马尾松林采伐迹地火烧黑炭对土壤活性碳氮库的影响

黑炭是火烧过程中不完全燃烧的产物,在火烧迹地的分布具有异质性。为了解黑炭输入量对土壤活性碳氮库的影响,选取中亚热带33年生马尾松人工林采伐迹地为研究对象,对比炼山1年后移除(B0)、单倍(B1)和双倍黑炭输入(B2)处理和未火烧对照土壤可溶性有机碳氮含量(DOC和DON)、矿质氮、土壤微生物量碳氮含量(MBC和MBN)之间的差异。结果表明:炼山对土壤DOC和DON含量的影响因土层而异,在0—10 cm土层,火烧土壤DOC和DON含量与对照土壤没有显著差异,而在10—20 cm土壤要显著低于对照土壤(P0.05)。火烧土壤矿质氮、土壤MBC和MBN含量均低于对照土壤,但差异未达到显著性水平(P0.05)。火烧土壤含水率、pH、全碳和全氮、铵态氮、土壤MBN含量均与黑炭输入量成正比,特别是在10—20 cm土层,B2处理土壤铵态氮含量显著高于B0和B1处理(P0.05)。对于土壤MBN,黑炭输入处理(B1和B2)火烧土壤MBN含量与对照土壤没有显著差异,而去除黑炭处理(B0)火烧土壤MBN含量则显著低于对照土壤(P0.05)。结果说明黑炭输入对火烧土壤的微生物群落恢复和N素保持具有积极意义,因此亚热带人工林管理过程中应重视黑炭的利用。     

Spatial and temporal patterns of morel fruiting

The biotic and abiotic factors conditioning morel fruit body production are incompletely known. We examined spatial and temporal patterns of Morchella esculenta fruiting over five years in a wooded site in Missouri, USA. Fruiting onset was inversely correlated with spring air and soil temperatures, whereas abundance was positively correlated with rain events (>10 mm) during the 30 d preceding fruiting. The two years with the greatest fruiting had the shortest fruiting seasons (6–7 d). Fruiting season length was positively correlated with soil warming, suggesting that a narrow range of optimum soil temperatures favour the explosive production of fruit bodies. All woody stems of at least 1 cm diam were mapped and stem diameter and crown condition were noted. Morel fruit bodies were significantly closer to stems of Carya spp., Tilia americana and Ulmus americana than predicted by the frequencies of these woody species or their contribution to the total basal area on the site. Although intra-annual clustering of fruit bodies was often observed, inter-annual clustering was not. The spatial pattern of M. esculenta fruiting appears to be associated with vegetation pattern, whereas the onset and abundance of fruiting are determined by the interaction of spring temperatures with availability of supporting precipitation.     

Responses of ant communities to experimental fire regimes on rangelands in the Victoria River District of the Northern Territory

Abstract Fire is a significant feature of Australia's savannas. Its use is being encouraged for cattle rangeland management, but there is little knowledge of the ecological effects of prescribed fire regimes on native biodiversity. The responses of ant communities to five experimental fire regimes over 2 years are reported from the Victoria River District in the semi‐arid tropics of northern Australia. The experiment was stratified at two levels: soil type (red and black) and fire treatment (unburnt; burnt twice in successive years in early (May) or late (October) dry season and unburnt thereafter; and burnt twice, 3 years apart, in early or late dry season). Ants were sampled twice in April, corresponding with the end of the 1997 and 1998 wet seasons. Ant species richness was not responsive to fire treatment, but reduced with time since fire on black soil. Total ant abundance also reduced with time since fire on the black soil, with significant different abundances in burnt versus unburnt plots in the 1998 sample. Soil type and sampling time had the greatest influence on ant community composition in multivariate analysis than did fire regime, although there were moderate gradients of time since fire with the black soil plots. The abundance of 19 species were significantly different between fire regimes in anova , 13 on red soil and six on black soil. The abundance of eight species (four each on red and black soil) changed significantly with time since fire, with seven promoted by burning. Ant functional group profiles changed little with fire. Total ant abundance and richness had significant relationships with key pasture species and vegetative variables. The responses of ants largely recapitulated those of plants, birds and reptiles on the same plots. It is envisaged that ants will have an important role to play in the sustainable management of Australia's rangelands aiding the off‐reserve conservation of biodiversity.     

The effect of regeneration burns on the growth,nutrient acquisition and mycorrhizae of Eucalyptus regnans F. Muell. (mountain ash) seedlings

This study was conducted to compare the effects on the growth of Eucalyptus regnans seedlings of unheated soil and soil heated to different extents (as indicated by soil colour–bright red or black) in burnt logging coupes, and to separate the effects of heating of the soil on direct nutrient availability and on morphotypes and effectiveness of ectomycorrhizae. Burnt soils were collected from three logging coupes burnt 2, 14 and 25 months previously and unbumt soil from adjacent regrowth forests. Compared to unburnt soil, the early seedling growth was stimulated in black burnt soil from all coupes (burnt 2, 14 and 25 months previously). Seedling growth was generally poor in red burnt soil, especially in soil collected 2 months after burning. However, the concentration of extractable P was extremely high in red burnt soil, especially in soil collected 2 months after burning. In black burnt soil, extractable P was increased in soil 2 months after burning, but not in the soils collected 14 or 25 months after burning. However, both total P content and concentration in seedlings were increased in all collections of black burnt soil. Frequency of ectomycorrhizae was high in seedlings grown in all black burnt soils, but the mycorrhizal mantles were poorly developed in seedlings in black burnt soil collected 2 months after burning. Seedlings were also ectomycorrhizal in red burnt soil, except in soil collected 2 months after burning. Fine root inocula from seedlings grown in black burnt soils collected 14 and 25 months after burning significantly stimulated both seedling growth and P uptake compared with the uninoculated control, whereas the fine root inocula from the seedlings grown in all the other soils did not. These results suggest that, in black burnt soil, both direct nutritional changes and changes in the ectomycorrhizae may contribute to seedling growth promotion after regeneration burns. The generally poor seedling growth in red burnt soils is likely to have been due to N deficiency as the seedlings in these soils were yellow-green and the tissue concentrations of N were significantly lower than in other treatments. This revised version was published online in June 2006 with corrections to the Cover Date.     

Molecular characterization of Morchella species from the Western Himalayan region of India

The molecular diversity of thirty-two different Morchella cultures/fruiting bodies, collected from the Western Himalayan region was studied in this investigation. Considerable taxonomic confusion exists regarding many species of Morchella. Although classical taxonomy is helpful in identification for many ascomycetes, morels exhibit considerable morphological diversity and there is disagreement in the identification of morel species. Phylogenetic analyses based on DNA sequences could help in sorting out morel taxonomy which is essential to better define the morel diversity. In this study, sequence analysis revealed that in the Western Himalayan region of India, both yellow (M. crassipes, M. spongiola) and black morels (M. elata, M. angusticeps, and M. gigas) were prominent along with two Verpa species. Phylogenetic analysis by maximum parsimony, maximum likelihood and Bayesian inference revealed two different clades and a clear distinction between yellow and black morels.     

羊肚菌烂柄病发生对土壤真菌群落结构的影响

为了解羊肚菌(Morel)烂柄病的发生对土壤真菌群落结构的影响,采用Illumina MiSeq高通量测序技术,对健康羊肚菌根际土、烂柄病发病子实体根际土及相同环境下未栽培羊肚菌土壤的真菌群落结构进行研究。结果表明,测序样品共获得344 163条序列,归为7个真菌门。各样品真菌多样性分析结果表明,未栽培土壤真菌群落多样性较高,栽培羊肚菌根际土壤真菌多样性显著降低,烂柄病发生后土壤真菌多样性增加。群落结构分析表明,烂柄病根际优势真菌类群为拟青霉属(Paecilomyces)、木霉属(Trichoderma)、葡萄穗霉属(Stachybotrys)、枝顶孢属(Acremonium)、Paratritirachium、Zopfiella、被孢霉属(Mortierella)和柄孢壳属(Podospora)。烂柄病的发生改变了土壤真菌群落结构,促进了根际真菌的繁殖。为了解羊肚菌烂柄病的发生、传播机理及防治提供了参考。     

Ecological characterization of Morel (Morchella spp.) habitats: A multivariate comparison from three forest types of district Swat,Pakistan

Morchella spp. are wild edible mushrooms growing ephemerally under particular environmental conditions in temperate regions of the world. The present study was aimed to outline some principal eco-edaphic characteristics influencing distribution of these mushrooms from three different forest types of Swat, Pakistan. A randomized circular plots were laid down along the transect line in 14 stands in study areas. Environmental variables were recorded and soil characteristics were determined, analyzed and compared. Five species were collected from N to NW slope at elevation range of 1100-2695m asl. Mean relative humidity of 58.7%, range of air temperature 13 °C-27 °C and soil temperature 6-26 °C were recorded at morel growing sites. A higher canopy cover (average 57%) favours sporocarp formation in morels. Soil analysis showed that morel preferably appeared in sandy loam to loamy textured soil at slightly acidic to neutral pH (mean=6.4) and with consistently higher organic matter (1.5%) and salt activities (mean = 38.8 μS) in the soil. IVI calculation showed that Pinus wallichiana A. B. Jackson, Juglans regia L., Abies pindrow Royle, Cedrus deodara (Roxb. ex D. Don) G. Don were dominant trees and Viburnum grandiflorum Wall. ex DC, Hedra nepalensis K. Koch, Hert and Sarcococca saligna (D. Don) Muell. Arg. were shrub species associated with morels. Whilst Fragaria nubicola (Hook.f.) Lindl., Viola canescens Wall ex Roxb. and Podophyllum hexandrum Roylae were the predominant herbs in morel habitat. This study will help to understand the natural habitat and to provide a base line information for the future conservation and management planning in the area.     

Stationarity of climate-growth response is only marginally influenced by the soil moisture regime in Western Siberia

Stationary (time-stable) relationships between a tree-ring proxy and climatic drivers are a prerequisite for using tree rings as paleo-climatological archives, but non-stationarity has been detected worldwide. Here we use a classical, temperature-sensitive treeline site in Western Siberia to specifically test the influence of micro-site conditions (wet versus dry) on the stationarity of climate-growth relationships in three co-existing conifer species: Larix sibirica Ledeb., Picea obovata Ledeb., and Pinus sibirica DuTour. We test two commonly used tree-ring proxies, annual tree-ring width (TRW) and maximum latewood density (MXD), using moving windows and the bootstrapped transfer function stability test (BTFS). Summer temperature is the main driver of tree growth in all three species, but non-stationarities exist in all species and both tree-ring proxies. For TRW, we found stationarity only for larch from both micro-sites, while for MXD, we found stationarity for spruce from both micro-sites, and for pine from the wet micro-site. Micro-site variability did not seem to affect stationarity in any systematic way. We highlight the necessity to systematically test the influence of different methods of stationarity tests, since BTFS was more sensitive than moving-window analysis. Taken together, our results underscore the importance of testing the assumption of stationarity for diverse micro-sites, different species and proxies at all sites prior to any tree-ring based temperature reconstruction, since even within one site results can be drastically different.     

Artificial cultivation of true morels: current state,issues and perspectives

Morels (Morchella, Ascomycota), which are some of the most highly prized edible and medicinal mushrooms, are of great economic and scientific value. Morel cultivation has been a research focus worldwide for more than 100 years, and the outdoor cultivation of morels has succeeded and expanded to a large scale in China in recent years. In this study, we review the progress in recent research regarding the life cycle and reproductive systems in the genus Morchella and the current state of outdoor cultivation. Sclerotia formation and conidia production are two important phases during the life cycle. The morel species cultivated commercially in America is M. rufobrunnea based on molecular phylogenetic analysis. The species currently cultivated in China are black morels, including M. importuna, M. sextalata and M. eximia. The field cultivation of morels expanded in the majority of the provinces in China with a yield of fresh morels of 0–7620?kg per ha. The key techniques include spawn production, land preparation and spawning, the addition of exogenous nutrition, fruiting management and harvesting. The application of exogenous nutrition is the most important breakthrough in the field of morel cultivation, but the mechanism remains unclear. It was estimated that the total amount of field cultivated fresh morels was ～500 t in 2015–2016. We also discuss the potential issues remaining in the current literature and suggest directions for future studies.     

Effects of clear-cutting and slash burning on soil respiration in Chinese fir and evergreen broadleaved forests in mid-subtropical China

Soil respiration (Rs) was measured over 2 years in mature, clear-cut, and clear-cut with slash burnt stands of Cunninghamia lanceolata Lamb. (Chinese fir) (CF) and secondary evergreen broadleaved forest (BF) located in Fujian Province, southeastern China from late October 2001 to 2003. Rs was measured as CO₂ evolved in situ using the soda lime absorption method. Soil temperature and moisture content at 10 cm depth were monitored in treatments of clear-cut (CC) and slash burnt (SB) and undisturbed controls. Respiration levels varied seasonally with maximum rates observed from May to July. Both, CC and SB plots showed increase in Rs for the first 3 months after treatments but for the subsequent 2 years the Rs in the CC and SB stands fell below that of controls. There were no significant difference in soil temperature among treatments in each forest, while the CC and SB treatments resulted in reduced soil moisture contents. Relationships between Rs and soil environmental variables were examined via a regression analysis. A combination of soil temperature and soil moisture content proved to be a reliable predictor of CO₂ evolution in control plots, but not in CC and SB plots. We concluded that the effect of forest management on Rs is a combined result of changes in other factors rather than soil temperature and moisture. This study contributes to our understanding of how common forestry management practices might affect soil carbon sequestration, as Rs is a major component of ecosystem respiration.     

Epigeous macrofungal succession in the first five years following a wildfire in karri (Eucalyptus diversicolor) regrowth forest in Western Australia

Abstract Following a wildfire in 17–25‐year‐old regrowth karri (Eucalyptus diversicolor) forest in the southwest of Western Australia, plots were established in burnt and similarly aged unburnt forest to monitor the fruiting of macrofungi. Thirty‐six plots on 10 sites (five burnt, five unburnt) were surveyed over a 5‐year period. Plots were surveyed every 2 weeks in the macrofungal fruiting season (April to October) and monthly for the remainder of each year. A total of 332 species were recorded. Fire did not impact significantly on mean species richness. However, a distinct mycoflora was recorded on burnt sites, and species composition on burnt sites changed substantially for each year following the fire and after 5 years was still different from that on unburnt sites. Nineteen percent of species recorded were regarded as being present as a direct result of the fire. The study also demonstrated the variable nature of macrofungal sporophore production in the absence of disturbance and the importance of regular sampling. Five distinct succession groups of post‐fire fungi were recognized. The adaptive traits of post‐fire fungi in relation to fire and the management of fire for macrofungal diversity are discussed.     

Prescribed burning in a Eucalyptus woodland suppresses fruiting of hypogeous fungi, an important food source for mammals

Fruit bodies of hypogeous fungi are an important food source for many small mammals and are consumed by larger mammals as well. A controversial hypothesis that prescribed burning increases fruiting of certain hypogeous fungi based on observations in Tasmania was tested in the Australian Capital Territory to determine if it applied in a quite different habitat. Ten pairs of plots, burnt and nonburnt, were established at each of two sites prescribe-burnt in May 1999. When sampled in early July, after autumn rains had initiated the fungal fruiting season, species richness and numbers of fruit bodies on the burnt plots were extremely low: most plots produced none at all. Both species richness and fruit body numbers were simultaneously high on nonburnt plots. One of the sites was resampled a year after the initial sampling. At that time species richness and fruit body abundance were still significantly less on burnt plots than on nonburnt, but a strong trend towards fungal recovery on the burnt plots was evident. This was particularly so when numbers of fruit bodies of one species, the hypogeous agaric Dermocybe globuliformis, were removed from the analysis. This species strongly dominated the nonburnt plots but was absent from burnt plots in both years. The trend towards recovery of fruit body abundance in the burnt plots one year after the burn was much more pronounced with exclusion of the Dermocybe data. The Tasmanian-based hypothesis was based mostly on the fruiting of two fire-adapted species in the Mesophelliaceae. Neither species occurred on our plots. Accordingly, the results and conclusions of the Tasmanian study cannot be extrapolated to other habitats without extensive additional study. Implications for management of habitat for fungi and the animals that rely on the fungi as a food source are discussed.     

DNA polymorphism in morels: complete sequences of the internal transcribed spacer of genes coding for rRNA in Morchella esculenta (yellow morel) and Morchella conica (black morel).

The internal transcribed spacer (ITS) of the gene coding for rRNA was sequenced in both directions with the gene walking technique in a black morel (Morchella conica) and a yellow morel (M. esculenta) to elucidate the ITS length discrepancy between the two species groups (750-bp ITS in black morels and 1,150-bp ITS in yellow morels.     

Plant size and season of burn affect flowering and fruiting of the grasstree Xanthorrhoea preissii

Flowering and fruiting were assessed on 14 populations of the grasstree, Xanthorrhoea preissii Endl., occurring in the Darling Range near Perth, Western Australia. Independent of site, season of burn or year of flowering, there was a strong relationship between plant height, which varied from 0.1 to over 2 m, and the incidence of postfire flowering, which varied from 1% (winter burn) to 75% (summer burn) of grasstrees present. There was no relationship between inflorescence dimensions, or flower or fruit production on a spike basis, and plant size/age (height). When standardized for height, spring‐burnt populations produced 40% as many inflorescences as autumn‐burnt populations and 20% as many as summer‐burnt populations. Inflorescences produced by spring‐burnt plants were moderately smaller than those by summer–autumn‐burnt plants. Fruit density per spike in autumn‐burnt plants was 80% of that in spring–summer‐burnt plants. The net effect was an average of 70 000 fruits produced per 100 summer‐burnt plants, 22 000 in autumn‐burnt plants, and 14 000 in spring‐burnt plants. Ecophysiological explanations of these results and their implications for population dynamics have yet to be explored.     

Quantification of extraradical mycelium of Tuber melanosporum in soils from truffle orchards in northern Spain

Quantification of extraradical mycelium of black truffle (Tuber melanosporum) has been carried out in a natural truffle ground and in seven truffle orchards (around 20 years old) established in Tierra Estella and Valdorba sites, within the natural distribution area of the black truffles in Navarre (northern Spain). Specific primers and a Taqman® probe were designed to perform real-time PCR with DNA extracted from soil samples. Amplification of T. melanosporum DNA was obtained from 131 out of the 160 soil samples. The detection limit of the technique was 1.48 μg mycelium/g of soil. The extraradical mycelium biomass detected in the soil from the natural truffle ground was significantly greater (up to ten times higher) than the mycelium biomass detected in any of the orchards. Soil from productive, nonirrigated orchards in the Tierra Estella site contained significantly more extraradical mycelium than the rest of orchards irrigated, productive of T. brumale, or nonproductive. The comparison of soil mycelium biomass in nonirrigated evergreen oak orchards in both sites showed significantly more mycelium biomass in the Tierra Estella site. This study is the first attempt to quantify extraradical mycelium of T. melanosporum in the soil using Taqman® probes. The obtained quantitative results are of special interest to evaluate the fungal response to cultural treatments and to monitor the dynamics of the extraradical mycelium of T. melanosporum in the soil.     

Effects of soil physicochemical properties and stand age on fine root biomass and vertical distribution of plantation forests in the Loess Plateau of China

The responses of aboveground parts of the forest to changes in environmental factors and stand age is well studied, but the same is not true for the belowground parts of the forest. Two plantation black locust (Robinia pseudoacacia L.) forest sites were taken in the Loess Plateau of China, one in the drier, infertile, more sandy area of the middle Loess Plateau, and another in the wetter, fertile, more clay-filled area of the southern Loess Plateau. At each site, both a younger (8-year-old) plantation stand and an older (30-year-old) plantation stand were included to study the effects of soil physicochemical properties and stand age on the fine root (<2?mm) biomass and vertical distribution of black locust forests. Root samples were taken with soil cores to a depth of 100?cm. The fine root biomass decreased from the middle site to the southern site for both stand ages, as expected, and the decrease could be due to a higher fine root N concentration associated with a higher fine root turnover rate at the southern site. There was a similar rooting pattern, though not deeper, in the drier, sandy site as predicted based on soil water infiltration and evaporation demands. The different effects of stand characters (e.g., tree density, tree height) on the fine root distribution as compared with the environmental properties may contribute partly to the similar pattern found in the two sites. The fine root biomass increased with stand age in both sites. In contrast to the evident difference in fine root biomass, there was no clear trend in the fine root vertical distribution pattern with stand age. Our results indicate that fine roots are likely to respond to changes in soil physicochemical properties and stand age by changing fine root biomass rather than by varying rooting pattern.     

Spatio-Temporal Dynamic of Tuber magnatum Mycelium in Natural Truffle Grounds

Tuber magnatum produces the world''s most expensive truffle. This fungus produces very rare ectomycorrhizas which are difficult or even impossible to detect in the field. A “real-time” PCR assay was recently developed to quantify and to track T. magnatum mycelium in soil. Here, this technique was used to investigate the spatial distribution of T. magnatum extra-radical mycelium in soil productive patches and its dynamic across seasons. This study was carried out in four different natural T. magnatum truffle grounds located in different Italian regions. During the fruiting seasons, the amount of T. magnatum mycelium was significantly higher around the fruiting points and decreased going farther away from them. Moreover, T. magnatum mycelium inside the productive patches underwent seasonal fluctuations. In early spring, the amount of T. magnatum mycelium was significantly higher than in summer. In summer, probably due to the hot and dry season, T. magnatum mycelium significantly decreased, whereas in autumn it increased again and was concentrated at the putative fruiting points. These results give new insights on T. magnatum ecology and are useful to plan the most appropriate sampling strategy for evaluating the management of a truffle ground.     

Myxomycete distribution varies among leaf litters of different vegetation in a local secondary forest of warm-temperate western Japan

Although many myxomycetes inhabit leaf litter on the forest floor and have feeding stages in litter layers, there has been little understanding regarding how the different types of leaf litter in a forest influence myxomycetes to distribute. In this study, I focused on the microhabitat distribution of foliicolous myxomycetes within a local secondary forest that consisted of various vegetation types in warm-temperate western Japan. Newly defoliated leaf litters were collected from the ground surfaces of seven different sites and then incubated in trays at a forested site throughout the entire fruiting seasons (in situ incubation method). Forty-eight species of myxomycetes (with varieties treated as species) were found in a total of 4042 samples. Leaf litters derived from different vegetation sites yielded diverse myxomycete assemblages, i.e. the Quercus glauca site yielded the richest myxomycete community (26 species), followed by Quercus variabilis site (24), Prunus verecunda site (22), Cinnamomum camphora site (21), Castanopsis cuspidata site (18), Pinus densiflora site (7) and bamboo site (7). Several myxomycete species were found to be preferentially distributed in deciduous broadleaf or evergreen leaf litter. The fraction of vegetative cover of deciduous and evergreen trees influenced the species richness and diversity of myxomycetes. Leaf litter heterogeneity derived from forest vegetation and defoliation season influenced the myxomycete distribution and species diversity. Research using in situ incubation method demonstrated that heterogeneous myxomycete microhabitats are distributed at a small spatial scale in a local forest.