大竹缘蝽生物学习性观察及防治初探

大竹缘蝽 (N otobitus excellens Distant,缘蝽科 Coreidae)在云南新平一年发生一代。成虫于竹包衣内与绿竹缘蝽 (Cloresmue Pulchellus)、狭竹缘蝽 (N.elongates Hsiao)等混聚越冬。若虫严重危害龙竹 (Dendrocalamus giganteus Munro)新笋。越冬期成虫及发笋期若虫空间分布型为聚集分布。印楝素防治若虫效果较好 ;并可在聚集高峰期采用相应的人工防治措施。     

Spectrophotometrical characteristics in the near infrared region in beech (<Emphasis Type="Italic">Fagus crenata</Emphasis>) and pine (<Emphasis Type="Italic">Pinus densiflora</Emphasis>) litters at the various decomposing stages

We examined the relationships between the absorptional characteristics in the near infrared region and the chemical changes of decomposing beech (Fagus crenata) and pine (Pinus densiflora) litters. Spectra as well as the concentrations of chemical substances approached each other and converged with decomposition, although both initial characteristics differed markedly between beech and pine. This indicated that the fundamental chemical structures were almost the same, although their organochemical composition differed. Specific absorption bands for lignin, polysaccharide, and protein were identified at 2,140 and 1,670 nm, 2,270, 1,720, 1,590, and 1,216 nm, and 2,350 nm, respectively. Absorbance at 1,670 nm, peculiar band of aromatics, showed a positive correlation with lignin concentration, which suggested the relative increment of aromatics due to condensed lignin in decomposing litters. Absorbance at 2,140 nm, characterized as the C–H bond in HRC = CHR, showed a negative correlation with lignin concentration, which suggested the decrements of some structures such as side-chains in lignin polymers unrelated to aromatics. Absorbance at 2,270, 1,720, and 1,216 nm, specified to O–H/C–O/C–H bonds in saccharide, might reflect the change of polysaccharide during decomposition because they showed a positive correlation to polysaccharide concentration. In the same way, absorbance at 2,350 nm, identified to the C–H/CH₂ bonds in protein, showed a negative correlation to nitrogen concentration in decomposing litters, which might indicate that the C–H/CH₂ bonds in protein decreased with decomposition due to microbial consumption of carbon in protein. Our findings suggested the possibility that the spectral changes indicate the litter digestibility during decomposition and that also explain the compositional change in decomposing litters.     

Chemical analysis of the product in acid-catalyzed solvolysis of cellulose using polyethylene glycol and ethylene carbonate

Degradation and decomposition of cellulose were studied in an acid-catalyzed solvolysis treatment of biomass using polyethylene glycol (PEG) and ethylene carbonate (EC). The solvolysis reaction was followed by a typical reaction system of wood liquefaction that uses sulfuric acid catalyst at 140° or 150°C at atmospheric pressure. The methods of fractionation and chemical analysis of the degraded cellulose in the solvolyzed product are discussed. The solvolyzed product was separated into several fractions, and they were hydrolyzed to release glucose and levulinic acid to determine the quantity of glucosides and levulinates in the solvolysis product. The data clearly showed that the solvolysis reaction had the same mechanism when using PEG or EC. Degradation of cellulose leads to the formation of glucosides, which then decompose, resulting in a levulinic acid structure, and producing a water-insoluble fraction. The conversion rates of both glucosides and levulinates strongly depend on the reaction conditions of the solvolysis. In particular, EC promotes faster conversion of the reactions. The method discussed here is a chemical analytical technique for characterization of the products of wood liquefaction.     

PEG bulking of wood cell walls as affected by moisture content and nature of solvent

Movement of polyethylene glycol (PEG) 1000 from wood cell lumens into adjacent cell walls was studied for different cell wall moisture contents (MCs) and PEG solvents; relative amounts of PEG that penetrated into the cell walls were estimated by Raman microscopy. It was shown that samples treated with PEG from chloroform solution adsorb less PEG than samples treated with PEG-water solution even in the case of samples with open cell wall structure near fibre saturation point MC. Reconditioning of PEG-chloroform treated samples at high relative humidities enhanced PEG bulking of cell walls, but not to the maximum amounts observed with PEG-water treatments. Raman microscopy was a useful tool for estimating relative PEG amounts in the cell walls.     

Petroleum flotation technique upgrades the germinability of <Emphasis Type="Italic">Casuarina equisetifolia</Emphasis> seed lots

The germination of Casuarina equisetifolia Forst seed lots is low (40–50%) even when freshly collected. This study aimed at upgrading the germination performance by removing non-germinable seeds using petroleum flotation technique. Seeds collected from 19 individual trees in seedling seed orchards in India were assessed using X-ray to determine the proportion of different seed lot fractions. The feasibility of petroleum ether as a separation medium was tested. Morphological characters of floating and sunken seeds were further studied using image analysis technique to examine their effects on the separation efficiency. The X-ray analysis revealed a large quantity of shrivelled, empty and insect-damaged seeds, altogether accounting 50%, which were the causes of low percentage germination of un-graded seed lots (48%). Petroleum flotation resulted in 90% germination in the sunken fraction and 4% in the floating fraction. The separation was distinct for most seed lots, except few seed lots that had relatively low germination in the sunken fractions and more than 10% germination in the floating fractions. As a whole, petroleum flotation appears to be a feasible technique to upgrade the germination of C. equisetifolia seed lots, and its efficacy is influenced by wing surface area, seed density and wing quotient of filled and empty seeds.     

Variations in soil chemical properties and microbial biomass in artificial gaps in silver fir stands

Changes in soil chemical and microbiological parameters in small (185 m²) and medium (410 m²) gaps, created in mature silver fir (Abies alba Mill) stands (mean height 30 m) in the Calabrian Apennines (Southern Italy), were studied over 2 years. Medium gaps had high soil temperature and photosynthetically active radiation (PAR) transmittance and low soil moisture. Within small gaps we detected a greater amount of organic matter, with respect to under canopy cover sites and medium gaps. Moreover, a different trend of the organic matter between small and medium gaps was observed. In the medium gaps, with respect to under canopy cover sites and small gaps, we found a relatively low content of organic matter, associated to a lower amount of humic acid, which suggested that the organic substrate undergoes a mineralization rather than a humification process. An opposite trend was observed in small gaps, where the increase of organic matter content, associated to an increase of humic acid and microbial biomass, suggested a better humification process. Moreover, in small gaps the highest level of urease and the greatest fluorescein diacetate (FDA) hydrolysis were observed. The different trend of organic matter observed in small and medium gaps may be related to changes in the environmental conditions. PAR transmittance, significantly higher in medium gaps, contributed to increase soil temperature and decrease soil moisture, affecting soil microbial populations and organic matter trend. These results suggest that the creation of small gaps represents the silvicultural practice with minor environmental impact.     

Carbon inventory methods and carbon mitigation potentials of forests in Europe: a short review of recent progress

The role of European forests and forest management in the carbon balance has received much attention in research recently. This was particularly motivated by the recognition of forest management as one possible measure countries may adopt in the framework of the Kyoto Protocol to reduce the concentration of greenhouse gases in the earth’s atmosphere. The main method to assess carbon budget in forests is based on traditional forest inventories. This method requires the conversion of measured stem volume to carbon pools. This conversion has been identified as a large source of uncertainty in past assessments. Over the last 5 years, intensive research efforts have resulted in significant advances in the reliability of forest inventory based carbon budgets. In parallel, the impact of forest management on the carbon balance of forest ecosystems has been investigated and the carbon mitigation potential of these activities has been analysed. This paper reviews the progress that was made in these two fields of research with a particular focus on European forests.

Barriers and Opportunities for the Development of Small-scale Forest Enterprises in Europe

The article introduces the background and summarises main research findings of the research articles in this special issue. The focus is on the key issues relevant for forest-based entrepreneurship development in small-scale forestry in relation to both wood and non-wood forest products and services (NWFP&S). The article draws special attention to changing forest ownership, changing owners’ motives and values, and the evolving role of forest owners’ associations in Europe. The paper draws attention to the finding that many small-scale forest owners do not treat their forest as an income-generating asset. The ownership of the forests may be more important as symbolic capital than as a source of income. This is quite opposite to the traditional wood production model that for instance most of the Forest Owners Association’s still follow. In relation to NWFP&S, the taxonomy and indicators for NWFP&S are discussed and some conclusions from studies on forest recreation innovation and NWFP&S marketing are presented. The NWFP&S sector is traditionally product-oriented, which is strategically peculiar because the long distances from rural production areas to the customers would suggest highest orientation on marketing. Also surprising is the low level of segmentation in the sector.

The Embeddedness of Collective Action in Nepalese Community Forestry

Collective action by local communities has been recognised as crucial for effective management of natural resources, particularly the management of forests in rural settings in developing countries. However, the processes and outcomes of collective action in forest management are often analysed through a narrow rational choice model, ignoring the impacts of wider social, political and economic processes in conditioning peoples’ decisions to act (or not to act) collectively. Optimistic assumptions are made for collective action being instrumental to enhance both social and ecological outcomes, but there is a paucity of empirical evidence on how and why the condition of forests has improved (or deteriorated) under collective action, and what impacts the change in forest condition has on various groups within local communities. This study critically examines the emergence, evolution and outcomes of collective action in a case of community forestry in Nepal. A mix of qualitative and quantitative methods has been used to collect primary data from the forest, households, key informants and focus groups. The emergence and outcomes of collective action is found to be embedded in social, economic and political relationships, where powerful actors control the use of forests in order to ensure conservation, thereby resulting in the underutilisation of forest products. Poor users, who depend heavily on forests, are found to be worse off economically under community forestry, but still engage in collective action for a variety of socio-political reasons. This contradicts the conventional wisdom which assumes that people only cooperate when they benefit from cooperation. It is concluded that a deeper understanding of the embeddedness of community forestry is needed in order to achieve the potential of collective action.

哈茨木霉天冬氨酸蛋白酶基因SA76的3＇RACE扩增和序列分析

由EST获得全长cDNA对于结构基因组学和功能基因组学都是至关重要的,cDNA末端快速扩增技术RACE是该领域中的重要研究方法.利用BD SMART RACE技术扩增编码分泌天冬氨酸蛋白酶SA76基因的3＇末端,将其与哈茨木霉cDNA文库中的SA76基因的EST序列进行序列拼接,获得2019bp的全长cDNA序列,其开放读码框长1593bp,5＇非编码区266bp,3＇非编码区201bp,编码530个氨基酸,有信号肽.哈茨木霉天冬氨酸蛋白酶基因与玉蜀黍赤霉、粗糙脉孢菌、球毛壳菌天冬氨酸蛋白酶基因的同源性分别为53%, 37%, 36%.利用BD SMART RACE技术首次从哈茨木霉中克隆天冬氨酸蛋白酶基因,为验证SA76基因的功能奠定基础,为进一步研究蛋白酶的作用机制及生物防治功能提供依据.