The Far-Infrared Surveyor (FIS) for AKARI

The Far-Infrared Surveyor (FIS) is one of two focal plane instruments on the AKARI satellite. FIS has four photometric bands at 65, 90, 140, and 160 um, and uses two kinds of array detectors. The FIS arrays and optics are designed to sweep the sky with high spatial resolution and redundancy. The actual scan width is more than eight arcmin, and the pixel pitch is matches the diffraction limit of the telescope. Derived point spread functions (PSFs) from observations of asteroids are similar to the optical model. Significant excesses, however, are clearly seen around tails of the PSFs, whose contributions are about 30% of the total power. All FIS functions are operating well in orbit, and its performance meets the laboratory characterizations, except for the two longer wavelength bands, which are not performing as well as characterized. Furthermore, the FIS has a spectroscopic capability using a Fourier transform spectrometer (FTS). Because the FTS takes advantage of the optics and detectors of the photometer, it can simultaneously make a spectral map. This paper summarizes the in-flight technical and operational performance of the FIS.Comment: 23 pages, 10 figures, and 2 tables. Accepted for publication in the AKARI special issue of the Publications of the Astronomical Society of Japa

Scale-dependent effects of windthrow disturbance on forest arthropod communities

The effect of disturbance on local communities may operate via a spatial landscape context. We examined the scale-dependent effects of windthrow disturbance caused by a large typhoon on three arthropod communities in a temperate forest of Japan. Canopy arthropods were collected by beating foliage, forest-floor arthropods were collected by sweeping the vegetation, and flying arthropods were collected in Malaise traps. To assess the "functional spatial scale" at which arthropods responded to tree-fall disturbance, the gap rate was quantified at different spatial scales by sequentially enlarging the radius of a circular landscape sector by 10 m from 10 to 500 m. We then analyzed the responses of order richness and abundance to the gap rate for each arthropod community. The spatial scale of the significant best-fitting model, which was selected from the models fitted to the gap rate at stepwise spatial scales, was regarded as the arthropod-specific functional spatial scale. Arthropod order richness was not dependent on the gap rate. In contrast, arthropod order abundance depended significantly on the gap rate in many orders, but varied in the response direction and functional spatial scale. These order-specific, scale-dependent responses to tree-fall gaps would complicate interactions among organisms, leading to complex community organization. An understanding of the spatial processes that link the use of space by organisms with the spatial scale at which ecological processes are experienced is required to elucidate the responses of populations, communities, and biotic interactions to disturbances in a spatial landscape context

Characterization of the complete chloroplast genome of Betula chichibuensis (Betulaceae), a critically endangered limestone birch

Betula chichibuensis is a critically endangered limestone birch confined to the Chichibu and Kitakami mountains in central and northeastern Japan, respectively. In this study, we assembled and characterized the complete chloroplast genome of B. chichibuensis. The whole chloroplast genome was 160,791 bp in length, consisting of a large single-copy (LSC) region of 89,504 bp and a small single-copy (SSC) region of 19,175 bp, separated by a pair of inverted repeat (IR) regions of 26,056 bp. It contained 133 genes, including 88 protein-coding genes (80 PCG types), 37 tRNA genes (30 tRNA types), and eight rRNA genes (four rRNA types). The overall GC content of the chloroplast genome was 36.01%. Phylogenetic analysis resolved B. chichibuensis as sister to the clade containing B. pendula

Inter- and Intraspecific Patterns in Resprouting of Trees in Undisturbed Natural Forests along an Elevational Gradient in Central Japan

Resprouting is an important functional trait for determining community dynamics and the persistence of individuals and populations. However, community-wide research on resprouting has primarily focused on severely damaged trees. We investigated resprouting from trees in a range of undisturbed natural forests along an elevational gradient in central Japan and analyzed the data at inter- and intraspecific levels. First, we formulated interspecific relationships among resprout production, parent stem growth, multi-stemmedness, and dominance in forest communities using a structural equation model (SEM). Second, we analyzed intraspecific variation in the resprout number per stem for nine resprouting species using a hierarchical Bayesian method. We found that resprout production and parent stem growth were negatively correlated; resprouting resulted in multi-stemmed adult forms, and species with multi-stemmed forms tended to be less dominant in undisturbed forest communities. We observed various intraspecific resprouting responses to parental and environmental factors. For example, soil temperature had generally positive effects for most species, whereas dbh appeared to have only weak effects on a few species. Our SEM summarized well the direct and indirect relationships of species’ traits, including resprout production, in the undisturbed forests. The observed intraspecific patterns in the resprouting responses can serve as a starting point for understanding species’ traits within this context

International Biodiversity Observation Year in Western-Pacific and Asian regions (DIWPA-IBOY) : a case report on species rarity and spatio-temporal variability of species composition in Lepidoptera and Coleoptera communities from a temperate forest of northern Japan

An international project, DIWPA-IBOY, took place for simultaneously observing biodiversity throughout the Western-Pacific and Asian regions in 2001–2003, as one of the core projects for International Biodiversity Observation Year, a crosscutting network activity of DIVERSITAS (an international programme of biodiversity science). DIWPA-IBOY provides extensive data on species diversity obtained by the standardized method. Under this project, 51,742 individuals of Lepidoptera and 11,633 of Coleoptera were collected by light traps from the Tomakomai Experimental Forest of Hokkaido University, one of the core DIWPA-IBOY sites, in the cool-temperate region of northern Japan. Based on these data, this study examined the relative abundance distribution (RAD) to evaluate the amount of rare species in the Lepidoptera and Coleoptera communities. The beta diversities between sampling seasons, forest strata, and trap sites were also assessed to evaluate the spatio-temporal variability of species composition in these communities. In the analysis of the RAD, the best-fit model was selected from the log-Normal, Zipf–Mandelbrot, and Zipf models differing in the tail length of the RAD, i.e., the proportion of rare species. To explore the beta diversity between samples, the abundance-based Jaccard index with an unseen species estimator was calculated, and then a hierarchical clustering analysis was conducted. As a result of RAD analysis, the Coleoptera community was regarded as containing a larger proportion of rare species than the Lepidoptera community. The seasonal compartmentalization of the community, deduced from the beta-diversity analysis, was finer in Lepidoptera (seven assemblages recognized) than in Coleoptera (three assemblages). The spatial (vertical and horizontal) compartmentalization was negligible in both communities. The coincidence of the larger proportion of rare species and the lower beta diversity between seasons in the Coleoptera community was explained by the longer life spans of beetles compared to moths, based on the assumption that the length of life span acts as a temporal agent for mass effect on the analogy of the migration rate as a spatial agent for mass effect

Relationships between soil properties and environmental factors along elevational gradients in the University of Tokyo Chichibu Forest

森林土壌の生態系機能を維持管理する上で，土壌特性と環境要因の関係を理解することは重要 である。急峻な地形を有する秩父演習林では，その土壌特性が植生のみならず，標高や傾斜度，曲率などの地形によって規定されると考えられる。そこで，本研究では，深度別の土壌特性（pH，全炭素量，全窒素量，CN 比）と，植生（樹木の種多様性，針葉樹率）および地形（標高，傾斜度および斜面方位，曲率，累積流量）の関係を報告し，土壌特性に対する各環境要因の相対的重要性を調べた。土壌pH は土壌が深くなるにつれ上昇し，標高と樹木の種多様性は有意な負の関係を示していた。土壌特性と各環境要因の関係を線形混合モデルにより解析した結果，表層土壌のpH については標高と植生が最も重要な変数であった。一方で，深度10-20 cm と20-30 cmの全窒素量においては，南側で流速が小さい場所で多くなる傾向が示され，地形が標高や植生より土壌特性に強い影響を及ぼし得ることが明らかとなった。これらの結果から，森林の土壌特性に対する局所的な地形や標高に沿った植生変化の重要性が示唆された。It is important to understand the relationship between environmental factors and soil properties in managing the ecosystem functions of forest soils. In the University of Tokyo Chichibu Forest (UTCF), located in a steep mountainous region, soil properties are prescribed by topographic factors such as elevation, slope, and curvature as well as vegetation. In this study, we investigated soil properties (pH, total carbon contents, total nitrogen contents and CN ratio) for each depth, and vegetation (tree diversity and the proportion of coniferous trees) and topography (elevation, slope, aspect, curvature and flow accumulation) in UTCF, and examined the relative importance of environmental factors to soil properties. Soil pH increased with depth and tree diversity showed a significant negative correlation with elevation. In topsoil layers (0-5 cm and 5-10 cm), elevation was the most important variable in explaining soil pH, based on analyses of linear mixed models. On the other hand, total nitrogen content in the 10-20 cm and 20-30 cm depths increased toward sites with south facing slopes and low flow rate, where these topographic variables have stronger influences than elevation and vegetation. These results suggested the importance of local topographic factors and vegetation changes to soil properties along elevational gradients