Fomannoxin production by different spruce isolates of Fomes annosus

In vitro production by five isolates of Fomes annosus obtained from diseased spruce trees in Irish Forestry plantations is compared. Identification of these isolates as five distinct strains is based on quantitative differences in fomannoxin production, differences in linear growth rate and mycelial interaction between isolates in paired culture.     

Allelopathic effects of invasive Eucalyptus camaldulensis on germination and early growth of four native species in the Western Cape,South Africa

Eucalyptus camaldulensis Dehnh. (red river gum; Myrtaceae) is an invasive tree in riparian habitats of the Western Cape, South Africa, where it replaces indigenous vegetation and affects ecosystem functioning. These invasions lead to changes in river geomorphology and reduction in stream flow. The mechanisms that drive these effects are poorly understood. The potential for allelopathic effects of aqueous extracts of E. camaldulensis tissues and of soil and litter collected beneath E. camaldulensis trees on the germination and seedling growth of four selected native plant species was investigated in a greenhouse experiment. Soils collected beneath E. camaldulensis trees were used in three treatments: untreated soils, sterilised soils and sterilised soils overlaid with a eucalypt litter layer. In addition, soils collected from underneath native species were used in two treatments: untreated soils and soils overlaid with a eucalypt litter layer. All soil treatments were watered with three E. camaldulensis leaf, bark and root aqueous treatments. Compounds present in the aqueous extracts and fresh samples were identified using gas chromatography. Soil and aqueous treatments showed varying effects on germination and seedling growth of the four native species. Germination and seedling growth of Olea europaea subsp. africana and Dimorphotheca pluvialis were significantly reduced by E. camaldulensis root and bark aqueous extracts as well as by the soils treatments. The addition of eucalypt litter to native and sterilised soils reduced shoot and root growth of all four native species. Compounds such as -phellandrene, eucalyptol, p-menth-1-en-8-ol and -pinene, which have the potential to inhibit germination and plant growth, were identified in E. camaldulensis aqueous extracts and fresh samples. Although the methods applied in this study had limitations (e.g. lack of control treatment to litter addition), the results provide an additional motivation to prioritise removal of invasive E. camaldulensis stands from riparian ecosystems. Restoration initiatives should target native species that are not negatively affected by allelopathy.     

植物抽提物对苹果炭疽病菌分生孢子的抑制作用

森林生态网络体系“点”建设需要为城市森林郊区生态经济型林果模式构建寻求具有植物抑菌素的绿化树种及植物。选用十大功劳(Mabonia bealil)、龙柏(Sabina chinensis Kaizuca)、鹅绒藤(Cynanchum chinense R．Br)、银杏(Ginkgo biloba Linn．)、苍耳(Xanthium sibircum)等5种植物叶片样品的丙酮提取液研究其对苹果炭疽病菌(Glomerella cingulata)分生孢子萌发的抑制作用。结果表明,十大功劳、苍耳植物抽提物抑制苹果炭疽病菌分生孢子萌发的抑制率大于75％;鹅绒藤的抑制率在58．9％;银杏、龙柏的抑制率分别为3．9和17．9％。十大功劳和苍耳2种植物对苹果炭疽病菌分生孢子萌发的抑制作用强。     

Inhibition of forage seed germination by leaf litter extracts of overstory hardwoods used in silvopastoral systems

Silvopastoral management strategies seek to expand spatial and temporal boundaries of forage production and promote ecosystem integrity through a combination of tree thinning and understory pastures. We determined the effects of water extracts of leaf litter from three species of overstory hardwood trees, yellow poplar, red maple, and white oak, on germination of common forage species: alfalfa, red and white clover, crabgrass, orchardgrass, and tall fescue without and with endophytes to increase understanding about potential interactions between silvopastures and overstory deciduous trees. Litter extracts reduced germination in red and white clover in a concentration dependent manner with greatest effects observed for poplar > maple > oak extracts. These reductions were linearly related to increasing osmolality and electrical conductivity of the leaf extracts. Modified Gompertz growth curve models, fit to data, further indicated treatment with litter extracts, especially poplar, delayed and slowed germination. Similarly, cumulative germination of a variety of grasses was inhibited by filtered 6 % (w/v) litter extracts with the effects of poplar > maple > oak. However, germination of all forages resumed after rinsing extract-treated seeds with water indicating inhibition could be due, in part, to osmotic effects of extracts or water-soluble allelopathic compounds. Final germination varied with forage species and extract type, but in most instances, did not reach the level of the control further suggesting specific ion toxicities as well. Management practices that account for the interactions between trees and forages are needed to ensure successful establishment and persistence of mixed species swards in silvopastoral systems.     

Fomannoxin,a phytotoxic metabolite of Fomes annosus: in vitro production,host toxicity and isolation from naturally infected Sitka spruce heartwood

The effect of different culture conditions on growth and production of fomannoxin and the sesquiterpene phytotoxin fomannosin by a single isolate of Fomes annosus was studied. Whereas fomannoxin was produced by actively growing hyphae, fomannosin production was associated with the declinning growth phase of the fungus. The presence of fomannoxin in chloroform extracts from the stained stein heartwood zone of Fomes annosus diseased Sitka spruce trees was established. Fomannosin however was not detected. Toxicity of fomannoxin to germinating seeds and young seedlings of Sitka spruce was demonstrated.     

Allelopathic effects of <Emphasis Type="Italic">Pinus halepensis</Emphasis> and <Emphasis Type="Italic">Quercus coccifera</Emphasis> on the germination of Mediterranean crop seeds

Agroforestry is a leading alternative for food security and forest conservation. A full understanding of positive and negative, i.e. allelopathic, interactions between crops and forest trees is necessary for producing crops and conserving forests especially within the threatened Mediterranean forest ecosystems. The present study explored the allelopathic effects of green and senescent leaf and soil extracts of two agroforestry trees—Pinus halepensis and Quercus coccifera—on the germination of wheat, barley, lentil, chickpea, and fababean as the major grain crops of Jordan. Results revealed that allelopathic effects reduced seed germination of these crops. Germination reduction reached a maximum of 75% in fababean treated with green extracts of Q. coccifera and differed among crops and extract sources, but not between tree species. Comparing between green and senescent leaf and soil extract, regarding their effect on germination percentage, it was noticed that these effects were similar in some crops and were different in others. Germination responses were generally different between cereals and legumes where cereals tend to be less affected by allelopathic influences than legumes, especially fababean. We suggest using cereals such as wheat and barley in agroforestry practices in the Mediterranean region of Jordan.     

Die Wirkung von Monoterpenen auf das Mycelwachstum von Fomes annosus (Fr.) Cooke

The effect of monoterpenes on the mycelial growth of Fomes annosus (Fr.) Cke. Four monoterpenes, singly and in mixture, were tested for their effect on the mycelial growth of Fomes annosus. Inhibition was caused by all the substances, the severity depending on material and concentration. The inhibition was not maintained over the entire study period.     

Zum Vorkommen von Fomes annosus (Fr.) Karst. im Boden von Fichtenbeständen (Picea abies Karst.)1

Occurrence of Fomes annosus in the soil of spruce stands (Picea abies Karst) . In stands of spruce Fomes annosus was found to occur in a viable state in the litter and soil to a depth of 25 cm. Successful isolations were obtained from 153 samples out of a total of 216. In ca. 40% of the 153 samples Fomes annosus could be isolated from 9 mg of soil; in the remaining samples it was found either in 90 mg, 230 mg or in 900 mg. The results raise the possibility of direct infection of the roots of spruce by Fomes annosus from the soil.     

Fomes annosus (Fr.) Cke. und andere Stammfäulepilze in einem Douglasienbestand,Pseudotsuga menziesii (Mirb.) Franco1

Fomes annosus (Fr.) Cke. and other decay fungi in a Douglas fir stand, Pseudotsuga menziesii (Mirb.) Franco. 40% of the trees in a 40 years old Pseudotsuga menziesii stand showed butt rot. 85 trees were analysed for decay fungi. Fomes annosus, the most frequent fungus, also invaded the sap wood. Factors of the soil favourable to the rot and the possibility of transmission of the most frequent decay fungus, Fomes annosus, from (a) neighbouring spruce stands, (b) from the roots of Scots pine from the previous crop arc discussed. Caniophora puteana was isolated from about 10% of the butt rots. The importance of Calocera viscosa which grew out of the central decay of twelve trees as a decay fungus is still under investigation.     

Influence of acidity on the growth of Trichoderma viride Pers. ex Fr. and on the inhibitory effect of its filtrates against Fomes annosus (Fr.) Cke. in artificial cultures

This work reports results of observations on mycelial dry weight yield, pH changes and the inhibitory effect of filtrates of Trichoderma viride on linear growth of the mycelium of Fomes annosus. The maximum mycelial yield of T. viride, derived from spores was obtained within the pH range 2,5–3,1. The greatest inhibitory effect of filtrates on the mycelial growth of F. annosus occurred at an initial pH of the Trichoderma cultures from 2,0-3,5. At other pH-values, no inhibition was found.     

Wundfäule in Fichtenwaldungen mit alten Schälschäden

Wound decays in spruce stands following bark stripping . 2083 trees in 91 sample plots on four trial areas (24 ha) were examined for bark stripping and decay. Only 25% of trees showed no injury. Of the injured trees, 73% showed some degree of decay, 10% discoloration. and 17% neither decay nor discoloration. Of the wood destroying fungi isolated Fomes annosus was dominant and appeared to be the most important and widespread of the wound inhabiting fungi in the test area. Besides the Basidiomycetes a considerable number of other fungi was isolated. The most frequent was Cylindrocarpon cylindroides var. tenue.     

Study on biological characteristics ofHendersornia acicola

The morphological and cultural characteristics ofHendersonia acicola Munch & Tub., isolated from the needles ofPinus sylvestris var.mongolica Litvin, were described. The fungi was cultured on three kinds of media and the speed of mycelial growth and the required time to produce conidia were different. On the medium of needle decoction agar, the fungi grew fast and produced conidia after 5 days culturing. On PDA came second and it needed 7 days to produce conidia. On the medium of maize flour agar, it grew slowly and produces conidia after 27 days incubating. The fungi cannot produce conidia under darkness on all three kinds of media. The conidia can germinate at 8°C–28°C. The optimum conditions for conidia to germinate are 25°C, RH 100% and pH 4 and under these conditions it only takes four hours for conidia to germinate. The conidia germination is not affected by light     

Litter of an alien tree, <Emphasis Type="Italic">Casuarina equisetifolia</Emphasis>, inhibits seed germination and initial growth of a native tree on the Ogasawara Islands (subtropical oceanic islands)

We investigated the effects of the accumulation of litter of an alien tree, Casuarina equisetifolia, on the initial establishment of Schima mertensiana, a tree native to the Ogasawara (Bonin) Islands, in the northwestern Pacific Ocean, in field and greenhouse experiments. The field experiment compared emergence of seedlings in forests dominated by C. equisetifolia with those in native forests, with and without litter removal. The greenhouse experiment compared seedling germination and biomass among 12 treatments that included two soil types (collected from the C. equisetifolia and native forests), two litter types (C. equisetifolia and native litter), and three amounts of litter (5, 15, or 45 g/pot). Significantly fewer S. mertensiana seedlings emerged at sites dominated by C. equisetifolia than at sites of native species in the field experiment. Litter removal tended to increase seedling emergence. Fewer and smaller S. mertensiana seedlings germinated with greater litter cover regardless of soil type or litter type in the greenhouse experiment. Our results demonstrate that C. equisetifolia litter suppresses germination and initial growth of S. mertensiana, and that the main cause of the suppression is the greater amount of litter accumulated under C. equisetifolia forest floor rather than factors such as the nature of the soil or litter between native and alien species.     

Biotic interactions in a Mediterranean oak forest: role of allelopathy along phenological development of woody species

Plant–plant chemical interactions in forests can have a strong impact on the biodiversity and dynamics of these ecosystems, particularly in Mediterranean forests where plants exhibit a high secondary metabolite diversity. Allelopathic interactions in Mediterranean ecosystems have been mostly studied in the first stages of ecosystem dynamics, shrublands and pine forests, but little is known about these interactions in mature oak forests. In this study, the allelopathic effect of three main woody species of downy oak forests (Quercus pubescens, Acer monspessulanum and Cotinus coggygria) on germination and growth of two herbaceous species (Festuca ovina and Linum perenne) was tested through aqueous extracts obtained from different leaf phenological stages (green, senescent and litter). The germination velocity of the two target species was inhibited by the aqueous extracts of senescent leaves from all the woody species. The growth of F. ovina seedlings was affected by aqueous extracts of green leaves of all the woody species, while the growth of L. perenne was only affected by aqueous extracts of green leaves of A. monspessulanum. This shows that (i) allelochemicals released by leaf leachates of the dominant woody species could control the dynamic of the herbaceous species, and then their potential competition with trees and (ii) allelopathic effects of woody species are related to their phenological stage and seem consistent with the development stage of target species.

     

Seed bank and regeneration dynamics of <Emphasis Type="Italic">Emmenopterys henryi</Emphasis> population on the western side of Wuyi Mountain,South China

Emmenopterys henryi Oliv. (Rubiaceae) is an endangered tree species that is native to China. The wild populations of E. henryi have declined rapidly because of its poor natural regeneration, but the actual regeneration processes are not yet understood. In field tracking surveys and experiments in the Wuyishan Nature Reserve in Southeast China to determine the most important stage that affects the regeneration process, seed bank characteristics, seed germination, and seedling growth dynamics were studied in the typical habitats of E. henryi, Phyllostachys pubescens and broad-leaved forests. Results showed that in both P. pubescens and broad-leaved forests, more than 70% of the E. henryi seeds were distributed in moss and litter layers, and few were found in the soil beneath them. However, seed germination in the soil layer was significantly higher than in the moss and litter layers. Seed density, overall seed quality, and germination rate in the broad-leaved forest were significantly higher than in P. pubescens forest. Seed germination was highest in the microsites around the edge of the crown projection area of E. henryi mother trees. The order of survival rate of the seedlings on different ground surfaces was soil > moss > litter. In both habitats, the average seed density was 24.9 seeds m^?2, and the total germination rate was less than 3.5‰. However, seedlings developed from only 1% of the germinated seeds, indicating that the seed germination is the most important stage in the natural regeneration of E. henryi.     

Cultural characteristics and pathogenicity of Melanconium juglandinum

Cultural characteristics and pathogenicity of Melanconium juglandinum, the agent of the black pustular dieback of Juglans spp. in Europe were investigated. Melanconium juglandinum was consistently isolated from diseased twigs and branches of Persian (English) walnut trees (Juglans regia) in Central Italian Apennine valleys. In growth and conidia germination tests, the fungus was shown to be active within a broad range of temperatures (5–30°C), with the optimum being between 20 and 30°C. Monthly artificial inoculations performed over a period of 2 years with mycelial plugs on 2-year-old seedlings of Persian (English) walnut developed symptoms within 15 days with maximum canker length occurring when inoculation was carried out between June and August. Koch's postulates were fulfilled and M. juglandinum was proved to be a virulent pathogen.     

Das Keimverhalten der Konidiosporen von Fomes annosus (Fr.) Cke. bei Einwirkung verschiedener Standortfaktoren

The Influence of site factors on the Germination of Fomes annosus conidiospores . Cultures grown up on a source with an easily utilisable C-source produce conidia with a lower germination rate. An easily utilisable C-source in the medium promotes germination. Different strains vary individually in their germination behaviour in respect to temperature. Short-time-strains have an optimum between 12–28°C, longtime-strains have a peak at about 24°C. Some strains tend to suddenly alter their germination rate at a lower or higher temperature, thus increasing the plasticity of the fungus. Germination behaviour with regard to pH is strainspecific. The optima lie between pH 4,0–6,5. The pH influences the germination rate more than the nutrients status of the soil. The standard deviations in germination behaviour for some soils are large. Between the various origins of strains there are no significant differences.     

The effects of microhabitat,plant litter,and seed burial on the regeneration of Quercus wutaishanica and Pinus tabulaeformis

The effects of microhabitat (shrubs and herbs), plant litter, and seed burial on the regeneration of Liaodong oak (Quercus wutaishanica Mayr) and Chinese pine (Pinus tabulaeformis Carr.) were studied in three typical stands (Liaodong oak forest, Chinese pine plantation, and grassland) in the Loess Plateau, China. We monitored the establishment and growth of seedlings of these two woody species in sown experimental plots, in which shrubs and herbs, plant litter, and seed burial were manipulated. In the grassland, shrubs and herbs facilitated Liaodong oak establishment, with no effect on the establishment of Chinese pine. In the two forest stands, shrubs and herbs primarily had an inhibition effect on the establishment of these trees. The effects of plant litter were facilitation or inhibition, depending on the target species and the habitat. Seed burial had a positive effect on seedling establishment. In all three habitats, shrubs and herbs had inhibition effects on seedling growth of both tree species. Plant litter and seed burial did not influence seedling growth in either species. Liaodong oak and Chinese pine use different regeneration strategies during early stages of succession and similar strategies during late stages of succession.     

Tree-to tree variation on Picea abies in growth inhibition against Fomes annosus

The spread of Fomes annosus was measured on a set of 20 mature trees which were artificial inoculated. These observations were compared with growth observations and laccase activity of F. annosus grown on wood dust from the same 20 trees. Although variation between Fomes strains as well as between trees was recorded, correspondance between field and laboratory observations was absent in the present material.     

Genetic variation in Picea abies (L.) Karst. and Fomes annosus (Fr.) Cke. shown by growth of the fungus on wood dust

Growth of Fomes annosus is studied by a test based on growth of previously starved hyphae on sawdust of heartwood of Picea abies as the only nutrition. Our observations show that the method can be used to distinguish beween different spruce individuals or clones, between different Fomes annosus strains and between different growing sites of the trees.