Phylogenetic and differentiation analysis of the trunk rot pathogen Fomitiporia tsugina in North America

Fomitiporia hartigii s.l. is an important trunk rot pathogen of conifers throughout the Northern Hemisphere. In North America, this pathogen primarily attacks Tsuga, but is also found on Abies, Picea and Pseudotsuga. Previous research showed that isolates of F. hartigii from North America represent a distinct phylogenetic species, known as F. tsugina. However, that conclusion is based on limited data. To better understand the phylogenetic relationships of F. tsugina in North America, a phylogenetic analysis was performed using three loci (internal transcribed spacer, nuclear large subunit and tef1) with 23 isolates originating from the northern United States, Canada and central Europe. North American isolates formed a monophyletic group with significant statistical support, confirming previous reports that F. tsugina represents a unique phylogenetic species, distinct from European F. hartigii s.s. Population subdivision between isolates of F. tsugina from eastern (Massachusetts, Michigan, New Hampshire, New York and Wisconsin) and western (British Columbia, Colorado, Oregon and Washington) North America was investigated. Tests of gene flow and genetic differentiation based on region of origin detected significant variation (F_ST = 0.761; K_ST = 0.625, p < 0.01), suggesting gene flow between the two populations may be limited. Neutrality tests revealed significant, negative departures from the standard neutral model, which could indicate that a purifying or stabilizing selection has maintained low levels of polymorphisms in the population, perhaps favouring an advantageous phenotype. Further studies are required to better understand the occurrence of F. tsugina on Abies and Picea in boreal forests outside the natural range of Tsuga.     

Production of a polyclonal antibody to Phellinus pini and examination of its potential use in diagnostic assays

In order to differentiate among Phellinus pini, Inonotus tomentosus and Inonotus circinatus a polyclonal antibody was raised to a N-terminal part of 25-kDa P. pini-specific protein. The specificity of the polyclonal antibody produced against a synthetic N-terminal peptide of this protein was investigated for diagnostic purposes using Western immunoblot, indirect enzyme-linked immunosorbent assay (ELISA), and inhibition ELISA techniques. The N-terminal synthetic peptide, used as the immunogen, was found to be more than 80% pure by reverse-phase high-performance liquid chromatography. Following immunization, antisera were collected at three different time intervals. The antibody molecules were purified from the crude antisera using immunoaffinity gel chromatography. Following one-dimensional sodium dodecylsulfate-polyacrylamide gel electrophoresis, Western immunoblot analysis showed that the P. pini I polyclonal-antibody detected the immunogen, the 25-kDa protein, in all but one of the P. pini isolates examined, but in none of the isolates of the nontarget species I. tomentosus and I. circinatus. Nevertheless, cross-reactivity was a problem because the P. pini I polyclonal-antibody also recognized bands at other molecular weights in nearly all of the isolates of the other species tested. With the indirect ELISA the P. pini isolates tended to have higher affinity for the polyclonal antibody than the nontarget species, but some cross-reactivity did occur. Inhibition ELISAs, performed over a range of soluble antigen concentrations (1.56–400 ng/100 μl), failed to show a clear distinction between P. pini and the two Inonotus spp. The low level of cross-reactivity observed for I. tomentosus isolate 52 (9%) was also apparent in the indirect ELISA analysis. All three assays indicated that P. pini isolate 41 was the most antigenic. Despite cross-reactivity, the antibody is useful in Western immunoblots for the diagnosis of most P. pini isolates.     

北亚热带土地利用变化对土壤有机碳垂直分布特征及储量的影响

利用野外调查的方法,研究了北亚热带地区土地利用变化对土壤有机碳的垂直分布特征及储量的影响.研究结果表明:(1)除茶园土壤外,不同林分土壤有机碳含量均以0～10cm土层最大,随着土层深度的增加,含量总体表现为下降的趋势;茶园土壤有机碳含量在0～30cm土层范围内增加,30cm以后表现下降的趋势;(2)次生林转变成农耕地以后土壤有机碳含量平均下降21.1%,而转变成集约经营早竹林后,土壤有机碳含量平均下降近48.5%;1m深度以内,土壤有机碳平均含量由高到低的顺序为:茶园、灌木林、次生林、粗放经营毛竹林、集约经营毛竹林、马尾松林、农耕地、杉木林和早竹林;(3)土壤有机碳储量随土层深度变化的趋势和土壤有机碳含量变化趋势基本一致;次生林转变成长期经营的农耕地后,土壤有机碳储量下降22.5%,而转变成长期集约经营早竹林后土壤有机碳储量则下降51.4%9种土地利用类型中,土壤有机碳储量由高到低的顺序为:茶园、灌木林、次生林、粗放经营毛竹林、马尾松林、农耕地、集约经营毛竹林、杉木林和早竹林.     

松针褐斑病菌和松针红斑病菌的风险分析

参照国内外有害生物风险分析(Pest Risk Analysis,简写PRA)方法,从有害生物的国内分布状况、潜在的危害性、寄主植物的经济重要性、传播扩散的可能性以及风险管理的难易程度等方面对松针褐斑病菌和松针红斑病菌的风险性进行定性和定量分析,评价结果表明:两者在我国均属于中度危险的森林有害生物,建议列入相关省区的检疫性林业有害生物补充名单进行管理。     

Emulating natural disturbances: the role of silviculture in creating even-aged and complex structures in the black spruce boreal forest of eastern North America

Ecosystem-based forest management is based on the principle of emulating regional natural disturbance regimes with forest management. An interesting area for a case study of the potential of ecosystem-based forest management is the boreal forest of north-western Québec and north-eastern Ontario, where the disturbance regime creates a mosaic of stands with both complex and simple structures. Old-growth stands of this region have multi-storied, open structures, thick soil organic layers, and are unproductive, while young post-fire stands established following severe fires that consumed most of the organic soil show dense and even-sized/aged structures and are more productive. Current forest management emulates the effects of low severity fires, which only partially consume the organic layers, and could lead to unproductive even-aged stands. The natural disturbance and forest management regimes differ in such a way that both young productive and old-growth forests could ultimately be under-represented on the landscape under a fully regulated forest management regime. Two major challenges for ecosystem-based forest management of this region are thus to: (1) maintain complex structures associated with old-growth forests, and (2) promote the establishment of productive post-harvest stands, while at the same time maintaining harvested volume. We discuss different silvicultural approaches that offer solutions to these challenges, namely the use of (1) partial harvesting to create or maintain complex structures typical of old-growth stands, and (2) site preparation techniques to emulate severe soil burns and create productive post-harvest stands. A similar approach could be applied to any region where the natural disturbance regime creates a landscape where both even-aged stands established after stand-replacing disturbances and irregular old-growth stands created by smaller scale disturbances are significant.     

The North American P group of Heterobasidion annosum s.l. is widely distributed in Pinus pinea forests of the western coast of central Italy

The distribution of the North American P group of Heterobasidion annosum s.l., recently reported from a Pinus pinea forest in the surroundings of Rome, was studied using mating tests and DNA fingerprinting (mitochondrial DNA, random amplified microsatellite technique and two group‐specific markers). This fungus is present in several forests and small plantations along the Tyrrhenian coast of the Italian peninsula, within an area approximately 100 km long, extending from Fregene in the north to the National Park of Circeo in the south, and 27 km wide including the city of Rome. In pine forests of Castelporziano, Castel Fusano and Anzio, where US troops resided during the Second World War, the North American P group is more frequent than the European P group. The low number of mating alleles in the Italian population of the North American P group supports the hypothesis of its origin from a small number of introductions. The near 100% sexual compatibility between the North American and European P groups, together with inconsistencies in results obtained with different identification methods of these groups, suggests that hybridization between the North American and European P populations occurs occasionally.     

Pedicularis and Castilleja are natural hosts of Cronartium ribicola in North America: a first report

White pine blister rust disease, caused by the introduced pathogen Cronartium ribicola, has severely disrupted five‐needled pine ecosystems in North America. A 100‐year effort to manage this disease was predicated in part on the premise that the pathogen utilizes only species of Ribes (Grossulariaceae) as alternate hosts on this continent. The current study presents the first conclusive demonstration that some species in the family Orobanchaceae (Pedicularis racemosa and Castilleja miniata) are functioning as alternate hosts in a natural ecosystem of North America. This finding has implications for improving our understanding of epidemiology, pathogen adaptation and host–pathogen interactions within white pine blister rust.     

北美落基山自然风光与动植物纪事

北美洲落基山脉纵贯加拿大西南和美国西北部,跨越北极带、寒带和温带高原气候带,是全球著名山脉之一。有奇特的高原地貌、世界最大的冰原、众多冰河、瀑布、高原湖泊、温泉及间歇喷泉等自然景观,以及多种植被、特有动物,每年吸引来自世界各地的众多游客。美国、加拿大政府和联合国教科文组织重视环保,在落基山脉建立众多国家公园,其中有7处划定为《世界遗产目录》《世界遗产公园》。国家公园重视环保,订立各种保育措施,值得借鉴。     

Peridermium pini (Pers.) Lev. and the Resin-top Disease of Scots Pine: II. Lesion Anatomy

The stages in the formation of Peridermium pini lesions aredescribed. The hyphae of the parasite were septate, uninucleate,and intercellular, with unbranched haustoria penetrating allphloem cells and xylem parenchyma cells. Lesion extension occurredby apical growth of the hyphae along the outer edge of the functionalphloem. The hyphae stretched unbroken across the active cambium.Active centripetal and longitudinal growth of the mycelium occurredin the resin ducts of the xylem, the hyphae commonly reachingthe pith. Spermogonia were produced in late summer and fall,aecia appeared in spring. In lesion xylem, tracheids were shorter,rays taller, more numerous and wider, but ray cell height remainedunchanged. Fusiform rays increased in number and size and verticalresin ducts increased in number. Changes in xylem tissues didnot become evident until two to four years after invasion ofthe cambium by the mycelium. Invasion of the secondary phloemresulted in an increase in number and size of the longitudinalphloem parenchmya cells, while changes in phloem rays were similarto those in xylem rays.     

Terpene response of Picea abies and Abies alba to infection with Heterobasidion s.l.

The monoterpene composition of Picea abies and Abies alba resin was analysed in relation to growth by Heterobasidion spp. Fifteen‐year‐old P. abies and A. alba trees were inoculated on branches with three species of Heterobasidion annosum s.l. After 4 months of incubation, each host was colonized to a significantly greater degree by the pathogen specific to that host (H. parviporum on P. abies, H. abietinum on A. alba) than by the other fungi. Analysis of the enantiomeric monoterpene profiles in the spruce and fir showed that the response in terms of the relative proportions of the monoterpene compounds in the resin differed between tree species. Following challenge with Heterobasidion spp., A. alba trees did not show changes in monoterpene composition in addition to those in the wounding response (increase in (−)‐α‐pinene and (−)‐camphene, and decrease in β‐phellandrene). In P.abies, (−)‐α‐pinene, (+)‐α‐pinene and δ‐3‐carene increased following Heterobasidion attack but not after wounding alone.     

北美地区杨树木材利用现状与前景

过去20多年, 北美地区的杨树已经从杂草树种转变为产生巨大经济效益的用材林树种, 杨树木材因其具有较高纤维素含量和较低的木质素含量, 适合用作纸浆和纸制品的原料。杨木制浆方法有机械法、化学法、半化学法和化学机械法, 杨木浆可以作为高级纸、纸板、新闻纸和包装纸。杨木牛皮纸浆与针叶材牛皮纸浆混合, 具有良好的成纸性能, 透明度高, 适合制作高级用纸。杨木也是传统的锯材、单板和胶合板工业的原材料, 用来生产锯材、单板、胶合板、木质复合板、包装箱、集装箱、火柴杆和筷子等。最近10年杨木定向刨花板和结构复合板产量显著增加, 利用前景广阔。从资源生产的角度来看, 在改良木材化学组成、纤维质量和自然耐久性等方面进行木材性质改良的转基因杨树研究取得了长足进展。从资源利用角度来看, 高价值的工程复合板和高得率的纸浆和纸产品将会在未来发展中快速增长。     

Inonotus dryadeus in North America: new records,hosts, distribution and incidence

Inonotus dryadeus is newly reported in eastern Canada (Ontario) on Acer platanoides and Acer saccharinum, both new hosts, and Ulmus americana. The host range, incidence, and available distributional data in continental North America are summarized in a table. The fungus occurs primarily on Quercus, Abies, and Tsuga. Occasionally, it is found on Picea and Pinus as well as many other hardwood trees. Colder climates and host differences in the boreal forests may be limiting distributional factors. Inonotus dryadeus appears to favour very old trees. The maximum known width of the fruiting body is revised upward to 74.9 cm.     

Nitrate dynamics of forested watersheds: spatial and temporal patterns in North America,Europe and Japan

The relationships of nitrogen biogeochemistry are reviewed, focusing on forested watersheds in North America, Europe and Japan. Changes in both local and global nitrogen cycles that affect the structure and function of ecosystems are described. Within northeastern United States and Europe, atmospheric deposition thresholds of ~8 and ~10 kg N ha⁻¹ year⁻¹, respectively, result in enhanced mobilization of nitrate. High nitrate concentrations and drainage water loss rates up to 22 kg N ha⁻¹ year⁻¹ have also been found near Tokyo. Although atmospheric deposition may explain a substantial portion of the spatial pattern of nitrate in surface waters, other factors also play major roles in affecting the spatial patterns of nitrogen biogeochemistry. Calcium availability influences the composition of the vegetation and the biogeochemistry of nitrogen. The abundance of sugar maple is directly linked to soil organic matter characteristics and high rates of nitrogen mineralization and nitrification. Seasonal patterns of nitrate concentration and drainage water losses are closely coupled with differences in seasonal temperature and hydrological regimes. Snow-dominated forested catchments have highest nitrate losses during snowmelt. Watersheds in the main island of Japan (Honshu) with high summer temperatures and precipitation inputs have greatest losses of nitrate occur during the late summer. Understanding future changes in nitrate concentrations in surface waters will require an integrated approach that will evaluate concomitantly the influence of both biotic and biotic factors on nitrogen biogeochemistry.     

Consumption rate and susceptibility to parasitic nematodes and chemical molluscicides of the pest slugs Arion hortensis s. s. and A. distinctusJ. Iglesias, B. Speiser, Biological and chemical control of Arion hortensis s. l. slugs

The species complex Arion hortensis s.?l. is among the most important pestiferous slugs in Europe. The species A. distinctus Mabille and A. hortensis de Férussac have traditionally been grouped together under the denomination A. hortensis. Therefore, neither the feeding behaviour nor the susceptibility of the individual species to control measures are known. In the laboratory, mean daily consumption of lettuce was similar for both species. In a series of laboratory bioassays, A. distinctus and A. hortensis s.?s. were exposed to the rhabditid nematode Phasmarhabditis hermaphrodita and to the chemical molluscicides metaldehyde and iron phosphate, and their feeding and health were measured. Both species showed a similar and low susceptibility to the biocontrol agent P. hermaphrodita. In field-collected slugs, the incidence of nematodes was much lower in A. hortensis s.?l. than in Deroceras reticulatum or Arion lusitanicus. Metaldehyde and iron phosphate affected both slug species similarly. Therefore, our results do not indicate any major difference between the two slug species of agronomical relevance.     

The occurrence of Phellinus tremulae (Bond.) Bond. and Borisov as a primary parasite in Populus tremula L.

Phellinus tremulae was inoculated on Populus tremula. It spread in the sapwood and inner wood of a living tree without other organisms being present. Plating experiments with wood meal from different parts of a sound tree showed that there were very few, if any, propagules of micro organisms in the sound wood, neither were there any organisms found in front of the decay of P. tremulae at the top of the decay column. These results support the theory that P. tremulae is a primary parasite in aspen. Decay fungi grown on fresh and autoclaved wood of aspen had very different growth rates. Most of the fungi tested grew best on autoclaved sapvvood. The difference in growth rate on fresh and autoclaved heartwood was lcss significant, suggesting that there is a barrier in the living wood which is destroyed by autoclaving. P. tremulae was thc only fungus that grew best on fresh inner wood.     

北美雷击火概率预测技术及其应用效果评价

从模型结构、预测原理、建立方法、应用效果和未来发展等几个方面,对北美,特别是加拿大安大略省雷击火概率预测模型进行了介绍,并探讨了该模型在我国大兴安岭地区的适用性,使国内相关领域的研究人员能够比较全面地了解此系统,可为建立适用于我国林区雷击火的概率预测系统提供参考。     

Cypress mortality (mal del cipres) in the Patagonian Andes: comparisons with similar forest diseases and declines in North America

Widespread mortality of Cordilleran cypress (Austrocedrus chilensis) occurs in developed and pristine forests in south-western Argentina and possibly south-eastern Chile. Affected trees may die rapidly but mortality is commonly preceded by several decades of severely restricted radial stem growth. Roots are often affected by one or more types of decay. Cypress mortality, locally termed ‘mal del cipres’, is similar to a major forest disease in North America: Port-Orford-cedar (Chamaecyparis lawsoniana) root disease in Oregon and California and a major tree decline: Alaska yellow-cedar (Chamaecyparis nootkatensis) decline in south-east Alaska. This paper discusses several hypotheses concerning mal del cipres and compares current forest decline research in Patagonia with North America.