Estimation of fire cycle has been conducted by using the negative exponential function as an approximation of time-since-fire distribution of a landscape assumed to be homogeneous with respect to fire spread processes. The authors imposed predefined fire cycles on a virtual landscape of 100 cell × 100 cell, and obtained a mosaic composing of patches with different stand ages (i.e. time since fire). Graphical and statistical methods (Van Wagner 1978; Reed et al. 1998) were employed to derive fire cycle from the virtual landscape. By comparing the predefined and the derived fire cycles, the two methods and tested the effects of sample size and hazard of burning (i.e., stand’s susceptibility to fire in relation to its stand age) were evaluated on fire cycle deviation. The simulation results indicated a minimum sample size of 10 times of the annual burnt area would be required for partitioning time-since-fire distribution into homogeneous epochs indicating temporal change in fire cycle. Statistically, there was significant difference among the imposed and the derived fire cycle, regardless of sample sizes with or without consideration of hazard of burning. Both methods underestimated the more recent fire cycle without significant difference between them. The results imply that deviation of fire cycle based on time-since-fire distribution warrants cautious interpretation, especially when a landscape is spatially partitioned into small units and temporal changes in fire cycle are involved.

Populux × canescens was cultivated on solid substrate and treated by salt (150 mM NaCl). The growth parameters including new leaf formation, height increment, diameter at the base increment, fresh and dry mass of leaf, stem, coarse root, and fine root were determined. The nutrient elements in leaves of samples under salt stress and the control, and the chlorophyll fluorescence of plants separated dark and light, initial fluorescence (F_o), and maximum fluorescence (F_m) were measured. Results showed that 150 mM NaCl treatment resulted in growth reduction of Populus × canescens. Nutrient element contents in the foliage of plants under salt stress were different from that of control. The foliar N-concentrations of plants under salt stress were not affected. Contents of Na under salt stress were 120 times as much as that under control. However, contents of S, K, P, Ca, Mg, Fe, Mn under salt stress were less than that under control. Salt stress caused damage in the PSII reaction centers, i.e. photo-inhibition couldn’t be repaired under dark situation. The yield of chlorophyll fluorescence showed that several parameters associated with PSII functions, e.g. F_v/F_o, F_v/F_m were not influenced at the first stage of salt stress treatment. However, after a period of time, PSII functions were significantly inhibited, which led to the decrease of carbon assimilation. These results suggest that salt stress (150 mM NaCl) did not affect photosynthetic chlorophyll fluorescence of Populus × canescens immediately. After four day of salt stress, PSII reaction centres were seriously damaged during photo-inhibition.

For finding the changes in CO₂, H₂O exchange and their stomatal regulation during ex vitro acclimatization of regenerated Camptotheca acuminata plantlets, the net photosynthesis rate (P_n), respiration rate (R_d), light compensation point (L_c) and light saturation point (L_s), transpiration rate (Tr), stomatal conductance (g_s) and water use efficiency(WUE) were measured during 37 days of ex vitro acclimatization. The results showed that P_n sharply increased until 29 days, then slightly decreased. A substantial decrease in L _c and a substantial increase of L _s in the former two weeks were observed, indicating the light regime enlargement for effective leaf photosynthesis. Tr and g_s abruptly decreased during the first week then linearly increased until 29days ex vitro acclimatization, reflecting the strong regulation effect of stomata on water changes of ex vitro acclimating plantlets. Stomatal regulation effect on CO₂ exchange was different from that on water exchange, i.e. P_n was almost independent of g_s during the first week, while P_n was significantly correlated with g_s thereafter (i.e. dual patterns). Different from dual patterns of g_s-P_n relation, the Tr monotonously linearly increased with g_s. Furthermore, WUE was almost independent on g_s during the first week, while a marked decreasing tendency with g_s was found thereafter. At the beginning of the acclimatization, WUE was mainly determined by photosynthetic capacity, while transpiration becomes a main determinant factor for WUE from 7 to 37 days’ acclimatization.

Lyantria dispar larvae were fed with the leaves of Populus deltoids seedlings exposed to methyl jasmonate (MeJA) for 24 h. The growth and development of the larvae were investigated, and phenolics contents in treated leaves including pyrocatechol, caffeic acid, coumarin, ferulic acid and benzoic acid were also surveyed by high-pressure liquid chromatography (HPLC). Results indicated that approximate digestibility, efficiency of conversion of ingested food, efficiency of conversion of digested food, and weight of the larvae were inhibited obviously, especially from the sixth day, which may result from the increase of total phenolics contents in treated leaves. This result provides strong supports for MeJA acting as the airborne signal molecule between woody plants.

The soil drought stress experiment in different durations (no watering within 3d, 6d, 9d, 11d individually) was conducted to study the drought-resistant capacity of one-year-old seedlings for the native tree species (Machilus yunnanensis) in Yunnan Province and the introduced tree species (Cinnamomum camphora). The leaf water potential, chlorophyll content, proline content and plasma membrane permeability for two species seedlings were measured in different soil drought conditions. The results showed that, on the 9^th day of drought stress, the leaf water potential of two species decreased obviously, whereas the free proline content and plasma membrane permeability increased sharply. On the 11^th day, the leaf water potential of C. camphora seedlings was lower than that of M. yunnanensis seedlings; the plasma membrane permeability in C. camphora seedling leaves increased much more than that in M. yunnanensis seedling leaves, which showed that the injury to the former by soil drought stress was more severe than that to the latter. The free proline content in M. yunnanensis seedling leaves continued to increase on the 11^th day, but that in the C. camphora seedling leaves started to drop obviously, indicating that the reduction of osmotic regulation substance in C. camphora seedling leaves after the 11^th day was unable to maintain the osmotic balance between the plasma system and its surroundings and the water loss occurred inevitably. Comprehensively, M. yunnanensis seedlings enhanced the drought-resistance in the course of soil drought stress by maintaining higher leaf water potential and by increasing osmotic regulation substance to promote cell plasma concentration and maintain membrane structure integrity so as to reduce water loss. The subordination function index evaluated with fuzzy mathematic theory also showed that the drought-resistant capacity of M. yunnanensis seedlings was stronger than that of C. camphora seedlings.

This study was performed in five villages of Sandwip Upazila, Chittagong district with a view to identify the tree resources, utilization pattern and economic return of major fruit and timber tree species. Information collected from a total of 60 households ranging from marginal, small, medium and large categories. Number of plant species increased with the increase of homestead area. A total of 33 plant species were recorded from the homegarden, of which 19 were fruit and 14 were timber tree species. Considerable number of vegetables was also planted under the shade of the homestead trees. The investment analysis showed that average benefit-cost ratios were greater than one, net present values were positive and internal rate of returns were more than 10%. Long term investment on horticulture and timber tree species is highly profitable if species like Artocarpus heterophyllus, Cocos nucifera, Tectona grandis and Swietenia macrophylla are planted.

The biodiversity was studied in 26 communities with different structures tructures in Maoershan National Park and Liangshui Natural Reserve of Northeast Forestry University in Heilongjiang Province, China. Composition index (CI) was taken as a parameter to quantify the community dynamics, which can nicely describe forest community dynamics, meanwhile, the relationship between diversity and community dynamics were also investigated and analyzed. Results showed that the total number species of community, richness, evenness, and Shannon-Wiener diversity index were obviously different in every community. The richness decreased with the increasing CI of every community, which means richness was in inverse proportion to community dynamics. The Shannon-Wiener index of every community increased from the initial stage to the middle stage of succession, and then decreased in the climax stage. The coverage weighted foliage-height diversity index increased along with the increase of CI, which was similar as the pattern diversity.

Flowering pattern and seedling establishment of umbrella bamboo (Fargesia murieliae (Gamble) Yi) were studied in its native habitat, Mount Shennongjia in Central China. Here in 1996–2000, over 95% of the bamboo plants simultaneously flowered and died, extending from lower elevations to the higher mountains along the altitude and from southwest to northeast along the mountain settings. Bamboo seedlings emerged after the simultaneous flowering, achieving an average density of 5 460 seedlings· m⁻² in the autumn of the year following the flowering. After a high mortality throughout the first winter, bamboo seedlings remained a stable density in following 2–4 years (1130–1230 seedlings· m⁻²). Seedling density positively related to the coverage of parent bamboo, but negatively to the herb layers.

The basic method of DNA extraction (CTAB) was improved as the multi-times STE-CTAB extraction method and used to extract the DNA of birch leaved in this experiment. Results showed that the improved method is suitable not only for genomic DNA extraction of birch but also for that of other plants. The purity of genomic DNA extracted by the multi-times STE-CTAB extraction method is higher than that by one time STE-CTAB method, and it does not need the process of RNase. The factors of influencing ISSR system were explored based on the genomic DNA of birch extracted by the two methods. The optimal conditions for ISSR system were determined as follows: Mg²⁺ concentration is 1.5–3.0 mmol·L⁻¹, dNTP concentration 0.10–0.25 mmol·L⁻¹, the quantity of Taq polymerase 0.5–2.0 U, template DNA 30–100 ng, and the concentration of primer is 0.2–0.4 μmol·L⁻¹, and the reaction program was as: initial denaturation for 5 min at 94°C, 30 cycles of denaturation for 30 s at 94°C, annealing for 30 s at 51 °C, extension for 30 s at 72°C, and a final 7 min extension at 72 °C.

The study describes the scope of clonal propagation of guava (Psidium guajava Linn.) by stem cutting collected from mature stockplants. Cuttings were treated with 0, 0.2%, 0.4% and 0.8% IBA solution and rooted in the non-mist propagator. Rooted cuttings were allowed to grow in the polybags filled with soil and cow-dung mixed in the ratio of 3: 1 (by volume) for three months to assess the steckling capacity and initial growth performance. The study reveals that the species is amenable for clonal propagation by mature stem cutting. The highest rooting percentage (60%) was observed in the cuttings treated with 0.4% IBA solution followed by 0.2% IBA and the lowest was in controlled cuttings. The maximum number of primary root (32.7) was developed in the cuttings treated with 0.8% IBA solution followed by 0.4% IBA and the lowest was in the cuttings without IBA treatment. The highest survival percentage (70.9) was observed in the cuttings rooted with 0.4% IBA treatment and the lowest (58.3) was in the cuttings without any treatment. However, there was no significant variation in height growth of cutlings due to IBA treatments in rooting.

TREE submodel affiliated with TREEDYN was used to simulate biomass dynamics of Masson pine (Pinus massoniana) forest under different managements (including thinning, clear cutting, combining thinning with clear cutting). The purpose was to represent biomass dynamics involved in its development, which can provide scientific arguments for management of Masson pine forest. The results showed the scenario that 10% or 20% of biomass of the previous year was thinned every five years from 15 to 40 years made total biomass of pine forest increase slowly and it took more time to reach a mature community; If clear cutting and thinning were combined, the case C (clear cutting at 20 years of forest age, thinning 50% of remaining biomass at 30 years of forest age, and thinning 50% of remaining biomass again at 40 years of forest age) was the best scenario which can accelerate speed of development of Masson pine forest and gained better economic values.

Polyethylene octene elastomer (POE) as impact modifier was incorporated into wood/polypropylene composites (WPC) to enhance the impact strength of the composite. Two extruding routes, i.e. direct extruding route and two-stage extruding route, were adopted to produce Wood Powder/PP/POE ternary composites. The mechanical and dynamic mechanical analysis (DMA) properties of the composites were investigated. The results showed that the addition of POE can increase the impact strength of the composites, and the composites produced via two-stage extruding route showed superior mechanical properties. The results of the DMA confirmed the mechanical tests.

A study was conducted to investigate the effects of compatibilizers, including Maleic anhydride grafted polypropylene (MA-PP) and maleic anhydride grafted ethylene-propylene-diene copolymer (MA-EPDM), on wood-flour/polypropylene (WF/PP) composites. WF/PP composites were prepared by direct extrusion profiles using a twin-screw/single-screw extruder system. DMA analysis showed that the loss factor of composites decreased and the storage modulus improved in the presence of MA-PP, which indicated much better interfacial adhesion between the PP matrix and wood flour filler than in the absence of compatibilizer. Morphological feature based on SEM observation showed that MA-PP and MA-EPDM improved the dispersion of the wood particles in the plastic matrix. MA-EPDM is a soft segment, although it improved the interfacial adhesion, storage modulus decreases with adding of MA-EPDM. As compatibilizer of wood-flour/polypropylene composites, both DMA analysis and SEM feature proved that MA-PP was superior to MA-EPDM.

A compound multi-functional sensor was designed by the study on the on-line testing technology of wood-based panels, and its properties of shape, functions, size, resistance to special environment were studied in details. The operational principles of different sensors, technical flow of manufacturing, development of software systems of special functions, and the assessments of technical specification were also be introduced. This sensor adopted many new technologies, such as the applications of piezoresistant effect and heat sensitive effect can effectively measure the pressure and temperature, digital signal processing technology was used to extract and treat signals, and resist interference, encapsulation technology was used to keep the normal run of sensor under a harsh environment. Thus, the on-line compound multi-functional temperature/pressure sensor can be applied better to supervise the production of wood-based panels. All technical specifications of the compound multi-functional sensor were tested and the results met the requirements of the equipments.

The EC₅₀ values of matrine and oxymatrine against five forest pathogenic fungi (Fusarium oxysporum, Valsa pini, Cladosporium oxysporum, Sphaeropsis sapinea, Marssonina brunnea) were examined by bioassay methods. The results demonstrated that matrine and oxymatrine had strong inhibitory activities to the conidium germination of the tested fungi. The EC₅₀ values of matrine for inhibiting the conidium germination of Marssonina brunnea, Cladosporium oxysporum, Sphaeropsis sapinea were 123 μg·mL⁻¹, 272 μg·mL⁻¹, 1133 μg·mL⁻¹, respectively, and the EC₅₀ values of oxymatrine for inhibiting the conidium germination of Fusarium oxysporum, Sphaeropsis sapinea were 532 μg·mL⁻¹, 601 μg·mL⁻¹, respectively. The hyphal growth of the fungi was also significantly inhibited by matrine and oxymatrine. The EC₅₀ values of matrine inhibiting the conidium germination of Sphaeropsis spainea, Valsa pini, Fusarium oxysporum were 428 μg·mL⁻¹, 535 μg·mL⁻¹, 592 μg·mL⁻¹, respectively. The EC₅₀ values of oxymatrine inhibiting the conidium germination of Valsa pini, Fusarium oxysporum were 323, 618 μg·mL⁻¹, respectively. In the synergetic tests the EC₅₀ values of the mixtures of thiophanate methyl (or chlorthalonil) and matrine (or oxymatrine) were lower than 34 μg·mL⁻¹ while their co-toxicity coefficients were significantly higher than 100. It indicated that the mixture of the alkaloids and the chemical had potential practical utilization in controlling certain forest fungal diseases.

Fifty cultivated Catharanthus roseus seedlings were selected for tip-pruning treatment and the effects of tip-pruning on seedling growth and source-sink regulation were investigated for revealing physiological mechanisms of plants. The results showed that tip-pruning treatment resulted in obvious inhibition of apical dominance and enhancement of branching numbers. The contents of soluble sugars, acid sucrose invertase activity (AI) had a great change in differently positional leaves of the seedling. The sink strength in tip leaves of seedlings dramatically declined after tip-pruning treatment, while that in the leaves at the middle and bottom of seedlings had no obvious changes. The inhibition of apical dominance of tip leaves of seedlings was caused by the diminished sink strength due to tip-pruning treatment.

The fresh leaves of China green tea, Camellia sinensis, were collected from Fuyang, Zhejiang Province, China, in April. The tea polyphenols was extracted by four different methods (homogenized with distilled water at room temperature, homogenized with 0.3% citric acid (w/v) at room temperature, 5-min boiling and homogenized with distilled water at room temperature, homogenized with 85°C distilled water), and after preserving at room temperature, the change of the Epigallocatechin gallate (EGCG) contents of the extracts was investigated. Results indicated that the EGCG content of homogenate extracted with 85°C distilled water was the highest before the extract was preserved, followed by that of the extract homogenized with 0.3% citric acid at room temperature. During preservation, EGCG content changed obviously. The EGCG contents of homogenates extracted with distilled water at room temperature and 85°C distilled water declined quickly and separately reduced to 21.52% and 54.6% of their initial contents after preservation for 12 h. The EGCG contents extracted by 0.3% citric acid (w/v) solvent at room temperature and 5-min boiling/homogenized with distilled water at room temperature declined relatively slowly, and separately reduced to 76.9% and 85.16% of their initial contents after preservation for 12 h. It was also found that the citric acid can prevent the degradation of EGCG and the extract solution color is light green

A study was conducted to determine the antimicrobial activities of essential oil from Artemisiae argyi leaves. The sample of the essential oil was analyzed by GC-MS. From 18 compounds representing the oils, Eucalyptole (18.42%), Spathulenol (14.32), 4-Methyl-1-(1-methylethyl)-3-cyclohexen-1-ol (3.10%), 3-Carene (2.64%) appeared as the main components. The screening of antimicrobial activity of the essential oil was evaluated using agar diffusion and broth microdilution methods. Gram-positive bacterial were more sensitive than gram-negative bacterial of the 8 microorganisms, and Staphylococcus aureus ATCC 6538 showed the lowest MIC (0.3125%) and MBC (0.625%). In the disc diffusion assay, Staphylococcus epidermidis ATCC 49134 and Bacillus subtilis ATCC 6633 showed obvious inhibitory activity. Survival curve showed that, 2MIC of Artemisiae argyi essential oil had a lethal effect on Candida albicans within the first 1 h. Results presented here suggest that the essential oil of Artemisiae argyi leaves possesses antimicrobial properties, and provides scientific foundations for exploition of Artemisiae argyi.

The present study was undertaken to determine the effects of different levels of urea-N fertilizer in addition to ipil-ipil tree litter on yield of rice and insect prevalence. The field study was conducted at the Agroforestry Field Laboratory, Bangladesh Agricultural University, Mymensingh during July–December 2004. The treatments included 0, 90, 180, and 270 kg urea per hectare. All four treatments received five tons ipil-ipil tree litter per hectare. The experiment was laid out in a randomized complete block design (RCBD) with four replications. The results showed that the different treatments significantly influenced the yield and yield component viz. total tillers/hill, effective tillers/hill, filled grains and unfilled grains/panicle. The highest yield of 4.62 t·hm⁻² with an increase of 21.57% over the control was recorded in treatment 180 kg urea·hm⁻², which was statistically similar to treatment 90 kg urea·hm⁻². The prevalence of insects viz. green leafhopper, brown plant hopper, rice bugs, leaf folder and stem borers were mostly correlated with N-levels. The prevalence of insects in general gradually increased with the increase of N. Therefore, this study suggests that the combined application of organic materials (tree litter of ipil-ipil) and N-fertilizer of 90 kg·hm⁻² may produce good yield while minimizing insect prevalence in the rice field.

The Sanjiang Plain is a vast area of alluvial floodplains and low hills in northeast Heilongjiang Province. Because of the excessive land reclamation in the past, the whole forest area and the quality have decreased. In the view of sustainable development, this paper analyzed the possibilities for Non-timber Forest Product in terms of developing potentialities, markets, social effects and the status of NTFPs in several counties of Sanjiang Plain. The result showed that, active development and management for NTFPs is an optimistic option to how to balance the wetlands conservation and sustainable economic development.