Population genetics of the wood-decay fungus Phlebia centrifuga P. Karst. in fragmented and continuous habitats

The basidiomycete Phlebia centrifuga is a wood-decay fungus characteristic for unmanaged old-growth forests of spruce, a habitat that has become increasingly fragmented due to forest management. The aim of this study was to investigate the genetic population structures of P. centrifuga in both continuous and fragmented habitats, and estimate the potential impact of fragmentation on the genetic diversity of the fungus. Three hundred fifteen single spore isolates (representing 47 spore families and 33 single isolates) from eight populations across northern Europe (Russia, Finland, and Sweden) were screened with seven microsatellite markers and arbitrary primed polymerase chain reaction with the M13 minisatellite. The two molecular methods generally gave the same pattern for the genetic population structure. There were no significant differences between the observed and the expected heterozygosities, and the inbreeding coefficient (FIS) did not indicate any inbreeding. The fixation index (FST) revealed a general pattern with little to moderate genetic differentiation for the majority of populations, while the southernmost Swedish population Norra Kvill was the only one showing high differentiation from about half of the other populations. Swedish population Fiby with the shortest distance to the continuous habitat was moderately differentiated from most of the others and to the largest extent differed from geographically closest population of Norra Kvill. The results indicate that the fragmentation of old-growth forest in Russia and Finland is more recent than the fragmentation in Sweden, and the genetic population structures of P. centrifuga in northern Europe might be related to differences in forest landscape dynamics between the two areas.     

Development of microsatellite markers for the red‐listed wood‐decay fungus Phlebia centrifuga

Seven polymorphic microsatellite markers were developed for the wood‐decay basidiomycete Phlebia centrifuga. The primers were identified using two techniques, based on intersimple sequence repeats (ISSR) and amplified fragment length polymorphism (AFLP), respectively. The markers were screened on 27 isolates from Europe and North America. Two markers varied only on a worldwide scale, but not within Europe. The other five showed variation on both scales. These markers will now be used to characterize populations of P. centrifuga, which is red‐listed as near‐threatened in its natural habitat due to human disturbance.     

Long-distance spore dispersal in wood-inhabiting Basidiomycetes

Eight species of wood-inhabiting basidiomycetes ( Laurilia sulcata, Peniophora aurantiaca, Resinicium bicolor, Scytinostroma galactinum, Terana caerulea, Trichaptum abietinum, T. biforme and T. fuscoviolaceum ) were used in a spore-trapping test to evaluate their individual ability for long-distance spore dispersal. Petri dishes with single spore mycelia were used as baits. In the experiment, carried out at the Botanical Institute in Göteborg, spores from the air were regularly captured. Surprisingly, spores were captured from species whose nearest known natural occurrence was located quite far from Göteborg. The closest population of Peniophora aurantiaca is about 1000 km south of Göteborg. The results from this experiment support the hypothesis that fungal spores are widely and efficiently dispersed. Such a broad and extensive dispersal ability is of vital importance, especially for wood-inhabiting species which are highly dependent on a substrate which is onlv temporarily available.     

Forest fragmentation truncates a food chain based on an old-growth forest bracket fungus

We studied the effect of forest fragmentation on the insect community inhabiting an old-growth forest specialist bracket fungus, Fomitopsis rosea , in eastern Finland. Samples of the fungus from large non-isolated control areas were compared with samples from forest fragments in two isolation time classes; 2–7 yr and 12–32 yr since isolation. Fomitopsis rosea hosted a species-rich community with relatively many specialized old-growth forest insects. The numerically dominant food chain consisted of F. rosea , the tineid moth Agnathosia mendicella and the tachinid fly Elfia cingulata , a specialist parasitoid of A. mendicella . The frequency of F. rosea on suitable fallen spruce logs and the frequency of A. mendicella in fruiting bodies were significantly lower in the forest fragments than in the control areas. The median number of trophic levels decreased from three in the control areas to one in the fragments that had been isolated for the longest period of time. The parasitoid was completely missing from the fragments isolated for 12–32 yr. Our results show that in boreal forests habitat loss and fragmentation truncate food chains of specialized species in the course of time since isolation.     

Cellulolytic enzymes of the ligninolytic white-rot fungus Phlebia radiata

The ligninolytic fungus Phlebia radiata growing in a low-nitrogen medium with Avicel cellulose as the sole carbon source produced a full spectrum of celluloytic enzymes. Some properties of these enzymes were investigated during the growth of the fungal culture.     

Environmental distribution of four Carex species (Cyperaceae) in an old-growth forest

We conducted an in-depth characterization of the range of micro-environments (1 m) in which four Carex species (C. backii, C. communis, C. plantaginea, and C. platyphylla) grow in the understory of an old-growth, deciduous forest in southern Québec, Canada. All four species occurred in significantly different micro-environments. Carex plantaginea was found at the wet end of a moisture gradient, in soils with high nitrate availability. Carex backii and C. platyphylla were found at the dry end of the moisture gradient, with C. backii occupying soils with higher phosphorus availability than C. platyphylla. Carex communis, the only ant-dispersed species studied, was found in the broadest range of environmental conditions. Our results suggest that environmental heterogeneity and interspecific microhabitat preferences are important for the maintenance of local species diversity in the forest understory, not only for common species as demonstrated in previous studies, but for infrequent species, and those within a functional group (upland Carex species). However, there was some evidence that the distributions of C. backii and C. communis were not in equilibrium with current environmental conditions, indicating that historical factors, such as dispersal and colonization events, may also have important effects on the distributions of these species and the maintenance of species diversity in old-growth forest.     

Bioluminescence characteristics of a tropical terrestrial fungus (Basidiomycetes).

Freshly collected samples of luminous mycelium of a terrestrial fungus from Panama were investigated for their bioluminescence characteristics. Taxonomic identification of fungal species could not be determined because of the lack of fruiting bodies. Fluorescence excited by 380 nm illumination had an emission spectrum with a main peak at 480 nm and additional chlorophyll peaks related to the wood substrate. Bioluminescence appeared as a continuous glow that did not show any diel variation. The light production was sensitive to temperature and decreased with temperatures higher or lower than ambient. Bioluminescence intensity was sensitive to hydration, increasing by a factor of 400 immediately after exposure to water and increasing by a factor of 1 million after several hours. This increase may have occurred through dilution of superoxide dismutase, which is a suppressive factor of bioluminescence in fungus tissue. The mycelium typically transports nutritive substances back to the fruiting body. The function of luminescent mycelium may be to increase the intensity of light from the fungus and more effectively attract nocturnal insects and other animals that serve as disseminating vectors for fungal spores.     

Mn-dependent peroxidase from the lignin-degrading white rot fungus Phlebia radiata

A homogeneous Mn-dependent peroxidase (MnP) was purified from the extracellular culture fluid of the lignin-degrading white rot fungus Phlebia radiata by anion exchange chromatography. The enzyme had a molecular weight of 49,000 and pI 3.8. It was a glycoprotein, containing carbohydrate moieties accounting for 10% of the molecular weight. Mn-peroxidase was capable of oxidizing phenolic compounds in the presence of H2O2, whereas the effect on nonphenolic lignin model compounds was insignificant. MnP contained protoporphyrin IX as a prosthetic group. During enzymatic reactions H2O2 converted the native MnP to compound II. Mn2+ was essential in completing the catalytic cycle by returning the enzyme to its native state. The oxidation of ultimate substrates was dependent on superoxide radicals, O2- and probably on Mn3+ generated during the catalytic cycle. MnP exhibited high activity of NADH oxidation without exogenously added H2O2. It was shown to produce H2O2 at the expense of NADH.     

岷江上游亚高山林区老龄林地上生物量动态变化

中国川西亚高山森林中的天然林大部分为成过熟的老龄林,对其生物量动态研究有助于了解其碳储量的动态变化规律.利用全国森林资源连续清查的27个固定样地数据,基于地上各器官生物量与树干胸径(D)和树高(h)的异速生长方程,估算了岷江上游亚高林山老龄林地上生物量密度的动态变化特征及其时空变化规律.结果表明,(1)从1988～2002年期间,老龄林地上生物量密度净增量为(27.311±15.580)Mg·hm-2,平均每年增长率为(1.930±1.091 )Mg·hm-2·a-1,平均每年枯损率为(2 271±1.424)Mg·hm-2·a-1;(2)地上生物量变化受各径级保留木生长量、枯损量及进界生长量影响,其中20～40cm径级保留木生长量与生物量净增量最大,>80cm径级生物量增量最小,40～60cm和60～80cm径级生物量在调查期间净增量出现负增长.(3)岷江上游老龄林地上生物量动态变化具有时空异质性,同一样地在不同调查间隔期或同一调查期间不同样地间生物量变化不同,不仅有增量数值大小差异,还表现为生物量增量的正负差异.     

Tree dispersal strategies in the littoral forest of Sainte Luce (SE-Madagascar)

Zoochory is the most common mode of seed dispersal for the majority of plant species in the tropics. Based on the assumption of tight plant-animal interactions several hypotheses have been developed to investigate the origin of life history traits of plant diaspores and their dispersers, such as species-specific co-evolution, the low/high investment model (low investment in single fruits but massive fruiting to attract many different frugivores versus high investment in single fruits and fruit production for extended periods to provide food for few frugivores), and the evolution of syndromes which represent plant adaptations to disperser groups (e.g. birds, mammals, mixed). To test these hypotheses the dispersal strategies of 34 tree species were determined in the littoral forest of Sainte Luce (SE-Madagascar) with the help of fruit traps and tree watches. The impact of fruit consumers on the seeds was determined based on detailed behavioral observations. Phenological, morphological and biochemical fruit traits from tree species were measured to look for co-variation with different types of dispersal. No indication for species-specific co-evolution could be found nor any support for the low/high investment model. However dispersal syndromes could be distinguished as diaspores dispersed by birds, mammals or both groups (mixed) differ in the size of their fruits and seeds, fruit shape, and seed number, but not in biochemical traits. Five large-seeded tree species seem to depend critically on the largest lemur, Eulemur fulvus collaris, for seed dispersal. However, this does not represent a case of tight species-specific co-evolution. Rather it seems to be the consequence of the extinction of the larger frugivorous birds and lemurs which might also have fed on these large fruits. Nevertheless these interactions are of crucial importance to conserve the integrity of the forest.     

Physiological effects of Shinrin-yoku (taking in the atmosphere of the forest) in an old-growth broadleaf forest in Yamagata Prefecture, Japan

The physiological effects of "Shinrin-yoku" (taking in the atmosphere of the forest) were examined by investigating blood pressure, pulse rate, heart rate variability (HRV), salivary cortisol concentration, and immunoglobulin A concentration in saliva. Subjective feelings of being "comfortable", "calm", and "refreshed" were also assessed by questionnaire. The subjects were 12 male university students aged from 21 to 23 (mean+/-SD: 22.0+/-1.0). The physiological measurements were conducted six times, i.e., in the morning and evening before meals at the place of accommodation, before and after the subjects walked a predetermined course in the forest and city areas for 15 minutes, and before and after they sat still on a chair watching the scenery in the respective areas for 15 minutes. The findings were as follows. In the forest area compared to the city area, 1) blood pressure and pulse rate were significantly lower, and 2) the power of the HF component of the HRV tended to be higher and LF/(LF+HF) tended to be lower. Also, 3) salivary cortisol concentration was significantly lower in the forest area. These physiological responses suggest that sympathetic nervous activity was suppressed and parasympathetic nervous activity was enhanced in the forest area, and that "Shinrin-yoku" reduced stress levels. In the subjective evaluation, 4) "comfortable", "calm", and "refreshed" feelings were significantly higher in the forest area. The present study has, by conducting physiological investigations with subjective evaluations as supporting evidence, demonstrated the relaxing and stress-relieving effects of "Shinrin-yoku".     

Basidiospore Numbers in Agaricus bisporus (Lange) Imbach

The number of spores per basidium in the cultivated mushroom Agaricus bisporus can be readily determined using the light microscope.     

Tree size distributions in an old-growth temperate forest

Despite the wide variation in the structural characteristics in natural forests, tree size distribution show fundamental similarities that suggest general underlying principles. The metabolic ecology theory predicts the number of individual scales as the −2 power of tree diameter. The demographic equilibrium theory predicts tree size distribution starting from the relationship of size distributions with growth and mortality at demographic equilibrium. Several analytic predictions for tree size distributions are derived from the demographic equilibrium theory, based on different growth and mortality functions. In addition, some purely phenomenological functions, such as polynomial function, have been used to describe the tree size distributions. In this paper, we use the metabolic ecology theory, the demographic equilibrium theory and the polynomial function to predict the tree size distribution for both the whole community and each species in an old-growth temperate forest in northeastern China. The results show that metabolic ecology theory predictions for the scaling of tree abundance with diameter were unequivocally rejected in the studied forest. Although these predictions of demographic theory are the best models for most of the species in the temperate forest, the best models for some species ( Tilia amurensis , Quercus mongolica and Fraxinus mandshurica ) are compound curves (i.e. rotated sigmoid curves), best predicted by the polynomial function. Hence, the size distributions of natural forests were unlikely to be invariant and the predictive ability of general models was limited. As a result, developing a more sophisticated theory to predict tree size distributions remains a complex, yet tantalizing, challenge.     

Intraspecific variability in Peniophora aurantiaca (Basidiomycetes)

Intraspecific, genetic variation was studied in Peniophora aurantiaca using the internal transcribed spacer regions of the nuclear ribosomal RNA region (ITS). Specimens originating from Canada, Greenland and Switzerland were compared. The ITS sequence data were similar with only 11 phylogenetically informative characters, but an allopatric differentiation was obvious. Overall variability is high within the North American specimens compared with the Swiss specimens which had almost no variable characters.     

Disturbance dynamics and history of an old-growth subalpine fir (Abies fargesii) forest in central China

Disturbance history of an old-growth subalpine fir (Abies fargesii) forest in the Shennongjia Mountains of central China was reconstructed using dendroecological methods. Increment cores were extracted from 468 trees within six 100 m × 50 m permanent transects distributed across the old-growth subalpine fir forest of 300 ha. Growth patterns of 299 fir cores were examined for abrupt increases in radial growth to indicate formation of past canopy gaps and for rapid early radial growth to indicate establishment in past canopy gaps. The results showed that 70.8 % of the canopy fir trees experienced an average of 0.78 (ranging from 0 to 2) major release event for an average of 15.8 (ranging from 10 to 24) years, and an average of 1.94 (ranging from 0 to 3) moderate release events for an average of 25.6 (ranging from 10 to 36) years before they reached canopy. Recruitment pulse of trees coincided temporally with the peak of disturbance rate from the 1900s to the 1910s, suggesting occurrence of intense disturbance events during the time period. Radial growth analyses indicated that a history with small-scale disturbance events has resulted in the formation of the old-growth subalpine fir forest, and stand-replacing disturbances might not be necessary for the development of the forest. This study provides strong evidence that there are substantial variations in the disturbance severity and frequency over time. Most disturbance events might rather cause treefall gaps than clear large areas of forest at once. Thus, the old-growth subalpine fir forest experienced frequent gap-scale disturbances and few large-scale disturbances in its development history.     

Speciation and distribution inCorticiaceae (Basidiomycetes)

Evolutionary processes inCorticiaceae (wood-inhabiting basidiomycetes) are discussed on the basis of sibling species analysis, colonization strategies, and the known present distribution. It is proposed that the phylogenetical differentiation of basidiocarp structures may be very old and many species have remained unchanged. Subsequent evolution has to a great part been the effect of biological interaction with the environment, like colonization of new substrata, and the formation of species complexes may be a consequence of this. The amount of spores liberated from a single basidiocarp is regarded as an adaptive character for dispersal mainly in the immediate environment. The actual, wide distribution of many species is supposed to be associated with expansion of pertaining forest types in the past. When rapid expansion of a species occurs it is likely to be connected with occupation of a new ecological niche. Finally, the consequences for fungal communities in modern forestry are discussed.     

Structure of extracellular polysaccharide produced by lignin-degrading fungus Phlebia radiata in liquid culture

The extracellular material (EM) produced by the white rot fungus Phlebia radiata cultured in an N-limited liquid medium was studied. Carbohydrate analysis showed maximum concentration of glucose as the major monosaccharide component of EM was found on postinoculation day 9. Beyond day 9 of cultivation the proportion of glucose decreased suggesting that the glucan component of EM had been further metabolized. The analysis of EM at day 9 revealed the presence of the following monosaccharides (in relative %): glucose (62); galactose (16); mannose (13); xylose (4); and fucose (5). The carbohydrate analysis together with the presence of protein in EM corresponds to a mixture of glucan and glycoprotein. Purification by trypsin treatment yielded an enriched glucose-containing extracellular polysaccharide (EPS). Methylation analysis identified EPS as (1-3)-beta-D-glucan highly branched at C-6. The structure of the glucan was confirmed by 13C-NMR spectroscopy. The results suggest that P. radiata's EPS is entangled with a glycoprotein in a complex that makes the extracellular sheath surrounding the hyphae.     

中国哈宁管菌属(担子菌纲)的首次报道

报道了中国担子菌纲一新记录属——哈宁管菌属Henningsomyces,并对采集于云南省迪庆州香格里拉县千湖山冷杉倒木上的一新记录种雪白哈宁管菌Henningsomyces candidus进行了详细描述。该菌最典型的形态特征是担子果由许多白色小管直立排列而成,菌丝体为一体系,同时具有简单分隔和锁状联合,担孢子薄壁、光滑、近椭圆形,菌管口的菌丝呈明显的树状分枝。