a decline in tree condition, indicating that gloomy scale management should begin prior to a visible decline in tree condition. Our results inform management of gloomy scale in cities. [ABSTRACT FROM AUTHOR]

We revisit a case of mimicry in Amorphophallus involving visual mimicry of lichens and colonies of cyanobacteria on their tree-trunk sized petioles. We investigate the entire genus for similar defensive coloration types and report a defensive leaf coloration strategy in several Amorphophallus spp. that involves mimicry, camouflage and plant-mimicking that results in defensive visual masquerade. We propose that the visual expression of lichen and cyanobacteria mimicry enables the huge and fleshy petioles to look like solid non-edible tree trunks, a classic case of masquerade, probably as defence against herbivores. The results are discussed in a phylogenetic and evolutionary context. [ABSTRACT FROM AUTHOR]

Background Tree stem diameters and electrical stem potentials exhibit rhythmic variations with periodicities of 24–25 h. Under free-running conditions of constant light or darkness these rhythms were suggested to be mediated by the lunisolar gravitational force. Scope To further unravel the regulation of tree stem diameter dilatations, many of the published time courses of diameter variations were re-evaluated in conjunction with the contemporaneous time courses of the lunisolar tidal acceleration. This was accomplished by application of the Etide program, which estimates, with high temporal resolution, local gravitational changes as a consequence of the diurnal variations of the lunisolar gravitational force due to the orbits and relative positions of Earth, Moon and Sun. In all instances investigated, it was evident that a synchronism exists between the times of the turning points of both the lunisolar tide and stem diameter variations when the direction of extension changes. This finding of synchrony documents that the lunisolar tide is a regulator of the tree stem diameter dilatations. Conclusions Under the described experimental conditions, rhythms in tree stem diameter dilations and electrical stem potentials are controlled by the lunisolar gravitational acceleration. [ABSTRACT FROM AUTHOR]

Williamson's Sapsuckers (Sphyrapicus thyroideus) are montane woodpeckers threatened by widespread tree removal activities and climate change. Current forest management plans focus on nesting trees, but the incorporation of foraging trees would lead to a more effective management strategy to mitigate habitat loss for this species. We investigated the selection of foraging trees in forests managed for timber extraction and maintenance of wildlife values using foraging observations of 27 radio-tagged adult Williamson's Sapsuckers during the breeding season in 2 regions (Okanagan and Western} of their limited Canadian range. Characteristics of foraging trees (88% of observations on live trees, 11% on dead trees} differed with foraging mode. Large, live Douglas-firs (Pseudotsuga menziesii; 22.5 cm dbh) were used for gleaning and sap feeding on tree trunks in both regions, whereas trees used for trunk pecking were mostly large, senescent western larches (Larix occidentalis) in the Okanagan region and large, dead ponderosa pines (Pinus ponderosa) in the Western region (average dbh = 46 cm). For overall foraging activities, Williamson's Sapsuckers selected large, live Douglas-firs with signs of resin exudation and blistering (pitching), and avoided live lodgepole pines (Pinus conforta), quaking aspens (Populus tremuloides), and ponderosa pines. Larger trees and standing dead conifer trees were reused more often for foraging than smaller and live trees. The quality of Williamson's Sapsucker habitat could decrease over the long term if forest management practices reduce the overall size of trees or alter tree species composition to promote lodgepole pine. Forest management should focus on retaining and promoting large live Douglas-fir trees and large senescent or standing dead conifers (also used for nesting}, which can be achieved by using thinning, prescribed fire, partial harvesting, and tree retention strategies. [ABSTRACT FROM AUTHOR]

Tree trunk annual increments are markedly reduced in mast years. There are two hypotheses that could explain the mechanism for this phenomenon: (1) a reduction in the duration of growth due to switching the resource allocation from somatic growth to seed production; (2) reduction of growth rate due to resources being shared between somatic growth and reproduction simultaneously. In this study, we aimed to test these hypotheses in Fagus crenata Blume from the point of view of resource allocation. The radial growth patterns in F. crenata during a year without reproduction (2014) and a masting year (2015) were monitored using a digital dendrometer. At the same time, shoot growth patterns were monitored by sampling branches from the top of the canopy. Data obtained using the digital dendrometer were fitted to a sigmoidal function, and the parameters of the function were evaluated with a hierarchal Bayesian approach; estimated parameters were used to represent the properties of trunk growth phenology. Trunk growth started synchronously just after leaf unfurling in both mass-fruiting (F15) and limited-fruiting (NF15) trees in 2014 and 2015. Reproduction reduced the growth rate in 2015. This was due to the resources being allocated for the development of cupules and for formation of relatively thick branches, both of which occurred simultaneously with trunk growth. There was no clear difference in the duration of radial growth between F15 and NF15 trees in the 2 years, although seed maturation started after trunk growth ceased. As a result, the annual trunk radius increment was reduced in the F15 trees in 2015. These results suggested that reduction of radial growth rate (Hypothesis 2) caused the reduction in annual trunk increment of reproducing trees of this species. [ABSTRACT FROM AUTHOR]

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is an invasive and polyphagous herbivore that has been problematic in Mid-Atlantic fruit orchards, many of which are adjacent to woodlands containing its wild hosts. Our tree census in woodlands bordering 15 Mid-Atlantic apple orchards revealed 47 species of deciduous trees and shrubs, 76.6% of which were recorded hosts of H. halys. Tree of heaven was most common and abundant overall. Halyomorpha halys nymphs have a substantial walking dispersal capacity, and their fitness is enhanced by feeding on multiple hosts. Directional and temporal patterns of nymphal H. halys movement on selected wild hosts and apple and peach trees at the orchard-woodland interface were monitored in 2014 and 2015 using passive traps to capture nymphs walking up and down tree trunks. Weekly captures from mid-May to late September or mid- October were compared among hosts across both seasons. Despite higher total nymphal captures in 2014 than 2015, the seasonal trends for both years were similar and indicated bivoltine H. halys populations. In both years, more nymphs were intercepted while walking up than down and captures of upward- and downward-walking nymphs varied significantly among the hosts. All instars were captured, but captures of second instars predominated. Captures reflected seasonal changes in instar distribution and consisted predominantly of younger and older nymphs, early and later in the season, respectively. Results are discussed in relation to host and seasonal effects on themovement of nymphs at the orchard-woodland interface, and the implications for H. halys management. [ABSTRACT FROM AUTHOR]

When related species coexist, selection pressure should favor evolution of species recognition mechanisms to prevent interspecific pairing and wasteful reproductive encounters. We investigated the potential role of pheromone and acoustic signals in species recognition between two species of tree-killing bark beetles, the southern pine beetle, Dendroctonus frontalis Zimmermann, and the western pine beetle, Dendroctonus brevicomis LeConte, in a narrow zone of sympatry, using reciprocal pairing experiments. Given the choice of adjacent con- or heterospecific female gallery entrance in a log, at least 85% of walking males chose the entrance of the conspecific, and half the males that initially entered heterospecific galleries re-emerged and entered the conspecific gallery within 15 min. Waveform analysis of female acoustic "chirps" indicated interspecific differences in chirp timing. Males may use information from female acoustic signals to decide whether to enter or remain in the gallery. Individuals in forced heterospecific pairings (produced by confinement of a heterospecific male within the female entrance) did not differ in pheromone production from individuals of conspecific pairs. However, due to the absence of the right species of male, galleries with heterospecific pairs released an abnormal pheromone blend that lacked at least one key component of the aggregation pheromone of either species. The complete aggregation pheromone (i.e., the pheromone blend from entrances with pairs) does not appear to deter interspecific encounters or confer premating reproductive isolation per se; however, it may confer selective pressure for the maintenance of other reproductive isolation mechanisms. [ABSTRACT FROM AUTHOR]

Termites are a key functional group in the forest ecosystem, but they damage trees. To investigate the termite infestation pattern on the whole tree, we cut 108 blackboard trees, Alstonia scholaris (L.) R. Br., and 50 Japanese cedars, Cryptomeria japonica (L. f.) D. Don, into sections. The bark surface and cross sections of the tree trunk were examined along the axes. A high percentage of blackboard trees (92.6%) was infested by fungus- growing termites, Odontotermes formosanus (Shiraki), but damage was limited to the bark surface at a 2-m height. The infestation rate of dampwood termites, Neotermes koshunensis (Shiraki), was only 4.6% (5/108), and all infestations were associated with trunk wounds. N. koshunensis was found at significantly higher portion of a tree than O. formosanus. Among 50 Japanese cedars, 20 living trees were not infested by any termites, but 26 of the 30 dead trees were infested by subterranean termites, Reticulitermes flaviceps (Oshima), which excavated tunnels in the trunk. The infestation rate at basal sections was higher than that at distal sections. Only one Japanese cedar tree was infested by another dampwood termite, Glyptotermes satsumensis (Matsumura). The two dominant termite species, O. formosanus and R. flaviceps, had subterranean nests and infested trees from bottom up. The two primitive termites N. koshunensis and G. satsumensis had low infestation rates and are most likely to infest trees by alates from top down. The niche segregation in trees of three termite families, Kalotermitidae, Rhinotermitidae, and Termitidae, was distinct. [ABSTRACT FROM AUTHOR]

Since a substantial portion of respired CO2 remains within the stem, diel and seasonal trends in stem CO2 concentration ([CO2]) are of major interest in plant respiration and carbon budget research. However, continuous long-term stem [CO2] studies are scarce, and generally absent in Mediterranean climates. In this study, stem [CO2] was monitored every 15 min together with stem and air temperature, sap flow, and soil water storage during a growing season in 16 stems of Quercus pyrenaica to elucidate the main drivers of stem [CO2] at different temporal scales. Fluctuations in sap pH were also assessed during two growing seasons to evaluate potential errors in estimates of the concentration of CO2 dissolved in xylem sap ([CO2*]) calculated using Henry's law. Stem temperature was the best predictor of stem [CO2] and explained more than 90% and 50% of the variability in stem [CO2] at diel and seasonal scales, respectively. Under dry conditions, soil water storage was the main driver of stem [CO2]. Likewise, the first rains after summer drought caused intense stem [CO2] pulses, suggesting enhanced stem and root respiration and increased resistance to radial CO2 diffusion. Sap flow played a secondary role in controlling stem [CO2] variations. We observed night-time sap pH acidification and progressive seasonal alkalinization. Thus, if the annual mean value of sap pH (measured at midday) was assumed to be constant, night-time sap [CO2*] was substantially overestimated (40%), and spring and autumn sap [CO2*] were misestimated by 25%. This work highlights that diel and seasonal variations in temperature, tree water availability, and sap pH substantially affect xylem [CO2] and sap [CO2*]. [ABSTRACT FROM AUTHOR]

We evaluated a combination of noninsecticidal alternatives to control trunk-damaging dogwood borer, Synanthedon scitula (Harris), consisting of novel barrier technologies, used alone or in combination with mating disruption. Barrier formulations evaluated included fibrous barriers of nonwoven ethylene vinyl acetate (EVA) and nonfibrous barriers of rubberized paint (elastomer) used in building coatings. To examine efficacy of dogwood borer control in orchards, all barrier trials were replicated in field tests, both in combination with mating disruption and without it. Trunk inspections to determine whether mating disruption and barriers effectively reduced actual tree infestation showed pheromone disruption significantly reduced infestation compared with the untreated check, but was not as effective as trunk handgun sprays of chlorpyrifos. EVA trunk barriers were effective in preventing borer infestation compared with untreated trees. The elastomer did not differ from the check or the EVA treatment. There was no interaction between disruption and barrier treatments. Barrier field life and durability was assessed over 2 yr by comparing degradation over time due to weathering and other environmental effects including animal damage. The EVA persisted and remained more intact than the elastomer, but was in need of reapplication after 2 yr. Barriers were also screened for efficacy against voles in small-plot trials in nonorchard locations with known high vole pressure; they were tested either alone, combined with a repellent (thiram), or, in the case of the elastomer only, combined with an abrasive (sand). Only the EVA significantly lowered vole chewing damage relative to the untreated checks. [ABSTRACT FROM AUTHOR]

Trunks of large trees play an important role in whole-plant water balance but technical difficulties have limited most hydraulic research to small stems, leaves, and roots. To investigate the dynamics of water-related processes in tree trunks, such as winter embolism refilling, xylem hydraulic vulnerability, and water storage, volumetric water content (VWC) in the main stem was monitored continuously using frequency domain moisture sensors in adult Betula papyrifera trees from early spring through the beginning of winter. An air injection technique was developed to estimate hydraulic vulnerability of the trunk xylem. Trunk VWC increased in early spring and again in autumn, concurrently with root pressure during both seasons. Diurnal fluctuations and a gradual decrease in trunk VWC through the growing season were observed, which, in combination with VWC increase after significant rainfall events and depletion during periods of high water demand, indicate the importance of stem water storage in both short- and long-term water balance. Comparisons between the trunk air injection results and conventional branch hydraulic vulnerability curves showed no evidence of ‘vulnerability segmentation’ between the main stem and small branches in B. papyrifera. Measurements of VWC following air injection, together with evidence from air injection and xylem dye perfusion, indicate that embolized vessels can be refilled by active root pressure but not in the absence of root pressure. The precise, continuous, and non-destructive measurement of wood water content using frequency domain sensors provides an ideal way to probe many hydraulic processes in large tree trunks that are otherwise difficult to investigate. [ABSTRACT FROM AUTHOR]

Seasonal and inter-annual dynamics of growth, non-structural carbohydrates (NSC) and carbon isotope composition (δ13C) of NSC were studied in a beech forest of Central Italy over a 2-year period characterized by different environmental conditions. The net C assimilated by forest trees was mainly used to sustain growth early in the season and to accumulate storage carbohydrates in trunk and root wood in the later part of the season, before leaf shedding. Growth and NSC concentration dynamics were only slightly affected by the reduced soil water content (SWC) during the drier year. Conversely, the carbon isotope analysis on NSC revealed seasonal and inter-annual variations of photosynthetic and post-carboxylation fractionation processes, with a significant increase in δ13C of wood and leaf soluble sugars in the drier summer year than in the wetter one. The highly significant correlation between δ13C of leaf soluble sugars and SWC suggests a decrease of the canopy C isotope discrimination and, hence, an increased water-use efficiency with decreasing soil water availability. This may be a relevant trait for maintaining an acceptable plant water status and a relatively high C sink capacity during dry seasonal periods. Our results suggest a short- to medium-term homeostatic response of the Collelongo beech stand to variations in water availability and solar radiation, indicating that this Mediterranean forest was able to adjust carbon–water balance in order to prevent C depletion and to sustain plant growth and reserve accumulation during relatively dry seasons. [ABSTRACT FROM AUTHOR]

Background and Aims There is increasing evidence that suppressed bud burst and thus epicormic shoot emergence (sprouting) are controlled by water–carbohydrate supplies to entire trees and buds. This direct evidence is still lacking for oak. In other respects, recent studies focused on sessile oak, Quercus petraea, have confirmed the important constraints of sprouting by epicormic ontogeny. The main objective of this paper was thus to provide provisional confirmation of the water–carbohydrate control and direct evidence of the ontogenic constraints by bringing together results already published in separate studies on water status and distribution of carbohydrates, and on accompanying vegetation and epicormics, which also quantify epicormic ontogeny. Methods This paper analyses results gained from a sessile oak experiment in which part of the site was free from fairly tall, dense accompanying vegetation. This experiment was initially focused on stand water status and more recently on the carbohydrate distribution of dominant trees. External observations of the epicormic composition and internal observations with X-ray computer tomography were undertaken on 60 and six trees, respectively. Key Results Sprouting was more intense in the part of the stand free from accompanying vegetation and on upper trunk segments. A clear effect of epicormic ontogeny was demonstrated as well: the more epicormics a trunk segment bears, the more chances it had to bear sprouts. Conclusions These results indirectly infer water–carbohydrate control and show direct evidence of constraints by epicormic ontogeny. These results have far-reaching consequences related to the quantification of all functions fulfilled by any type of epicormic structure in any part of the tree. [ABSTRACT FROM PUBLISHER]

Background and Aims During their lifetime, tree stems take a series of successive nested shapes. Individual tree growth models traditionally focus on apical growth and architecture. However, cambial growth, which is distributed over a surface layer wrapping the whole organism, equally contributes to plant form and function. This study aims at providing a framework to simulate how organism shape evolves as a result of a secondary growth process that occurs at the cellular scale. Methods The development of the vascular cambium is modelled as an expanding surface using the level set method. The surface consists of multiple compartments following distinct expansion rules. Growth behaviour can be formulated as a mathematical function of surface state variables and independent variables to describe biological processes. Key Results The model was coupled to an architectural model and to a forest stand model to simulate cambium dynamics and wood formation at the scale of the organism. The model is able to simulate competition between cambia, surface irregularities and local features. Predicting the shapes associated with arbitrarily complex growth functions does not add complexity to the numerical method itself. Conclusions Despite their slenderness, it is sometimes useful to conceive of trees as expanding surfaces. The proposed mathematical framework provides a way to integrate through time and space the biological and physical mechanisms underlying cambium activity. It can be used either to test growth hypotheses or to generate detailed maps of wood internal structure. [ABSTRACT FROM PUBLISHER]

Many species of lizards effectively traverse both two and three-dimensional habitats. However, few studies have examined maximum locomotor performance on different inclines. Do maximum acceleration and velocity differ on a level and inclined surface? Do lizards pause more on an inclined surface? To address these questions, Sceloporus woodi lizards ( N = 12) were run in the laboratory on a level trackway and a vertical tree trunk. This species is known to frequently utilize both vertical and horizontal aspects of its habitat. Average maximum acceleration on the vertical surface exceeded that on the level surface, although average maximum velocity exhibited the opposite pattern. The average number of pauses during level locomotion was lower compared to vertical locomotion. In addition, the average location of the first pause on the level surface was 0.51 m, which is farther than the average for vertical locomotion where the first pause was at 0.35 m. The combination of performance and pause data suggests that the relative lack of pausing during level locomotion allows individuals to reach higher maximum velocities on level surfaces because they accelerate over greater distances. The increased pausing when moving vertically could be a result of high energetic demands of vertical locomotion, or greater microhabitat complexity as a result of branching and/or refuges. The faster acceleration exhibited during vertical locomotion by S. woodi likely offsets the frequent pauses. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, , 83-90. [ABSTRACT FROM AUTHOR]

The article discusses a study on efficacy of trunk treatment with three materials cotton seed oil, and lime and motor oil, was evaluated for the control of apple clearwing, in an apple orchard during two years. It was found that population reductions in lime treatment were significant in the second year, the effect was at a much reduced level in comparison to the two oil treatments. It was observed that used motor oil and cotton oil have potential for the control of moth.

Phloea subquadrata Spinola, 1837 (Pentatomoidea: Phloeidae) belongs to a small family of sap feeding bugs that live on tree trunks, on which they are cryptic because of their coloration and flat body. There are a few studies concerning phloeid anatomy and biology, but almost nothing is known about their ecology. In this study, population dynamics and structure of P. subquadrata on the host tree Plinia cauliflora (Myrtaceae) were investigated during 3 yr in a semideciduous forest in southeast Brazil. Nymphs and adults were active all year round, but the egg-laying season was mainly restricted to the warm, rainy season (September-March). Population density slightly increased at the end of this season because of reproduction. Population age structure changed markedly overtime, with nymphs reaching the adult stage in the subsequent early-to-mid rainy season; Abiotic factors, such as rainfall and temperature, were correlated with female oviposition and population dynamics and phenology. Sex ratio was male-biased, not differing from 1:1 only during the adult recruitment period (October-January). Under dry weather conditions, phloeids were distributed closer to the base of the tree trunks when compared with rainy conditions. Our results suggest that seasonality and variations in weather conditions are important driving forces of population dynamics and phenology of P. subquadrata, as well as the microhabitat selection on host trees. [ABSTRACT FROM AUTHOR]

Emergence, attraction to traps, and seasonal abundance of cerambycids (Coleoptera) whose larvae injure Cupressaceae were studied under natural conditions in southern Connecticut between 1999 and 2005. Adults of the Asian cerambycid Callidiellum rufipenne (Motschulsky) emerged from trunk sections of Thuja occidentalis L. between late March and mid-May. In contrast, the native Atimia confusa confusa (Say) emerged from trunk sections of Juniperus virginiana L. between late August and mid-October. Emerged adults of both cerambycids had a 1:1 sex ratio, and the emergence of Callidiellum rufipenne showed protandry. In a comparison of four trapping methods, sticky bands stapled to trap logs and dead trees of J. virginiana had the highest density of adults of A. confusa confusa and Callidiellum rufipenne. Based on adults trapped on sticky bands on trap logs, dead trees, or girdled trees of J. virginiana or T. occidentalis at different locations, Callidiellum rufipenne was active on hosts for 5-8 wk between April and June; Semanotus ligneus ligneus (Say) for 4 wk in April; Callidium frigidum Casey for 5 wk between early May and early June; and A. confusa confusa for ≈12 wk between April and early July and again for 2-5 wk between September and late October. Catches of A. confusa confusa were significantly female-biased. Number of beetles captured usually was not correlated with the size of the sticky band on trap logs, cut trees, or girdled trees. This is the first quantitative study on emergence, trapping, and seasonal abundance of cerambycids associated with Cupressaceae in northeastern North America. [ABSTRACT FROM AUTHOR]

Five-year-old early maturing peach trees (Prunus persica (L.) Batsch cv. Flordastar grafted on GF-677 peach rootstock) were subjected to three irrigation treatments from March 18 to November 10, 2006. Control plants (T0 treatment) which received irrigation in excess of their crop water requirements (1089.7 mm) were compared with plants watered according to sap flow (SF; T1 treatment) or maximum daily trunk shrinkage (MDS; T2 treatment) measurements, so as to maintain SF and MDS signal intensities (control SF/SF in T1 and MDS in T2/control MDS, respectively) close to unity. When SF or MDS signal intensity on at least two of three consecutive days was at or below unity, irrigation was reduced by 10%. When the MDS signal intensity on at least two of three consecutive days exceeded unity, irrigation was increased by 10%. During the experiment, estimated crop evapotranspiration was 704.9 mm, and the cumulative amounts of applied water in the T1 and T2 treatments were 463.2 and 654.5 mm, respectively. The MDS-signal-intensity-driven irrigation schedule was more suitable than the SF-signal-intensity-driven irrigation schedule because it was more sensitive and reliable in detecting changes in plant water status, preventing the development of detectable plant water stress. Moreover, it had no effect on fruit size. We conclude that peach tree irrigation scheduling can be based on MDS measurements alone. Changes in the irrigation protocol assayed were proposed to reduce MDS signal intensity deviations above unity, for example, by increasing the irrigation scheduling frequency or the amount of water applied, or both. Irrigation schedules based on maintaining MDS signal intensities close to unity could be applied when local crop factor values are unavailable. [ABSTRACT FROM PUBLISHER]

Spatial and temporal dynamics of bark beetles in single tree trunks of Pinus armandi were studied in Qinling Mountains, Shaanxi Province, China. Ten species of engraver bark beetles attacked from healthy to withered Chinese white pines, but seven species were commonly detected every year in Qinling forest ecosystem. Dendroctonus armandi and Hylurgops longipilis were common species at the lower of trunks, and Ips acuminatus, Polygraphus sinensis, and Pityogenes japonicus primary distributed in the middle of trunks, whereas population densities of Cryphalus lipingensis and C. chinlingensis centralized at the upper trunks and branches of Chinese white pines. On the time series, D. armandi, as a dominant species in Chinese white pines of Qinling forest ecosystem, mainly attacked healthy and weakened trees and cooperated with blue stain fungus that resulted in the declining abruptly resistance and triggered the secondary bark beetles to attack the infected or withered host trees. Attacking and colonizing phenology of bark beetles in Qinling forest ecosystem are caused by complex interactions among spatial and trophic competition and cooperation and exhibit particular spatial and temporal patterns. Our results support the view that competition and cooperation within bark beetles are a critical factor to influence bark beetles spatial and temporal distribution, and stability of bark beetles' ecosystem, D. armandi, I. acuminatus, P. japonicus, P. sinensis, C. lipingensis, C. chinlingensis, and H. longipilis in Chinese white pine of Qinling forest ecosystem. [ABSTRACT FROM AUTHOR]

In tree trunks, the motor of gravitropism involves radial growth and differentiation of reaction wood (Archer, 1986). The first aim of this study was to quantify the kinematics of gravitropic response in young poplar (Populus nigra x Populus deltoides, `14551') by measuring the kinematics of curvature fields along trunks. Three phases were identified, including latency, upward curving, and an anticipative autotropic decurving, which has been overlooked in research on trees. The biological and mechanical bases of these processes were investigated by assessing the biomechanical model of Fournier et al. (1994). Its application at two different time spans of integration made it possible to test hypotheses on maturation, separating the effects of radial growth and cross section size from those of wood prestressing. A significant correlation between trunk curvature and Fournier's model integrated over the growing season was found, but only explained 32% of the total variance. Moreover, over a week's time period, the model failed due to a clear out phasing of the kinetics of radial growth and curvature that the model does not take into account. This demonstrates a key role of the relative kinetics of radial growth and the maturation process during gravitropism. Moreover, the degree of maturation strains appears to differ in the tension woods produced during the upward curving and decurving phases. Cell wall maturation seems to be regulated to achieve control over the degree of prestressing of tension wood, providing effective control of trunk shape. [ABSTRACT FROM AUTHOR]

The most significant biotic and abiotic stress agents of water extremity, salinity, and infection lead to wood decay and modifications of moisture and ion content, and density. This strongly influences the (di-)electrical and mechanical properties and justifies the application of geophysical imaging techniques. These are less invasive and have high resolution in contrast to classical methods of destructive, single-point measurements for inspecting stresses in trees and soils. This review presents some in situ and in vivo applications of electric, radar, and seismic methods for studying water status and movement in soils, roots, and tree trunks. The electrical properties of a root-zone are a consequence of their moisture content. Electrical imaging discriminates resistive, woody roots from conductive, soft roots. Both types are recognized by low radar velocities and high attenuation. Single roots can generate diffraction hyperbolas in radargrams. Pedophysical relationships of water content to electrical resistivity and radar velocity are established by diverse infiltration experiments in the field, laboratory, and in the full-scale ‘GeoModel’ at Kiel University. Subsurface moisture distributions are derived from geophysical attribute models. The ring electrode technique around trunks images the growth ring structure of concentric resistivity, which is inversely proportional to the fluid content. Healthy trees show a central high resistivity within the dry heartwood that strongly decreases towards the peripheral wet sapwood. Observed structural deviations are caused by infection, decay, shooting, or predominant light and/or wind directions. Seismic trunk tomography also differentiates between decayed and healthy woods. [ABSTRACT FROM PUBLISHER]

Knowledge of sap flow variability in tree trunks is important for up-scaling transpiration from the measuring point to the whole-tree and stand levels. Natural variability in sap flow, both radial and circumferential, was studied in the trunks and branches of mature olive trees (Olea europea L., cv Coratina) by the heat field deformation method using multi-point sensors. Sapwood depth ranged from 22 to 55 mm with greater variability in trunks than in branches. Two asymmetric types of sap flow radial patterns were observed: Type 1, rising to a maximum near the mid-point of the sapwood; and Type 2, falling continuously from a maximum just below cambium to zero at the inner boundary of the sapwood. The Type 1 pattern was recorded more often in branches and smaller trees. Both types of sap flow radial patterns were observed in trunks of the sample trees. Sap flow radial patterns were rather stable during the day, but varied with soil water changes. A decrease in sap flow in the outermost xylem was related to water depletion in the topsoil. We hypothesized that the variations in sap flow radial pattern in a tree trunk reflects a vertical distribution of water uptake that varies with water availability in different soil layers. [ABSTRACT FROM PUBLISHER]

Growth refers to an increase in dimensions with time and is implicit in the expected continual increase in tree dimensions. Tree diameters, however, could decrease during the growing season due to water depletion. Annual negative growth measurements are usually attributed to human error and not to other physiological or physical processes. Although seasonal and diurnal fluctuations of diameter have been well documented, perennial decrement of diameter has not been the focus of physiological research. The aim of this work was to analyse the potential causes of decrease in annual diameter growth related to tree mortality due to self-thinning in Nothofagus pumilio forests and to quantify the variations in water depletion of the tree trunks. Some trees did present negative annual diameter increments associated with a water content decrease in the trunks (77 per cent in live trees compared with 56 per cent in recently dead individuals), which produced a contraction (more than 8 per cent of the initial diameter) in the wood and the bark. Trees could survive during 2-5 growth seasons with continual decreases in their diameters (14 per cent, standard error 5 per cent of the trees in the studied stand) until the water content reached a limit where mortality resulted. Therefore, the occurrence of data showing a diameter decrease in successive forest inventories may be due to physiological and physical processes in the natural dynamics of the stand, and not exclusively be explained away as the results of human measurement errors. [ABSTRACT FROM AUTHOR]

The article discusses the findings of a study suggesting that accurate branch length estimation in partitioned Bayesian analyses requires accommodation of among-partition rate variation and attention to branch length priors. It was found that among-partition rate variation affect estimates of tree length.

We studied imidacloprid application methods and timing to control the hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), in forests. The methods compared were 1) soil injection near the trunk; 2) soil injection dispersed throughout the area under the canopy; 3) soil drench near the base of the trunk; and trunk injection with the 4) Arborjet, 5) Wedgle, and 6) Mauget systems. The applications were made in the fall and the following spring. Adelgid populations on the hemlocks (Tsuga spp.) were assessed in the fall of two successive years after the treatments. Relative to the untreated control trees, all the soil applications resulted in population reductions, but none of the trunk injections resulted in reductions. Fall and spring treatment efficacy did not differ. Reductions by the soil treatments were between 50 and 100% (avg 80%) by the first fall and 83-100% (avg 98.5%) by the second fall. Analysis of imidacloprid residues using enzyme-linked immunosorbent assay found residues in sap, needles, and twigs 1 mo to 3-yr after application. A laboratory dose-response bioassay using excised, adelgid-infested hemlock branches with cut ends immersed in serial dilutions of imidacloprid determined the LC50 value to be 300 ppb, based on an exposure of 20 d. A high degree of suppression of the adelgid on forest trees was associated with residues in hemlock tissue >120 ppb 2 yr after soil treatment. Although precise relationships between residues and efficacy are elusive, it is clear that soil application of imidacloprid resulted in chronic residues of imidacloprid in tissues and suppression of adelgid populations for >2 yr. [ABSTRACT FROM AUTHOR]