ABE  Nobuyuki

IIDA  Kazuaki

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ABE, Nobuyuki

IIDA, Kazuaki

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Estimation of Carbon Stock in Even-aged SugiForests Using Satellite Image Data著者 ABE  Nobuyuki, IIDA  Kazuakijournal orpublication titleJournal of Integrated Field Sciencevolume 6page range 9-13year 2009-03URL http://hdl.handle.net/10097/487759Original PaperEstimation of Carbon Stock in Even-aged Sugi Forests Using Satellite Image DataNobuyuki ABE  and Kazuaki IIDAFaculty of Agriculture, Niigata University,Ikarashi 2-8050, Niigata 950-2181 JAPANe-mail: tomiko@agr.niigata-u.ac.jpKeywords: LandsatTM, IKONOS, Forest register, SubcompartmentReceived 26 July 2008; accepted 2 October 2008Abstract A Japanese cedar occupies 40% of an artificial plantation of Japan, and is most artificial plantation resources. The amount of biomass of sugi plantation was presumed using satellite data. The biomass can be easily presumed from volume. Therefore, volume presumption is important. From a result of analyzing the relationship between volume and digital number of the band according to wavelength in the amount of biomasses of LandsatTM Images, the band five showed the highest correlation between volume and digital number. And, high resolution satellite image data (IKONOS) were visually excellent and its posi-tion of an investigation plot is also clear. Then, the relationship between a plot volume and the digital number classiﬁ ed by band was analyzed. Regression was obtained between digital number of band3 and volume from IKONOS data. Every subcompartment volume was presumed using these regressions and the map of biomass estimated from volume was showed. On the other hand, in forest register of Japan, volume for every subcompartment has added up only one value. We analyzed volume from plot, volume from forest register and volume from satellite data?and investigated whether estimated volume accuracy of which was the highest. As a result, the estimated vol-ume from satellite data was the best. IntroductionWith Kyoto Protocol coming into effect, reduc-tion of CO2 emission is an urgent subject. The report of IPCC was performed last year (2007). The report predicts future global warming. According to this, it predicts that the earth environment of 50 years after will be in a very severe state. As prescribed in Kyoto Protocol Article 3, paragraphs 3 and 4, plantations and forests under management are regarded as carbon stock, and we need to estimate carbon stock ﬁ xed by forests in Japan. Usually, the carbon stock fixed by forests is estimated from the timber volume, which is obtained by summing up the values listed in forest registers managed by each prefecture.  However, the volume listed in the forest register often differs greatly from the real volume. The timber volumes listed in the forest registers are calculated using a growth equation for each tree species input-ted in a computer. The difference between the timber volumes listed in the forest register and real timber volume in the forests is uncertain until survey. From a result of analyzing the relationship between volume and digital number of the band according to wave-length in the amount of biomasses of LandsatTM Images, the several bands showed the correlation be-tween volume and digital number. On the other hand, the use of high resolution image data is effective for small sized private forest. But, swath wide is 11km. It is difﬁ cult to estimate biomasses for wide area . In this study, therefore, we established a method of estimating timber volume in sugi plantations in Aga-cho using LandsatTM data, and IKONOS images for even-aged area, and estimated the carbon stock in the sugi plantations from the distribution pattern of the timber volume.     Investigation Area and Study MethodsOutline of investigation plotsFirst, we set up 73 investigation plots within whole Aga-cho area. Second, we set up 45 plots within Torii and Toyomi even-aged forest stand consolidation in Aga-cyo. The Torii forest stand consolidation planted JIFS, 6 : 9 ? 13 (2009)10the Japan cedar of 10ha in 1977 and Toyomi forest in 1976 to 1978 of same Japan cedar stand of 10ha in Aga-cho. Volume’s range was from 213m3/ha to 1372m3/ha and age’s range was from 36 to 81 in case of whole Aga-cho area. In case of Torii and Toyomo, volume’s range was from 88m3/ha to 313m3/ha.  The timber volume was estimated from the measured values, and it was converted to timber volume per ha. For the analysis, timber volume(m3/ha), sum of sec-tion areas at breast height (basal area, m2/ha), average tree height(m), number of standing trees(number/ha) and tree age(year) were used. Used image data.LandsatTM image taken on June 3, 2001 was used. And, IKONOS image taken on May 29, 2002. Land-satTM image resolution was 30m×30m and IKONOS was 4m(color) and 1m(pan). Correction of position on image and determination of digital number(DN) in each plot.Easily detectable plots(co-ordinate) on the im-age were surveyed in the ﬁ eld using the Differential Global Positioning System(DGPS), (Trimble Co., Pathﬁ nder Pro XR) and the position of each plot on the image was corrected. Especially, this method was effect in case of IKONOS. Then the average of DN corresponding to the position of each plot was ob-tained.Estimation of timber volume from forest register in Aga-choRelationship between timber volume(m3/ha) and each image of digital number(DN) in each plot was analyzed. We used LandsatTM, and IKONOS images. LandsatTM images are effective for wide area, like whole Niigata Prefecture. On the other, high resolu-tion images are effective to obtain more detailed in-formation for small area. Most of the sugi plantations are smaller than 1 ha. This is the characteristic of private forests in Niigata Prefecture not only in Aga-cho but also in other areas. Timber volume in such a small compartment can not be estimated well using the image with a low resolution. We used average DN with plots. Plot size is 20 m multiplied by 20 m. Determination of digital number(DN) in the sub-compartments corresponding to different plot sizesHitherto, timber volume in a district has been es-timated from the regression formula between DN on the satellite image and timber volume in the cor-responding plot (Ahern et al.1991, Ardo 1992, Gem-mell 1995), DN in the plot is the sum of the DN of each pixel included in the subcompartment. We ana-lyzed the relationship between the average DN in the plot and the timber volume in the plot, because the average DN in the plot is considered to reﬂ ect the av-erage of tree densities and growth stages of the trees in the plot.Expression of errorAverage errors of timber volume estimated from forest registers and IKONOS, LandsatTM image against the real timber volume in the plot(real value) are shown by root mean square error(RMSE).RMSE= Where, N is sample number (number of plots).In case of even-aged stand in Torii and Toyomi, we showed total volume and volume/ha in forest register, real volume and estimated volume from IKONOS image. Results of AnalysisRelationship between average DN and timber vol-ume in each plotRelationship between timber volume and DN band 5 of Landsat in Aga-cho (Kimura 2003). It is shown R2= -0.58.  Relationship between average DN at band 3 of IKONOS and timber volume in Aga-cho area is shown R2=-0.50 (Abe and Ishida 2004). Relation-ship between average DN at pan and timber volume in even-aged stand in Torii and Toyomi is shown R2=0.7(Fig.1). Pan is showed in signiﬁ cant at the 5% level relation between DN and timber volume.Accuracy of estimation of timber volume RMSE in case of Aga-cho.The RMSE was calculated for the timber volume estimated from forest registers and LandsatTM, IKO-NOS images. The result of the RMSE of timber vol-ume estimated from forest registers and each images were shown on table1.Results from images are a little accurate than forest registers. Thus, it is possible to reduce the estimation error of timber volume by using high resolution im-Abe et al.11Fig. 1. Relationship between average DN(IKONOS PAN) and Volume Estimation of Carbon Stock in Even-aged Sugi Forests Using Satellite Image DataRMSELANDSAT 219 Forest register 222IKONOS 220 Forest register 239Table 1. RMSEFig. 2. Carbon stock in even-aged stand in Torii and Toyomi        Dark shows high biomass and light shows small biomassages.  On the other hand, total and /ha volume in Torii and Toyomi area were calculated. In this case, forest register is presumed more nearly excessively than an actual value. Estimation of carbon stock in Aga-cho DistrictCarbon stock can be estimated by multiplying tim-ber volume by a coefﬁ cient(Matsumoto 2001).  Carbon stock =timber volume ×expansion coefﬁ cient ×bulk density×rate of carbonexpansion coefﬁ cient                               (1); bulk density0.32t/m3  rate of carbon;0.5In this study, the volumes of branches, leaves and underground part were not examined. Since we exam-ined the correlation between estimated timber volume and carbon stock, here, we did not multiply the tim-ber volume by expansion coefﬁ cient, and calculated carbon stock in timber volume from timber volume ×bulk density×rate of carbon.The average error of timber volume estimated from images were smaller than that estimated from the for-est register. Then, the distribution of timber volume in sugi plantations of Aga-cho area were estimated from the DN by equation of each subcompartment. Even-aged carbon stock shows per 20mx20m in Torii and Toyomi(Fig.2.). DiscussionThere are many reports on the relationship between DN at various wavelengths of the subcompartment of LandsatTM image and timber volume in the plot, and on what kind of regression formula is applicable to the relationship. Ahern et al. (1991) obtained R2= 0.808 between DN at band 4 and timber volume in the stands of Picea and Abies in Canada. Ripple et al. (1991) examined the correlation between the timber volume of 25- to 148-year old Douglas ﬁ r and DN at band 4(wavelength) and expressed the correlation by exponential equation with R2=0.704. The maximum timber volume of Ahern et al. (1991) was as low as 250m3 and that of Ripple et al. (1991) was 800m3. Gemmel(1995) examined conifer forests mainly com-posed of Douglas ﬁ r(average timber volume 300m3/ha,maximum 500m3/ha), and obtained R2=0.97 for the quadratic equation between DN of LandsatTM image and the timber volume. For the data of LandsatTM, exponential expression tends to be applied when the timber volume is large. Ardo (1992) reported R=-0.80 between logarithmic function of DN at band 5 and timber volume. Ito (2004) obtained R2=0.40 between exponential func-tion of DN at band5 and timber volume. Numbers of data are 73, and Ito(2004) divided data into the area and investigated relationship between digital number and timber volume for every area in sugi plantation. These value R2= 0.37 ~ 0.79 between power function of DN at band 5 by area.  Kimura (2003) obtained R2=0.69,at the maximum, between power function of the timber volume of sugi plantations in Niigata 12Prefecture and DN at band 5 of Landsat image. Until now, mentioned above report was the case that the relation between DN at a certain time and a timber volume part factor or the region was narrow.However, Ito’s report (2004) is the example of analysis of change of the data from the Niigata whole region, and a timber volume part factor with Kimura’s report (2003) with time, and the past scene. It means that both relations are signiﬁ cant that regression was materialized between a digital number of band5 and timber volume in the report of both Kimura and Ito. On the other hand, Trotter et al. (1997) obtained only R2<0.3 between the DN at band 3.4 and timber vol-ume in radiate pine stand. In that stand, the range of tree age was only 21 to 29 years old. In the stand with similar tree age, correlation between DN and timber volume may be low.         The correlation between timber volume and DN at band3(visible spectrum) of high resolution satel-lite images were expressed by exponential equation, which was different from the correlation between the timber volume and DN in the infrared region of the LandsatTM image. The IKONOS image provides 11-bit information and DN varies from 0 to 2047. Although Puhr and Donoghue (2000) argued that the range of DN is too narrow for the maximum timber volume, it may not be applicable to the estimation in this study. However, DN in this study varied only from 88 to 134, although timber volume in the inves-tigated plots varied from 324 to 913m3/ha in Aga-cho. In the future, we need to examine what kind of forest factors is effectively examined by 11-bit information, for instance, by examining the stands at different growth stages.On the other hand, there are no reports on the esti-mation of timber volume using high-resolution satel-lite images. Wulder et al.(2000) estimated the basal area using optical sensor loaded on airplane. In that report, however, timber volume was not estimated from the sum of the basal area.The difference in average DN between the plots with large and small timber volumes may be caused by the difference in crown size and the size of gap among individuals. In the average DN in each plot, information on the individual size and stand densi-ties may be included. Because the aim of this study is to estimate the carbon stock fixed by forests, we analyzed only the relationship between the DN and timber volume.  As prescribed in Kyoto Protocol Article 3, para-graph 4, a forest under sustainable management is evaluated as a carbon stock. The area investigated in this study is a forestry region from old times, and the plantations are pruned and thinned using forest tech-nology. Expression of the forest condition from the size of carbon stock as shown in Fig.2. is expected to be useful and accumulation of such information should justify further the estimation of carbon stock ﬁ xed by forests.ConclusionsLandsatTM images are effective for wide area, like whole Niigata Prefecture. On the other hand, high resolution images are effective to obtain more detailed information for small area. The correlation between timber volume and DN at band 5 of Land-satTM satellite images was expressed by power func-tion from data  in Aga-cho area. On the other hand, high resolution images are ef-fective to obtain more detailed information for small area. Most of the sugi plantations are smaller than 1 ha. This is the characteristic of private forests in Ni-igata Prefecture not only in Aga-cho area but also in other areas. But, image price is very expensive and swath wide is narrow. The ﬁ rst high-resolution satel-lite ALOS of Japan was launched in 2006, and, the ALOS Data is cheap and swath wide is 70km. It is expected to provide data for application to forestry.  ReferencesAbe, N. and T. Ishida (2004) Estimation of Carbon Stock in sugi plantations using high-resolution QuickBird images. The role of forests for coming generations-philosophy and technology for forest resource management-, Edited by:Kenji NAITO, Japan Society of Forest Planning Press, 221-229. Ahern, F. J., T. Erdle, D. A. Maclean, I. D. Kneppeck (1991) A quantitative relationship between forest growth rates and Thematic Mapper reflectance measurements. Int. J. Remote Sens.12:387-400.Ardo (1992) Volume quantiﬁ cation of coniferous for-est compartments using spectral radiance recorded by Landsat Thematic Mapper. Int. J. Remote Sens.13: 1779-1786.Ito, K. (2004) Analysis of stand structure in sugi plantation of Niigata Prefecture using Landsat ETM+. Master thesis of Niigata Universitry, pp.49 Abe et al.13(in Japanese).Gemmel, F. (1995) Effects of forest cover, Terrain, and scale on timber volume estimation with the-matic mapper data in a Rocky Mountain site. Re-mote Sens. Environ.51: 291-305. Kimura, W. (2003) Estimation of sugi stand structure using Landsat Thematic Mapper. Master thesis of Niigata Universitry, pp.62 (in Japanese).Matsumoto, M. (2001) Amount of carbon stock and carbon absorption in Japanese forest. Forest Sci-ence No.33.Puhr, C. B., D. N. M. Donoghue (2000) Remote sens-ing of upland conifer plantations using Landsat TM data.-A case study from Galloway, south-west Scotland. Int. J. Remote Sens.21: 633-646.Rippel, W. J., S. Wang, D. L. Isaacson, D. P. Paine (1991) A preliminary comparison of Landsat The-matic Mapper and Spot-1 HRV multispectral data for estimating coniferous forest volume. Int. J. Re-mote Sens.12: 1971-1977.Trotter, C.M., J. R. Dymond, C. J. Goulding (1997) Estimation of timber volume in a coniferous plan-tation forest using LandsatTM.  Int. J. Remote Sen., 18: 2209-2223.Wulder, M., K. O. Nieman and D. G. Goodenough (2000) Local maximum ﬁ ltering for the extraction of tree l ocations and basal area from high spatial resolution imagery.  Remote Sens. Environ. 73: 103-114.Estimation of Carbon Stock in Even-aged Sugi Forests Using Satellite Image Data

Estimation of Carbon Stock in Even-aged Sugi Forests Using Satellite Image Data

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Estimation of Carbon Stock in Even-aged Sugi Forests Using Satellite Image Data

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