Journal of Northeast Forestry University

The paper deals with the stand structure and yield of black locust (Robinia pseudoacacia L.) forests mixed with white (Populus alba L.) in various proportions, partly applying a new methodological approach. The main stand structure and yield factors were determined separately for each species, measured stem by stem, using the volume functions prepared for each species. The ratio of the volumes of the species (A and B) in mixed and in pure stands (based on volume tables) was determined. A close relationship has been found between the ratio by relative total volume and the proportion (by the number of stems) of the species. The relative surplus in the volume of the mixed stands varied between 1.24–1.55 at the age of 16 compared to the control, i.e. the yield of pure stands of the species concerned. The trial has also proven that if two species have a fast initial growth rate and a similar rotation age, they can be planted in mixed stands resulting in mutual advantages.

Density effects on the growth and self-thinning of Eucalyptus urophylla stands were examined for 7 years. The reciprocal equation of the competition-density (C–D) effect was used to describe the C–D effect in even-aged pure stands of E. urophylla during course of self-thinning and showed a good fit to the data. The time trajectories of mean stem volume-density nearly paralleled the y-axis during early growth stages of stands, and then began to curve left. Finally, the mean stem volume-density trajectories of the low-, middle- and high-density stands tended to follow the self-thinning lines with slopes of − 2.01, − 1.90 and − 1.99, respectively. With increasing physical time t, the biological time τ increased rapidly during early growth stages and became slow gradually during later growth stages. Realized density-initial density curves tended to become more or less flat with increasing initial density, indicating the existence of an asymptotic value for density at a given time. The coefficient ε, the reciprocal of which represents the asymptotic density at a given time, increased with increasing biological time τ, indicating that the asymptotic density decreased with increasing stand age. Final yield Y(t) increased gradually with increasing stand age.

We characterized 14 anonymous nuclear loci from Pinus thunbergii Parl., an important pine species native to Japan. One hundred and twenty-six single nucleotide polymorphisms (SNPs) were identified from these loci, giving a frequency of 1 SNP per 51 bp. Nucleotide diversity (θ) ranged from 1.06 × 10−3 to 11.87 × 10−3, with an average of 4.99 × 10−3. Only one locus (mK45) deviated significantly from the Hardy-Weinberg equilibrium. Thirteen of 14 loci were applicable in other pine species. These loci will be useful for nucleotide variation studies and will provide material for SNP-based marker development in P. thunbergii and related species.

The Asian longhorned beetle (ALB), Anoplophora glabripennis, is a well-known stem borer with high polyphagous properties causing frequent outbreaks in northeast China. An attractant-based trap is needed to improve the sensitivity, reliability, and efficiency for detection of the beetle. In this study, the effects of attractants, trap types and color synergy of a trapping system were evaluated. Attractant blends comprised of the male-produced, two-component pheromone plus plant volatiles were used in the field in Hengshui city. Plant volatiles (e.g., 1-pentanol, and 2-pentanol) in combination with male pheromones increased the mean number of trapped ALB compared to the pheromone alone. Males responded better than females to traps baited with plant volatiles alone, whereas traps emitting plant volatiles plus pheromone, regardless of trap type, captured more females than males. The ALB-trapping efficiency of a modified flight intercept panel trap was more than ten times as high as a woodborer panel trap and 1.2 times a flight intercept panel trap. The 1-pentanol and 2-pentanol attractants alone or in combination with male-produced pheromone were more effective for monitoring ALB than common lures. In laboratory Y-tube olfactometer experiments, the color brown was better at increasing attraction of both males and females to 1-pentanol, 2-pentanol, 1-pentanol + pheromone, and 2-pentanol + pheromone compared to the clear-glass control arm. The findings provide a reliable and effective trap system to monitor ALB infestations.

Forest fires are influenced by several factors, including forest location, species type, age and density, date of fire occurrence, temperatures, and wind speeds, among others. This study investigates the quantitative effects of these factors on the degree of forest fire disaster using nonparametric statistical methods to provide a theoretical basis and data support for forest fire management. Data on forest fire damage from 1969 to 2013 was analyzed. The results indicate that different forest locations and types, fire occurrence dates, temperatures, and wind speeds were statistically significant. The eastern regions of the study area experienced the highest fire occurrence, accounting for 85.0% of the total number of fires as well as the largest average forested area burned. April, May, and October had more frequent fires than other months, accounting for 78.9%, while September had the most extensive forested area burned (63.08 ha) and burnt area (106.34 ha). Hardwood mixed forest and oak forest had more frequent fires, accounting for 31.9% and 26.0%, respectively. Hardwood-conifer mixed forest had the most forested area burned (50.18 ha) and burnt area (65.09 ha). Temperatures, wind speeds, and their interaction had significant impacts on forested area burned and area burnt.

Genetic diversities and genetic differentiations of the four Pinus koraiensis populations (Gaofeng Forestry Farm at Tangwanghe in Yichun City, Erdaobaihe Town in the Changbai Mountains, Shengshan Forestry Farm in Heihe City, in China, and the suburb of Vladivostok City in Russia) were analyzed by using ISSR-PCR technique. The results of 15 primers amplification showed that the ratio of polymorphic site of P. koraiensis population was 60.7%. Each primer had 3.6 polymorphic sites. The diversity levels of the four P. koraiensis populations were rather higher compared with those of other Pinaceae species. The genetic diversity levels of P. koraiensis populations grown in the center region were higher than those grown in the edge zone. The genetic diversity of P. koraiensis mainly came from the interior of the population, accounting for 73% of total genetic diversity. There were no positive correlation between genetic distances and geographical distances for the four P. koraiensis populations. The gradual decrease of natural distribution region of P. koraiensis was due to anthropic destroy and environmental factors (i.e. fire and wind throw), rather than the lower genetic diversity.