重度盐碱地营造杨树人工林土壤改良效果

为探讨重度盐碱地营造杨树人工林对土壤的改良效果,本实验以黑龙江省肇东市重度盐碱地作为研究对象,采用小穴改良"一字沟"觅食丘式原位修复、小穴改良"十字沟"觅食台式原位修复和小穴改良"井字沟"觅食坛式原位修复的方法对重度盐碱地进行改良。研究结果表明:实施不同改良措施后土壤特性发生了显著变化,土壤pH值、电导率含量显著下降;土壤碳酸根含量显著下降,交换性钙、镁含量显著提高;土壤胡敏酸和壳聚糖含量明显提高,土壤肥力增加。因此,本研究所采用的三种不同的改良措施具有良好的改良效果。     

Superior wood for violins--wood decay fungi as a substitute for cold climate

Violins produced by Antonio Stradivari during the late 17th and early 18th centuries are reputed to have superior tonal qualities. Dendrochronological studies show that Stradivari used Norway spruce that had grown mostly during the Maunder Minimum, a period of reduced solar activity when relatively low temperatures caused trees to lay down wood with narrow annual rings, resulting in a high modulus of elasticity and low density. The main objective was to determine whether wood can be processed using selected decay fungi so that it becomes acoustically similar to the wood of trees that have grown in a cold climate (i.e. reduced density and unchanged modulus of elasticity). This was investigated by incubating resonance wood specimens of Norway spruce (Picea abies) and sycamore (Acer pseudoplatanus) with fungal species that can reduce wood density, but lack the ability to degrade the compound middle lamellae, at least in the earlier stages of decay. Microscopic assessment of the incubated specimens and measurement of five physical properties (density, modulus of elasticity, speed of sound, radiation ratio, and the damping factor) using resonance frequency revealed that in the wood of both species there was a reduction in density, accompanied by relatively little change in the speed of sound. Thus, radiation ratio was increased from 'poor' to 'good', on a par with 'superior' resonance wood grown in a cold climate.     

Gene expression in Eucalyptus branch wood with marked variation in cellulose microfibril orientation and lacking G-layers

In response to gravitational stresses, angiosperm trees form tension wood in the upper sides of branches and leaning stems in which cellulose content is higher, microfibrils are typically aligned closely with the fibre axis and the fibres often have a thick inner gelatinous cell wall layer (G-layer). Gene expression was studied in Eucalyptus nitens branches oriented at 45 degrees using microarrays containing 4900 xylem cDNAs, and wood fibre characteristics revealed by X-ray diffraction, chemical and histochemical methods. Xylem fibres in tension wood (upper branch) had a low microfibril angle, contained few fibres with G-layers and had higher cellulose and decreased Klason lignin compared with lower branch wood. Expression of two closely related fasciclin-like arabinogalactan proteins and a beta-tubulin was inversely correlated with microfibril angle in upper and lower xylem from branches. Structural and chemical modifications throughout the secondary cell walls of fibres sufficient to resist tension forces in branches can occur in the absence of G-layer enriched fibres and some important genes involved in responses to gravitational stress in eucalypt xylem are identified.     

Growth and Wood/Bark Properties of Abies faxoniana Seedlings as Affected by Elevated CO2

Growth and wood and bark properties of Abies faxoniana seedlings after one year's exposure to elevated CO2 concentration (ambient 350 (=1= 25) μmol/mol) under two planting densities (28 or 84 plants/mz) were investigated in closed-top chambers. Tree height, stem diameter and cross-sectional area, and total biomass were enhanced under elevated CO2 concentration, and reduced under high planting density. Most traits of stem bark were improved under elevated CO2 concentration and reduced under high planting density. Stem wood production was significantly increased in volume under elevated CO2 concentration under both densities, and the stem wood density decreased under elevated CO2 concentration and increased under high planting density. These results suggest that the response of stem wood and bark to elevated CO2 concentration is density dependent. This may be of great importance in a future CO2 enriched world in natural forests where plant density varies considerably. The results also show that the bark/wood ratio in diameter, stem cross-sectional area and dry weight are not proportionally affected by elevated CO2 concentration under the two contrasting planting densities. This indicates that the response magnitude of stem bark and stem wood to elevated CO2 concentration are different but their response directions are the same.     

Identification of differentially expressed proteins in poplar leaves induced by Marssonina brunnea f. Sp. Multigermtubi

Black spot disease in poplar is a disease of the leaf caused by fungus. The major pathogen is Marssonina brunnea f. sp. multigermtubi. To date, little is known about the molecular mechanism of poplar （M. brunnea） interaction. In order to identify the proteins related to disease resistance and understand its molecular basis, the clone ＂NL895＂ （P. euramericana CL＂NL895＂）, which is highly resistant to M. brunnea f. sp. multigermtubi, was used in this study. We used two-dimensional gel electrophoresis （2-DE） and mass spectrometry （MS） to identify the proteins in poplar leaves that were differentially expressed in response to black spot disease pathogen, M. brunnea f. sp. multigermtubi. Proteins extracted from poplar leaves at 0, 12, 24, 48, and 72 h after pathogen-inoculation were separated by 2-DE, About 500 reproducible protein spots were detected, of which 40 protein spots displayed differential expression in levels and were subjected to Matrix assisted laser desorption/ionization time of flight mass spectrometry （MALDI-TOF MS） followed by database searching. According to the function, the identified proteins were sorted into five categories, that is, protein synthesis, metabolism, defense response and unclassified proteins.     

Symptoms, Wood Lesions and Fungi Associated with Esca in Organic Vineyards in Languedoc-Roussillon (France)

We analysed symptoms, wood lesions and fungi associated with esca in mature organic vineyards in the Languedoc‐Roussillon region. Most previous surveys concerning esca syndrome were conducted in conventionally managed vineyards in other regions. We first found that esca may be present at a very low level in vineyards that were not treated with sodium arsenite. Affected vines displayed three types of symptoms: leaves with interveinal necrosis, wilt of entire branches and these two symptoms in combination. During the 3‐year survey, not all affected vines displayed symptoms every year and the same vine rarely displayed the same symptom or combination of symptoms in successive years. The incidence of esca appeared to be correlated with the percentage of vines that died during the survey but no correlation was found with either mortality before the survey or with the age of the vineyard. Observation of cross‐sections of a total of 210 vines with esca symptoms and isolation of fungi from the wood lesions led to similar results to those obtained in conventionally managed vineyards. Four different lesions were identified: a white rot lesion, a brown lesion in a central position, a brown lesion in a sectorial position and a scattered black spotting in healthy wood. The most frequently observed fungal species were Fomitiporia mediterranea (Fom), Phaeomoniella chlamydospora, Phaeoacremonium aleophilum and Eutypa lata. The white rot lesion caused by Fom was generally accompanied by one or more other lesions in the same vine. Similarly, Fom was generally isolated with one or several other fungi. No relationship was detected between the expression of external symptoms and any specific lesion or fungus. Our study also showed that esca and Eutypa dieback are often superimposed in our region of sampling.     

Oak woodland restoration: testing the effects on biodiversity of mycetophilids in southern Sweden

The effect of harvesting biofuel and woodland restoration on biodiversity is debated. To evaluate the effects of partial cutting on more organism groups, we used pairwise experimental and undisturbed control stands in a large landscape. On average 26% of the basal area including 50–95% of the understorey was harvested at each of 15 oak-rich forest sites. Our earlier results of partial cutting suggested a positive short-term effect for vascular plants and beetles and no or minor negative effects for fungi. Here we analyse the response of mycetophilids (Diptera: Sciaroidea excl. Sciaridae), a neglected but species-rich insect group that was strongly disfavoured by clear-cutting in previous studies. Increased deadwood (slash) caused increase in the number of individuals of mycetophilids associated with wood or wood fungi. The rarefaction species numbers of mycetophilids declined after the treatment, but the absolute number of species was not affected. Our results indicate that a 25% harvest can be compatible with conservation of vascular plants, fungi, saproxylic and herbivorous beetles and mycetophilids in temperate hardwood stands of the type studied. However, more studies are needed to determine what level(s) of stand thinning can be tolerated by different taxa in landscapes with small fragmented conservation stands.