Yoshinobu Hoshino

Object-based classification of IKONOS data for vegetation mapping in Central Japan

Vegetation mapping using IKONOS data was implemented at a countryside study area in central Japan, where small patches of various plant communities are mixed together in a complicated mosaic pattern. Pixel-based and object-based classifications using only spectral features were implemented and their accuracies were compared. In addition, the object-based classification was also performed on a combination of spectral and textural features, with a stepwise regression model used in the discriminate analysis to select the most relevant features. Classifications were implemented at four levels, the highest of which used seven vegetation categories. The object-based classification proved more accurate than the pixel-based classification. In addition, the addition of textural features generated significant improvements in accuracy. The overall classification accuracy and Kappa coefficients at the highest level were 52.8% and 0.373 for the pixel-based classification; 58.9% and 0.458 for the object-based with spectral features only; and 65.0% and 0.542 for the object-based with additional features. Some problems with misclassification remained, but the overall results demonstrate that object-based classification of very high resolution satellite images using additional features is a practical tool for vegetation mapping in Japan.

Disturbance by large herbivores alters the relative importance of the ecological processes that influence the assembly pattern in heterogeneous meta‐communities

Disturbance caused by large herbivores can affect the relative importance of ecological processes in determining community assembly and may cause a systematic loss of biodiversity across scales. To examine changes in the community assembly pattern caused by an overabundance of large herbivores in Japan, we analyzed community composition data from before and after the overabundance occurred. The community assembly pattern becomes more random after the deer overabundance. In addition, result of variation partitioning revealed decrease in importance of environmental processes and increase in importance of spatial processes. However, response of turnover rate, niche breadth, and niche overlap was heterogeneous, according to scale of each environmental gradient. Our results emphasize the importance of conserving habitat specialists that represent the local environment (habitat type and topography) at various altitudinal ranges to maintain biodiversity at regional scales under the increasing pressure of large herbivores.

Direct coupling: a possible strategy to control fruit production in alternate bearing

We investigated the theoretical possibility of applying phenomenon of synchronization of coupled nonlinear oscillators to control alternate bearing in citrus. The alternate bearing of fruit crops is a phenomenon in which a year of heavy yield is followed by an extremely light one. This phenomenon has been modeled previously by the resource budget model, which describes a typical nonlinear oscillator of the tent map type. We have demonstrated how direct coupling, which could be practically realized through grafting, contributes to the nonlinear dynamics of alternate bearing, especially phase synchronization. Our results show enhancement of out-of-phase synchronization in production, which depends on initial conditions obtained under the given system parameters. Based on these numerical experiments, we propose a new method to control alternate bearing, say in citrus, thereby enabling stable fruit production. The feasibility of validating the current results through field experimentation is also discussed.

Masked Palm Civet Paguma larvata Summer Diet Differs between Sexes in a Suburban Area of Central Japan

Abstract. We studied the summer (June–August) diet of the masked palm civet (Paguma larvata) in a suburban area of Ibaraki Prefecture, using the stomach contents from road-killed carcasses. Specifically, our aim was to examine (i) monthly changes and (ii) if food habits differed between sexes, based on frequency of occurrence (FO) of the main food classes consumed. From 2009 to 2014, 61 civet carcasses were collected along the three major national highways in Ibaraki Prefecture. Civets consumed a wide range of foods such as insects, fruits, mammals, and earthworms. The FO of mammals and fruit taxa (cherries, strawberries, and persimmons) differed substantially among months, which likely reflected the peak availability of each food category/item. Females consumed amphibians, insects, and persimmons significantly more frequently than did males, likely relating to the higher food security demands of females while raising offspring. Overall, masked palm civets in Ibaraki Prefecture proved to be opportunistic and generalist feeders, eating primarily fruits and insects with a high frequency of occurrence in summer.