記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.15684/formath.09.008

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：森林計画学会  

Airborne laser profiling of mainland Ehime Prefecture, Japan was conducted to develop an entirely new method of land-cover classification, partly in preparation for the post-Kyoto national carbon budget accounting, and partly for correction of the existing government land-use statistics, which should constitute the very basis of the impending national carbon budget accounting of the Kyoto Protocol. The altimetry data was obtained by using NASA's Portable Airborne Laser System (PALS) along 23 parallel flight lines 4km apart from each other covering the whole mainland portion of the prefecture. Based on the resulting surface profile representing topography and structures on the ground with some reference to laser return intensity and nadir video images, land cover along the flight line was classified into "forest", "farmland", "residential and urban", and "others" using PALSA (PALS Analyzer), a software developed for this particular purpose. This line evaluation was then developed into area statistics by simply multiplying by the distance between the flight lines, i.e. 4km. The resultant land-cover estimates not only differed from the existing government statistics as much as the latter does within itself, but also helped to identify the causes and sources of discrepancy quantitatively. Thus it was concluded that coordinated use of this new method with the existing system of land-use statistics would improve the overall credibility of the land-use/land-cover statistics of the prefecture and the nation.

DOI： 10.20659/jfp.13.special_issue_245

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：森林計画学会  

With an objective of evaluating forest habitability for wildlife in terms of forest structure, wildlife abundance was observed using automated infrared sensor cameras while forest structure of the habitat was quantified with airborne laser profiling in three study areas of 400ha each set up around Mt. Ishizuchi-san, Mt. Myoujin-ga-mori, and Mt. Takanawa-san in Ehime Prefecture, Japan. Two parameters derived from airborne laser profiling, i.e. mean and standard deviation of standing timber stock in each study area, were used as structural indexes of forests, while the richness of fauna was quantified as the number of inhabitant species and their frequency of being captured by the automated camera. Of the four possible combinations of the forest and faunal parameters, only the one between the photographic capture frequency and standard deviation of standing timber stock revealed strong negative correlation. Thus it was reasoned that the variability in timber stock has resulted from altitude variability within a given study area which tends to be more pronounced in higher and more remote areas, leading to a conclusion that what is really correlated with wildlife abundance is the proximity to the human domain.

DOI： 10.20659/jfp.13.special_issue_215

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：森林計画学会  

The objective of the present study is to develop a transparent and verifiable model of volume estimation for conifer plantations using remote sensing. The model is to be independent from observation, that is, ground truths are not necessary for parameter fitting and model construction. To achieve it, the estimation process is divided into two steps: direct measurements of physical parameters of stand, and a stand volume estimation by an external model. As an external model, we adopt the stand density chart, which is a robust and general model of stand volume growth and estimation based on a semi-empirical growth model of even-aged stands. It can estimate a stand volume from a dominant height and a density, which can be directly measured by remote sensing. In the present study, firstly, the iso-height curves, a sub-model of the stand density chart, are created from the external inventory data. Then, the dominant heights and densities are directly observed by means of the airborne remote sensing. Finally stand volumes are estimated by the observed dominant heights and densities using the iso-height curves. We found that the new iso-height curves predicted the stand volume very well. The dominant height estimation was reasonably accurate, too. However, there was a room for improvement for the stand density estimation. This method will contribute the implication of the remote sensing technology to forest management by sharing the concept and values with foresters.

DOI： 10.20659/jfp.13.special_issue_295

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：森林計画学会  

Most of Japanese young plantation forests have reached an age when thinning is needed, but they have not yet been cut, and stand density is often too high. An economical method is needed for selecting stands that should be cut. We are developing a method of stand density estimation using aerial photography. In previous work, we devised a method for high resolution color aerial-photographs. It divides images into a series of color bands, and estimates stand densities by the brightness in a combination of different band images. Ground truthing is needed to improve precision. In our earlier work, we used a set of 22 plots for ground truthing. Here, we present ground truthing of mono-color aerial photographs obtained for a growing stock investigation project in Ehime prefecture, Japan. The project is to estimate the CO_2 sink potential for all forests in the prefecture. Vegetation profiles are measured by airborne laser altimetry assisted by a consecutive series of ground truth surveys. Performance of mono-color aerial photography method was rather poor, indicating that manual contrast adjustment should be improved.

DOI： 10.20659/jfp.13.special_issue_141

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：森林計画学会  

The timber stock of mainland Ehime prefecture was estimated using airborne laser profiling data. Our provisional analysis revealed that: 1) at 5,435km^2, the laser estimate of land area obtained as a simple product of flight path length and its 4km width was fairly consistent with the figure of 5,455km^2 by the Geographical Survey Institute, considered the most reliable of the government statistics; 2) on the other hand, at 176 million m^3 for the entire prefecture our estimate of standing timber stock turned out to be twice as much as the government figure of 87 million m^3; 3) judging from the precision in land-area estimation and results from other research, our estimate is considered more likely to represent the actual timber stock than the government figure; 4) thus airborne laser altimetry would provide more accurate national forest carbon budget for the Kyoto Protocol than does the existing national forest inventory; 5) at the present density of laser profiling transects, 4km apart from each other, however, no reasonable accuracy is expected at the municipality level.

DOI： 10.20659/jfp.13.special_issue_259

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE INC  

Forest dynamics are characterized by both continuous (i.e., growth) and discontinuous (i.e., disturbance) changes. Change detection techniques that use optical remotely sensed data to capture disturbance related changes are established and commonly applied; however, approaches for the capture of continuous forest changes are less mature. Optical remotely sensed imagery is well suited for capturing horizontally distributed conditions, structures, and changes, while Light Detection And Ranging (LIDAR) data are more appropriate for capturing vertically distributed elements of forest structure and change. The integration of optical remotely sensed imagery and LIDAR data provides improved opportunities to fully characterize forest canopy attributes and dynamics. The study described in this paper captures forest conditions along a corridor approximately 600 km long through the boreal forest of Canada. Two coincident LIDAR transects, representing 1997 and 2002 forest conditions respectively, are compared using image segments generated from Landsat ETM+ imagery. The image segments are used to provide a spatial framework within which the attributes and temporal dynamics of the forest canopy are estimated and compared. Segmented and classified Landsat imagery provides a context for the comparison of sufficiently spatially related LIDAR profiles and for the provision of categories to aid in the application of empirical models requiring knowledge of land cover. Global and local approaches were employed for characterizing changes in forest attributes over time. The global approach, emphasized the overall trend in forest change along the length of the entire transect, and indicated that key canopy attributes were stable, and transect characteristics, including forest canopy height, did not change significantly over the five-year period of this study (two sample t-test, p=0.08). The local approach analyzed segment-based changes in canopy attributes, providing spatially explicit indications of forest growth and depletion. The local approach identified that 84% of the Landsat segments intercepted by both LIDAR transects either have no change, or have a small average increase in canopy height (0.7 m), while the other 16% of segments have an average decrease in canopy height of 1.6 m. As expected, the difference in the magnitude of the changes was markedly greater for depletions than it was for growth, but was less spatially extensive. Growth tends to occur incrementally over broad areas; whereas, depletions are dramatic and spatially constrained. The approach presented holds potential for investigating the impacts of climate change across a latitudinal gradient of boreal forest. Crown Copyright (c) 2007 Published by Elsevier Inc. All rights reserved.

DOI： 10.1016/j.rse.2007.02.002

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記述言語：日本語   出版者・発行元：日本森林学会  

DOI： 10.11519/jfsc.118.0.2.0

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：The Japanese Forest Society  

シベリアは世界最大の森林地帯であり,その森林の炭素収支の評価が急がれている。本研究ではシベリアの亜寒帯林を対象に,炭素収支評価の重要なパラメータである葉面積指数(leaf area index, LAI)を,航空レーザー測距法を用いて広域的に推定する方法を提案した。対象域は中央シベリアを流れるエニセイ河流域で,その支流バクタ川沿いに設置した長さ200kmにわたるトランセクトの森林縦断プロフィールを航空レーザー測距法で計測した。このプロフィールの積分が森林蓄積やLAIとアロメトリー関係にあることを利用して現地実測調査により森林縦断プロフィールに対する蓄積とLAIの回帰を決め,これによりトランセクト全域のLAI分布を推定した。大まかな傾向として,標高の低下に伴う気温の上昇と永久凍土上の活動層の肥厚を反映して,LAIは上流から下流へと増加しているほか,地形による活動層の厚さに応じて局所的な変動がみられるなど,永久凍土とその上の活動層が森林特性を大きく規定していることが明らかになった。本研究のトランセクトはわずか200kmでしかないが,より広範な航空レーザー測距を行えばその生育環境と併せたシベリアの森林の特性が明らかになり,近い将来懸念される気候変動に対する反応の予測も可能となる。

DOI： 10.4005/jjfs.88.21

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00274182785?from=CiNii

掲載種別：研究論文（学術雑誌）   出版者・発行元：The Japanese Forest Society  

DOI： 10.4005/jjfs.88.103

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出版者・発行元：水文・水資源学会  

近年，気候変動への関心の高まりから，衛星データから算出した植生指標を用いて，葉面積指数（LAI）を広域に推定することが試みられている．しかしながら，既存の植生指標とLAIとの関係は非線形であり，両者は指数関数で近似されることが多い．このため，LAIの大きい（2以上）地域において，既存の植生指標ではLAIの大小の判別が難しい．そこで本研究では，多方向放射観測データに注目し，新たな植生指標NHVIを提案した．本研究では，植生の後方散乱方向への高い反射率（Hotspot）と前方散乱方向への低い反射率（Darkspot）から計算される指標であるHDSに注目した．そしてHDSにNDVIを乗じた値である，新指標NHVIを提案した．NDVIがLAIと指数近似であるのに対し，新指標NHVIはLAIと線形関係にある．すなわち，LAIが大きい地点において，新指標NHVIのLAI推定における優位性を確認できた．

DOI： 10.11520/jshwr.19.0.73.0

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記述言語：日本語   出版者・発行元：日本リモートセンシング学会  

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出版者・発行元：水文・水資源学会  

近年，太陽，センサと，対象がなす角度によって，取得される分光反射特性が異なる性質（BRDF）が，衛星データに及ぼす影響が懸念されている．そこで本研究では，カナダ北西部の山火事後の遷移段階にある植生を対象に，植生のBRDFが植生指標NDVIの値に与える影響を調べた．さらに，複数の植生指標（GEMI，バンド和で正規化した近赤外の反射率:nNIR）のBRDFに対する変動を変動係数を用いて比較した．観測角度の変化がNDVIに与える変動は，IKONOSが標準画像として販売する真下±15°の観測角度の違いで，0.1_から_0.2程度あった．また，各植生指標のBRDFに対する変動を比較すると，NDVIは特に地表面が露出する植生でBRDFに伴う反射率の変動の影響が表れることが分かった．さらに，焼け跡ではGEMIが，植生の侵入が始まった後の地点ではnNIRが，それぞれ最もこの変化に対する変動が小さくなった．

DOI： 10.11520/jshwr.18.0.41.0

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

DOI： 10.1016/s0378-1127(02)00567-4

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：森林計画学会  

The free (unobstructed) sight through the foliage layer of forest canopy is expected to depend on the density of the foliage, i.e. dense foliage shortens the free sight while sparse one extends it. Conversely, it is possible to estimate foliage density from the free sight. Furthermore, it is possible to estimate from the free sight the amount of leaves in terms of leaf area or leaf area index (LAI) as a product of estimated foliage density and the thickness of the foliage layer. This paper presents a simple theory of estimating LAI from the free sight along with its verification using a set of field data from boreal forest of Canada. Free sight through the canopy was measured using airborne laser altimetry (ALA). Laser beams emitted vertically from an aircraft are reflected from different layers of the canopy, ranging from the uppermost canopy surface to the ground. The distance that a laser beam travels unimpeded into the canopy was assumed to be the free sight or more aptly, the free path, and the mean of a number of penetrations within the canopy as a good measure of the amount of leaf area. We assembled a set of field leaf area and mean free path data for 13 boreal forest sites in central Alberta, Canada. We related leaf area density with mean free path and found an inverse relationship between them. Furthermore, we verified that LAI can be estimated as a product of mean free path-based leaf area density and an estimate of canopy depth (D) obtained based on the relationships we found between D and mean tree height (H) and between H and mean laser vegetation height.

DOI： 10.20659/jfp.8.1_9

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記述言語：英語  

The warming resulting from increasing anthropogenic carbon dioxide and other greenhouse gasses is expected to be most prominent in the subarctic-boreal region of the Northern Hemisphere. With the objective of setting up a baseline to monitor possible vegetation change in this region, a continuous vegetation profile extending 600km from Edmonton, Alberta to Cluff Lake, Saskatchewan, Canada was measured using an airborne infrared laser altimeter mounted on a helicopter. Then the distribution of leaf area index over the same 600km long transect was estimated from this vegetation profile based on a series of plot surveys on the ground to correlate the vegetation profile with leaf area index via standing stock. The distribution of leaf area index not only corresponded well with biome type, but also showed characteristic change in accordance with environmental gradient within a given biome, thus confirming that airborne laser altimetry is a powerful tool for measuring and monitoring such important vegetation characteristics as standing volume, leaf area index, etc. over an extensive area.

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