Norihiko Shiraishi

A review of strategies for wind damage assessment in Japanese forests

Forest management for minimizing wind damage risk requires predicting future wind damage as accurately as possible. However, previous studies carried out in Japan mostly focused on field observation and not on an extensive estimate of damage in various regions. This paper, therefore, aims to understand better approaches to the assessment of wind damage in Japan. First, basic descriptions of wind damage were reviewed including the process and types of tree and stand failures. Several factors relating to wind damage were also described including biological factors and stand characteristics. Second, the current methods of wind damage risk assessment were classified such as (1) observational/empirical, (2) statistical, and (3) mechanistic methods. Of the current methods, the mechanistic methods were acceptable in terms of their prediction of wind damage using the mechanistic behaviour of tree and stand as a result of wind pressure. Third, this paper reviewed previous case studies in Japan and showed that most studies of wind damage focused on particular typhoon events. Their conclusions might be difficult to apply to other settings for the estimation of future wind damage risk with the changes of stand condition (thinning, gap creation, etc.). Therefore, the mechanistic methods would be one of the most powerful approaches to estimate the possibility of future wind damage risk with changes of stand conditions. Further studies are required to develop the methods of wind damage risk assessment in Japan including the mechanical behaviour of tree and stand as a result of wind (typhoon) phenomena.

Genetic transformation of a Rhizomucor pusillus mutant defective in asparagine-linked glycosylation: production of a milk-clotting enzyme in a less-glycosylated form.

Rhizomucor pusillus 1116R3 has a defect in alg2 encoding a mannosyltransferase in the asparagine (N)-linked oligosaccharide biosynthetic pathway and produces proteins in less-glycosylated forms. For development of a genetic transformation system for this zygomycete, an uracil auxotroph (mutant 1116U17) as the host strain was derived by ultraviolet (UV) mutagenesis as 5-fluoroorotic acid-resistant colonies and the orotidine-5′-monophosphate (OMP) decarboxylase (pyr4) gene as a selection marker was cloned from the wild-type strain R. pusillus F27 by the polymerase chain reaction with primers designed on the basis of the pyr4 sequences from other fungi. The amino acid sequence of R. pusillus Pyr4 deduced from the nucleotide sequence showed high homology with the OMP decarboxylases from various fungi. The pyr4 gene on pUC19 (plasmid pRPPyr4) was introduced into protoplasts of R. pusillus 1116U17 by polyethylene glycol-assisted transformation. Transformation under optimized conditions yielded 5 Ura+ transformants with 1 μg pRPPyr4 DNA and 1 × 107 viable protoplasts. Southern blot analysis of the genomic DNA from the transformants showed that multiple copies of the pRPPyr4 sequence were integrated into the genome by homologous recombination at the pyr4 locus. For the purpose of production of a milk-clotting aspartic proteinase (MPP) in a less-glycosylated form, mpp from the wild-type strain was cloned in pRPPyr4 and introduced into protoplasts of R. pusillus 1116U17. Transformants obtained in this way contained multiple copies of mpp at the chromosomal mpp locus and produced MPP as a mixture of molecules having no sugar chains and Man0∼1GlcNAc2 at the two N-linked glycosylation sites in an amount about 12 times larger than the parent strain. The transformation system for R. pusillus 1116U17 would be useful for production of proteins with truncated N-linked oligosaccharide chains.

Characterization of alg2 encoding a mannosyltransferase in the zygomycete fungus Rhizomucor pusillus

ALG2 of Saccharomyces cerevisiae encodes the glycosyltransferase that mannosylates Man2GlcNAc2-dolichol diphosphate (PP-Dol) and Man1GlcNAc2-PP-Dol to form Man3GlcNAc2-PP-Dol. The genomic DNA and cDNA encoding an ALG2 homologue were cloned from the zygomycete fungus, Rhizomucor pusillus, and their nucleotide sequences were determined. The cloned cDNA under the control of the yeast GAL1 promoter complemented the temperature-sensitive (ts) growth of the alg2-1 mutant of S. cerevisiae, indicating that it represented a functional ALG2 homologue of R. pusillus. Five introns intervened the R. pusillus alg2 encoding a 455-amino-acid (aa) protein that showed end-to-end similarity in aa sequence to yeast Alg2 and contained a dolichol-binding consensus sequence (Val/Ile-x-Phe-x-x-Ile, where x is any aa) very near its C-terminus. The yeast alg2-1 gene had two mutation points at 377Gly to Arg and 386Gln to Lys. alg2-2 also contained two mutations at 54Glu to Lys and 377Gly to Arg. Site-directed mutagenesis of the fungal Alg2 and determination of their phenotypes in the yeast alg2-1 mutant showed that a mutation at 368Gly (equivalent to 377Gly of yeast Alg2) to Arg resulted in generation of a ts enzyme. The fungal Alg2 containing a mutation at the position corresponding to 54Glu or 386Gln of yeast Alg2 still complemented the ts growth of yeast alg2-1.

Risk assessment of wind disturbance in Japanese mountain forests.

Abstract: Wind damage of coniferous plantation forests containing hinoki (Chamaecyparis obtusa) and natural broad-leaved forests was studied in the Japanese mountains. Wind conditions determined using an air flow simulation model and historical wind disturbance records were integrated within a Geographic Information System (GIS). Based on the data set, the relationships between wind disturbance, wind speed, and stand height in plantation and natural forests were analyzed. A logistic analysis technique was applied to assess the probability of wind disturbance in stands that remained intact or were damaged as a result of the Isewan Typhoon. The results indicate that higher wind speeds and greater stand heights increase the probability of wind disturbance in both plantation and natural forests. Cross tabulation of the observed disturbance percentages in relation to wind speed and stand height in coniferous plantation forests and natural broad-leaved forests revealed that the former are more likely to be disturbed by strong winds than the latter. The logistic regression model enabled us to predict the likelihood of wind disturbance at our study site. Our results confirmed that it is possible, using wind condition prediction software, to analyze wind disturbance in mountain forests with complex terrain and steep slopes. Nomenclature: Murata et al., 2004.

Modeling Diameter Growth and Self-Thinning in Planted Sugi (Cryptomeria japonica) Stands

The objectives of this study were to analyze diameter growth in relation to natural thinning in high-density stands in even-aged, pure plantation forests and to develop a growth prediction system based on Japanese permanent plot data. Long-term data recorded in even-aged, pure, unthinned stand plots of Sugi (Cryptomeria japonica) forests were available. Relationships between log-transformed average diameter at breast height (DBH) and stand density were analyzed. In addition, the self-thinning ratio (STR) was analyzed from data gathered from unthinned permanent plots. Relationships between STR and the yield index, Ry (the ratio of actual stand volume to that at full stand density), were also analyzed and modeled. Based on these analyses, the diameter growth rate was formalized as a function of DBH, stand density and stand age, using parameters derived from full density curves. Goodness of fit of predictions of diameter growth in unthinned stands using the estimated parameters were evaluated by comparing predicted stand density and DBH with those observed in the permanent plots. The average error rate, derived by averaging the absolute values of all calculated error rates for the estimated stand density, was 1.8% with a maximum of 6.4%. The average error rate for the DBH was 2.9%, with a maximum of 8.1%. The squared Pearsons correlation coefficients of predicted and observed average DBH were between 0.97 and 1.0.

Cost-effectiveness analysis of subsidy schemes for industrial timber development and carbon sequestration in Japanese forest plantations

This study uses simulations to investigate the effects of implementing two different Japanese forestry subsidy systems on timber production and carbon stock, and examines the consequences for harvesting strategies. An existing Local Yield Table Construction System (LYCS), a wood conversion algorithm, and a harvesting cost model were used in the simulations to test the applicability of different subsidies to the thinning of stands. Using forest inventory data collected by local government staff, simulation output was used to calculate forestry profits, carbon stocks, subsidies, the amount of labor required, and the cost effectiveness of investing in subsidies. By comparing the output of simulations based on two scenarios, we found that both the clear-cutting area and the amount of harvested timber were larger under Scenario 2, in which the rules governing subsidy allocations are more relaxed, than under Scenario 1, in which the rules are more restrictive. Because the harvested timber under Scenario 1 was mainly produced by clear-cutting, the forestry profits and the subsidy predicted in the early period of the simulation, were larger under Scenario 1 than under Scenario 2. In contrast, the carbon stock was larger under Scenario 2 than under Scenario 1. The simulation model is likely to be useful for improving Plan-Do-Check-Act cycles implemented in Japanese forest management systems.

A Growth Prediction System for Local Stand Volume Derived from LIDAR Data

Recent advances in light detection and ranging (LIDAR) technology have enabled the estimation of valuable canopy parameters (e.g., crown diameter, leaf area, and canopy structure) that are difficult to obtain through in situ surveys. The objective of this study was to assess the utility of LIDAR-derived measurements of crown and growth parameters to model and predict the growth of sugi (Cryptomeria japonica) stands located in the University of Tokyo Forest, Chiba Prefecture, Japan. Initially, we confirmed that crown lengths and widths of trees in stands of various densities obtained from LIDAR data correlated with those measured in situ. Then, we developed a crown growth model from repeated LIDAR measurements of stands, suggesting that LIDAR data are adequate for this purpose, and indicating that crown surface area and tree volume growth were linearly related (R2 = 0.90; p < 0.01; RMSE tree volume < 0.02 m3). The model also provided robust predictions of the volume growth of local forests in 10 × 10 m plots based on LIDAR-derived estimates of crown surface areas. Future work should test the applicability of this growth model to facilitate practical forest management.

A method to maximise forest profitability through optimal rotation period selection under various economic, site and silvicultural conditions

BackgroundMaximising forest profitability is important from both economic and ecological perspectives. Managers of forest areas gain utility by optimising profits, and maximising the efficiency of a forest stand is also beneficial to the natural environment. This study presents a method to estimate and visualise forestry profitability based on variables defined in previous studies. The design space included economic and forest stand factors that can affect profitability. A contribution index analysis identified factors that significantly impact profitability, and these factors were then applied to data collected from a forest area in Japan. The effects of the two primary factors, discount rate and rotation period length, on a measure of profitability, the soil expectation value, were visualised in three-dimensional space.MethodsThe site used in this study, located by Morotsuka village in the Miyazaki Prefecture, Japan. Variables previously found to have significant effects on forestry profitability were used to define a design space of variables for calculating and displaying profitability, after which data from the cited study were used to estimate the variables’ SEV contribution indices. The effects of the important factors for forestry profitability were then analysed and visualised. Dimensions of the design space were constructed from previously published forestry inventory data and consisted of two stand condition factors, three site condition factors, one economic condition factor and one silvicultural planning factor. This study used previously published inventory data regarding stand age, site index and tree species. Additionally, the forestry profit simulator was used to estimate the optimal rotation period in terms of soil expectation value. The relationships between SEV and these significant factors were then graphically visualised. The significant factors identified as described above were used to estimate SEV-based profitability distributions, based on the inventory data used to construct the design space and optimal rotation periods, for the studied forest.ResultsChanges in rotation period affected forestry profitability. However, the effect depended on stand, site and economic conditions. In scenarios characterised by relatively low site productivity index and harvesting area, which results in low profitability, rotation period changes did not have a strong effect on profitability. On the other hand, it was vital to select the optimal rotation period for high profitability areas as even a small deviation had a significant impact on profitability. Furthermore, it was shown that by synchronising the harvesting times of small, adjacent stands, the overall profitability increased through reductions in forest management costs.ConclusionsThese results can help local forest management increase profitability through cooperation with individual forest owners. The presented method also has risk management applications, as it could be used to estimate the effects of external uncertainty variables on forest profitability.

Forest Certification Schemes in Japan, Indonesia, and Malaysia: Background and Reality

Forest certification is a market-driven, institutional system that promotes environmentally conscious, socially acceptable, and economically sustainable forestry management practices through third-party evaluation and certification. Despite the use of the word “institutional,” which gives the connotation of it being a government service, it is generally a private initiative. As well, the certifiers and the companies they evaluate both actively participate in the scheme. Forest management entities, once granted certification, make use of it through advertising or by stamping or labeling their logs and other wood products with a logo that communicates the organization’s achievement. When consumers choose to purchase their products, they are, in effect, supporting good forest management. Forest certification is considered a viable means for differentiating from wood illegally logged or produced through unsustainable forestry management practices.