Abstract:We investigated the capabilities of a canopy height model (CHM) derived from aerial photographs using the Structure from Motion (SfM) approach to estimate aboveground biomass (AGB) in a tropical forest. Aerial photographs and airborne Light Detection and Ranging (LiDAR) data were simultaneously acquired under leaf-on canopy conditions. A 3D point cloud was generated from aerial photographs using the SfM approach and converted to a digital surface model (DSMP). We also created a DSM from airborne LiDAR data (DSML). From each of DSMP and DSML, we constructed digital terrain models (DTM), which are DTMP and DTML, respectively. We created four CHMs, which were calculated from (1) DSMP and DTMP (CHMPP); (2) DSMP and DTML (CHMPL); (3) DSML and DTMP (CHMLP); and (4) DSML and DTML (CHMLL). Then, we estimated AGB using these CHMs. The model using CHMLL yielded the highest accuracy in four CHMs (R 2 = 0.94) and was comparable to the model using CHMPL (R 2 = 0.93). The model using CHMPP yielded the lowest accuracy (R 2 = 0.79). In conclusion, AGB can be estimated from CHM derived from aerial photographs using the SfM approach in the tropics. However, to accurately estimate AGB, we need a more accurate DTM than the DTM derived from aerial photographs using the SfM approach.

Abstract:Soil layers play an important role in hydrological processes, particularly in forested basins. For example, thick soil layers can store rainwater temporarily and drain it gradually. In the Mekong River Basin, especially in Cambodia, evergreen and deciduous forests are widely distributed. However, we have no data on soil conditions such as thickness and hardness that affect water storage capacity in forested areas. To clarify the water storage role of forest soils in the lower reaches of the Mekong River Basin, we investigated the distribution of soil thickness using a handy dynamic cone penetrometer in three Cambodian provinces: Kampong Thom, Kratie, and Mondul Kiri. Soil thickness was greater than 8 m in a deciduous forest in Kampong Thom. In some evergreen forests, apparent soil thickness varied from the rainy to dry seasons because of specific grain size distributions; for example, the soils were rock hard in the dry season and soft in the rainy season. In Kratie, deciduous forests prevailed and soil thickness was shallow at less than 3 m. In Mondul Kiri, forests were mainly formed on a basaltic plateau, and soil thickness was greater than 7 m. Soil thickness and hardness differed among the soil types in these three provinces, as did water storage capacity. The maximum water storage capacity was 1350 mm in an evergreen forest distributed on Acrisols in Kampong Thom. In contrast, the minimum water storage capacity was 225 mm in a deciduous forest distributed on Leptosols in Mondul Kiri. We constructed a soil thickness map for the study area in Kampong Thom that was mainly covered with evergreen forest; the distribution of soil thickness was related to elevation, with soil thickness increasing 0Ð13 m per 1 m increase in elevation, except in a deciduous mixed swamp forest area.

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expanding the potential scope of concepts by including forest degradation and acknowledging the importance of conservation, the sustainable management of forests and the enhancement of forest carbon stocks (REDD plus) 15 . Methodological guidance is requested by developing country parties for activities relating to reducing emissions from deforestation and forest degradation (Decision 4/CP.15) 15 in order to establish robust and transparent na- IntroductionDeforestation in the tropics will remain a major source of carbon emissions in the coming decades 1 . International discussion has focused on mechanisms providing economic incentives for reducing CO 2 emissions from deforestation in developing countries (REDD) 14 and JARQ 46 (2), 187 -192 (2012) AbstractAs a feasibility study for applying a simplified method to estimate CO 2 emissions from deforestation and forest degradation in tropical forests, we estimated the nationwide forest tree biomass carbon stock using data from 100 permanent sampling plots (PSPs) set by the Forestry Administration, Cambodia in seasonal forests in Cambodia. Averaged tree carbon stocks and SE-Standard error were at 158.8 ± 7.3 Mg C ha -1 for evergreen and semi-evergreen forests and 55.2 ± 6.9 Mg C ha -1 for deciduous forests in 1998 (the first census) and for the second census in 2000-2001, 163.8 ± 7.8 Mg C ha -1 and 56.2 ± 6.7 Mg C ha -1 , respectively. The averaged tree biomass carbon stock differed significantly between the two forest types. Using the forest cover for 2006 and the averaged carbon stock for 2000-2001, the national-level forest tree carbon stock in the early to mid-2000s was estimated at 824.2 ± 39.2 Tg C for evergreen forests and 263.9 ± 31.3 Tg C for deciduous forests, and 1,088.1 ± 50.2 Tg C in total. By repeating this calculation for all forest areas by remote sensing and averaged tree carbon stock via ground-based measurement with PSPs, we could monitor the total tree carbon stock in nationwide forests in Cambodia. We also presented the possible reasons for uncertainty related to the present tree biomass carbon stock of forests and recommendations in order to improve the accuracy of the carbon stock using PSP systems in Cambodia.

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Cryptomeria japonica (sugi) and Chamaecyparis obtusa (hinoki) are major Japanese timber species whose plantation area accounts for 44 and 25%, respectively, of the plantation forests in Japan. Physiology, anatomy and ecology of the species have been intensively studied for this half century, which now forms a huge stock of information. These data, however, were scattered in diverse sources, including papers, bulletins of research institutes, reports of other kinds and books, and were presented in nonstandardized, diverse styles in each source. This paper

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