Characterization of Pyrofomes demidoffii from Ethiopian Afromontane forests

Pyrofomes demidoffii is a basidiomycetous fungus that causes a white heart rot in living junipers (Juniperus spp.). Morphological characters and genetic variation in species of Pyrofomes were investigated for specimens from Ethiopia, Tanzania, Macedonia, USA and Costa Rica. In addition, the behaviour of isolates from Ethiopia was studied in vitro. The Ethiopian specimens had relatively larger basidiospores than collections from other countries and showed a high sequence similarity in the ITS region of rDNA sequences with most of strains evaluated in this study (95–100%), but only 89–92% with P. demidoffii from the USA. Phylogenetic analysis of ITS‐5.8S rDNA sequences resulted in two well‐supported (99–100% bootstrap value), separate clades of P. demidoffii. Deeper branches were less well supported (bootstrap < 90%), but the two geographically and phylogenetically separated clades within P. demidoffii may still represent sister groups. For Ethiopian strains, the temperature optimum was between 20 and 25 °C and the pH optimum was around 5.0. A phylogenetic study with additional genetic markers and with a more representative collection of samples is needed.     

Pathogenicity of seed‐associated fungi to Podocarpus falcatus in vitro

Twenty‐nine fungi that were isolated from seeds and female cones of Podocarpus falcatus from natural forests in Ethiopia, were assessed for their impact on seeds and seedlings of the same host. Based on the results from in vitro seed inoculation tests, we could group the fungi into five categories as: (i) isolates that were pathogenic only to seeds and had no obvious impacts on the germlings; (ii) isolates that were pathogenic only to the germlings; (iii) isolates that were pathogenic both to seeds and the emerging germlings; (iv) isolates that were more or less harmless; and (v) isolates that were germination promoters. Inoculation tests were also performed on 4–7‐day‐old aseptically grown seedlings. Fusarium oxysporum and Polyporus sp., were strongly pathogenic to both seeds and seedlings, while Nectria gliocladioides, Peniophora cinerea and Pestalotiopsis neglecta also demonstrated pathogenicity but to a lesser extent. Other isolates, e.g. Diaporthe spp. resulted in increased germination of P. falcatus seeds and no pathogenicity to seedlings. However, further investigations are required in order to find out how these fungi behave under nursery or field conditions.     

Growth and ecophysiology of seedlings of Podocarpus falcatus in plantations of exotic species and in a natural montane forest in Ethiopia

The potential role of exotic tree plantations in facilitating successional processes on degraded areas was evaluated in southern Ethiopia by comparing seedling characteristics, transpiration and photo-synthetic performance of Podocarpus falcatus seedlings in Eucalyptus plantation, Pinus plantation, adjacent natural forest and clear-felled plantation site. P. falcatus seedlings exhibited differences in architecture between Eucalyptus and Pinus plantations. They had higher leaf area, shorter internode length and greater number of lateral branches in Eucalyptus plantation. At similar vapor pressure deficit (VPD), P. falcatus transpired much less than E. saligna, especially at higher VPDs. Analysis of fluorescence parameters in the leaves showed no significant differences in the level of dark-adapted and light-adapted fluorescence yield (Fv /Fm and ΔF/Fm, respectively), electron transport rate (ETR) and nonphotochemical quenching (NPQ) among seedlings grown inside plantations and adjacent natural forest, indicating similar photosynthetic performance. Nevertheless, there was evidence of photoinhibition in P. falcatus in the clear-felled site which had low fluorescence yield but high values of NPQ as protection from photoamage. The light response curves of ETR, NPQ and ΔF/F m , showed similar light saturation behavior among the seedlings grown inside plantations and natural forest and suggested a sequence of light-adapted to shade-adapted behavior in Natural forest > Eucalyptus plantation > Pinus plantation. The results show the structural flexibility, better water-use and adaptability of P. falcatus in its use of the understory environment of plantation species.     

Identification of the Armillaria root rot pathogen in Ethiopian plantations

Armillaria root rot is a well‐known disease on a wide range of plants, world‐wide. In Ethiopia, the disease has previously been reported on Pinus spp., Coffea arabica and on various native hardwoods. The causal agent of the disease has been attributed to Armillaria mellea, a species now known to represent a complex of many different taxa. The aim of this study was to determine the extent of Armillaria root rot and the identity of the Armillaria sp. in Ethiopian plantations. As part of a plantation disease survey in 2000 and 2001, samples were collected in plantations at and around Munessa Shashemene, Wondo Genet, Jima, Mizan and Bedele, in south and south‐western Ethiopia. Basidiocarps were collected and their morphology studied. Morphological identification was confirmed by sequencing the intergenic spacer (IGS‐1) region of the ribosomal rRNA operon and comparing data with published sequences of Armillaria spp. Armillaria isolates were collected from Acacia abyssinica, Pinus patula, Cedrela odorata and Cordia alliodora trees. Sporocarps were found on stumps of native Juniperus excelsa. Basidiocarp morphology and sequence data suggested that the fungus in Ethiopia is similar to that causing disease of Pinus spp. in South Africa and previously identified as A. fuscipes. This identification was confirmed for all isolates, based on sequence data. Armillaria fuscipes is known to be common in southern Africa. Its widespread occurrence in Ethiopia suggests that it is also the major cause of Armillaria root rot in that country.     

Ecological consequences of an exotic fungal disease in eastern U.S. hardwood forests

Exotic pests and pathogens can cause extensive mortality of native species resulting in cascading effects within an ecosystem. As ecosystems lose species to exotic enemies, ecosystem function may be disrupted if the ecological roles are not filled by the remaining species. To illustrate this concept, this paper examines the impacts of an exotic fungus (Discula dectructiva) on flowering dogwood (Cornus florida), historically a common understory tree species in eastern U.S. hardwood forests. Recent studies indicate that dogwood plays an important role in the health and ecological integrity of forest ecosystems throughout the eastern U.S. by increasing the availability of calcium in the biota-rich surface horizons of forest soils. However, Discula destructiva causes a disease, dogwood anthracnose, which can rapidly kill dogwood trees. This paper also illustrates how past fire has increased dogwood density and improved tree health in areas infected with anthracnose, suggesting that prescribed fire may offer a tool for land managers to maintain dogwood as a component in eastern U.S. hardwood forests by shifting the “ideal” disturbance regime of this previously fire-intolerant species.     

浅析南宁园博会罗汉松园景观营造

为探究新时代背景下植物主题园的景观营造,以第十二届中国(南宁)国际园林博览会罗汉松园为例,通过对罗汉松Podocarpus spp.主要造景植物和园林应用的认识,结合"中国写意山水画"景观特点和审美理论,打造入口迎宾区、松溪别院区、明月山溪区、山谷俯涧区、白玉坡景区和次生林带区6大景观分区,并针对各分区的景观布局、植株选择与配置及其植物文化塑造等方面特点,总结罗汉松园在罗汉松造景树整形特征、突出主景罗汉松的配置手法和天人合一自然山水园形式表达方面的营造技法。     

Response of fungal and plant communities to management-induced overstorey changes in montane forests of the Western Carpathians

The effect of forest management on biodiversity is a crucial issue for sustainable forestry and nature conservation. However, the ways in which management affects macrofungal and plant communities and diversity of mountain temperate forests still remain poorly understood. We performed a random sampling stratified by stand age and stand type on the sites of temperate montane fir–beech forests. Diversity of macrofungi and the vascular plant understorey in beech- and spruce-dominated managed stands was investigated and compared to primeval forests located in the Po?ana Biosphere Reserve, Western Carpathians. Both the vascular plant and the macrofungal communities were altered by management, and the response of the macrofungal species (especially wood-inhabiting fungi) was more pronounced in terms of species composition change. Species turnover evaluation seems to be an important tool of forest natural status assessment, because alpha diversity did not change as much as species composition. Certain species of Carpathian primeval forests were confirmed as good indicators for natural forest change; others were proposed. Species pool and mean number of species per plot were the highest in unmanaged fir–beech forests, and species diversity significantly decreased in spruce plantations. The number of species decreased significantly due to the change of canopy tree species composition only in the macrofungal communities. As an outcome for forest management, we recommend keeping mixed forests involving all natural tree species and providing at least a minimal amount of dead wood necessary for wood-inhabiting organisms and leaving some area of unmanaged natural forests within complexes of managed stands.     

林木病原真菌——赤黏壳科(Erythrogloeaceae)的识别与鉴定

赤黏壳科Erythrogloeaceae包含了多种植物枝干溃疡病菌及叶斑病菌,是间座壳目Diaporthales中一类重要的林木病原菌。本文分析了赤黏壳科的分类学历史和研究现状,总结了赤黏壳科4属21种的分类学特征,编制分种检索表,并构建了该科适用的系统发育树,对后续相关研究工作以及林木病害防治工作提供技术支撑。     

Sphaceloma murrayae Jenk. & Grods., a pathogen new to Europe on Salix spp.

A Sphaceloma species causing greyish‐white leaf spots of several Salix species is described and illustrated. This is the first record for Europe of the mitosporic fungus identified as Sphaceloma murrayae, which was formerly known to occur only in New Zealand, Argentina and the US. In addition to information on symptoms and hosts, similar fungi occurring on willow, which can be confused with the new fungus are also discussed.     

罗汉松夏季扦插育苗技术研究

通过正交试验设计研究在夏季(6月~10月)高温条件下,不同种类生根促进剂、不同遮光率的遮阳网及不同木质化程度的插穗对罗汉松扦插生根率、生根数及生根长的影响和不同插穗下切口型及不同扦插基质对罗汉松扦插生根的影响。结果表明:在夏季高温条件下罗汉松扦插以生根促进剂ABT-1#(A2)+遮光率90%遮阳网(B3)+半木质化的绿枝(C1)组合最好,生根率高达96.8%、生根数达8.6条、生根长达9.8 cm;不同插穗下切口型及不同基质扦插试验中以斜切+80%红心土+20%珍珠岩最佳,生根率高,生根多且长。     

Effects of wounding and fungal infection with Armillaria ostoyae in three conifer species. II. Host response to the pathogen

Structural responses in the bark and wood were described following penetration by Armillaria ostoyae in the roots of 20‐ to 30‐year‐old Douglas‐fir, western hemlock and western redcedar trees. Tissue necrosis presumably caused by fungal exudates was commonly observed at inoculum contact. In Douglas‐fir and western hemlock, A. ostoyae interfered with the initiation of active defence mechanisms involving the development of a lignified zone of impervious tissue (IT), necrophylactic periderm (NP) formation and compartmentalization of infected woody tissue. Breaching of IT and NP barriers was frequent, particularly around the clusters of sclereid cells in western hemlock. In western redcedar, the IT zone was inconspicuous. Induced rhytidome formation occurred in western redcedar either simultaneously with or after completion of NP development. The formation of this tissue facilitated en masse sloughing of infected tissue from the surface of roots. In western redcedar, traumatic phloem resin ducts formed in tangential bands surrounding the margin of expanded lesions. Effective compartmentalization in western redcedar was achieved by a barrier zone comprised of a higher‐than‐average number of axial parenchyma that accumulated polyphenolic deposits. A combination of host‐mediated defence mechanisms in western redcedar resulted in a significantly higher frequency of effective resistance reactions than in western hemlock or Douglas‐fir.     

利用城市森林服务"经营城市"

经营城市的关键在于改善城市环境，可利用城市森林建设为城市的发展提供匹配的自然生态条件和生产、生活、休闲环境。通过提高生态环境质量，强化城市形象、优化城市品质、提升城市的经济吸引力和社会召唤力。     

Responses of oaks and tanoaks to the sudden oak death pathogen after 8 y of monitoring in two coastal California forests

Sudden oak death, caused by Phytophthora ramorum, is widely established in mesic forests of coastal central and northern California. In 2000, we placed 18 plots in two Marin County sites to monitor disease progression in coast live oaks (Quercus agrifolia), California black oaks (Q. kelloggii), and tanoaks (Lithocarpus densiflorus), the species that are most consistently killed by the pathogen in these areas. Through early 2008, the numbers of newly infected trees increased for all species. The infection rate for trees that were asymptomatic in 2000 was 5.0% y⁻¹ for coast live oaks, 4.1% y⁻¹ for black oaks and 10.0% y⁻¹ for tanoaks. Mortality rates were 3.1% y⁻¹ for coast live oaks, 2.4% y⁻¹ for black oaks, and 5.4% y⁻¹ for tanoaks. Mortality not attributed to P. ramorum was 0.54% y⁻¹ for coast live oaks, and 0.75% y⁻¹ for tanoaks. Weibull survival models of trees that were asymptomatic in 2000 provided overall median survival times of 13.7 y for coast live oaks, 13.8 y for black oaks, and 8.8 y for tanoaks. Survival of infected (bleeding) trees declined to 9.7 y for coast live oaks, 6.2 y for black oaks, and 5.8 y for tanoaks. Ambrosia beetle attacks on bleeding trees further reduced modeled survival times by 65–80%, reaffirming the earlier finding that beetle attacks on bleeding cankers considerably reduce survival. Across all plots, the modeled time for 90% of trees that were asymptomatic in 2000 to become infected is 36.5 y for coast live oaks and 15.4 y for tanoaks. There was a trend toward higher infection rates as tree diameter increased. Greater than 90% of living coast live oaks that failed during the study had extensive beetle tunneling at the site of the break. Disease intensity in coast live oaks at the plot level was positively associated with bay laurel (Umbellularia californica) basal area and negatively associated with Pacific madrone (Arbutus menziesii) basal area. This study demonstrates the use of survival modeling to characterize the effects of epidemic disease on different species and to project the future of forests infected with tree pathogens.     

福建省竹柏资源状况及开发利用前景分析

我国生物柴油的研究与开发虽起步较晚,但发展速度很快,部分科研成果已达到国际先进水平,研究内容涉及到油脂植物的分布、选择、培育、遗传改良及其加工工艺和设备.竹柏(Podocarpus nagi)是福建省的乡土树种,种子粒大.种实含油率37.22%以上,单位面积种实产量高,作为燃料油树种具有广阔的发展前景.通过对福建省的竹柏资源调查、主要经济性状调查结果分析.根据竹柏的生长、繁殖特点,对竹柏作为能源树种的发展前景、途径进行了初步探讨.     

The integration of planted and natural forests in a regional landscape

The 10,700 km² region of northwestern Oregon, USA, is dominated by mountainous forested landscapes fringed by agricultural lands and rapidly expanding urban areas. The Douglas-fir/western-hemlock trees, admixed with other species, in the mild, moist regional climate with rich soils are among the most highly productive of temperate forests. Timber harvest has been the dominant land use for much of this century. Many current forest stands are planted, and have the potentials to be managed and shaped for a variety of traditional and evolving forestry objectives. The ages, resilience and productivity of these forests and mosaics of land ownerships permit a variety of future scenarios of forested landscapes, constrained largely by capacities of social organizations to plan and execute management for desired future conditions. This revised version was published online in June 2006 with corrections to the Cover Date.     

Aging in Pacific Northwest forests: a selection of recent research

This paper provides an overview of the work reported at a symposium on age-related changes in the structure and function of forests in the United States Pacific Northwest. Some of the work presented at this meeting is reported in the peer-reviewed papers comprising this journal issue. Age-related changes in leaf structure, CO2 assimilation rate, stable carbon isotope ratio, nitrogen concentration and stomatal limitation were demonstrated at many organizational scales. At larger scales, age-related changes were reported in canopy structure and light profile, stand productivity, tree mortality and respiration. These data raise new questions about the potential interaction among the structural and functional changes in aging forests, and indicate many avenues for future research concerning tree growth and ecosystem functioning.