Beziehungen zwischen dem Ernährungszustand der Fichte (Picea abies Karst.), ihrem Kernfäulebefall und der Pilzhemmwirkung ihres Basts1

Relationships between nutrition and heart rot attack of Norway spruce (Picea abies Karst.) and the fungistatic effect of its inner bark . The fresh inner bark of Norway spruce stems and roots inhibits mycelium growth of Fomes annosus on malt agar. Nearly all fungistatic substances of the inner bark can be extracted with chloroform and acetone. The acetone-soluble fraction, which amounts to 13–27% of bark dry matter, was analysed. Up to now 12 phenolic substances have been identified, 5 of them have proved to inhibit Fomes annosus in vitro. Open-air-experiments showed, that desiccation of the root-zone, manganese deficiency and nitrogen hypertrophy decrease the inhibitory effect of the inner bark as well as its content of fungistatic substances. The degree of heart rot attack in older spruce stands was found to be negatively correlated with the N-, Fe- and Mn-concentrations in needles.     

Penetration and colonization of oak roots by Armillaria mellea in Wisconsin

The level of Armillaria mellea activity on root systems of living and herbicide-killed oâks was assessed. Epiphytic rhizomorphs were almost always present on living and dead oak roots. After an oak was killed or completely defoliated, A. mellea usually penetrated directly through the root-collar bark and spread rapidly in the cambium. Sapwood in the root collar and main lateral roots was colonized within 2 years. The production of thizomorphs from this region was assessed on trees that had been killed by herbicide sprays 2 to 14 years before sampling.     

黄皮树种源苗木性状遗传参数及其相关选择效率研究

对湖南省黄皮树１１个种源１年生苗木４个性状组２０个性状的遗传参数及其相关选择效率作了测定和分析。其结果表明：（１）４个性状组中,１７个性状在种源间存在显著差异,其中,生产力性状组的性状表型及遗传变异系数较大,而幼苗、复叶和地上生长性状组的表型及遗传变异较小;（２）地上生长性状间、生产力性状间及其相互间具有显著的表型相关和遗传相关,这为黄皮树地上与地下、生长与生产力性状间的相关选择提供了理论依据;（     

In vitro screening of angiotensin I-converting enzyme inhibitors from Japanese cedar (Cryptomeria japonica)

Screening and isolation of angiotensin I-converting enzyme (ACE) inhibitors from Japanese cedar (Cryptomeria japonica) based on the in vitro ACE inhibitory assay were attempted. The ethanol extract from outer bark showed the highest inhibitory activity (IC₅₀ is 16g/ml) among 24 extracts prepared from roots, leaves, heartwood, sapwood, inner bark, and outer bark by successive extraction with four solvents. The fractionation of the outer bark ethanol extract followed by the bioassay resulted in the isolation of two strong ACE inhibitors, catechin and dimeric procyanidin B3. The bioassay of three flavan-3-ols including (+)-catechin and six flavones revealed that most of these compounds have high ACE inhibitory activity. The results suggest that the phenolic hydroxyl group at the C7 position and heterocyclic oxygen atom of these compounds are important for expressing the inhibitory activity.     

Effect of flooding of soil on growth,stem anatomy,and ethylene production of cryptomeria japonica seedlings

Flooding of soil for 55 days altered the rate of growth and stem anatomy of 9‐month‐old Cryptomeria japonica seedlings. Although flooding did not affect height growth it reduced the rate of dry weight increment of seedlings while increasing stem diameter. The reduction in dry weight increment of seedlings resulted largely from decay of roots and, to a lesser extent, from inhibition of growth of roots and needles. The increased diameter growth of flooded seedlings resulted largely from an increase in bark thickness associated with increased phloem production and greater amount of intercellular space. Flooding reduced xylem increment in submerged stems but increased it above the water level because of larger tracheids rather than more tracheids per radial file. Flooding also increased lumen diameters of tracheids, decreased tracheid wall thickness (as a proportion of tracheid diameter), and stimulated formation of axial parenchyma cells in the xylem. Cryptomeria japonica seedlings adapted to flooding by forming adventitious roots, primarily on the original root system and submerged portion of the stem. Such new roots originated in the xylem ray parenchyma. Flooding stimulated ACC synthesis in roots and ethylene production in stems. The role of ethylene in alteration of stem anatomy is discussed.     

Bark phenolics of American beech (Fagus grandifolia) in relation to the beech bark disease1

The amount of total extractable phenols was determined for bark sections obtained from behind cankers naturally induced by Nectria coccinea var. faginata and from behind mechanically inflicted wounds on stems of American beech. Healthy bark from susceptible trees was found to contain a similar level of phenolics as bark from trees determined to be resistant to the beech bark disease. Six months after wounding, wound-altered bark from susceptible trees was found to be lower in phenols than woundaltered bark from resistant trees. Inoculation of wounds with N. coccinea var. faginata resulted in decreased phenolic levels in bark sections nearest the wound surface, and increased phenolic levels in sections nearest the vascular cambium, several mm distant. Phenolic levels in injured or infected bark appear to follow similar patterns as those resulting from injury or infection of xylem tissues.     

Pinus taeda L. response to differential inoculum density of Leptographium terebrantis colonized toothpicks

Bark beetle‐vectored ophiostomatoid fungi, Leptographium terebrantis, is inoculated on the roots and lower stems of stressed Pinus species during the feeding activity of bark beetle. To determine the exact host response following inoculation, it is critical to challenge the host with a realistic amount of fungal inoculum. Thus, we designed a series of stepwise experiments using L. terebrantis colonized toothpicks which focused on the inoculum transfer from the toothpicks to excised Pinus taeda stem segments and living saplings, respectively, at different inoculum densities. The toothpicks served as a substrate for fungal growth and sporulation and the inoculation showed their utility in eliciting host's response to the pathogen. The inoculated fungus caused blue‐stain and sapwood occlusions in P. taeda stems and saplings, respectively. The volume of occluded, visually damaged sapwood increased by 1.96 cm³ per radial inoculation point on average. Fungal colonized toothpicks can be used as a suitable alternative to agar discs for studying bark beetles vectored fungi and their host interactions.     

Lesion formation and host response to infection by Armillaria ostoyae in the roots of western larch and Douglas‐fir

The process of lesion formation and host response to natural infection by Armillaria ostoyae were studied in the roots of western larch (Larix occidentalis) and Douglas‐fir (Pseudotsuga menziesii ssp. glauca) trees in the three age classes, 6–8, 18–19 and 85–95 years. The characteristics of lesions on infected roots were recorded and bark samples were dissected from infection points and lesion margins in the field and stored in liquid nitrogen for macroscopic study in the laboratory. Infection in the roots of 6‐ to 8‐year‐old trees advanced freely, overcoming any host resistance, quickly girdling the root collar and killing the trees. In 18‐ and 19‐year‐old trees, however, 43% of infections on western larch and 27% of the infections on Douglas‐fir roots were confined to lesions bounded by necrophylactic periderms with multiple bands of phellem. Host response was similar in 85‐ to 95‐year‐old trees, but the percentage of confined lesions was higher than in younger trees. The results suggest that larch shows resistance to A. ostoyae at a younger age and with greater frequency than Douglas‐fir.     

Pathogenicity and virulence of Armillaria sinapina and host response to infection in Douglas‐fir,western hemlock and western redcedar in the southern Interior of British Columbia

The frequency of infection, lesion characteristics and anatomical changes in phloem and cambial tissues caused by Armillaria sinapina were studied on inoculated trees of Douglas‐fir, western hemlock and western redcedar and compared with results of A. ostoyae inoculations previously reported on the same host species. Similar percentages of inoculations resulting in infection of roots on the three hosts indicate that A. sinapina and A. ostoyae are equally pathogenic. Armillaria ostoyae was more virulent than A. sinapina as demonstrated by fungal exudates from A. ostoyae inoculum blocks, which appeared to cause lesions on roots; the higher frequency at which lignified impervious tissue (IT) and necrophylactic periderm (NP) developed in bark and following cambial invasion, compartmentalization; the large proportion of roots that showed no visible host response; the large zones of IT formed under continuous stimulation by A. ostoyae advancing in inner bark; and the high frequency of breaching of NP barriers. Spread of A. sinapina mycelium in host species appeared slower than that of A. ostoyae, particularly in Douglas‐fir and western hemlock. In western redcedar, A. ostoyae induced stronger host responses than those following invasion by A. sinapina, which included further expansion of the induced rhytidome response, traumatic phloem resin duct formation and higher numbers of polyphenolic parenchyma comprising its barrier zone. Where damage by A. sinapina ensued, it was always associated with high inoculum potential. The ecology of virulent and less virulent species of Armillaria in natural forests is discussed.     

Response of balsam fir and hemlock roots to injuries

Drill wounds in balsam fir and hemlock roots activated the nonspecific resistance mechanisms of compartmentalization in wood and necrophylactic periderm in bark. Tangential bands of resin ducts localized around the wounds constituted the barrier zones in the secondary xylem of conifer roots. Barrier zones were more extensive in roots which showed symptoms characteristic of invasion by fungi and bacteria after wounding. This observation supports an expanded definition of barrier zones; barrier zones may form not only in response to mechanical wounds but also in response to xylem injury caused by pathogens. Multiple bands of resin ducts were common in young xylem when bark lesions developed around wounds. Necrophylactic periderms isolared dead bark from living bark. Development of phellem cells with dark contents and thick suberized walls, typical of exophylactic periderm, followed initiation of necrophylactic periderm. The wound responses were similar in both balsam fir and hemlock.     

Torque required to twist and cut loose Scots pine stumps

Abstract

Stump wood is a possible source of renewable energy, but before its potential as a fuel can be utilised to a high degree, new harvesting techniques should be developed to reduce the environmental impact (notably ground disturbance) of harvesting stumps. The forces required to lift and drag stumps out of the soil are known. In this study, two unknown and important parameters were addressed: the torque required to uproot stumps by twisting them and the torque required to cut lateral roots around stumps. A new, improved stump-twisting rig was designed and used in trials with 28 Scots pine (Pinus sylvestris) trees (breast-height diameter over bark, 153–427 mm). The measured torque requirements ranged from 10 to 50 kNm. Twisting stumps required more torque than cutting lateral roots around stumps and the required torque increased with increases in stump size. The results indicate that a wrist on a big feller-buncher, but not a conventional rotator used on forest machines, should be able to generate sufficient torque to cut the roots around stumps such as those used in this study.     

Root‐colonizing ophiostomatoid fungi associated with dying and dead young Scots pine in Poland

Ophiostomatoid fungi are carried by various bark beetles. However, very little is known about the role of these fungi in conifer roots. We studied ophiostomatoid fungi in roots of dying and dead Pinus sylvestris trees and tested the potential phytotoxicity of some isolates using a sensitive bioassay with Lepidium sativum in Poland. Fungi were identified based on their morphology and DNA sequencing. Three ophiostomatoid fungi, Leptographium procerum, Sporothrix inflata and Ophiostoma pallidulum, were isolated from the roots. The most abundant soil‐borne fungus, S. inflata, and relatively rare O. pallidulum were isolated for the first time from roots of dying and dead pine trees. The frequency of S. inflata and O. pallidulum correlated with tree decline. The fungi were isolated more frequently from roots of dead than dying trees. Sporothrix inflata and O. pallidulum slightly reduced the stem and root growth of L. sativum. Leptographium procerum reduced more significantly root than stem growth. This species reduced root elongation 32–54% after 10–17 days of incubation.     

Nitrogen absorption,translocation and distribution from urea applied in autumn to leaves of young potted apple (Malus domestica) trees

We studied the absorption, assimilation, translocation and distribution of nitrogen (N) from urea applied in autumn to leaves of 1-year-old potted Fuji/M26 apple (Malus domestica Borkh) trees. In early October, all leaves of each tree were painted with either 3% urea (enriched to 10 atom % with 15N) or water (control trees). Four trees were harvested before the treatment and N and amino acid contents were determined. Four trees from each treatment were harvested at 2, 4, 7, 10, 15 and 20 days after urea or water application. Total N, amino acids and 15N in leaves, bark, xylem, shank and roots were analyzed to determine uptake and mobilization of N from urea. Most uptake of 15N by leaves occurred during the first 2 days following application of urea. The mean rate of absorption during these 2 days was 0.29 g m-2 day-1. Amino acids in leaves, bark and roots increased significantly after urea application compared with control values. The highest concentrations of amino acids in leaves and bark occurred 4 days after application, whereas the highest concentrations of amino acids in roots occurred 10 days after application. Total 15N content in leaves peaked 2 days after urea application and then decreased, whereas 15N content in roots and bark increased throughout the experiment. Total 15N content in xylem and shank was low. Leaves absorbed 35% of the 15N applied as urea, and 63.6% of absorbed 15N was translocated out of leaves within 20 days after urea application. We conclude that N from urea was converted to amino acids in leaves after foliar application in autumn, and roots and bark were the main sinks of N from urea applied to leaves.     

Phytophthora root and collar rot of mature Fraxinus excelsior in forest stands in Poland and Denmark

In recent years, Common ash (Fraxinus excelsior) throughout Europe has been severely impacted by a leaf and twig dieback caused by the hyphomycete Chalara fraxinea. The reasons for its current devastating outbreak, however, still remain unclear. Here, we report the presence of four Phytophthora taxa in declining ash stands in Poland and Denmark. Phytophthora cactorum, Phytophthora plurivora, Phytophthora taxon salixsoil and Phytophthora gonapodyides were isolated from rhizosphere soil samples and necrotic bark lesions on stems and roots of mature declining ash trees in four stands. The first three species proved to be aggressive to abscised roots, twigs and leaves of F. excelsior in inoculation experiments. Soil infestation tests also confirmed their pathogenicity towards fine and feeder roots of ash seedlings. Our results provide first evidence for an involvement of Phytophthora species as a contributing factor in current decline phenomena of F. excelsior across Europe. Specifically, they may act as a predisposing factor for trees subsequently infected by C. fraxinea. Phytophthora species from ash stands also proved to be aggressive towards a wide range of tree and shrub species commonly associated with F. excelsior in mixed stands. Although damage varied considerably depending on the Phytophthora species/isolate–host plant combination, these results show that many woody species may be a potential source for survival and inoculum build‐up of soilborne Phytophthora spp. in ash stands and forest ecosystems in general.     

Strategies of attack and defence in woody plant–Phytophthora interactions

This review comprises both well‐known and recently described Phytophthora species and concentrates on Phytophthora–woody plant interactions. First, comprehensive data on infection strategies are presented which were the basis for three models that explain invasion and spread of Phytophthora pathogens in different woody host plants. The first model describes infection of roots, the second concentrates on invasion of the trunk, and the last one summarizes infection and invasion of host plants via leaves. On the basis of morphological, physiological, biochemical and molecular data, scenarios are suggested which explain the sequences of reactions that occur in susceptible and tolerant plants following infections of roots or of stem bark. Particular emphasis is paid to the significance of Phytophthora elicitins for such host–pathogen interactions. The overall goal is to shed light on the sequences of pathogenesis to better understand how Phytophthora pathogens harm their host plants.     

Leishmanicidal evaluation of extracts from native plants of the Yucatan peninsula

Methanol extracts were prepared from different parts of 18 plants collected in the Yucatan peninsula and evaluated in an in vitro bioassay for leishmanicidal activity against Leishmania mexicana promastigotes. The ten most potent plant extracts (IC(50)<50 microg/ml) were Aphelandra scabra leaves, Byrsonima bucidaefolia bark, Byrsonima crassifolia bark, Clusia flava leaves, Cupania dentata bark, Diphysa carthagenensis leaves, Dorstenia contrajerva whole plant, Milleria quinqueflora roots, Tridax procumbens whole plant, and Vitex gaumeri bark.     

Phytophthora cambivora in Oregon and its pathogenicity to Chrysolepis chrysophylla

A new canker disease causing mortality of golden chinquapin trees [Chrysolepis chrysophylla (Dougl.) Hjelmqvist], in Oregon was recently observed. Most of the symptomatic or dead trees were located near roads. The cankers on the lower boles of trees are similar to those caused by species of Phytophthora on other trees in western North America. The cankers in the inner bark were reddish‐orange in colour and extended upward from necrotic roots. Phytophthora cambivora (Petri) Buisman was isolated from the cankers; identity was confirmed by morphological comparison with known isolates and internal transcribed spacer sequence analysis. Pathogenicity was confirmed by inoculation of chinquapin seedlings and mature trees. Seven of nine isolates from chinquapin were A2 mating type; 27 of 28 isolates from other hosts in Oregon and Washington were A1 mating type.     

Response of Ocotea bullata,Curtisia dentata and Rapanea melanophloeos to medicinal bark stripping in the southern Cape,South Africa: implications for sustainable use

Tree bark is commonly used for traditional medicine in southern Africa and further afield. Increasing demand and commercialisation have resulted in the overexploitation of many species, posing a major challenge to forest managers to develop mechanisms for sustainable resource use. An experimental bark harvesting research project was initiated in the southern Cape, South Africa, to inform best practices for bark harvesting based on tree response to bark stripping. The species selected for the study, Ocotea bullata, Curtisia dentata and Rapanea melanophloeos, are much sought after and well represented in southern Cape forests. The treatment entailed removing vertical strips of bark, 1 m in length and of different strip widths, covering the full range of tree size classes ≥10 cm DBH. The treatments were applied during two seasons, winter and summer. Evaluations were done every six months to assess tree response to bark stripping in terms of bark regrowth through phellogen edge and sheet development, and susceptibility to insect and fungal damage. The results show a differential response of tree species in terms of phellogen edge and sheet growth, as well as susceptibility to fungal and insect attack. Rapanea melanophloeos was the most vulnerable to fungal and insect damage and displayed little bark regrowth following wounding. Curtisia dentata showed best bark regrowth through sheet development. Only O. bullata, though, showed adequate bark regrowth (through edge development) to allow for sustainable strip harvesting. Bark regrowth is influenced by season of stripping, although this is difficult to define considering the wide range of environmental and other factors affecting tree response to bark removal. Smaller trees are more vulnerable to bark stripping, especially with a wide strip, with poorer bark regrowth than bigger trees.     

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Abstract

The volume of bark is a function of bark thickness and tree diameter, thus bark and tree volume calculations depend on accurate determination of bark thickness. Bark thickness is affected by a number of inherent and external factors. The purpose of this study was to examine the factors affecting bark thickness and to derive models predicting bark thickness for Picea orientalis (L.) Link. This study indicated that bark thickness at breast height was strongly correlated with geographical aspect, tree age and diameter classes, and bark thickness increased as tree age or diameter class increased in sunny or shady aspect. Diameter over bark at breast height explained 50% of the variations in double bark thickness at breast height on shady aspects and 68% of the variations in double bark thickness of P. orientalis at breast height on sunny aspects. By adding tree age to the functions, the coefficient of determination increased by 1–2%. Thus, not only tree ages and diameters, but also the aspect in which trees grow should be taken into account to calculate the amounts of wood and bark in P. orientalis.     

Estimating bark volumes for 16 native tree species on the Sierra Madre Occidental,Mexico

Abstract

The Sierra Madre Occidental ecoregion accommodates some of the richest biodiversity anywhere in North America and contains about two-thirds of the standing timber biomass in Mexico. Worldwide forest trees provide an industrial output of about 363 million cubic meters, with the volume of bark accounting for an estimated 10% of total tree volume, so that bark is a very important nonwoody product. In this study, the proportion of bark volume (PBV) and its correlation with selected tree characteristics as well as the relationship between total tree volume and wood volume (WV) and total volume and bark volume (BV) were calculated for the first time for the 16 common and commercially most important tree species in the temperate pine-oak forest region of El Salto (Durango) on the Sierra Madre Occidental, Mexico. Measurements were made on 2,027 felled trees. The PBV in the species investigated ranges from 0.129 to 0.260 depending on the species and genus, with a mean value of 0.175. BV and WV can be accurately estimated. The approach used in this study is simple and effective, and very user-friendly. The method is recommended for researchers wishing to develop bark models for other tree species.