Showing papers on "Bark published in 2001"

Comparative aggressiveness of standard and variant hybrid alder phytophthoras, Phytophthora cambivora and other Phytophthora species on bark of Alnus, Quercus and other woody hosts

Abstract: Pathogenicity tests were carried out on the bark of Alnus glutinosa with 19 isolates of the standard (near-tetraploid) hybrid alder phytophthora, nine isolates representing its known heteroploid variants and 11 isolates of P. cambivora, a probable parent species of the hybrid. Over a 4-year period, 12 experiments were conducted on living alder logs incubated at 20°C. Most isolates of the standard hybrid and those of the ‘Dutch variant’ were highly aggressive to alder bark. Isolates of the ‘Swedish’, ‘UK’ and ‘German variants’, and of P. cambivora, were only weakly pathogenic. Also, isolates of P. fragariae, P. cinnamomi, P. sp. ‘O-group’, P. cryptogea, P. megasperma, P. gonapodyides and P. citricola were either weakly or nonpathogenic. Rates of lesion development were greatest on logs cut during July–October, slower on logs cut between November and March and zero on logs cut during April, indicating a strong seasonal effect. Other evidence indicated that lesion development was subject to critical thresholds of host resistance. The standard hybrid was nonpathogenic to the bark of four other hardwood and two conifer species, indicating that it is relatively host specific. In contrast, P. cambivora was an aggressive pathogen on live bark of Quercus and Castanea. The significance of these results is discussed.

Facultative Intraguild Predation by Larval Cerambycidae (Coleoptera) on Bark Beetle Larvae (Coleoptera: Scolytidae)

Abstract: Larvae of the Carolina sawyer Monochamus carolinensis (Olivier) (Cerambycidae) and bark beetle larvae (Scolytidae) often simultaneously feed in phloem of recently killed pine trees. Our investigations reveal that M. carolinensis larvae may act as facultative intraguild predators of bark beetle larvae. Phloem sandwiches were used in four experiments to examine inter- and intraspecific interactions. We discovered that all sizes of M. carolinensis larvae killed bark beetle larvae. Seventy-six percent of the killed bark beetle larvae were consumed by M. carolinensis, including 58% that were entirely ingested. Cannibalism in M. carolinensis occurred in every experimental trial. Based on this evidence, M. carolinensis, and possibly related cerambycid species associated with bark beetles, are facultative intraguild predators of larvae of other phloem inhabiting species. The consequences of this behavior may have important implications for bark beetle population dynamics.

The Existence of Bark and Stem Photosynthesis in Woody Plants and Its Significance for the Overall Carbon Gain. An Eco-Physiological and Ecological Approach

Abstract: Leaves are expected to be green (although they are sometimes reddish in the so-called blood forms or yellowish in the so-called aurea forms). The colour-determining pigments, the chlorophylls, are the cause of the leaves’ global importance in photosynthetic carbon fixation. The fact that stems can also contain chlorophyll is not directly evident. The outer bark layers are mostly brown (oak) or grey (beech, aspen) or sometimes even white (birch). However, bark tissues of younger twigs of trees are regularly greenish. The green colour is not caused by a surface layer of algae colonizing the outer wet parts of rhytidomes. By carefully peeling off layers of the dead outer bark of twigs and branches, a green colour indicates the presence of chlorophyll-containing tissues. The fact that the tree’s skeleton partly consists of green tissue has been known for centuries by bark-peeling basket makers, bast producers and even lovers who cut hearts into tree bark.

Carbon isotope discrimination in photosynthetic bark

Abstract: We developed and tested a theoretical model describing carbon isotope discrimination during photosynthesis in tree bark. Bark photosynthesis reduces losses of respired CO2 from the underlying stem. As a consequence, the isotopic composition of source CO2 and the CO2 concentration around the chloroplasts are quite different from those of photosynthesizing leaves. We found three lines of evidence that bark photosynthesis discriminates against 13C. First, in bark of Populus tremuloides, the δ13C of CO2 efflux increased from –24.2‰ in darkness to –15.8‰ in the light. In Pinus monticola, the δ13C of CO2 efflux increased from –27.7‰ in darkness to –10.2‰ in the light. Observed increases in δ13C were generally in good agreement with predictions from the theoretical model. Second, we found that δ13C of dark-respired CO2 decreased following 2–3 h of illumination (P<0.01 for Populus tremuloides, P<0.001 for Pinus monticola). These decreases suggest that refixed photosynthate rapidly mixes into the respiratory substrate pool. Third, a field experiment demonstrated that bark photosynthesis influenced whole-tissue δ13C. Long-term light exclusion caused a localized increase in the δ13C of whole bark and current-year wood in branches of P. monticola (P<0.001 and P<0.0001, respectively). Thus bark photosynthesis was shown to discriminate against 13C and create a pool of photosynthate isotopically lighter than the dark respiratory pool in all three experiments. Failure to account for discrimination during bark photosynthesis could interfere with interpretation of the δ13C in woody tissues or in woody-tissue respiration.

Acacia nilotica L. Bark Removes Toxic Elements from Solution: Corroboration from Toxicity Bioassay Using Salix viminalis L. in Hydroponic System

Abstract: The present investigation deals with the advantages and potential of the Acacia nilotica bark as an adsorbent of toxic metals. Bark (1 g) when added to 100 ml of aqueous solution containing 10 μg ml-1 metal solution exhibited different metal adsorption values for different metals. The order of metal adsorption being Cr ≥ Ni > Cu > Cd > As > Pb. A similar trend of metal adsorption was observed when the bark is reused (1st recycle) Cr> Ni > Cu > Cd > Pb and also in the column sorption. In order to verify the metal removal property of A. nilotica bark, toxicity bioassay with Salix viminalis stem cuttings in hydroponic system augmented with Cd, Cr, and Pb together with A. nilotica bark powder was carried out. The results of toxicity bioassay confirmed the metal adsorption property of the bark powder. The functions of toxicity studies include leaf area, root length and number of new root primordia produced per stump. The leaf area, root length, and the number of new root primordia increased considerab...

Ophiostomatoid fungi associated with three pine-infesting bark beetles in South Africa.

Abstract: Xu Dong Zhou, Z. Wilhelm de Beer, Brenda D. Wingfield & Michael J. Wingfield (2001). Ophiostomatoid fungi associated with three pine-infesting bark beetles in South Africa. Sydowia 53(2): 290-300. Three species of exotic bark beetles, Hylastes angustatus, Hylurgus ligniperda and Orthotomicus erosus, occur on Pinus spp. in South Africa. Although these bark beetles have been reasonably intensively studied in South Africa, little is known regarding their associated fungi. In this study, 1558 samples (beetles and galleries) were collected from P. patula and P. elliottii plantations. In total, 1254 fungal isolates were encountered and 500 of them are maintained. Forty additional isolates previously collected and stored in a culture collection were also included. Nine different ophiostomatoid species were identified. Among these, Leptographium serpens, L. lundbergii, and Ophiostoma ips, were most frequently encountered. Ophiostoma galeiformis, O. piceae and L. procerum are newly recorded from South Africa.

Decaying wood in tree trunk hollows as a natural substrate for Cryptococcus neoformans and other yeast-like fungi of clinical interest

Abstract: The occurrence of Cryptococcus neoformans var. neoformans and other yeast-like fungi of clinical interest in decaying wood inside tree trunk hollows, bark and other plant materials is reported. The var. neoformans was isolated from 3 of 45 (6.6%) wood and one of 390 Eucalyptus bark samples. Two of the positive wood samples came from a tree trunk hollow of Butea monosperma (Family: Papilionaceae) growing in Roshan Ara Garden, Old Delhi whereas the third was from a trunk hollow of Tamarindus indica (Family: Papilionaceae) growing outside of Talkatora Garden, New Delhi. The solitary positive Eucalyptus bark sample originated from Amritsar. The isolations of var. neoformans from decaying wood inside trunk hollows of B. monosperma and T. indica constitute the first record of the natural occurrence of this pathogen in association with these trees. The observation reinforces the recent evidence for decaying wood inside trunk hollows of some trees to be a new natural habitat of the variety neoformans. Besides, in consonance with their essentially saprobic character, a number of other yeast-like fungi were sporadically isolated. This includes, Cryptoccus laurentiiCryptococcus albidusCandida lusitaniaeC. guilliermondiiC. kruseiC. tropicalisC. zeylanoidesTrichosporon cutaneumRhodotorula mucilaginosaR. glutinisGeotrichum capitatumG. klebahnii and Sporobolomyces salmonicolor.Cryptococcus neoformans var. gattii was not found in any of the 702 samples of plant materials, including the bark and detritus of Eucalyptus camaldulensis and E. tereticornis trees. A more extensive environmental survey, covering divergent climatic regions, is warranted to identify the natural reservoirs of var. gattii in India.

Age-dependent bark photosynthesis of aspen twigs.

Abstract: The photosynthetic performance of trembling aspen (Populus tremula L.) twigs and leaves was studied in relation to selected structural features of aspen bark. PFD transmittance of intact periderm was reduced by about 90% in current-year twigs through peridermal thickening. However, because of drastic changes within the bark microstructure, PFD transmittance increased in 1-year-old twig segments up to 26% of the incident PFD. On a unit surface area basis, the chlorophyll content of young twigs (425 mg Chl m–2) almost reached that of leaves (460 mg Chl m–2). The chlorophyll content of aspen bark chlorenchyma was clearly age-dependent, even increasing in current-year twigs with advancing internodal age. The low bark chlorophyll a/b ratios (about 2.6 compared with 3.9 in leaves) indicate that bark chloroplasts are shade-adapted. Positive net photosynthesis was not found in aspen twigs, but apparent respiration was distinctly reduced in the light due to light-driven carbon refixation (bark photosynthesis) within the chlorenchymal tissues. Under constant microclimatic conditions, dark respiration rates were strongly correlated with stem-internal CO2 refixation. In accordance with increasing dark respiration rates, the efficiency of this carbon recycling was generally greater in the metabolically more active, younger twig segments than in older segments; carbon refixation rates reached up to 80% of dark respiration values. At least in young twigs and branches and thus in the light-exposed outer parts of tree crowns, respiratory CO2 losses by the tree skeleton could efficiently be reduced. Refixation of carbon dioxide may be of great importance for carbon budgets in the environmentally controlled or pathogen-induced leafless states of deciduous aspen trees.

Within and between-tree variation of bark content and wood density of eucalyptus globulus in commercial plantations

Abstract: Eucalyptus globulus trees, 15 years old, were sampled at different heights from commercial pulpwood plantations in two sites in Portugal. Bark thickness was higher in the site with better growth and always decreased from the tree base to the top. Bark content was site independent and on average 11% of stem dry weight, higher at the base and top, and lower at 35% height level.Tree mean wood basic density averaged 600 kg /m3 and 568 kg /m3 for best and worst site, respectively, and was not correlated with tree growth. Wood density increased from base to top of the tree. Between-tree variation was low with coefficients of variation of site mean below 10%. Bark density (374 kg /m3 and 454 kg /m3 for best and worst site, respectively) did not show significant within tree variation. Average tree wood density could not be predicted with reasonable accuracy using a breast height sampling and better results were obtained using a sampling as a percentage of total height (e.g. 15%).

Nitrogen forms in bark, wood and foliage of nitrogen-fertilized Pinus sylvestris

Abstract: Cycling of soluble non-protein N compounds is thought to be indicative of the N-nutritional status of trees. We determined the major N forms in bark, wood and foliage and estimated the dependence of prevalent N forms on N availability in Pinus sylvestris L. trees from northern Sweden. Trees subjected to severe N limitation and trees that had been fertilized with an average 64 kg N ha(-1) year(-1) for 25 years were analyzed. Bark and wood samples were collected by tangentially cryo-sectioning the trunk into 30-microm thick sections, from the bark to the functional xylem. Soluble amino compounds were extracted from the sections for analysis. Sap samples from twigs were obtained by centrifugation, and bark samples from twigs were obtained by tissue extraction. In both needles and bark, arginine dominated the amino-N pool. Because arginine concentrations in needles increased with N fertilization, arginine dominance of the amino-N pool in needles was higher in N-fertilized trees than in control trees. In bark, N fertilization resulted in a large increase in glutamine concentration, so that glutamine accounted for a larger proportion of the amino-N pool in bark in N-fertilized trees than in control trees. Glutamine dominated the amino-N pool in wood of control trees. Nitrogen fertilization resulted in an increased proportion of arginine in the wood amino-N pool. We conclude that the composition of the amino-N pools in bark, wood and foliage is highly sensitive to N supply. The composition of the amino-N pools can contribute to the regulation of tree N-nutritional status, which is mediated by shoot to root signalling by long-distance transport of amino compounds.

Investigating tree bark as an air-pollution biomonitor by means of neutron activation analysis

Abstract: The olive tree (Olea europaea) is an icon of southern Europe and awidespread evergreen in mainland Portugal. First results of a continuing studyon the ability of olive-tree bark to act as an air-pollution biomonitor arepresented and discussed here. Other than lower signals and an anticipatedsystemic control over some elements, there seems to be no a priori reasonfor ruling out the possibility of using bark in atmospheric trace-elementsurveys. In fact, nonparametric statistics show that, despite their relativemagnitude, the variation patterns of bark and lichen concentrations significantlyfollow one another all across the study area.

Impact of bark removal on survival of Taxus baccata L. (Himalayan yew) in Nanda Devi Biosphere Reserve, Garhwal Himalaya, India

Abstract: The Himalayan yew (Taxus baccata L.) is widely but sparsely distributed along the cool temperate belt between 2600 and 3300 m asl of the Nanda Devi Bio- sphere Reserve (NDBR), Garhwal Himalaya. Tradi- tionally, the bark of this plant is used for preparing beverages locally called Namkin Chay, medicines and its wood as a timber in various regions of the Him a- laya. However, due to its excessive collection for use in anti-tumour and anti-cancer drugs, the population of this species has been reduced to a large extent. A st udy carried out between April 1997 and October 2000 showed that the trees with average girth of 10 -90 cm were damaged through bark-stripping practices. The average consumption and collection of the bark was estimated to be 1.7 kg/family/year in the buffer zone villages of NDBR. It was noticed that the growth and survival of this species declined significantly when the bark was removed beyond a limit of average bark thickness (0.43 cm). Since bark collection is an impor- tant traditional activity and directly linked with the health and livelihood of the local people, it cannot be banned or stopped. It is suggested that if bark - removing practices are applied appropriately with minimum depth of 0.2 -0.3 cm from around the cir- cumference of the trees (> 40 cm cbh trunk) in a scattered manner, there will be minimum harmful effect on growth and survival of the trees. This paper describes the indigenous uses of Taxus baccata, impact of bark removal on survival and appropriate strate- gies for conservation/management of this species. TAXUS baccata L., Himalayan yew, locally known as 'Thuner' in various parts of the Western Himalaya, has greater economic and medicinal values than the other gymnosperms in the region. Taxus as an understorey tree is found in temperate forests in the Pacific, north -west of North America, East Asia, North Africa and Europe 1-4 . In

Bark consumption by small rodents in the northern and southern hemispheres

Abstract: The distribution and environmental conditions of bark consumption by small rodents were compiled for the northern and southern hemispheres. Main bark consumption occurred under snow at peak cyclic density and in the dry season of annually fluctuating rodent populations, respectively. The species responsible appeared more folivorous in the north. Among woody species that are damaged, a large number were in both cases exotics. Various defences against bark consumption have evolved, including secondary compounds. However, this defence appears inadequate when indigenous trees are grown under new environmental conditions. It is pointed out that the stem and bark are very sensitive components of perennial trees and bushes and that this potential but usually well protected resource will only be used in crucial situations by various mammals. In view of the many unsuccessful attempts to prevent small rodent damage by bark consumption, costs for rodent damage should be included in any cost–benefit analyses for plantations of exotic species or indigenous species under new conditions. Screening and even selection for resistant varieties may be needed at large scale plantations.

Triterpenes having antibacterial activity

Abstract: Methods of treating a bacterial infection and of killing or inhibiting bacteria are disclosed. The methods use derivatives of triterpenes that are abundant in birch bark and other plants. The triterpenes include betulin, allobetulin, and lupeol.

Volatiles from Potential Hosts of Rhopalicus tutela a Bark Beetle Parasitoid

Abstract: Host location cues for parasitic wasps that attack bark beetle larvae concealed under the bark of spruce trees were analyzed by collecting odor samples from entrance holes into the bark beetle galleries, isolated larvae, and pupal chambers with or without bark beetle larvae. Odor samples were collected by dynamic headspace adsorptions on Porapak Q or static adsorptions by using solid-phase microextraction (SPME) with Carbowax–divinylbenzene as the adsorbing phase. Samples were analyzed by coupled gas chromatographic–electroantennographic detection (GC-EAD) and GC-mass spectrometry (GC-MS). The antennae of Rhopalicus tutela females responded primarily to oxygenated monoterpenes that are typical for damaged host trees. These compounds are attractive to bark beetle parasitoids in long-range host location, suggesting that they are used in both long- and short-range host location. No differences could be detected between samples collected from pupal chambers with or without mature larvae. Larvae outside pupal chambers emitted low quantities of the same compounds present in empty pupal chambers. The data support the hypothesis that volatiles used by host foraging parasitoids arise from the interaction between introduced microorganisms and the bark and/or vascular tissue of the host tree rather than from the bark beetle larvae.

Non-host volatiles disrupt the response of the stenographer bark beetle, Ips sexdentatus (Coleoptera: Scolytidae), to pheromone-baited traps and maritime pine logs.

Abstract: Non-host volatiles (NHV) were tested on antennae of Ips sexdentatus with coupled gas chromatographic-electroantennographic detection (GC-EAD) Significant antennal responses were found to aggregation pheromone components, ipsdienol and amitinol, an attraction inhibitor, verbenone, and non-host bark volatiles extracted from Betula pendula, including trans-conophthorin (tC) and alcohols The tC, a blend of three green leaf alcohols (C6-alcohols), and a blend of two bark alcohols (C8-alcohols) were tested in combination for their ability to disrupt the attraction of the stenographer bark beetle to pheromone-baited traps, unbaited and pheromone-baited maritime pine logs The strongest disruptive effect resulted from the addition of the tC combined with the blends of NHV alcohols at high release rate, achieving an 83% reduction in trap catches, 89% reduction of attacks on unbaited pine logs, and 60% on baited logs It is proposed that the two types of NHV have an additive effect, tC playing a major role in pheromone disruption while the alcohols would interrupt host specific signals The results suggest that I sexdentatus uses both bark and green leaf volatiles from non-host tree species in the host selection process These NHV are promising disruptants, which could be used to prevent stenographer bark beetle attacks on log piles or standing trees in forest A mixture of conifers and broad-leaved species would also disturb olfactory guided host selection supporting the assumption that more diverse forests are less prone to pest insect outbreaks