Alteration of glutathione S-transferase properties during the development of <Emphasis Type="Italic">Micromelalopha troglodyta</Emphasis> larvae (Lepidoptera: Notodontidae)

Micromelalopha troglodyta (Graeser) is an important pest of poplar in China. Glutathione S-transferases (GSTs) are known to be responsible for adaptation mechanisms of M. troglodyta. The activities and kinetic constants of glutathione S-transferases in M. troglodyta were studied. Significant differences in glutathione S-transferase activity and kinetic characteristics were observed among five instars of M. troglodyta larvae. Furthermore, the inhibition of glutathione S-transferase activity in five instars by 24 inhibitors was conducted. The results show the inhibition of GST activity of different instars by 24 inhibitors was different. For GST activity in the 1st instar, chlorpyrifos, lambda-cyhalothrin, endosulfan, abamectin, fipronil and pyridaben were the best inhibitors tested, and for GST activity in the 2nd instar, tannic acid and quercetin were the most potent inhibitors tested, and for GST activity in the 3rd instar, the inhibitory effects of quercetin, chlorpyrifos and lambda-cyhalothrin were the highest, and for GST activity in the 4th instar, quercetin and lambda-cyhalothrin were the best inhibitors, and the inhibitory effect of phoxim was the highest for GST activity in the 5th instar. Our results show that glutathione S-transferases in different instars are qualitatively different in isozyme composition and thus different in sensitivity to inhibitors.     

Interaction analysis between slenderness ratio and resin content on mechanical properties of particleboard

The interaction between particle size and resin content is one of the most important structural parameters that can influence the accuracy of predictions about wood-composite properties. We developed three kinds of equation (linear, quadratic, and exponential) for each mechanical property of particleboard based on slenderness ratio and resin content at a constant density (0.7g cm -3 ). Results from SHAZAM software (version 9) suggested that the quadratic function was not significant, but the linear and exponential functions were significant. The interaction between particle size and resin content was analyzed by Maple 9 software. The results indicated that an exponential function can better describe the simultaneous effect of slenderness and resin content than a linear equation. Under constant resin content, particles with higher slenderness ratios increased more in modulus of rupture (MOR) and modulus of elasticity (MOE) than did particles with lower slenderness ratios. Edge withdrawal resistance (SWRe) values did not increase with increasing slenderness ratio.     

Assessment of natural regeneration status and diversity of tree species in the biodiversity conservation areas of Northeastern Bangladesh

A study was conducted at two-biodiversity conservation areas of Northeastern Bangladesh (a part of Sylhet Forest Division) to assess the species composition, diversity and density of natural regeneration of tree species both indigenous and exotic species. Data were collected by stratified random quadrate method during January 2010 to July 2010. Totally 200 circular plots of 2 m×2 m in size had 5 different habitat types of plants namely; forest, roadside, homestead (surrounding forest dwellers house), fallow land and others (canals, streams and tea gardens side), which included a total of 55 regenerating species belonging to 28 families. Meliaceae is the dominant family and shows the highest family importance value (26.3), having six species, followed by Moraceae (24.24). Among the five habitat types, forest (43 species) possess the highest number of species, followed by roadside (23 species). Total 15 exotic species among 9 families and 40 indigenous species with 24 families were recorded. For exotic species, Tectona grandis possess the highest relative density (11.7%) and relative frequency (10.5%); Senna siamea had highest relative abundance (7.83%). In case of indigenous species, Chickrassia tabularis possess the highest relative density (4.23%) and relative frequency (4%); Dipterocarpus turbinatus had the highest relative abundance (3.92%). Tectona grandis (29.66) and Chickrassia tabularis (10.8) had the highest IVI for exotic and indigenous species respectively. Different diversity indices such as Shanon-Winner diversity index, species diversity index, species richness index, species evenness index, Simpson index and species dominance index, etc. were applied to quantify definite diversity. The regeneration of species associated with low levels of disturbance was in the exotic species. Study suggests that proper protection from human disturbances and scientific management of natural regeneration of two-study forests may lead a rich biodiversity site in the country.     

Habitat associations of saplings and adults in an old-growth temperate forest in the Changbai mountains,northeastern China

Species-habitat association analysis is useful to detect spatial arrangement of individual plants, to discover rules about the distribution of species and to generate hypotheses about the possible underlying process controlling observed structures. Quantifying methods were used to classify habitats in terms of topographical variables in a mixed temperate broad-leaved Korean pine forest of the Changbai mountains in northeastern China. All of the 625 20 m × 20 m quadrats of the plot could be unambiguously assigned to one of three habitat categories (low-plateau, high-plateau and slope). Torus-translation tests were used to estimate species-habitat associations. Many species are clearly distributed in a biased fashion with respect to habitats. Fifteen (55.6%) out of 27 species showed strong positive or negative association with specific habitats. We compared species-habitat associations at the sapling and adult stages. Adjusted density values indicated few species exhibit extremely strong habitat associations. Only 9 out of 26 species had adjusted densities > 3 in the habitat for which they had strong positive affinity. Few species show the same associations at the small tree and large tree stages. Only 3 out of 22 occurring associations with a specific habitat appeared to have a consistent habitat association at the two stages. These results suggest that species-habitat associations exist in the 25-ha plot of the temperate forest of the Chang- bai mountains. Owing to limitations in our statistical methodology, we partly underestimated associations by ignoring rare species. Regeneration niches can contribute to co-existence, but regeneration niches due to habitat associations play a limited role in species co-existence, since most species show a similar trend in habitat associations at the sapling and adult stages. We should pay more attention to shifts in habitat associations, i.e. niche shifts at different stages of existence.     

A comparative study of mangrove ? oras in China and India

Species compositions in the mangrove habitats of China and India, especially on Hainan Island (China) and on the Sundarbans and the Andaman & Nicobar Islands (India), are of interest, showing several similarities and differences. The total mangrove areas of India cover about 6419 km 2 with 43 species (23 major and 20 minor species), while the mangrove areas of China cover about 150 km 2 with 26 speices (19 major and 7 minor speices). We carried out a comparison of mangrove floras in the Indian Sundarbans, Andaman & Nicobar Islands and in Hainan Island. The mangrove areas of the Indian Sundarbans comprise about 66.5% of the total Indian mangroves, presently covering an area of 4267 km 2 with 35 species from 22 genera and 16 families. There are 34 species from 17 genera and 13 families in the Andaman & Nicobar Islands. Hainan Island is considered a distribution center of mangroves; it has the largest number of mangrove species in China, i.e., 25 species from 15 genera and 12 families, accounting for about 96% of the total number of mangrove species in China. The mangroves of Hainan Island and the Andaman & Nicobar Islands belong to island types, while those of Sundarbans belong to inter-tidal deltaic types. Differences in soil type, rainfall, temperature, tidal fluctuation and other climatic features possibly cause variations in floristic composition of these regions.     

Characteristics of nucleotides and amino acids in cDNA sequence of xyloglucan endotransglycosylase cloned from <Emphasis Type="Italic">Anthocephalus chinensis</Emphasis>

Xyloglucan endotransglycosylase is an identified relaxation factor with functions of easing and extending of plant cell walls.Its activities are directly related to plant growth and elongation of organisms.Anthocephalus chinensis is a tall and fast growing evergreen tree species.We cloned the full cDNA sequence of AcEXT genes which is abundantly expressed in the cambium of A.chinensis.The sequence analysis of nucleotides and amino acids revealed the presence of a 1396 bp full cDNA sequence,including a 960 bp complete open reading frame(ORF) encoding a 320 amino acid protein.The deduced amino acid sequence of AcXET was homologous to the other known XET proteins and contained the conserved EIDFE catalytic site which was specific to all the XETs.Our data should serve as a foundation for further insight into AcXET gene molecular mechanisms during wood formation and cell wall engineering of woody plants.     

Segregation of <Emphasis Type="Italic">Eucalyptus tereticornis</Emphasis> Sm. clones for properties relevant to solid wood products

Introduction   

Wood quality is an important criterion in the selection of superior genotypes when breeding for solid wood.     

Carbon in heartwood,sapwood and bark along the stem profile in three Mediterranean <Emphasis Type="Italic">Pinus</Emphasis> species

• Context   

Understanding biological processes in forests is necessary to orientate ecosystem management towards potential C sequestration. To achieve this, information is required about changes in forest biomass C pools, including the stem components (bark, sapwood and heartwood).     

Impacts of tree canopy structure on wind flows and fire propagation simulated with FIRETEC

Introduction   

Forest fuel management in the context of fire prevention generally induces heterogeneous spatial patterns of vegetation. However, the impact of the canopy structure on both wind flows and fire behavior is not well understood.