FORMATH
Online ISSN : 2188-5729
ISSN-L : 2188-5729
9 巻
選択された号の論文の5件中1~5を表示しています
Original Article
  • T. Tiryana, S. Tatsuhara, N. Shiraishi
    2010 年 9 巻 p. 103-122
    発行日: 2010年
    公開日: 2020/05/22
    ジャーナル フリー

    Stand volume can be estimated from other stand variables by using multiple linear regression (MLR) or other ordinary regression models. MLR, however, only produces global parameter estimates that cannot reveal spatial variations in stand variables. In this study,we used a geographical weighted regression (GWR) method to investigate local spatial variations in the relationship between stand volume, stand age, and basal area of Acacia mangium plantations,and to examine whether a GWR model could provide better prediction accuracy than an MLR model. Stand data and geographical coordinates were obtained from 247 plantation sample plots. We analyzed the data using MLR and GWR methods by formulating a linear model that relates stand volume to stand age and basal area. Performance of the GWR model was compared with the MLR model in terms of their parameter estimates and goodness-of-fit statistics. We found that the GWR model was not only able to reveal local spatial variations in the relationship between stand volume, stand age, and basal area, but it also produced better prediction accuracy than the MLR model. The GWR model reduced AIC by 2%, increased R2adj up to 3%, and reduced RMSE by 14%, compared with those of the MLR model. The GWR model, therefore, could be useful for modeling spatial variations in stand attributes that cannot be revealed by ordinary regression models. Stand volume can be estimated from other stand variables by using multiple linear regression (MLR) or other ordinary regression models. MLR, however, only produces global parameter estimates that cannot reveal spatial variations in stand variables. In this study,we used a geographical weighted regression (GWR) method to investigate local spatial variations in the relationship between stand volume, stand age, and basal area of Acacia mangium plantations,and to examine whether a GWR model could provide better prediction accuracy than an MLR model. Stand data and geographical coordinates were obtained from 247 plantation sample plots. We analyzed the data using MLR and GWR methods by formulating a linear model that relates stand volume to stand age and basal area. Performance of the GWR model was compared with the MLR model in terms of their parameter estimates and goodness-of-fit statistics. We found that the GWR model was not only able to reveal local spatial variations in the relationship between stand volume, stand age, and basal area, but it also produced better prediction accuracy than the MLR model. The GWR model reduced AIC by 2%, increased R2adj up to 3%, and reduced RMSE by 14%, compared with those of the MLR model. The GWR model, therefore, could be useful for modeling spatial variations in stand attributes that cannot be revealed by ordinary regression models.

  • H. Han, J.-E. Song, A. Seol, J.-S. Chung
    2010 年 9 巻 p. 123-134
    発行日: 2010年
    公開日: 2020/05/22
    ジャーナル フリー

    This study assesses the applicability of combining the general standardization procedure (GSP) with principal component analysis (PCA) in ecological data analysis. For this purpose, we conducted a comparison of the performance of combined GSP and PCA with detrended correspondence analysis (DCA) in classifying the structure of species composition in natural forest stands at the Kwangneung Experimental Forest. Prior to analyzing the data using PCA, it was standardized using GSP to avoid the tendency of involutions accompanying PCA. Results showed that both approaches were successful in classifying stand species composition and provided ordination surfaces showing three separate groupsconiferous, deciduous and mixed forests. In terms of total explained variance, GSP-PCA seemed to demonstrate better performance than DCA. However, in classifying species composition structures by visual inspection of the ordination graphs, the ordination plots obtained using DCA were more effective than those generated using GSP-PCA.

  • K. Kamimura, S. Saito
    2010 年 9 巻 p. 135-152
    発行日: 2010年
    公開日: 2020/05/22
    ジャーナル フリー

    This study evaluates whether wind data at local meteorological stations can be used for studying wind damage in forested areas. Data from four Automated Meteorological Data Acquisition System (AMeDAS) stations and one weather station, located in the northern and southern portions of Hokkaido Island, was compared with wind data collected at flux towers located in the Teshio and Tomakomai regional forests. Anemometers were affixed to the flux towers at a height of 32 m in Teshio and 40 m in Tomakomai; thus, the data was assumed to adequately represent wind conditions in a forested area without vegetation effects. Mean wind speed at the AMeDAS stations and weather station sites was converted to extreme wind speed using roughness length on eight directions. This comparison was based on the storm (October to May) and typhoon (August and September) seasons. Subsequently, a distance-limited topographic exposure index (TOPEX) was calculated for all anemometer positions using 1, 2, 5, and 10 km distances from the position. We found that wind at sites with low TOPEX scores and small roughness length could significantly represent wind conditions in nearby forested areas. Wind speeds with high TOPEX scores but small roughness length occasionally showed correlation with conditions at the flux tower. Although additional study is required, using TOPEX with roughness length could be beneficial for deriving suitable wind data sets that correlate with wind conditions in nearby forested areas.

  • A. Yoshimoto, M. Konoshima, R. Marušák
    2010 年 9 巻 p. 153-172
    発行日: 2010年
    公開日: 2020/05/22
    ジャーナル フリー

    We investigate the effect of strip cutting under a strip shelterwood management scheme with adjacency requirements among strips. We compare results from an ordinary spatially constrained solution to a solution with strip windows in the management units. The comparison of management schemes is considered as a spatially constrained harvest scheduling problem, which is solved using the SSMART (Scheduling System of Management Alternatives foR Timberharvest) hybrid heuristic. SSMART uses a partitioning heuristic to solve spatially constrained harvest scheduling problems. Our experimental analysis shows that using strip windows to embed additional spatial buffers into the management scheme reduces profit by almost 30%. In our Slovakian Forest Enterprise case study, it reduces the harvest flow level and harvested area by approximately 30%, while the calculated flow fluctuation over time is 10 times smaller than that from the ordinary adjacency problem without strip windows. However, strip windows could play an indirect role in preserving some resources for future harvest, possibly meeting sustainable management objectives.

  • Yozaburo Ejiri
    2010 年 9 巻 p. 173-205
    発行日: 2010年
    公開日: 2020/05/22
    ジャーナル フリー

    This paper discusses development of a multi-country, multicommodity linear trade model that includes intermediate goods. This new model improves the author’s previous model by rigidly formulating the supply and demand conditions for each good according to the final demand for that good as a linear function of gross domestic product (GDP). Parameter domains of ϕoK (i.e., the level of public benefit - in monetary terms - provided by the forestry sector in country K, assuming that the forestry sector maintains its present output level) are investigated where the pattern of forestry specialization in each country reverses from its primary state. These domains were identified in three-dimensional ϕoK spaces. Public benefit was assumed to be directly proportionate to the country’s forestry output. Calculations were made using data from the “Asian International Input-Output Table 2000.” Simulations were conducted to examine interactions between Japan, the U.S., and China. Results showed that (1) if the present public benefit from the forestry sector in each country is not considered at all, then forestry output should be decreased in Japan, (2) when public benefit is considered, a “reverse domain” (in which desirable outputs increase) certainly exists within the range of ϕoJ =0 1.0(1010$/year) in the three-dimensional ϕoK spaces, and (3) when the agriculture, forestry, and fishery sectors are aggregated into one sector and public benefits from these sectors are evaluated together, this “reverse domain”exists within the range of ϕoJ =0 70(1010$/year) in the same spaces.

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