Search

To mitigate the negative effects of climate change, it is necessary to conserve carbon stocks in forests. Typhoons fell many standing trees and generate a substantial amount of coarse woody debris (CWD). In boreal forests, CWD contributes to maintaining carbon stocks for a long time after a disturbance because the decomposition rate of CWD is relatively low. We know that salvage logging after a disturbance tremendously decreases the forest carbon stock over the short term after logging but know little about its long-term effects. We targeted a catastrophic windthrow caused by a super typhoon in 1954 in boreal forests in northern Japan and estimated the long-term effects of salvage logging after the windthrow on the above- and belowground carbon stocks by comparing old-growth forests with low damage from the super typhoon in 1954 or any subsequent typhoons (OG), forests damaged by the typhoon with remaining CWD (i.e., windthrow, WT), and forests damaged by the typhoon followed by salvage logging (WT + SL). The CWD carbon stock of decay class 5 (i.e., the most decayed CWD) in WT was significantly larger than that in OG and WT + SL, suggesting that the CWD in decay class 5 in WT had been generated by the typhoon 64 years ago, and the negative effect of salvage logging on the carbon stock still remains apparent in the CWD carbon stock of decay class 5. The carbon stock of the organic (0) layer in WT was larger than that in WT + SL, probably because of three factors: (1) the slower decomposition rate of fallen leaves and twigs of conifers than broadleaves, as conifer litter is abundant in WT; (2) greater carbon transition from the CWD to the 0 layer in WT; and (3) the occurrence of a lower decomposition rate in the 0 layer in WT. However, the total carbon stock in WT + SL has almost recovered to the level of that in WT within the last 64 years. The carbon stocks of broadleaves that grew rapidly after the disturbance and the newly accumulated dead trees generated througho

We examined typhoon windthrow patterns in stand-scale permanent plots within three natural forests and the long-term dynamics of surviving trees in two of these plots. The aim was to verify whether predisturbance composition and structure affected windthrow damage and stand recovery. The stands, which were in Hokkaido, the northernmost main island of Japan, differed in pre-disturbance composition (coniferous, mixed and broadleaved stands) and structure, and the basal area losses by the windthrow event were 81-93 per cent. Tree mortality was significantly related to tree size (diameter at breast height) and species. The windthrow patterns differed among the three stands; and, windthrow severity was affected by the pre-disturbance composition and structure. The mortality of trees that survived the windthrow event was similar to 60 per cent in the two plots. The surviving trees comprised a majority of the canopy layer in the secondary stands. The relative basal area of surviving trees decreased rapidly with increasing tree density in the stand initiation stage but differed between plots. Consequently, the pre-disturbance composition and structure influenced windthrow severity, stand recovery and secondary succession in the recovered stands.

We examined typhoon windthrow patterns in stand-scale permanent plots within three natural forests and the long-term dynamics of surviving trees in two of these plots. The aim was to verify whether predisturbance composition and structure affected windthrow damage and stand recovery. The stands, which were in Hokkaido, the northernmost main island of Japan, differed in pre-disturbance composition (coniferous, mixed and broadleaved stands) and structure, and the basal area losses by the windthrow event were 81-93 per cent. Tree mortality was significantly related to tree size (diameter at breast height) and species. The windthrow patterns differed among the three stands; and, windthrow severity was affected by the pre-disturbance composition and structure. The mortality of trees that survived the windthrow event was similar to 60 per cent in the two plots. The surviving trees comprised a majority of the canopy layer in the secondary stands. The relative basal area of surviving trees decreased rapidly with increasing tree density in the stand initiation stage but differed between plots. Consequently, the pre-disturbance composition and structure influenced windthrow severity, stand recovery and secondary succession in the recovered stands.

東京電力福島第一原子力発電所では、汚染水の管理が社会的な問題となっており、海洋への流出を防ぐためシビアな対応が必要な状況が続いている。タンクや側溝内の水中における放射性物質濃度をダイレクトに測定し、モニタリングする手法として、プラスチックシンチレーションファイバ(PSF)の適用が考えられる。そこで、汚染水タンクの漏洩監視や側溝における簡易的なモニターとして適用するために、福島第一原子力発電所敷地内において、基礎的な検討を行った結果をまとめる。, In the Tokyo Electric Power Co.,Inc. the Fukushima Dai-ichi Nuclear Power Station, management of the contaminated water becomes the social problem, and the situation that severe correspondence is necessary continues to prevent an outflow to the ocean. Plastic scintillation fiber (PSF) can apply as technique to direct measure the concentration of radioactive material in the water at a tank and drainage. In this paper, the results of fundamental test was summarized to apply for monitoring of leakage to the tank and monitoring of drainage in the Fukushima Dai-ichi Nuclear Power Station., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Research 2016-011

We examined the dynamics of stand structure and composition over 60 years in two natural secondary forest plots in central Hokkaido, Japan, that had been severely disturbed by a stand-replacing windthrow in 1954. We determined temporal trends in tree density, species richness, species diversity, successional composition, and stand developmental stage. One of the plots contained a coniferous stand prior to the disturbance; the second plot contained a mixed stand. Tree density and species richness increased after the windthrow, and peaked in both stands in 1991, 37 years after the windthrow. Based on the dynamics of tree density and species richness, the stand development phase of both plots remained within the stand initiation stage until 1991, and then progressed to the stem exclusion stage by 2014, 60 years after the windthrow. Based on patterns of increasing tree density by species in both plots, vegetative regeneration was presumed to have contributed abundantly to the recovery of the stand after the windthrow. Species diversity increased after the windthrow as species richness increased in both stands; diversities peaked 23 or 32 years after the windthrow and declined slightly thereafter. Although the successional composition of the pre-disturbance coniferous stand regressed to an early stage under the influence of the windthrow, the relative importance of late-successional species approached the pre-disturbance value as the plot recovered. In contrast, the successional composition of the mixed conifer/hardwood plot was unaffected by the windthrow, but gradually changed to an early stage over several decades following the windthrow. The difference in successional composition between plots was likely a result of differences in pre-disturbance stand conditions between stands. Our 60-year permanent plot study determined stand and population dynamics, the duration of the stand initiation stage, and the interrelationships between diversity and species richness. Long

2011年3月11日に発生した東日本大震災による津波に起因した東京電力福島第一原子力発電所事故によって、大量の放射性物質が周辺に飛散した。事故直後より、放射線の分布を迅速かつ広範囲に測定する手法として、航空機等を用いた空からの測定方法が適用されている。本報告書には、平成26年度に実施した航空機モニタリングの結果についてまとめた。, By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (NPS), Tokyo Electric Power Company (TEPCO), caused by the East Japan earthquake and the following tsunami occurred on March 11, 2011, a large amount of radioactive materials was released from the NPP. These results of the aerial radiation monitoring using the manned helicopter in the fiscal 2014 were summarized in the report., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Research 2015-006

ここでは、水底の放射性セシウムの濃度を直接測定し、換算する手法(in-situ測定手法)の開発を行った。本方法は、p-Scannerと呼ばれる水中での使用可能な、プラスチックシンチレーションファイバ検出器を開発し、水底の広い面積を短時間に直接測定することを実現した。また、p-Scannerで得られた計数率は、検出器で値付けされた水中用のgamma線スペクトロメータと比較測定を行うことにより、湿潤重量当たりの放射性セシウムの濃度(Bq/kg-wet)に換算できるようにした。開発した手法を、福島県内の農業用ため池に適用し、放射性セシウムの濃度分布マップを作成し、本方法の有用性を示した。, Distribution of radiocesium existing on the waterbed such as lake or pond was concerned about at the present that passed for two years by an accident. Here, the direct measurement technique of the radiocesium concentration (in-situ measurement technique) was developed. This method was used an plastic scintillation detector (p-Scanner). This detector carried out quick measurement of a large area. In addition, the count-rate of p-Scanner was converted to the radiocesium concentration (Ba/kg-wet) by comparative measurement of gamma-ray spectrometer. We applied the technique to the agricultural pond in Fukushima and made a map of distribution of radiocesium concentration., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Research 2014-005

2011年3月11日に発生した東日本大震災による津波に起因した東京電力福島第一原子力発電所事故によって、大量の放射性物質が周辺に飛散した。放射線の分布を迅速かつ広範囲に測定する手法として、航空機等を用いた空からの測定方法が適用されている。本資料では、平成25年度に実施した航空機モニタリングの結果についてまとめる。, By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (NPS), Tokyo Electric Power Company (TEPCO), caused by the East Japan earthquake and the following tsunami occurred on March 11, 2011, a large amount of radioactive materials was released from the NPP. This document was summarized in the results of the aerial radiation monitoring using the manned helicopter in the fiscal 2013., 著者所属: 日本原子力研究開発機構(JAEA), JAEA-Research 2014-012

The effects of repeated mild stress on DNA and lipid metabolic damages in multiple organs of dyslipidemic mice, and the preventive role of metallothionein (MT) were investigated. Female adult wild-type and MT-null mice fed high-fat diet (HFD) or standard diet (STD) were repeatedly subjected to fasting or restraint for three weeks. The liver, pancreas, spleen, bone marrow and serum samples were taken for evaluating DNA damage, MT, glutathione (GSH), corticosterone, carnitine and adiponectin. Body weights of restraint groups were reduced with the intensity of stress increased, even if the energy intakes were higher than those of STD group. Hepatic GSH levels were reduced in HFD control group and were further reduced in stress groups, especially in restraint groups, while the hepatic MT and serum corticosterone levels were increased in concert with the intensity of stress. Cellular DNA damages were generally increased by the restraint stress, especially in MT-null mice. Hepatic carnitine levels of MT-null mice were markedly lower than those of wild-type mice. The data suggest that MT plays a preventive role by acting as an antioxidant in corporation with GSH decreased by repeated stress and that MT may be an essential factor for inducing carnitine under the stress.