Pathogenicity of three Phytophthora spp. causing late seedling rot of Quercus ilex ssp. ballota

Within a research project on quality of plants for forestation of agricultural lands, we studied the aetiology of a late seedling rot affecting holm oak (Quercus ilex ssp. ballota) in two forest nurseries in southern Spain. Major disease symptoms were foliage wilting and necrosis of feeder roots. Phytophthora cinnamomi, Phytophthora cryptogea and Phytophthora drechsleri were isolated from necrotic roots of holm oaks. Selected isolates of the three Phytophthora species were pathogenic to Quercus ilex ssp. ballota and Quercus suber seedlings in artificial inoculations. Soil flooding conditions were essential for infection and root rot development. There was no host specificity among the species, the isolates of P. cinnamomi being the most virulent in all inoculated plants. In these inoculations, Q. ilex ssp. ballota plants were more susceptible than those of Q. suber. This work is the first report of P. cinnamomi, P. drechsleri and P. cryptogea affecting Q. ilex ssp. ballota in forest nurseries.     

一种经济有效的森林土壤粗品DNA纯化方法

尽管人们采用多种提取方法乃至使用商品试剂盒,但从森林土壤中获得纯品DNA仍然是比较困难的事情。本文经多次研究探索提出了一种经济有效的森林土壤粗品DNA进一步纯化方法。此方法由两步组成:1.利用提取缓冲液将提取的粗品DNA溶解,经氯仿/异戊醇去除杂质后,再用异内醇沉淀析出DNA;2.使用普通凝胶回收试剂盒回收柱进一步纯化DNA。结果表明:经第一步纯化后,82%-91%腐殖酸杂质被除去。经第二步纯化后,残留的少量腐殖酸杂质被去除干净。经上述连续的两步纯化后获得的DNA非常纯净,可直接用于对抑制物非常敏感的常规PCR反应。本研究报道的DNA进一步纯化方法有效、经济且省时。此外,采用其它各种提取方法获得的土壤粗品DNA均可使用本方法进一步纯化。图4表2参15。     

PCR–DGGE method for in planta detection and identification of Phytophthora species

We have developed a method to detect multiple species of Phytophthora directly in infected plant tissues. The method is based on the polymerase chain reaction and uses Phytopththora‐specific primers and denaturing gradient gel electrophoresis (PCR–DGGE). The method distinguished most of the 16 Phytophthora species tested. Very closely related species might not, however, be identified using the method. The detection efficiency was high and successful in eight different plant tissues tested. The PCR–DGGE detection tool developed here will be a fast and inexpensive method suitable for pathogen surveys and research programmes.     

Bark necrosis of Acer pseudoplatanus L. in northern Britain

Severe bark necrosis in large Acer pseudoplatanus was studied at a site in northern England. Bark death occurred late in the growing season or in the dormant season on two occasions and was preceded by a notably dry summer in both cases. Of several fungi isolated from cankers and areas of recent bark necrosis, Nectria coccinea and Diplodina acerina were demonstrated to be capable of causing limited necrotic extension of physical wounds in healthy A. pseudoplatanus. A third sp., Phomopsis pustulata, though the most frequently isolated fungus, showed no such ability. It is proposed that summer drought in association with a variety of weakly pathogenic fungi can induce local bark necrosis in A. pseudoplatanus.     

An improved algorithm for mapping burnt areas in the Mediterranean forest landscape of Morocco

The identification of burnt forests and their monitoring provide essential information for the suitable management and conservation of these ecosystems. This research focuses on the use of remote sensing with MODIS sensor data in a Mediterranean environment, precisely in the Rif region known for its high occurrence of forest fires and the largest burnt areas in Morocco. It mapped the burnt areas during the summer of 2016 using spectral indices from MODIS images, namely the Normalized Burn Ratio (NBR) and the Burnt Area Index for MODIS (BAIM). Two field surveys were used to calibrate spectral indices and validate the maps. First, a monotemporal analysis using a single pre-fire image determined the appropriate threshold of the spectral indices (BAIM and NBR) for burn detecting. Secondly, a multitemporal method was applied based on dBAIM and dNBR images which represented pre-fire and postfire differences of the BAIM and NBR images, respectively. The results show that separate use of monotemporal postfire and multitemporal methods produced an overestimation of the burnt areas. Finally, we propose a new algorithm combining both methods for burnt area mapping that we name Burnt Area Algorithm. MCD45A1 and MCD64A1 MODIS burnt area products were compared to the proposed algorithm. Validation of the estimated burnt areas using reference data of the Moroccan High Commission for Water, Forests and Fight against Desertification showed satisfactory results using the proposed algorithm, with a determination coefficient of 0.68 and a root mean square error of 44.0 ha.     

Development of a quantitative real‐time PCR assay for the detection of Phytophthora austrocedrae,an emerging pathogen in Britain

A TaqMan real‐time PCR assay was developed for Phytophthora austrocedrae, an emerging pathogen causing severe damage to juniper in Britain. The primers amplified DNA of the target pathogen down to 1 pg of extracted DNA, in both the presence and absence of host DNA, but did not amplify any of the non‐target Phytophthora and fungal species tested. The assay provides a useful tool for screening juniper populations for the disease.     

Involvement of Phytophthora spp. in chestnut decline in the Black Sea region of Turkey

Chestnut blight caused by Cryphonectria parasitica is a serious disease of Castanea sativa in the Black Sea region of Turkey. During disease surveys, dieback and decline symptoms were observed on trees without apparent blight and ink disease symptoms. Black necroses, similar to those caused by Phytophthora infections, were noted on some of the chestnut coppices and saplings in one nursery in Ordu and led to an investigation into this disease complex. Only symptomatic plants showing dieback symptoms were investigated. Soil samples together with fine roots were collected from two directions, north and north‐east, approximately 150 cm away from the main stems. Phytophthora spp. were baited with young chestnut leaves. Three Phytophthora spp., P. cambivora, P. cinnamomi and P. plurivora, were identified from 12 soil samples collected from 73 locations, while from the nurseries, only P. cinnamomi was obtained. Phytophthora cinnamomi was the most common species, obtained from seven locations in five provinces and from four nurseries having similar symptoms mentioned above in different locations. Phytophthora cambivora and P. plurivora were less frequently obtained, from three to two stands, respectively. Phytophthora cinnamomi and P. cambivora were the most aggressive species when inoculated at the stem base on 3‐year‐old chestnut saplings, killing six saplings of eight inoculated in 2 months. The three Phytophthora species were first recorded on chestnut in Black sea region of Turkey with the limited samples investigated in a large area about 150 000 ha chestnut forest.     

An integrated method for matching forest machinery and a weight-value adjustment

Proper matching of forestry machinery is important when raising mechanization levels for forestry production. In the matching process, forestry machinery needs not only expertise, but also improved methods for solving problems. I propose combination of case-based reasoning （CBR） and rule-based reasoning （RBR） by calculating the similarity of quantitative parameters of various forestry machines in an analytical and hierarchical process. I calculated the similarity of machin-ery used in forest industries to enable better selection and matching of equipment. I propose a weight-value adjusting method based on sums of squares of deviations in which the individual parameter weights were modified in the process of application. During the process of system design, I put forward a design method knowledge base and generated a dynamic web reasoning framework to integrate the processes of forest industry machinery selection and weight-value adjustment. This enables expansion of the scope of the complete system and enhancement of the reasoning efficiency. I demonstrate the validity and practicability of this method using a practical example.     

辽宁省松毛虫性引诱剂监测林间操作技术

利用性信息素引诱昆虫,监测林业有害生物的种群动态是一项先进科学、操作简便、灵敏度高的监测实用技术。文中通过连续多年在辽宁省阜新蒙古族自治县进行的松毛虫性诱试验,总结出较为规范的松毛虫性诱剂监测林间操作技术。     

Host removal as a potential control method for Phytophthora cinnamomi on severely impacted black gravel sites in the jarrah forest

Removal of living plants from an area of Eucalyptus marginata (jarrah) forest on black gravel sites infested with Phytophthora cinnamomi significantly reduced subsequent pathogen recovery. Vegetation, including trees and annual and herbaceous perennial plants, was killed on the sites by herbicide application. To determine whether this treatment efficiently eliminated P. cinnamomi, soil samples were seasonally collected and baited to test for the presence of the pathogen. There were no recoveries on treated sites in autumn, 28 months after removal of all vegetation by herbicide application. To test whether this was the result of the complete elimination of the pathogen or whether inoculum remained, regrowth on sites was not controlled after this period leading to the re‐establishment of annual and herbaceous perennial species, some of which are hosts of P. cinnamomi. Recovery of P. cinnamomi after plant regrowth on the formerly treated sites indicated that for complete pathogen removal, sites need to remain free of vegetation for longer than 28 months. Overall, however, this study confirms that the pathogen is a weak saprophyte, and withdrawal of host material for a period of time may make eventual rehabilitation of these sites possible.     

Use of fungal biosystematics and molecular genetics in detection and identification of wood‐decay fungi for improved forest management

Advances in fungal biosystematics and molecular genetics have clarified relationships among the wood‐decay fungi and are providing new tools for their detection and identification. Species complexes of forest pathogens, including those within Heterobasidion, Armillaria, Laetiporus, and Phellinus, are being resolved. The ability to isolate fungal DNA directly from wood without in intermediate culturing step will greatly facilitate sampling and disease detection and has applications in forest disease management, hazard tree assessment, invasive species detection, and carbon cycling, sequestration and climate change research. Recent changes in fungal nomenclature and their application to forest pathology are discussed.     

Carbon concentrations and stocks in forest soils of Europe

This study presents the results of a series of evaluations of a continent-wide soil database (EU/UN-ECE Level I) with the aim to estimate baseline soil carbon concentrations and stocks. The methodology included the biogeographic stratification of soil carbon measurements throughout Europe using climatic zones derived from the Soil Regions Map of Europe. The presented stock estimates range from 1.3 to 70.8 t C/ha for the O-layer, and from 11.3 to 126.3 t C/ha for the mineral soil 0–20 cm (Germany: 0–30 cm) (5 and 95 percentiles). Histosols were excluded because of methodological differences and data gaps. When looking at the median values of the strata investigated, relationships were found. For example, carbon stocks in the O-layer of sandy soils are distinctly higher than those of fine-textured soils. However, the variability is so high that some of these relationships disappear. For example in western and central Europe, the level of carbon stocks in the mineral soil between shallow soils (Leptosols) and more deeply developed soils (Podzols and Cambisols) do not differ very much. It was also found that just the investigation of topsoils is not sufficient to understand the regional pattern of organic matter in forest soils – unless the subsoil becomes included as well. It is hypothesized that for Europe, the impact of site factors such as climate, texture and relief are difficult to extract from such a database if the data are only stratified according to macro-climatic areas. It has to be considered that the effect of systematic error in the database is quite large (but cannot be identified on the level of the current data availability). In order to receive a first impression of the landscape-level distribution of carbon, a map of carbon concentrations in the topsoil was generated. The results support the relationships found between carbon stocks and site factors, such as climatic zones and soil type. Compared to the much lower carbon concentrations of agricultural soils, the results demonstrate clearly the importance of forest soils for the terrestrial carbon cycling in Europe.     

Tree-ring: a suitable implement for spatial and temporal fire distribution analysis in savanna woodland and dry forest

Based on 120 stem discs collected during3 months of fieldwork along a 12 km route,the history of fires in the Wari Maro Forest(09 1000 N–02 1000E) over the past century in savanna woodland and dry forest was reconstituted.Three major ecological areas are characterized:one highly burnt zone located between two relative less burnt areas.By analyzing tree rings,246 fire scars were identified.The scars were caused by 51 fire years,occurring at a mean interval of 2.23 years.From 1890 to1965,only 6 years with fires were recorded from sampled trees.Since 1966,no year has passed without fire.The fire frequency point scale reached 14 years.This was the case of Burkea africana,which has been identified as a species tolerant to fire and could be planted to create a natural firewall.In contrast,Anogeissus leiocarpa is highly sensitive to fire,and in a dry forest ecosystem that burns seasonally,it requires a special conservation plan.Two new concepts are described:the rebarking of trees after fire and Mean Kilometer Fire Interval.The first concept was tested with Daniellia oliveri(Rolfe) Hutch & Dalz trees,and the second concept was used to evaluate spatial fire distribution.We demonstrate that savanna woodland and dry forest were subject to a degradation process caused by destructive fires related to vegetation cover clearance and illegal logging.     

Cross‐infectivity of oil palm by Phytophthora spp. isolated from perennial crops in Malaysia

Bud rot disease or “Pudricion del cogollo” (PC) of oil palm is a major constraint on production in Colombia and neighbouring countries such as Brazil, Costa Rica, Ecuador, Nicaragua, Panama, Peru and Surinam. To date, there are no documented reports of Phytophthora disease of oil palm in South‐East Asia. This research, therefore, was conducted to determine the pathogenic potential of Phytophthora palmivora and Phytophthora nicotianae on oil palm using both in vitro and nursery inoculation experiments. In vitro inoculation of both P. palmivora and P. nicotianae on immature oil palm leaflets caused discoloration within 2 days of inoculation and incubation at 25 ± 1.5°C, 100% RH. Similarly, in nursery trials, lesions formed on the buds (unopened leaflets) 3 days after inoculation with P. palmivora or P. nicotianae zoospore suspensions. No lesions developed on untreated leaflets in either in vitro or nursery inoculation experiments. Phytophthora spp. were re‐isolated from leaflet lesions and confirmed as the inoculated pathogens.     

The potential of 44 native and non-native tree species for woodland creation on a range of contrasting sites in lowland Britain

A series of species trials were set up to investigate the establishmentand early growth (up to 14 years old) of 44 native and non-nativetree species on a variety of different site types in lowlandBritain. On good quality lowland afforestation sites, Platanusx hispanica (London plane) established and grew more successfullythan the native trees tested, and may be an example of a speciesthat could theoretically be established in anticipation of futureclimate change. Experiments on a variety of community woodlandsites indicated that a range of exotic species, such as X Cupressocyparisleylandii (Leyland cypress), may have the potential for establishinga woodland cover on poorly restored land where few other treeswould grow. However, on less challenging, better restored sites,a wide range of native species also grew successfully. Furtherlong-term and larger scale trials on a wider variety of sitesare required to confirm the potential of the species testedfor British conditions. The results from these experiments alsoshowed that relative growth rates of different species can varythrough time, highlighting the danger in making premature judgementsabout species suitability based solely on very early tree growth.     

Pollen morphology and trichome types of Betula spp. in the Hyrcanian forests of northern Iran

Pollen and trichome morphology of the genus Betula were evaluated from three main habitats in Iran using light and electron microscopy.Pollen types were identical and tri-porate;however,in terms of quantitative data,some differences were observed in exine(outside)wall thickness,length of polar axis and length of equatorial axis,possibly due to the environment.Pollen alone is insufficient to separate species of Iranian birch.Investigation of the trichome trait(small hairs or other outgrowths)revealed that birch species in Iran belong to:(1)Betula litwinowii Doluch.according to the low density of trichomes on the adaxial surface of the leaves and the lack of trichomes on the abaxial surface and many trichomes on the petioles;(2)Betula pendula Roth.due to the absence of trichomes on the adaxial surface and the low density of trichomes on the abaxial surface;and,(3)in the adaxial and abaxial surfaces of leaves and petioles,the trichomes had different types of pilose(long,soft hairs),and this strengthens the possibility of a different species or more likely a hybrid of B.pendula.     

落叶松与水曲柳混交林特征研究综述

落叶松和水曲柳是我国东北地区的主要造林树种,适合我国东北地区广泛栽培。本文对现有国内外落叶松和水曲柳种间关系、立地条件以及混交优势对生长的影响进行总结,其结果对落叶松和水曲柳混交林的经营及管理具有重要的理论意义。     

An improved low-input method for establishing calliandra hedgerows on small-scale farms in western Kenya

Direct seeding methods for nitrogen (N)-fixing tree-legumes by small-scale farmers were developed and studied in humid and sub-humid areas of western Kenya. We focused on the first six months of establishment of calliandra (Calliandra calothyrsus Meissner) multipurpose hedgerows. Direct seeding became effective, reliable, and significantly better than for zero-control treatments when improving A) water uptake by scratching the hard seeds with a sandal against a hard, rough surface, B) phosphorus (P) nutrition by mixing 150 g/m of kitchen wood-ash (1.3% P) into a 10 cm deep, 20 wide cm soil band 5 cm below the seeds, and C) root nodulation by transferring 100 g/m Rhizobium-colonised soil, or 0.5 crushed, incubated nodule, from a calliandra hedge. The field germination was 90% after two weeks, and the hedges were green and about 2 m tall in the dry season six months later. This revised version was published online in June 2006 with corrections to the Cover Date.     

Replacing coniferous monocultures with mixed-species production stands: An assessment of the potential benefits for forest biodiversity in northern Europe

Conifer dominated plantations in central and northern Europe are associated with relatively low ecological values, and in some cases, may be vulnerable to disturbances caused by anthropogenic climate change. This has prompted the consideration of alternative tree species compositions for use in production forestry in this region. Here we evaluate the likely biodiversity costs and benefits of supplanting Norway spruce (Picea abies) monocultures with polycultures of spruce and birch (Betula spp.) in southern Sweden. This polyculture alternative has previously been evaluated in terms of economic, recreational, and silvicultural benefits. By also assessing the ecological implications we fill a gap in our understanding of the range of socio-ecological benefits that can be achieved from a single polyculture alternative. We project likely broad scale changes to species richness and abundance within production stands for five taxonomic groups including ground vegetation, tree-living bryophytes, lichens, saproxylic beetles, and birds. Our research leads us to three key findings. First, the replacement of spruce monocultures with spruce–birch polycultures in the managed forest landscapes of southern Sweden can be expected to result in an increase in biological diversity for most but not all taxa assessed, but it is unlikely to improve conditions for many red-listed forest species. Second, modification of other aspects of forest management (i.e. rotation length, dead wood and green tree retention, thinning regimes) is likely to contribute to further biodiversity gains using spruce–birch polycultures than spruce monocultures. Third, the paucity of empirical research which directly compares the biodiversity of different types of managed production stands, limits the extent to which policy relevant conclusions can be extracted from the scientific literature. We discuss the wider implications of our findings, which indicate that some climate change adaptation strategies, such as risk-spreading, can be readily integrated with the economic, environmental and social goals of multi-use forestry.