This case study analysis examines how overstory and topographic conditions impact regeneration of Abies sachalinensis (Abies) in a selection forest at the University of Tokyo Hokkaido Forest in Northern Japan. The analysis includes 1,382 inventory plots that were regularly surveyed between 1995 and 2004. The density of Abies juveniles and basal area of mature Abies overstory trees were calculated for each plot. Five topographic conditions—elevation, slope angle,curvature, solar radiation, and the topographic wetness index—were examined through spatial analyses using ArcGIS software with 10-m grid digital elevation models. A general linear mixed model analysis was performed to determine site factors affecting the abundance of Abies juveniles. Results indicated that basal area of mature overstory Abies, slope angle, curvature, and solar radiation had positive effects on the abundance of Abies juveniles, while elevation had a negative effect. These factors may be related to the distribution of dwarf bamboo (Sasa senanensis and S. kurilensis) and pathogenic fungus (Racodium therryanum or Herpotrichia juniperi), both of which are recognized as major inhibitors of natural regeneration in Hokkaido.
The objective of this study was to investigate the effect of the initialstand age distribution on the carbon dynamics of sugi (Cryptomeria japonica) planted forests on a national scale. We ran simulations of carbon dynamics of sugi planted forests for all of Japan from 2005 to 2050 using the simulation system developed in previous a study. The initial stand age distributions were set as follows: Case 1) actual distribution, Case 2) 30-year younger distribution, Case 3) 30-year older distribution, and Case 4) uniform distribution. The carbon removal rate was higher for Cases 2 and 4 than Case 1 for the earlier simulation period, but as the young stands decreased, the carbon removal rate also decreased in the later simulation period. These results indicated that the effect of the initial stand age distribution on national-scale carbon dynamics was limited in a 45-year simulation. Through this simulation study, we reconfirmed that young stands are essential for maintaining the national-scale carbon removal rate, and also that clearcutting and subsequent replanting are critical for future carbon absorption.
The importance of studying the ecology of coppice forests in Japan has risen recently amid growing demands to reestablish utilization of their tangible resources. The objective of the paper is to assess whether the spatial distribution of trees at an undisturbed aging coppice follows some common pattern and how its composition changes with time. Coppice forests in Japan usually grow on steep lands and conventionally used forest inventory methods and methods used in ecological studies are time-consuming. Therefore, a rapid sampling approach based on measurements of angles and distances was used to achieve the objectives of this study. The field survey was conducted at coppice stands harvested 48, 60 and 77 years ago. Results suggest that distribution of the trees at aging-coppices shifts toward a regular spatial pattern. However, the process toward this regularity is slow and the distributions of individual trees were still not significantly di!erent from a random pattern. Use of the combined angle-distance methodology is rapid and the data collected can be useful for planning ecologically-friendly management of coppice forests.
This study proposes a new approach to assess the aesthetic quality of forest areas using false color infrared aerial photographs and image analysis techniques. The proposed approach is applied to open evergreen woodlands in Portugal, which are dominated by Q. ilex subsp. rotundifolia. Aesthetic quality is assessed using the following indicators: spatial pattern, crown condition, percent crown cover,and a tree mortality index. Results suggest a number of these indicators, including spatial patterns, crown conditions, and percent crown cover, can quickly and efficiently be assessed using readily available aerial photography databases. The proposed method is especially useful for large-scale field surveys that may precede more detailed field assessments of specific areas.
First, the basic concept of the author’s previous multi-country multicommodity Ricardian model including intermediate goods is made clear by using an improved model with two countries and two goods, which is applicable even in cases in which the relative prices of each good change. Then, as a new example of the application of this multi-country multi-commodity model, in the context of the trade area consisting of Japan, the U.S., and China, this study examines how the pattern of specialization suggested by this optimal solution changes when maximization of total GDPs in the trade area is planned under the restriction that targeted reduction of Japanese intermediate demand for electricity is imposed, as compared to the case without this restriction. The results are as follows. When the intermediate demand for Japanese electricity is restricted, the optimal solution suggests that Japan should increase the output of the forestry sector and decrease the output of transportation equipment, etc. This is the reverse pattern of the specialization in the case without the restriction. The reason for this reversal is that, as in other countries, Japanese forestry has a substantially lower input of electricity than other sectors and, therefore, has the possibility of providing a comparative advantage even though its relative labor productivity is low.
The purpose of this study was to develop a model to estimate the annual available amount of forest biomass resources under profitable forest management in the Nasushiobara city and Kanuma area of Tochigi prefecture, Japan. Economic balances regarding 60-year rotation were estimated based on two types of timber-harvesting systems (conventional operation system conducted by chainsaw and mini-forwarder, and mechanized operation system introducing processor and forwarder), and three types of forest biomass harvesting systems (normal extraction, landing sale, and no biomass extraction) in each subcompartment. The most economical timber and forest biomass harvesting system for each subcompartment was applied. As a result, the number of profitable, nonprofitable, and roadless subcompartments were 1,801; 1,625; and 2,330 of the total 5,756 subcompartments in Nasushiobara city whereas they were 8,940; 3,014; and 20,897 of the total 32,851 subcompartments in the Kanuma area. Then, the annual available amount of forest biomass resources was estimated as the annual supply potential of profitable subcompartments. The annual available amount of the forest biomass resources was 7,805 m3/year and 50,313 m3/year in Nasushiobara city and Kanuma area, respectively. This available amount meets the annual demand of 6,000 m3/year of a 500 kW woody biomass power generation plant planned in Nasushiobara city, and the annual demand of 12,000 m3/year of a chip production factory in the Kanuma area.
A growth function is a mathematical functional form that models longitudinal growth over time. Longitudinal growth is often difficult to model because of variation in the observed data, which makes it difficult to fit a growth curve. Thus, several different functional forms have been proposed as growth functions. Growth functions are typically selected based on how well they fit the data - final analysis is fully based on the selected function. If the wrong growth function is selected, results may be skewed or invalid, underscoring the importance of proper model selection. There are no definitive guidelines for selecting the most appropriate growth function from the set of available candidates. We propose a statistical approach for growth form selection that uses Mallows' Cp criterion.
A planning program for circular forest road networks, including strip roads, was developed by considering water catchment areas. The forest road network planned by the program and the existing forest road network constructed by the forest owner were compared and examined using indices representing operational and traffic benefits. From the viewpoint of operational benefits, the average winching distance and ratio of average winching distance to the theoretical average winching distance for the road network based on water catchment areas were lower than those for road networks based on subcompartments. From the viewpoint of traffic benets, the average distance between the attainment points of the road network based on water catchment areas was shorter. In addition, a connectivity reliability analysis was conducted to evaluate the alternative function, which is considered an index of traffic benefits, by using a shallow landslide risk map. Road failure was assumed to occur when a forest road passed over a shallow landslide risk area. The connectivity reliability of the road network based on water catchment areas was the highest because of its ladder-shaped structure. The economic benefit per unit road length of the road network based on water catchment areas was also larger. Therefore, the road network based on water catchment areas was the most suitable for the applied forest road network, assuming that the network was completely established.
Functional Structural Plant Models (FSPM) facilitate decision making processes by rendering visualizations that permit decision makers to more easily evaluate multiple options or outcomes. This study simulates different stand management scenarios based on varying initial stand densities to demonstrate one potential application of FSPM as a decision making tool. We investigate the effects of several structural parameters on tree growth of Stone Pine (Pinus pinea L), and adjust them to model tree growth data collected in the field. Our simulation results show that individual trees develop more foliage when there is less competition, while greater competition (higher density) results in more foliage on a per hectare basis. The same relationship is observed for total biomass. Individual tree diameter growth is greater when there is less competition.
Competition among individual trees is a fundamental structuring feature of uneven-aged mixed-species stands. We developed a Bayesian model for neighborhood competition in uneven-aged mixed-species stands, in which the interspecic variability in competitive impact is explicitly represented. We used data from 16 permanent plots in the University of Tokyo Hokkaido Forest, where the diameter at breast height (DBH) of all trees has been repeatedly measured and mapped. To analyze the competitive effect of neighboring trees, we used the “Neighboring Competition Index”, an index in which the competitive effect of neighboring trees is predicted as a function of its DBH, distance from the target tree, and its species. Among three alternative models, a model that represented the interspecic variability to have a common mean value using hierarchical parameter structure exerted the lowest DIC (a criterion for model selection), followed by a model that represented it to be independent. The estimated interspecic variability was smaller than previously reported, in that we found only three out of 39 species were considered to have a signicant difference from other species. Our results showed that although there is clear evidence for interspecic variability, the species-specific effects are not independent of one another, but rather have some similarity. Our results provide a novel approach for efficiently predicting the complex competition in uneven-aged mixed-species stands.