Evergreen Oak Research Articles

Climate response of the soil nitrogen cycle in three forest types of a headwater Mediterranean catchment

Future changes in climate may affect soil nitrogen (N) transformations, and consequently, plant nutrition and N losses from terrestrial to stream ecosystems. We investigated the response of soil N cycling to changes in soil moisture, soil temperature, and precipitation across three Mediterranean forest types (evergreen oak, beech, and riparian) by fusing a simple process-based model (which included climate modifiers for key soil N processes) with measurements of soil organic N content, mineralization, nitrification, and concentration of ammonium and nitrate. The model describes sources (atmospheric deposition and net N mineralization) and sinks (plant uptake and hydrological losses) of inorganic N from and to the 0–10 cm soil pool as well as net nitrification. For the three forest types, the model successfully recreated the magnitude and temporal pattern of soil N processes and N concentrations (Nash-Sutcliffe coefficient = 0.49–0.96). Changes in soil water availability drove net N mineralization and net nitrification at the oak and beech forests, while temperature and precipitation were the strongest climatic factors for riparian soil N processes. In most cases, net N mineralization and net nitrification showed a different sensitivity to climatic drivers (temperature, soil moisture, and precipitation). Our model suggests that future climate change may have a minimal effect on the soil N cycle of these forests (<10% change in mean annual rates) because positive warming and negative drying effects on the soil N cycle may counterbalance each other.

Understanding the importance of intrapopulation functional variability and phenotypic plasticity in Quercus suber

Climate is one of the main abiotic factors influencing natural selection patterns. Year-to-year variation in climate is postulated to elicit temporal shifts in the direction and form of selection. Here, we examine the importance of trait means and plasticities for fitness under interannual variation in rainfall and assess the shifts in selection in cork oak. We performed selection analyses using the progeny of 45 mother trees established in a common garden experiment across two consecutive years that differed in rainfall. Growth and seven functional traits (specific leaf area, leaf size, leaf shape traits, 13-carbon isotope discrimination, and leaf nitrogen) related to drought tolerance were measured. Selection analyses showed fitness benefits of reduced specific leaf area (SLA) in a dry year and increased leaf size in a mesic year, indicating that they are key traits for this evergreen oak to cope with different water availabilities. SLA and leaf size were also particularly plastic traits, but the adaptive significance of plasticity could not be confirmed. The absence of correlation between growth across years using family means and the absence of correlations between SLA and leaf size suggested that fluctuating selection over time favored different maternal families under different annual weather conditions, which could promote functional diversity within populations in this long-lived species.

Composition and Structure of Himalayan Oak (Quercus leucotrichophora A. Camus) Forest under Various Degrees of Disturbance

Forest disturbance sometime considered as a tool of management as it believed that mid level disturbance constructs better micro-climatic conditions which ultimately boost up the plant diversity. The effect of different levels of disturbance on species composition and regeneration is very important. Present attempt was carried out in a temperate evergreen oak forest which was under various degree of disturbance. The study area is one of the large ranges of oak forest in Garhwal Himalaya and compensating various types of daily needs of local people. On the basis of IVI values Quercus leucotrichophora holds first position in all the disturbance zones whereas Myrica esculenta upgraded it's rank in highly disturbed zone and showed less impacted species by disturbance. Berberis aristata and Eupatorium adenophorum in shrub layer and Anaphalis adnata and Bidens pilosa in herb layer were found as disturbance friendly species because they attained higher rank in highly disturbed zone whereas Caryopteris foetida was found disturbance-sensitive in shrub layer. The banj oak regenerated well under mid disturbance as compared to no and high degree of disturbance and a sharp downfall in the species diversity was recorded with increasing magnitude of disturbance. Density-diameter curves showed a reverse trend of lower density in higher girth classes. The results of the study should be useful for the forest management strategies.

Seasonal variation of leaf wax n-alkane production and δ2H values from the evergreen oak tree, Quercus agrifolia

In order to understand the timing of leaf wax synthesis in higher plants, we analysed the variability in leaf wax n-alkane concentration, composition (expressed as average chain length (ACL)), and δ2Hwax values as well as plant source water δ2H values (xylem and leaf water) in the evergreen tree Quercus agrifolia over a period of 9 months, beginning with leaf flush. We identified three distinct periods of leaf development with the first month following leaf flush being characterized by de novo synthesis and possibly removal of n-alkanes. During the following 3 months, n-alkane concentrations increased sevenfold and δ2Hwax and ACL values increased, suggesting this period was the major leaf wax n-alkane formation period. During the remaining 4 months of the experiment, stable values suggest cessation of leaf wax n-alkane formation. We find that n-alkane synthesis in Q. agrifolia takes place over 4 months, substantially longer than that observed for deciduous trees.

Organic Carbon Storage in Evergreen Oak Forest Ecosystems of the Middle and High Moroccan Atlas Areas

We report carbon stock in biomass, litter and soil estimated for six locations in natural Quercus ilex L. stands of the Middle and High Moroccan Atlas. Twenty trees at each location were selected according to their diameter classes and felled to measure the biomass of trunk, branches, twigs and leaves and determine allometric relationships. Soil was sampled in five depths (0 - 15, 15 - 30, 30 - 50, 50 - 70 and 70 - 100 cm) and litterfall production measured in all tree stands. The total carbon stock in above-ground biomass ranged between 17 Mg&#183ha&#451 in A&#239t Aamar stand (High Atlas) and 91 Mg&#183ha&#451 in Ksiba stand (Middle Atlas). Perennial organs (trunk, branches and twigs) stored over 95% of the tree carbon stock. Soil organic carbon concentrations ranged from 0.01% (in 70 - 100 cm in all stands) to 8.1% (in 0 - 15 cm in the Ajdir stand in Middle Atlas). The total organic carbon stock in the soil ranged between 141.4 t&#183ha&#451 in Ajdir and 24.6 t&#183ha&#451 in Asloul. The litter contained 0.2 Mg C ha&#451 in the clearing (C2) stand of High Atlas and 14.3 Mg C ha&#451 in (Ajdir) of carbon. The best fitted model for predicting carbon stock in tree biomass was obtained by applying the allometric equation Y = aXb for each biomass fraction and stand, where Y is the aboveground biomass (dry weight) and X is the DBH (Mean diameter at breast height, 1.30 m). These previous data obtained in the present study confirm the important function of these natural forests as longterm C sinks, in forest biomass, litter and soil. The potential long term C storage of these systems is moderately high, especially in less-intensively managed forests that include large trees. The established relationship between DBH and carbon stock in different tree organs can be used for forest carbon accounting, and also synthesize available information on oak forest as a sink for atmospheric CO2, and identify the management options that may enhance the capacity for C capture/ storage in forest soils.

Effects of forest certification on the ecological condition of Mediterranean streams

SummaryForest certification, a proxy for sustainable forest management, covers more than 10% of the world's forests. Under forest certification, forest managers and landowners must comply with environmental, economic and social management standards aiming to promote forest conservation. Despite an increasing area of certified forests, there is a dearth of data on how forest certification is affecting the conservation of forest ecosystems and associated habitats.Here, we assess the effects of Forest Stewardship Council (FSC) certification, one of the largest certification schemes in the world, on the ecological condition of streams crossing Mediterranean evergreen oak woodlands.We used the Stream Visual Assessment Protocol (SVAP) to compare the ecological condition of streams located in areas with 3 and 5 years of certification, in non‐certified areas and in least disturbed streams.Forest certification positively affected the ecological condition of the surveyed streams, but its effects were only measurable after 5 years of certification. Streams with 5 years of certification had more continuous, dense and diverse riparian vegetation when compared to streams located in non‐certified areas. Moreover, the condition of streams located in areas with 5 years of forest certification was similar to the condition of least disturbed streams.Synthesis and applications. Forest certification promotes the ecological condition of streams occurring within Mediterranean evergreen oak woodlands. This mainly happens because in areas under forest certification, managers and landowners have to comply with management practices that require them to remove or reduce the main causes for stream degradation, allowing riparian habitats to recover. Within landscapes with large and increasing areas under forest certification, such as the Mediterranean cork oak woodlands, the positive effects of certification on the ecological condition of streams may spread across the hydrographic network in the medium to long term.

Developmental dynamics following selective logging of an evergreen oak forest in the Eastern Himalaya, Bhutan: Structure, composition, and spatial pattern

Brown oak (Quercus semecarpifolia, a.k.a. Kharsu, bji shing) is a biologically and economically important evergreen broadleaved tree that dominates moist temperate and lower-montane forests throughout the mid-elevation Himalaya. We demarcated two paired spatially explicit one-hectare plots in an experimentally harvested area and an unharvested old growth reserve of Q. semecarpifolia dominated forest in the Bhutan Himalaya. We compared the structure, species composition and diversity, and spatial relationships between the two plots. To test whether harvesting had been successful in establishing a new cohort of oak we compared regeneration in plots established in 1999, to data gathered over ten years after. Regeneration plots showed a paucity of Quercus regeneration in both stands. Logging did not reduce tree species richness; however, Shannon diversity, Simpson diversity, and evenness were all lower in the logged stand. We used univariate and bivariate Ripley’s-K functions to assess the spatial distribution of trees in both stands and test whether single tree felling had altered the spatial relationships among and between species. Understory species were clumped at scales >30m in canopy gaps in the old-growth reserve, whereas distribution in the logged plot was more random. Relationships between species show similar patterns with more than 80% of species showing significant clumping at scales from 12m to 30m, while ∼70% of relationships in the logged plot showed complete spatial randomness. In the old-growth reserve several species showed significant dispersion away from canopy dominant oaks. Scarce regeneration and significant changes in spatial pattern development in the harvested stand suggest changes to current silvicultural practice are needed.

Cynipidae (Hymenoptera: Cynipoidea) on Cyclobalanopsis (Fagaceae) in Mainland China, with the First Record of Sexual Generation of Cynipini in Winter

Abstract Cycloneuroterus wangi Abe, Ide, &amp; Odagiri sp. nov. and Dryocosmus nanlingensis Abe, Ide, &amp; Odagiri sp. nov. are described from Mainland China. Gall wasps associated with Quercus (Cyclobalanopsis) sessilifolia Blume, which is distributed in Japan, Taiwan, and Mainland China, have not yet been recorded. However, this evergreen oak species is considered to be the host plant of C. wangi on the basis of an observation in which eight females of this gall wasp species inserted their ovipositors into the buds of Q. (C.) sessilifolia. This is the first record of the Cynipidae (Hymenoptera: Cynipoidea) being associated with Cyclobalanopsis from Mainland China. As cynipids associated with Cyclobalanopsis have previously been known from Japan, Taiwan, and Vietnam, the discovery of C. wangi indicates that oak gall wasps associated with Cyclobalanopsis are widely distributed in Asia, as predicted previously. The collection of an adult male of D. nanlingensis by sweeping Fagaceae trees represents the first observation of a sexual generation of Cynipini in winter. Further investigations are necessary to elucidate the life cycle and to identify the host plant of D. nanlingensis. Cynipid species richness in broadleaf forests dominated by Fagaceae is considered to be high in Mainland China because of remarkable diversity of potential host plants, such as oaks and related taxa.

First identification of the pathogen causing tumor malformations in evergreen oaks in Spain

Aim of study: In recent years an increase in pests and diseases associated with truffle plantations has been detected in Spain. The appearance of tumor malformations in trunks and branches of Quercus ilex L. must be highlighted. These bumps have expanded dramatically since the increase in the number and density of truffle plantations. This pathology is not only found in plantations, but also in forests, and in trees of all ages.Area of study: the eastern mountains and the truffle plantations of the Iberian Peninsula.Material and methods: Positive results were obtained by using two types of PCR: Real-Time PCR and nested-PCR. They were carried out with primers that amplified 16S ribosomal gene sequences that are common to all known phytoplasmas.Main result: The disease manifests itself as an irregular thickening in branches of any age and in the trunk that results in the woody tissue cracking open, forming wounds. The affected branches usually undergo necrosis and in case of affecting the trunk, the tree will eventually die. After an extensive literature review and several failed attempts to isolate fungal and bacterial species from these tumors and wounds, the disease-causing organism has been identified as a Candidatus Phytoplasma.Research highlights: The appearance of this disease may endanger the profitability of an a priori profitable crop. Due to the intrinsic characteristics of the organism, and knowing that no phytosanitary treatment is able to control phytoplasmas, future works should be directed towards identifying the transmitter in order to control the disease.Key words: Candidatus Phytoplasma; PCR; Quercus ilex; black truffle; Tuber melanosporum.

Alkalinity and structure of soils determine the truffle production in the Pyrenean Regions

Aim of study: The program "Typology of truffle stations in the Pyrenean Regions" aimed to define the ecological conditions and culture practices that favor Tuber melanosporum growth and fruiting in this area.Area of study: Navarra, Catalonia, Midi-Pyrénées and Languedoc-Roussillon.Material and methods: The program was based on the survey of 212 wild and cultivated truffle beds of evergreen oaks (Quercus ilex). The data collected in the field consisted of photographs, samples of soil, roots and mycorrhizae, and information on cultural practices followed by truffle growers.Main results: (i) truffle soils are alkaline, from neutral, dolomitic, to moderately or very calcareous soils; (ii) truffle soils are light, well-structured and stable to water immersion; (iii) mycelium that colonizes roots survives in suboptimal conditions, but it does not necessarily bear ascocarps. Finally our results suggest that T. melanosporum is a relatively ubiquitous fungus able to grow, or at least to persist, in a wide range of physical and chemical soil conditions. We propose a probabilistic model of the environment favorable for fruiting, built around a two-dimensional graph with an axis for the chemical conditions, like soil alkalinity, and another axis for the physical conditions, like soil structure. Research highlights: Soil alkalinity and structure allow to built a convenient representation of the ecological capacity of a place to be good T. melanosporum habitat, and thus of the probability for truffle growers to harvest truffles according to the environmental properties of their truffle orchards.Keywords: dolomite; limestone; mycorrhizae; Quercus ilex; field survey; Tuber melanosporum.

Development of 13 polymorphic chloroplast DNA markers in Quercus gilva, a regionally endemic species in Japan

Quercus gilva is an evergreen oak species which is native to Japan, continental China and the islands of Taiwan. However, because of historical logging practices and habitat destruction in ancient times, Q. gilva is threatened with extinction in several regions of Japan. In this study, 13 polymorphic markers spanning the whole chloroplast DNA of Q. gilva were developed, using next-generation sequencing technology. These markers could distinguish between two individuals established in close proximity to one another as well as those from geographically-distinct regions. This indicates that the markers will be suitable for detecting the genetic structure and phylogeography of Q. gilva on both a large and a fine scale, potentially providing us with useful information for the conservation of this species.

Demographic history of a common pioneer tree, Zanthoxylum ailanthoides, reconstructed using isolation-with-migration model

The Japanese prickly ash, Zanthoxylum ailanthoides Siebold & Zucc. (Rutaceae), is one of the most common pioneer tree species that grow in disturbed areas, such as canopy gaps, in Japanese warm-temperate evergreen oak forests. The strong genetic structure of its current population might suggest long-term isolation of subpopulations by demographic events, in addition to ecological features of this species. Analyses of genome-wide nucleotide variation using model-based approaches are necessary to achieve a good understanding of the demographic history of a species. In this study, we analyzed the nucleotide variation in natural populations of Z. ailanthoides using a computer program that applied the isolation-with-migration model to quantitatively infer the demographic history. Nucleotide variations at 10 or 26 nuclear loci in six populations from a wide range of the species distribution were analyzed. The maximum likelihood estimate of the divergence time between the current populations in the two hypothetical refugia of Z. ailanthoides was approximately 24,000 years. Unexpectedly, the estimated size of the ancestral population was larger than the sizes of the two current populations. The results suggested a relatively recent divergence of these two populations and rapid formation of strong genetic structure among subpopulations. The large ancestral population may indicate a more complex demographic history during or after the last glacial period than the simple isolation-with-migration model implies.

First Report of Powdery Mildew Caused by Cystotheca wrightii on Quercus glauca in Korea.

Quercus glauca Thunb. (syn. Cyclobalanopsis glauca (Thunb.) Oerst.), known as ring-cupped oak or Japanese blue oak, is a dominant tree species commonly found in evergreen forests in East Asia (2). In May 2012, hundreds of Q. glauca were found heavily affected by a powdery mildew in several locations of Jeju Islands, Korea. Symptoms on overwintered leaves appeared as circular to irregular blackish violet to dark brown felt-like growths with numerous chasmothecia on abaxial leaf surfaces. New infections on current-year leaves started in early summer and were characterized by typical white patches with abundant sporulation on abaxial leaf surfaces. In early autumn, with formation of special aerial hyphae and without further sporulation, the patches turned light brown to brown. Formation of chasmothecia was noticed from late autumn. The adaxial leaf surface was free of powdery mildew growths and exhibited yellowing and discoloration. Voucher specimens were deposited in the Korea University Herbarium (KUS). Special aerial hyphae were falcate to curved, aseptate, at first hyaline, later deep brown to purplish brown, thick-walled, and 80 to 140 × 6 to 15 μm. Conidiophores were 175 to 245 × 10 to 12 μm, and produced 2 to 4 immature conidia in chains with a sinuate outline. Foot-cells of conidiophores were cylindrical and 80 to 120 μm long. Conidia were lemon- to barrel-shaped, 26 to 35 × 17 to 24 μm with a length/width ratio of 1.2 to 1.6, and devoid of fibrosin bodies. Primary conidia were apically conical and basally subtruncate. Germ tubes produced in the lateral to perihilar position of conidia were long and slender (3 μm wide). Chasmothecia were scattered or gregarious, partly embedded with special aerial hyphae, dark brown, spherical, 55 to 70 μm in diameter, and contained a single ascus. Chasmothecial peridia consisted of two layers. Exoperidia (outer layer) were composed of dark brown, polygonal cells 10 to 20 μm wide. Endoperidia (inner layer) consisted of hyaline, polygonal cells 10 to 15 μm wide. Appendages were basally attached, mycelioid, rare or few, and pale brown to rusty brown. Asci were short stalked, 55 to 72 × 35 to 46 μm, had a terminal oculus 10 to 20 μm wide, and contained 8 ascospores. Ascospores were oblong-elliptical, 22 to 27 × 10 to 12.5 μm, subhyaline, and contained 1 or 2 oil drops. The specific measurements and characteristics (especially falcate aerial hyphae) were consistent with those of Cystotheca wrightii Berk. & M.A. Curtis (1). Fungal DNA was extracted by the Chelex method. The internal transcribed spacer (ITS) region of rDNA of KUS-F27309 was amplified with primers ITS5/P3 and sequenced directly (4). The resulting 589-bp sequence was deposited in GenBank (Accession No. KF735066). A BLAST search in GenBank showed that the Korean isolate had 100% homology with C. wrightii on Q. glauca from Japan (AB000932). Powdery mildews of Q. glauca associated with C. wrightii have been known in Japan, Taiwan, and China (1,3), but not in Korea. Finding of C. wrightii on Q. glauca could pose a potential threat to other evergreen oak species in southern part of Korea.

Unravelling spatiotemporal tree-ring signals in Mediterranean oaks: a variance-covariance modelling approach of carbon and oxygen isotope ratios.

Identifying how physiological responses are structured across environmental gradients is critical to understanding in what manner ecological factors determine tree performance. Here, we investigated the spatiotemporal patterns of signal strength of carbon isotope discrimination (Δ(13)C) and oxygen isotope composition (δ(18)O) for three deciduous oaks (Quercus faginea (Lam.), Q. humilis Mill. and Q. petraea (Matt.) Liebl.) and one evergreen oak (Q. ilex L.) co-occurring in Mediterranean forests along an aridity gradient. We hypothesized that contrasting strategies in response to drought would lead to differential climate sensitivities between functional groups. Such differential sensitivities could result in a contrasting imprint on stable isotopes, depending on whether the spatial or temporal organization of tree-ring signals was analysed. To test these hypotheses, we proposed a mixed modelling framework to group isotopic records into potentially homogeneous subsets according to taxonomic or geographical criteria. To this end, carbon and oxygen isotopes were modelled through different variance-covariance structures for the variability among years (at the temporal level) or sites (at the spatial level). Signal-strength parameters were estimated from the outcome of selected models. We found striking differences between deciduous and evergreen oaks in the organization of their temporal and spatial signals. Therefore, the relationships with climate were examined independently for each functional group. While Q. ilex exhibited a large spatial dependence of isotopic signals on the temperature regime, deciduous oaks showed a greater dependence on precipitation, confirming their higher susceptibility to drought. Such contrasting responses to drought among oak types were also observed at the temporal level (interannual variability), with stronger associations with growing-season water availability in deciduous oaks. Thus, our results indicate that Mediterranean deciduous and evergreen oaks constitute two clearly differentiated functional groups in terms of their carbon and water economies, despite co-existing in a wide range of environments. In contrast, deciduous oaks form a rather homogeneous group in terms of climate sensitivity.

Genetic admixing of two evergreen oaks, Quercus acuta and Q. sessilifolia (subgenus Cyclobalanopsis), is the result of interspecific introgressive hybridization

In forests worldwide, Quercus is a major genus; however, the boundaries between the constituent species are relatively weak, and hybridization is reported frequently. In this study, we examined Quercus acuta and Quercus sessilifolia (subgenus Cyclobalanopsis), which have a putative hybrid—Q. x takaoyamensis. We investigated leaf morphological traits and microsatellites of Q. acuta and Q. sessilifolia in the area where the two species are both found. Although the leaf traits overlapped, the two species could be distinguished morphologically as demonstrated by principal component analysis based on a range of these traits. They were also genetically differentiated, with F ST = 0.104. However, they shared most of the alleles at all eight loci examined, and considerable genetic admixing was detected. Admixture analysis demonstrated that Q. acuta and Q. sessilifolia, respectively, contained 11 and 24 % of individuals with a probability of less than 0.9 of being correctly assigned to their species. Model-based testing showed that this admixing was created by not only shared ancestral polymorphism but also by hybridization. Effective population size and migration rate were estimated using the coalescent approach. We estimated 8.843 and 71.98 effective numbers of migrants per generation to Q. acuta and Q. sessilifolia, respectively. Theoretically, one to ten migrants per generation are required to prevent complete genetic differentiation. Based on the results of this study, it appears that genetic admixing, with sharing of most alleles, is probably common in the two species and is maintained by interspecific introgressive hybridization.

Genetic diversity and historical migration patterns of an endemic evergreen oak, Quercus acuta, across Korea and Japan, inferred from nuclear microsatellites

Forests dominated by broad-leaved evergreen trees cover a narrow zone of the southern coast of Korea as well as warm-temperate and subtropical regions of Japan. However, little is known about their establishment history, especially in Korea. Endemic Quercus acuta grows in Korea and Japan. We evaluated its genetic diversity, population structure, and degree of lineage admixture in terms of its distribution history. Analyses utilized seven nuclear microsatellites that were genotyped from 330 individuals of 16 populations. Genetic diversity was highest for the Japanese Kyushu populations. The allelic diversity of populations was similar between Jeju Island and Kyushu, implying that they are putative refugia. Although the mean FST value was very low, patterns for isolation-by-distance were strong and significant. Results from Bayesian clustering and Monmonier’s algorithm indicated that populations are roughly partitioned from west (Korea and Kyushu) to east (Japanese Honshu). Therefore, the two divisions within this species are demographically independent and may have arisen due to past fragmentation. In considering the mixed genetic structure between Korea and Kyushu populations, and the higher levels of genetic diversity in mainland Korea relative to Honshu, we hypothesized that this species has been able to survive within Jeju Island and Kyushu. Consequently, mainland Korea populations might have been shaped by range expansion that kept them well mixed from a continuous and large genetic resource.

Failure of Foliar-Applied Biostimulants to Enhance Drought and Salt Tolerance in Urban Trees

Urban environments present an array of environmental conditions detrimental to the biology of trees. Two major problems include deicing salts, a common soil pollutant, and drought. One potential option for managing these enviro mental disorders may be through the application of commercially available biostimulants, as these products are reported to enhance a plant's resistance to environmental stresses. Trials used containerized stock of evergreen oak (Quercus ilex), holly (Ilex aquifolium), rowan (Sorbus aucuparia), and beech (Fagus sylvatica) to evaluate the effectiveness of seven commercially available biostimulants as drought and salt protectant compounds. Results conclude that none of the biostimulants evaluated in this study provided any significant degree of salt or drought damage protection compared to water-treated controls.

Discovery of Cynipidae (Hymenoptera: Cynipoidea) from the Indochina Region, with Description of Three New Species

Abstract Plagiotrochus indochinensis Abe, Ide, Konishi, &amp; Ueno sp. nov., Dryocosmus okajimai Abe, Ide, Konishi, &amp; Ueno sp. nov., and Synophrus vietnamensis Abe, Ide, Konishi, &amp; Ueno sp. nov. are described from Vietnam. This is the first record of Cynipidae (Hymenoptera: Cynipoidea) from the Indochina region; the former two species belong to tribe Cynipini and the latter to the inquiline tribe Synergini. Based on the observation of a female P. indochinensis inserting its ovipositor into a young sprout of Quercus (Cyclobalanopsis) helferiana A. de Candolle in the field, this wasp species is considered to induce galls on this evergreen oak species. This article confirms that members of Cynipini that induce galls on Cyclobalanopsis (the ring cup oaks) are widely distributed in Asia, as predicted previously. Although D. okajimai was collected by sweeping an evergreen Fagaceae tree, its host remains to be clarified. Because the adults of S. vietnamensis were collected by sweeping an evergreen Fagaceae tree in June and dissecting a bud gall on Castanopsis sp. in September, it is considered that this wasp species has more than one generation a year. The gall-inducing ability and host plant specificity of S. vietnamensis should be examined carefully in future. The high species richness of Quercus L. and related genera in the Indochina region increases the likelihood of the existence of little-known, but potentially diverse, cynipid fauna in this region.

Persistence and detection of black truffle ectomycorrhizas in plantations: comparison between two field detection methods

Owners of black truffle (Tuber melanosporum) plantations are concerned about the persistence of its mycorrhizas and mycelium in the soil, especially until the appearance of the "truffle burn" areas and the triggering of sporocarp production, at least 5-7 years after planting truffle-inoculated seedlings. During this period, the farmer does not know whether his management is promoting black truffle development. To study the presence and abundance of T. melanosporum ectomycorrhizas in plantations, two sampling methods, direct sampling of root tips and soil core collection, are compared by analyzing 48 evergreen oak trees (Quercus ilex) inoculated with truffle. Those trees are grouped by age (<6, 6-9, >9 years old) and presence or absence of truffle production. T. melanosporum was present in 46 out of the 48 studied trees, and its ectomycorrhizas appeared in 65% of the ectomycorrhizal tips. Its abundance is significantly higher with productive trees and young trees. Direct sampling of root tips and soil core collection were equally effective in detecting this species, although soil core collection proved a better method to also evaluate ectomycorrhizal fungal diversity. To detect the presence of T. melanosporum in a given plantation, three samples suffice, with a single sample per random tree. Although the presence of mycorrhizas is not a sure sign of the future success of a black truffle plantation, its absence influences managers as to whether to continue culturing truffles in a plantation.

Inocybe aureocitrina (Inocybaceae), a new species of section Rimosae from Mediterranean evergreen oak forests

The new agaricoid species Inocybe aureocitrina, belonging to section Rimosae, is described and illustrated based on morphological and ecological characters. It is recognized by the pale citrine yellow when young to golden yellow or orange yellow pileus colour at maturity, habitat in evergreen oak calcareous forests and especially by the rather small spores, broadly ellipsoid and not reniform in profile. A comparison with the holotypes of two close taxa with yellowish colours, e.g. Inocybe obsoleta var. lutea and Inocybe fastigiata var. cerina, is presented. Illustrations of the macro- and micro-morphological features of this new species are given.