Bark Surface Research Articles

Relationship between tree bark surface temperature and selected meteorological elements

Abstract The results were obtained by measurements in 2014 and 2015 in an apple orchard in Starý Lískovec and Těšetice (South Moravia, Czech Republic, Central Europe) into fertile planting of apple trees. The results show that the bark surface temperature during the year slightly differs from the surrounding air temperature. In addition, it is in average a few tenths of a °C higher in the period before the onset of the vegetation and several tenths of a degree lower during vegetation. Causes of these differences appear to be associated with the flow of sap as well as with foliage. Although it can be reasonably assumed that the temperature of the bark surface on the south side will be significantly affected by the global radiation, our measurements did not demonstrate this dependency. It appears that the wind speed had significantly larger influence on the temperature differences in the non-vegetation period as at speeds over 3.5 m s−1, the drop of temperature is so significant that the bark surface is colder than the surrounding air. Comparison of the development of sums of daily and hourly effective temperatures above 10 °C has shown that where daily values do not show significant differences, hourly values differed so prominently that the calculated date of emergence of adult codling moth in the bark surface was approximately one week earlier than with the use of data for air temperatures.

Tree snakes’ keel gets a grip

To the untrained eye, most snakes look alike, but when Bruce Jayne observes a serpent, he sees many different features. ‘Sea snakes have paddle-shaped tails and gliding snakes are vertically flattened,’ he explains, adding that many species of tree snake have flattened bellies and sharp ridges running along both belly edges, known as keels. Jayne is also fascinated by how animals interact with their surroundings and is particularly intrigued by how tree snakes stop themselves from slipping on rugged bark surfaces. Reasoning that more rotund species would have problems getting a purchase on rough surfaces, as they would simply roll over bumps and ridges, while flat bellied species may be able to lodge the keel ridge against protrusions and lock themselves in place, Jayne recruited a team of students to test the tree-worthiness of three species, ranging from stout boa constrictors to corn snakes and agile brown tree snakes.First, Jayne, Steven Newman, Michele Zentkovich and Matthew Berns simulating the rugged surfaces encountered by snakes in the wild. ‘Variation in the roughness of the bark on natural vegetation is very complex and the spacing between various ridges and grooves can be quite irregular’, explains Jayne. So, instead of trying to mimic every detail on a branch, he focused on one aspect of bark structure – the height of ridges on the surface – by embedding 8 mm wide screws (at lengths of 1, 2, 10, 40 mm), spaced at 10 cm intervals, into the top face of long narrow poles that he inclined over a range of angles from horizontal to vertical. ‘The sheer number of trials was a significant challenge’, chuckles Jayne, estimating that the student trio must have videoed almost 10,000 movies of the snakes ascending poles over the course of the study.Analysing the snakes’ techniques, Jayne saw that on the steepest branches the boa constrictors and corn snakes preferred to grip the pole with one portion of the body and straighten other portions to slide the animal along using a concertina-like motion. However, the tree snake only resorted to this approach when presented with a smooth vertical pole, switching predominantly to sliding sinuously as soon as they were provided with the shortest pegs to lean on. As the pegs became longer the tree snakes dispatched with the concertina style of ascent entirely, while the boa constrictors and corn snakes continue shuffling until the pegs were quite long. Even at the shallowest pole angles, the boa constrictors seemed to struggle, preferring to shuffle along slowly; meanwhile the tree snakes slithered at higher speeds as the pegs became longer and the corn snakes’ performance fell somewhere in between. Even when the team set the tree snakes an additional challenge of negotiating a pole angled at 60 deg with the pegs positioned along the bottom face of the pole, the tree snakes seemed completely unfazed.But how were the tree snakes clinging on? ‘[They were] catching their keel on surface projections that were only 1 mm high’, Jayne says. Where the boa constrictors’ rotund bodies simply rolled over the shortest pegs – forcing them to grip the pole in their coils – the tree snakes were able to lock themselves onto the pole by running their keel ridges against the pegs like a rope passing through a pulley. And Jayne hopes that a better understanding of how tree snakes get a grip could help us design snake unfriendly surfaces, to prevent invasive species – such as the brown tree snake in Guam – from getting into places where they are not wanted.

Effect of bark beetle (Ips typographus L.) attack on bark VOC emissions of Norway spruce (Picea abies Karst.) trees

Abstract Climate warming driven storms are evident causes for an outbreak of the European spruce bark beetle (Ips typographus L.) resulting in the serious destruction of mature Norway spruce (Picea abies Karst.) forests in northern Europe. Conifer species are major sources of biogenic volatile organic compounds (BVOCs) in the boreal zone. Climate relevant BVOC emissions are expected to increase when conifer trees defend against bark beetle attack by monoterpene (MT)-rich resin flow. In this study, BVOC emission rates from the bark surface of beetle-attacked and non-attacked spruce trees were measured from two outbreak areas, Iitti and Lahti in southern Finland, and from one control site at Kuopio in central Finland. Beetle attack increased emissions of total MTs 20-fold at Iitti compared to Kuopio, but decreased the emissions of several sesquiterpenes (SQTs) at Iitti. At the Lahti site, the emission rate of α-pinene was positively correlated with mean trap catch of bark beetles. The responsive individual MTs were tricyclene, α-pinene, camphene, myrcene, limonene, 1,8-cineole and bornyl acetate in both of the outbreak areas. Our results suggest that bark beetle outbreaks affect local BVOC emissions from conifer forests dominated by Norway spruce. Therefore, the impacts of insect outbreaks are worth of consideration to global BVOC emission models.

The benefits of recycling: how photosynthetic bark can increase drought tolerance.

[Extract] Understanding the drought physiology of woody plants has become an increasingly important focus of plant science research in recent years, spurred on by concern about the potential for widespread tree mortality in response to drought stress caused by global warming (McDowell et al., 2008; Allen et al., 2010). However, there is one aspect of how woody plants cope with water deficits that has received very little attention: the role of carbon fixation by photosynthetic bark. This process may become especially important for maintaining physiological activity in woody tissues of drought-stressed trees as the supply of photosynthate from leaves dwindles, due to stomatal closure and impaired phloem translocation. In this issue of New Phytologist, Vandegehuchte et al. (pp. 998–1002) bring this process into the spotlight, and provide a compelling argument for why we should take more notice of that often-hidden, green layer of tissue that is ubiquitous beneath the smooth-bark surfaces of woody plants (Scott, 1907; Pfanz et al., 2002; Dima et al., 2006; Rosell et al., 2015).

Community structure of corticolous microalgae within a single forest stand: evaluating the effects of bark surface pH and tree species

Community structure of corticolous macro-epiphytes, such as lichens and mosses, usually strongly correlates with bark characteristics related to the taxonomic identity of the host tree. However, the reasons for the occurrence of similar patterns of microalgal corticolous biofilms are unclear and have rarely been investigated. In this study, we surveyed aerial phototrophic biofilms growing on the bark of Acer, Alnus, Fagus, Fraxinus and Picea trees in a single stand of a temperate forest. A flathead electrode was used to measure and evaluate the effect of bark surface pH on microalgal species richness and composition. In total, 47 distinct morphotypes were found, chiefly consisting of various coccoid green algae belonging to Trebouxiophyceae and Chlorophyceae. In addition, members of the Bacillariophyceae, Eustigmatophyceae, Streptophyta, Trentepohliales, Xanthophyceae and Cyanobacteria were also found. Bark pH and species richness of the samples were positively correlated; in the most acidic samples (from Picea and Alnus trees), only green algae occured. Aerial diatoms, Cyanobacteria, Xanthophyceae and Trentepohlia sp. were only found in the more basic samples. The species composition was significantly structured by the separated effects of host tree species, the bark pH and the sampling season. The observed non-random differences in community structure of the biofilms among host tree species indicated possible effects of deterministic processes, such as species sorting of microalgae along the environmental gradients.

Functionalized Bark for Recycled Polypropylene-Based Composites

A new method for the modification of the bark surface using N,N-diethyl-2,3-epoxypropylamine (DEEPA) was developed. As a result, the part of the bark phenolic hydroxyl groups were replaced with amine groups. The conditions of the modification were found, and the modified products were analysed. The different amount of the introduced amino groups in hardwood and softwood bark was gained by the various contents of lignin in the wood species. The recycled propylene-based composites filled with the modified bark were characterised by higher mechanical parameters in comparison with the composites filled with unmodified bark. The differences in the mechanical properties of the polymer composites filled with softwood - pine (Pinus sylvestris) bark and hardwood - grey alder (Alnus incana) bark has been established.

Large‐scale manipulation of oviposition substrata affects egg supply to populations of some stream‐dwelling caddisflies

Summary Oviposition substrata are a crucial resource for many stream‐dwelling insects and may have a strong effect on population densities. From February to March 2010, we conducted a large‐scale experiment manipulating the density of oviposition substrata available to two taxa, Cheumatopsyche spp. and Ecnomus spp. in Hughes Creek (south‐east Australia). These caddisflies oviposit on hard surfaces underwater. Hughes Creek has a sandy bed, and females rely predominantly on bark and wood as oviposition substrata. Bark density was manipulated in 25‐m‐long sites, creating a range of bark surface areas (SAs) spanning an order of magnitude, with appropriate controls. Estimates of the number of egg masses and bark SAs were obtained 22 and 55 days after the experiment commenced in each site. To characterise taxon‐specific oviposition site preferences and test whether preferences were dependent on overall bark availability, the conditions (velocity and emergence) of individual substrata were manipulated within sites. Egg masses were enumerated at approximately weekly intervals for 7 weeks. We found a strong relationship between the SA of bark at sites and the number of masses of Ecnomus spp., demonstrating that oviposition is limited by substrata availability. In contrast, the number of Cheumatopsyche spp. egg masses was not related to the total amount of bark available. Ecnomus spp. showed a weak preference for emergent compared to submerged bark, but did not respond to water velocity. Cheumatopsyche laid eggs predominantly in fast flows, regardless of bark emergence, which may explain the lack of a site‐level response because only a small proportion of bark occurred in fast flows even when bark was plentiful. Our results suggest that the strength of oviposition preferences may depend on overall background densities of substrata. Oviposition preferences and substrata availability interact to set the initial distribution (and density) of the next generation. Our study has wide implications for the management of streams with soft sediment beds, where bark and wood inputs from riparian vegetation provide not only food and habitat for larvae but also oviposition substrata that are critical to successful recruitment for some taxa.

Bacterial microflora isolated from the bark surface of poplars growing in areas where air pollution is very high

In the autumn of 1976 bacteria of the genera <i>Bacillus, Pseudomonas, Flavobacterium, Erwinia</i> and <i>Cellulomonas</i> were isolated from the bark surface of poplars growing in protective belts around several industrial plants. It was found that the qualitative and quantitative composition of the surface bacterial microflora changes in dependence on the degree of resistance of the poplars to the action of the dust emitted by the industrial establishment and containing high amounts of heavy metals.

Assessing and Measuring of Citrus gummosis (Phytophthora spp.) in Major Citrus Growing Areas of Ethiopia

Citrus production in Ethiopia is threatened by a number of biotic and abiotic factors. Among these citrus gummosis is one of the most important biotic constraints in the country. This study was conducted with the objective to measure and estimate the incidence and distribution of citrus gummosis (Phytophthora spp.) in major citrus growing areas of Ethiopia. Surveys were conducted in ten major citrus growing areas of Ethiopia. In each orchard, 30 trees were selected and totally 300 trees were assessed for gummosis incidence. These trees were sampled by making two diagonal transects across the field in the form of an “X”. A tree decline was scored on a 0-4 scale where 0=free of any decline symptom, 4=complete drying of the plant. A tree was defined and recorded as cankered when it had any of the following symptoms: discoloration of the bark surface, discoloration of the underlying tissues, dieback, dried the whole part of the plant and exudation of gum from infected tissues. Results showed that growth and fruit production are greatly reduced on trees infected by this disease. Cracked lesions that exude sap are found on infected scions, which become gradually girdled and killed. This symptom was prevailed in 90% of the surveyed citrus orchards. Gummosis was more frequent on scions (trunk and branch) which had 66.96% infection than rootstocks (33.02%). generally the issue needs more attention in the field management including harvesting method (avoid climbing on the tree rather through ladder), don’t touch the tree with the equipments and hands with mud probabily have an inoculums; when irrigating and weeding and finally use of fungicides when pruning of the diseased branch.

Factors affecting the stemflow of trees in the Brazilian Cerrado

AbstractStemflow is a hydrological flux that largely influences the input of rainwater to the soil and its spatial distribution. Here, we aimed to identify the factors influencing this hydrological flux by quantifying the stemflow of 129 trees in the Brazilian savannah. The attributes of individual trees were investigated as predictor variables influencing either stemflow volume or tree efficiency in generating stemflow—proportion of rainfall over the canopy flowing down the stem. The volume of stemflow was higher in trees that were large, had perennial leaves, and exhibited monopodial growth. However, the efficiency of a tree in generating stemflow was negatively correlated to its dimensions. The most efficient trees had a smooth bark surface, monopodial growth, and straight stems. There was large variation in efficiency among individuals, which is related to the high diversity of attributes among the studied trees. The small size of Cerrado trees explains the lower stemflow volume in comparison with trees in forest ecosystems. The efficiency observed in the Cerrado trees was also lower when compared to trees from other ecosystems, even in arid environments. Copyright © 2014 John Wiley & Sons, Ltd.

Erratum to: Hydrological properties of bark of selected forest tree species. Part I: the coefficient of development of the interception surface of bark

Erratum to: Hydrological properties of bark of selected forest tree species. Part I: the coefficient of development of the interception surface of bark

First Report of Geosmithia morbida on English Walnut and its Paradox Rootstock in California.

Geosmithia morbida, the causal agent of thousand cankers disease (TCD), is vectored by the walnut twig beetle (WTB), Pityophthorus juglandis, causing decline in eastern black walnut, Juglans nigra (4), and canker development on many Juglans species (5). In the summer of 2012, a survey for TCD incidence in English walnut, J. regia, in orchards in California identified many trees with WTB activity and characteristic TCD symptoms. Both the J. regia scion and its Paradox hybrid rootstock (J. hindsii× J. regia) were affected. In some cases, trees exhibited bleeding on the bark surface from WTB entrance holes. Removal of the outer bark revealed cankers in the phloem around the WTB galleries. Two samples were taken from scions and three samples were collected from rootstocks of trees in orchards in northern California. Pieces (~3 to 4 mm2) of symptomatic tissue were placed in acidified potato dextrose agar (APDA), and the plates were incubated for 4 to 5 days at 30°C. Samples exhibiting fungal growth similar in morphology to G. morbida were transferred to PDA plates to obtain pure cultures and then processed to obtain single-spore cultures. Culture morphology for five single-spore isolates (Gm103, Gm104, Gm105, Gm107, and Gm108) was similar to that described by Kolařík et al. (4) for G. morbida. Conidiophores were penicillate and verrucose. Conidia were narrowly cylindrical, 5.2 ± 0.06 × 2.2 ± 0.04 μm (n = 50). Single-spore isolates were then grown in 1% yeast extract glucose liquid culture for 7 to 10 days. DNA was extracted and the ITS region was amplified, including the 5.8S region by using primers ITS1F/ITS4. Sequences were assembled and deposited in GenBank under accessions KJ664793 to KJ664797. Sequences were compared to those in GenBank; all sequences matched (99 to 100% identity) the ITS sequences of G. morbida strain CBS 124663. Pathogenicity tests were performed on 28-cm-long detached branches of J. regia. Four branches per isolate were inoculated with a 5-mm-diameter mycelial plug from a 2-week-old culture. Branches were incubated at room temperature (23 ± 2°C) in a humidified container for 3 weeks, and then canker lengths were measured. Pieces of the cankered area were placed in APDA and incubated as described above with G. morbida re-isolated from the cankers for all of the isolates, completing Koch's postulates. Average canker lengths ranged from 48.6 ± 4.3 to 72.1 ± 7.1 mm. Re-isolated G. morbida exhibited the same growth and reproductive structure morphology in culture on PDA as the original cultures. TCD in association with WTB has been observed in California English walnut orchards since 2008 (1,2,3). However, this is the first report for completion of Koch's postulates and morphological and molecular confirmation of G. morbida in J. regia and the Paradox rootstock, the predominant rootstock used in commercial orchards. TCD is a concern to the walnut industry in California with over 245,000 bearing acres reported in 2012.

A new method to detect Lonsdalea quercina in infected plant tissues by real‐time PCR

SummaryPresymptomatic and accurate diagnoses of pathogens are essential for disease prediction and the timely application of bactericide. The bacterium Lonsdalea quercina (=Brenneria quercina) has been reported as the causal agent of drippy nut and bark canker disease on oak in California (US) and Europe. In recent years, it is also found on Populus × euramericana trees in Henan province of China. This bacterium causes longitudinal cankers of a few centimetres in size on the bark surface of the upper trunk. In this study, we developed two species‐specific PCR assays using primer pairs LqfF/LqfR and LqgF/LqgR for the rapid and accurate detection of the pathogenic bacteria in diseased plant tissues. The results show that the LqfF/LqfR primers amplified only a single PCR band of approximately 382 bp and the LqgF/LqgR primers yielded a PCR product of approximately 286 bp. The two primers were successfully adapted to real‐time PCR based on SYBR Green I used with the ABI 7500 system. The detection limit of the reaction was 0.1 pg genomic DNA per 20 μl PCR reaction volumes. The pathogen was mainly detected in the phloem of cankers as well as in the exudates of diseased trees, but was not found in the xylem or leaves. The size of pathogen in distribution was larger than the lesion. The results demonstrate that real‐time PCR assays can be used to detect the pathogen by extracting DNA directly from infected plant tissues. This method is a rapid, reliable method for the presymptomatic and accurate detection of L. quercina, providing a useful insight into epidemiological studies.

Densities of Agrilus auroguttatus and Other Borers in California and Arizona Oaks

We investigated within-tree population density of a new invasive species in southern California, the goldspotted oak borer, Agrilus auroguttatus Schaeffer (Coleoptera: Buprestidae), with respect to host species and the community of other borers present. We measured emergence hole densities of A. auroguttatus and other borers on the lower stem (bole) of naïve oaks at 18 sites in southern California and on co-evolved oaks at seven sites in southeastern Arizona. We sampled recently dead oaks in an effort to quantify the community of primary and secondary borers associated with mortality—species that were likely to interact with A. auroguttatus. Red oaks (Section Lobatae) produced greater densities of A. auroguttatus than white oaks (Section Quercus). On red oaks, A. auroguttatus significantly outnumbered native borers in California (mean ± SE of 9.6 ± 0.7 versus 4.5 ± 0.6 emergence holes per 0.09 m2 of bark surface), yet this was not the case in Arizona (0.9 ± 0.2 versus 1.1 ± 0.2 emergence holes per 0.09 m2). In California, a species that is taxonomically intermediate between red and white oaks, Quercus chrysolepis (Section Protobalanus), exhibited similar A. auroguttatus emergence densities compared with a co-occurring red oak, Q. kelloggii. As an invasive species in California, A. auroguttatus may affect the community of native borers (mainly Buprestidae and Cerambycidae) that feed on the lower boles of oaks, although it remains unclear whether its impact will be positive or negative.

Meteorological influences on stemflow generation across diameter size classes of two morphologically distinct deciduous species

Many tree species have been shown to funnel substantial rainfall to their stem base as stemflow flux, given a favorable stand structure and storm conditions. As stemflow is a spatially concentrated flux, prior studies have shown its impact on ecohydrological and biogeochemical processes can be significant. Less work has been performed examining stemflow variability from meteorological conditions compared to canopy structural traits. As such, this study performs multiple regressions: (1) to examine stemflow variability due to event-based rainfall amount, intensity, mean wind speeds, and vapor pressure deficit; (2) across three diameter size classes (10-20, 21-40, and >41 cm DBH); and (3) for two common tree species in the northeastern USA of contrasting canopy morphology--Liriodendron tulipifera L. (yellow poplar) versus Fagus grandifolia Ehrh. (American beech). On the whole, multiple regression results yielded significant positive correlations with stemflow for rainfall amount, intensity, and mean wind speed and a significant negative correlation for vapor pressure deficit (VPD). Tree size altered stemflow-meteorological condition relationships, where larger trees strengthened indirect stemflow-VPD and direct stemflow-rainfall and stemflow-intensity associations. Canopies of rougher bark and lower branch angle (represented by L. tulipifera) enhanced correlations for nearly all meteorological conditions via greater stemflow residence time (and longer exposure to meteorological conditions). Multiple regressions performed on leafless canopy stemflow resulted in an inverse relationship with wind speeds, likely decoupling stemflow sheltered solely on bark surfaces from VPD influences. Leaf presence generally increased direct stemflow associations with rainfall intensity, yet diminished stemflow-rainfall relationships. F. grandifolia canopies (exemplifying structures of smoother bark and greater branch angle) strengthened differences in stemflow associations with rainfall/mean wind speed between leaf states. These findings are placed in a conceptual interception loss path analysis, which shows the potential to alter common interception loss estimates in high stemflow stands.

Hydrological properties of bark of selected forest tree species. Part I: the coefficient of development of the interception surface of bark

The coefficient of development of the interception surface of bark allows for objective assessment of the degree of bark surface differentiation between different species. Inter-species differentiation of bark morphology and its variability progressing with tree age suggest that the hydrological properties of the bark of particular species depend on the degree of development of the outer bark surface of trees. The aim of the present research was to develop a method of calculating the actual bark surface with the use of the coefficient of development of the interception surface of bark, describing the degree of development of the outer bark surface of trees. The primary aim was to show inter-species differentiation of the coefficient of development of the interception surface of bark at breast height, as well as its variability within a single species, progressing with tree age. The present study shows the results obtained for 77 bark samples collected at the breast height of the following tree species: Pinus sylvestris L., Larix decidua Mill., Abies alba Mill., Picea abies L., Quercus robur L., Fagus sylvatica L., Acer pseudoplatanus L. and Betula pendula Ehrh. In all of the examined species, the coefficient of development of the interception surface of bark shows a distinct relation to the breast-height diameter. The highest values of coefficient of development of the interception surface of bark among the thickest trees are reached by: L. decidua—2.56, Pinus sylvestris—2.28 and B. pendula—2.44, whereas the lowest values are reached by the bark of European beech F. sylvatica—1.07. The coefficient of development of the interception surface of bark describes the morphological differentiation of the outer bark surface of trees in an objective way. Owing to its mathematical form, the coefficient of development of the interception surface of bark may be useful in the modelling of hydrological processes occurring in forest ecosystems.

Smooth bark surfaces can defend trees against insect attack: resurrecting a ‘slippery’ hypothesis

SummarySmooth bark on trees and shrubs was historically hypothesized to be an anatomical defence against epiphytic vegetation and phytophagous insects. This hypothesis has fallen from favour, yet no clear tests of bark texture as a defence against insects have been published.We tested the smooth bark defence hypothesis using bark beetles specialized in attacking pine trees as model insects, andPinus flexilis(limber pine) – a widespread tree that can have both smooth and rough bark surfaces on the same stem – as the model tree. We investigated the effects of bark texture on the locations of bark beetle attacks on trees with a combination of field surveys and experiments in the Colorado Rocky Mountains, USA.Bark beetle attacks were overwhelmingly located on rough bark surfaces and virtually absent from smooth bark. Increasing proportional coverage by smooth bark was negatively related to bark beetle attacks per square metre of bark surface. Experimental tests of bark beetles' ability to grip smooth versus rough bark revealed that bark beetles have difficulty gripping and quickly fell from smooth bark but not from rough bark.Smooth bark was negatively related to increasing tree size, but our models indicated that even partial coverage by smooth bark on a tree's trunk can significantly reduce total bark beetle attacks – this reduction likely improves tree fitness as bark beetles must aggregate to overcome tree defences.Synthesis. Our results indicate that smooth bark on trees can act as an anatomical defence against insects by reducing their ability to grip a tree's surface – even for insects specialized in attacking tree stems. Similar to other forms of anti‐insect defence (i.e. secondary chemistry, leaf toughness), smooth bark appears to be influenced by plant ontogeny whereby younger trees have greater defences than older trees. Understanding the adaptive significance of bark texture will require continued field and genetic study. Nevertheless, our results revealed that smooth bark texture increases tree resistance to phytophagous insects calling for the resurrection and vetting of the smooth bark defence hypothesis.

Morphological abnormalities in gall-forming aphids in a radiation-contaminated area near Fukushima Daiichi: selective impact of fallout?

To evaluate the impact of fallout from the Fukushima Daiichi Nuclear Power Plant accident on organisms, this study compared the morphology and viability of gall-forming aphids between the Fukushima population and control populations from noncontaminated areas. This study, in particular, focused on the morphology of first-instar gall formers derived from the first sexual reproduction after the accident. Of 164 first instars from Tetraneura sorini galls collected 32 km from Fukushima Daiichi in spring 2012, 13.2% exhibited morphological abnormalities, including four conspicuously malformed individuals (2.4%). In contrast, in seven control areas, first instars with abnormal morphology accounted for 0.0–5.1% (on average, 3.8%). The proportions of abnormalities and mortality were significantly higher in Fukushima than in the control areas. Similarly, of 134 first instars from T. nigriabdominalis galls, 5.9% exhibited morphological abnormalities, with one highly malformed individual. However, of 543 second-generation larvae produced in T. sorini galls, only 0.37% had abnormalities, suggesting that abnormalities found in the first generation were not inherited by the next generation. Although investigation is limited to one study site, this result suggests that radioactive contamination had deleterious effects on embryogenesis in eggs deposited on the bark surface, but a negligible influence on the second generation produced in closed galls. Furthermore, analysis of both species samples collected in spring 2013 indicated that the viability and healthiness of the aphids were significantly improved compared to those in the 2012 samples. Thus, the results of this study suggest the possibility that a reduced level of radiation and/or selection for radiation tolerance may have led to the improved viability and healthiness of the Fukushima population.

Rainfall partitioning, tree form and measurement scale: a comparison of two co‐occurring, morphologically distinct tree species in a semi‐arid environment

ABSTRACTThe partitioning of precipitation into interception, stemflow and throughfall is an important hydrological process in forested systems, influenced heavily by climate and plant form. This study examined whether the rainfall partitioning pathways reflect the often cited influence of tree morphology, using two species in a semi‐arid karst environment. Eucalyptus diversifolia ssp. diversifolia has a multi‐stemmed habit, smooth bark and true leaves. In comparison, Allocasuarina verticillata has a single trunk, rough bark and long, thin, vertical phyllodes. We hypothesized that multiple stems and a smooth bark would be more effective at generating stemflow compared with single stems with a rough bark surface. To test this, rainfall, throughfall and stemflow were collected over two years, and stemflow funnelling ratios were calculated. The degree of similarity in overall rainfall partitioning for the two species was remarkable; although some divergence was found each month, the partitioning regressions converged. For E. diversifolia, gross rainfall partitioned into interception, throughfall and stemflow averaged 30.9%, 66.4% and 2.7%, respectively. For A. verticillata, rainfall partitioning of gross precipitation into interception, throughfall and stemflow averaged 31.4%, 65.9% and 2.7%, respectively. Maximum stemflow funnelling ratio for E. diversifolia was 74 and for A. verticillata was 147, indicating that water from stemflow is likely to play an important ecohydrological role in this environment. We further compared these findings to 31 global studies and discussed the importance of scale (individual tree vs plot) and canopy cover when reporting or interpreting rainfall partitioning results. Copyright © 2013 John Wiley & Sons, Ltd.

Microfungi found on phellen of Jugulans nigra L. in Southeastern Ohio, USA

Bark surfaces from black walnut (<em>Jugulans nigra</em>) trees of three sites in southeastern Ohio, half. Five. and ten miles from the Ohio River, were used in late autumn to isolate fungi in culture. as well as to search for the presence of fungal mycelium and spores. The pH of the cork also was determined. Fifty six, mostly cosmopolitan, species of microfungi and several yeasts were isolated, almost all belonging to imperfect form genera. with the largest number of species in the genus <em>Penicillium</em>. No relationship of fungal presence to cork pH was found among the sites whose acidity was related to closeness to the industrialized river edge. Relatively few fungi were isolated. and even fewer spores, and only four mycelia) growths were found by electron microscopy. Several spores seen could not be matched with fungi that had been isolated. The bark seems to be a trapping surface for spores. rather than a place of fungal growth.