We investigated the habitat characteristics and population structure of a rare tree (Prunus pendula f. ascendens) with conservation flagship status in the upper reaches of the Inagawa River. We identified 356 individuals in the study area (ca. 210ha in total). Almost all individuals were found in land tracts affected by human activities. The frequency distribution of tree height and diameter at breast height (DBH) were unimodal, and the proportion of individuals <1.0m high was only 4.2%. Few individuals of this species were shaded by the canopy of other trees. The species was distributed mainly on lower slopes, and no individuals were found on ridges. Thus, P. pendula f. ascendens is a disturbance-dependent species with strong habitat preference for sunny sites with mesic soil. Almost individuals were located in the Ultra-Tamba Belt, suggesting that geological conditions regulate the distribution of this species. We propose measures for conserving P. pendula f. ascendens.

View full abstract

Lake Mizoro-ga-ike in Kyoto is a natural monument in Japan that contains a temperate floating mat bog and a diverse plant community. The lake has undergone eutrophication since the 1940s. Management to conserve the lake was begun in the 1960s. To evaluate the present condition of the lake, we investigated the quality of water collected in and around the lake in November 2005, 2006, and 2007 and the soil in the catchment forest in June 2006. The soil analyses indicated that the forest is nitrogen limited, and the water passing through the catchment is nutrient poor and suitable for conserving the lake. The water quality analyses indicated that the lake has three sources of pollution: water from a water purification plant to the southeast, contaminated water from a road that runs along the northern boundary, and sewage from a hospital to the northeast. Since January 2003, a pump has been used to deal with the effect of water leaking from the water purification plant. However, the condition of the lake did not change between 2003 and 2007 because the pumping is insufficient. Therefore, we cannot expect an improvement in the water quality unless a better pump is used.

View full abstract

The stream habitats of the Japanese giant salamander (Andrias japonicus) are becoming increasingly segmented and isolated by small agricultural dams and sand control dams. The goals of this study were to ascertain the inhibition of upstream movement of A. japonicus by small agricultural dams and to determine which conditions enable A. japonicus to move upstream over the dams. We tracked 104 individuals using a mark-recapture study over 1533m of the Hatsuka River in Hyogo Prefecture from July 2004 to December 2005. More than 10 individuals moved upstream of each dam, but the majority of individuals occurred downstream of the dams. Density ratios (density within 10m downstream of the dam/density in remaining 1473m) peaked in July 2004 (67.5) and in August 2005 (71.4). These peaks coincided with the migration season of A. japonicus, indicating that upstream movement of individuals was inhibited by the dams. Individuals tended to accumulate at the lower sides of dams that were higher than 80cm and lacked a gently-sloped detour. However, our observations suggest that if these dams were equipped with either asperities to facilitate a toehold or gently-sloped detours, A. japonicus could traverse these barriers.

View full abstract

Determining ecological indicators and habitat classifications using standardized methods at the catchment scale is crucial to ecosystem-based management. Through investigations of vegetation and environmental factors at 66 sites located in the Ichi River in Hyogo Prefecture, Japan, we classified the types of environments and the corresponding indicator communities at the catchment scale. Data were analyzed using the optimum clustering method, for which the correct number of clusters was determined by model-based clustering and indicator values (IndVal). The indicators of specificity and fidelity in either cluster were reflected in actual site conditions. Results indicated that physiotope may be important for habitat classification at the catchment scale.

View full abstract

This study was carried out in the western part of metropolitan Tokyo in an attempt to prevent the local extinction of Cephalanthera erecta (Thunb.) Blume. Seven quadrats (1×1m to 1×7m in size) were established around C. erecta populations under the forest canopy from April 2006 to January 2008. Plant height, the number of leaves and flowers, and the length and width of each leaf were measured. In mid-June 2007, 23 of 194 individuals were dug up, their roots were cut into 2-cm pieces, and cross-sections were examined. The percentage of cells infested with mycorrhiza in each root section was determined. The percentage of cells infected with mycorrhiza clearly increased from basal to apical and in branching roots. Significant positive correlations were found between the amount of infecting mycorrhiza and the numbers of leaves and flowers, leaf area, and drymatter production of C. erecta. It is thought that greater mycorrhiza infection may increase the biomass of C. erecta. Therefore, in situ conservation of the population of C. erecta that is associated with mycorrhizal fungi is quite important.

View full abstract

Many exotic stag and rhinoceros beetles are imported to Japan every year. This has raised various issues, such as competition and hybridization between exotic and native taxa, and experimental verification of this has been reported. However, most reports focus on exotic stag beetles, and the rhinoceros beetles have received little attention. It is necessary to perform the same risk assessment for rhinoceros beetles as has been done for stag beetles. This study examined whether the exotic rhinoceros beetle Chalcosoma chiron chiron can establish itself in Japan and whether it will compete with the Japanese horned beetle Trypoxylus dichotoma septentrionalis, affecting its feeding behavior. Adult C. chiron chiron survived at an equal rate with T. dichotoma septentrionalis, and C. chiron chiron also laid eggs in the field and fed on the sap of Quercus serrata. Although the eggs hatched, the larvae could not survive the winter. The activity time of male C. chiron chiron overlapped that of male T. dichotoma septentrionalis. When fighting, C. chiron chiron usually defeated T. dichotoma septentrionalis. These results suggest that the possibility of C. chiron chiron becoming established in Japan is low, but this species competes with T. dichotoma septentrionalis and affects its feeding behavior.

View full abstract

On Rebun Island, Hokkaido, Japan, approximately seven individuals of the lady's slipper orchid Cypripedium calceolus grow in an area protected for C. macranthos var. rebunense. If the C. calceolus plants are not indigenous, as some botanists have suggested, they could threaten the protected population of C. macranthos var. rebunense through gene introgression. The present study attempted to determine the pollinators of C. calceolus to estimate the possibility of hybridization between the two Cypripedium species. In June 2007, 25 insect taxa belonging to Coleoptera, Diptera, Lepidoptera, and Hymenoptera were observed visiting flowers of C. calceolus. Judging from the frequent flower visits, suitable body sizes, and appropriate intrafloral behaviors, Lasioglossum calceatum was considered the main pollinator for C. calceolus, although other small bees of the genera Lasioglossum, Halictus, and Andrena were also legitimate pollinators. We concluded that hybridization between the two Cypripedium species is likely to occur only rarely on Rebun Island because (1) small bees seldom visit flowers of C. macranthos var. rebunense and their body sizes are usually too small to pollinate the bumblebee-pollinated flowers, and (2) queens of the bumblebee Bombus pseudobaicalensis, the main pollinator of C. macranthos var. rebunense, are too large to enter the small flowers of C. calceolus.

View full abstract

Phenological shifts in alpine plants, which are sensitive to global warming, are one possible indicator for detecting the effects of warming at early stages. The responses of flowering time to cumulative ground temperature and long-term trends in flowering phenology were examined for Callianthemum miyabeanum in the dry alpine grasslands of Mt. Apoi. The date of first flowering and daily mean temperature at the ground surface were monitored in three populations from 2005 to 2008. To estimate the date of first flowering, the accuracy of a temperature-sum model was assessed by changing the threshold temperature and starting date for accumulation using 10 data sets. The starting date was assumed to be the day following a period of time during which the temperature consistently rose above the base point for bud break. The mean values of cumulative temperatures for flowering onset over the 10 data sets were calculated for every combination of the assumed threshold temperatures and starting dates, after which dates of first flowering were estimated. As a result of comparisons between estimated and observed dates of first flowering, a threshold base of 1℃ and a starting date of the day following that on which the temperature reached 6℃ were chosen as the optimum model. The dates of first flowering from previous years were estimated based on the optimum model using ground surface temperature estimated from the air temperature at Urakawa Town. Results indicated that the date of first flowering has advanced by 7.6 days during the last 100 years.

View full abstract

The non-migratory population of the Tancho or Japanese Crane, Grus japonensis, was on the brink of extinction in the late 19th century because of habitat loss and deterioration and over-hunting. Since the 1950s, however, the population has increased to over 1,300 due to supplemental feeding in winter. Unfortunately, about 70% of the wetlands in Hokkaido have been destroyed. Consequently, the density of breeding pairs in the remaining wetlands continues to increase, and cranes are now feeding closer to people during the spring and summer months and using small wetlands near humans as breeding sites. Ironically, this habituation to humans was promoted by the protection provided to cranes by local people, which caused the cranes to become more tolerant of human disturbance. Therefore, it is necessary for humans to develop new attitudes in order to promote the welfare of the cranes. For their safety, cranes must be conditioned to keep their distance from humans. In addition, existing wetlands throughout Hokkaido must be protected and, where possible, destroyed wetlands should be restored to provide breeding habitats for the expanding crane population. These goals can be achieved through the active commitment not only of a few specialists and administrators, but also of all local people and stakeholders, to furthering adaptive management procedures.

View full abstract

From 31 July 2003 to 26 July 2007, we investigated the distribution of the endemic Japanese crayfish Cambaroides japonicus and the introduced signal crayfish Pacifastacus leniusculus in the Kushiro District of Eastern Hokkaido, Japan. We collected C. japonicus and P. leniusculus at six sites, C. japonicus only at seven sites, and P. leniusculus only at one site. At five sites where only C. japonicus was collected and at five sites where both species were collected, we determined the lowest position where C. japonicus was collected. At the sites where only C. japonicus was collected, it was collected in the headwaters and in the lower reaches, but at the sites where P. leniusculus was collected C. japonicus was collected only in the headwaters. At ten sites where C. japonicus was collected and at ten sites where P. leniusculus was or had been collected, we measured the pH and concentrations of dissolved oxygen (DO), chemical oxygen demand (COD), NH_4^+-N, NO_3^--N, and PO_4^<3->-p using BTB test paper, pH-indicator paper, and an ion selective pack test. No differences were observed in the values measured at the collection sites of the two species. This study was carried out by five high school students under the tutelage of a teacher.

View full abstract

After an over 44-year absence, a female Blakiston's fish owl Ketupa blakistoni, was discovered in northern Hokkaido, Japan, in 2006. The owl was born in 1987 in central-eastern Hokkaido, 96km from her new location. With the goal of reestablishing a breeding population in northern Hokkaido, a male owl that had spent 10 years in captivity was relocated to the area in October 2007. The male was kept in a cage within the range of the wild female for 2 weeks prior to release. Supplementary feeding continued after release, and hunting of these supplementary fish was frequently observed. Monitoring during the 4 months after release revealed that daytime roosts were concentrated within 400m of the release point. Although the frequency of calling, which is associated with territorial advertising and intra-pair communication, was much lower than in a wild breeding pair, the two focal individuals appeared to have a close relationship, as they shared roost sites and frequently hunted together. Unfortunately, the male drowned in a fish farm pond in June 2008. Nevertheless, the relocation of captive individuals, particularly to isolated single-settler habitats, should be a priority among conservation strategies for Blakiston's fish owls in Japan.

View full abstract

With increasing numbers of sika deer Cervus nippon, primary forests have declined considerably since the 1980s on the Ohdaigahara Subalpine Plateau, central Japan. However, a comprehensive survey of the vegetation on the plateau has not been conducted since 1983. Therefore, in 2001, we surveyed the vegetation on the plateau in 197, 20×20-m quadrats, analyzed species composition using the phytosociological methodology, and generated a vegetation map. After 1983, Carici-Piceetum jezoensis var. hondoensis rhododendretosum quinquefolii and associated Sasa nipponica extended their ranges in the eastern part of the plateau, whereas Abieti homolepidis-Fagetum crenatae sasetosum borealis expanded in western areas. In the eastern region of the plateau, Rhododendron quinquefolium, which was rarely browsed by sika deer, became prominent, the areas with few P. jezoensis trees increased, and the forest floor became densely covered with Sasa nipponica, which is highly tolerant of sika deer browsing. In the western region, Sasamorpha borealis, which had previously covered the forest floor, was replaced by Skimmia japonica, which is not preferred by sika deer.

View full abstract

We investigated the current status of sika deer (Cervus nippon Temminck) using three informational sources: field observations, information from park volunteers, and information from visitors, in Hakone, Japan. Sika deer were recorded in western areas of Hakone that neighbor Shizuoka Prefecture. Evidence of feeding on plants by sika deer was rarely observed. These results suggest that the sika deer invasion in Hakone is currently at an initial stage. Although serious sika deer problems have not yet occurred, precautionary measures and monitoring are necessary to avoid damage to the flora of Hakone.

View full abstract

In recent years, much attention has been paid to conserving forest biodiversity. This fact is not surprising, given that 65% of terrestrial taxa depend on forest ecosystems. The challenge facing future forest ecosystem managers is to conserve forest biodiversity and prevent natural degradation in the face of detrimental human activities. This review focuses on forest management issues in Sweden, where human activities have affected forests over a long period of time. In Sweden, the forests have been divided into small parcels for private ownership. As a result, forest management is contingent upon the desires of many individual landowners, greatly hindering the creation of large protected areas to initiate conservation practices. However, forest managers in Sweden have devised a new approach that focuses on timber productivity while also maintaining biodiversity. In addition to national parks and nature reserves, some productive forests, so-called "woodland key habitats," on private land harbor red-listed species that are protected from logging. New forest harvest practices, such as leaving live and dead trees as potential habitat for many biota (including threatened species), have been introduced throughout the country. As a result, Sweden has made biodiversity a priority in private forests used for timber production. Such novel matrix management practices would be very useful in restoring, conserving, and managing Japanese forests, which have similarly been inexorably changed by long-term human activity.

View full abstract

Bears are popular, and are often regarded as umbrella species by conservationists and wildlife societies. This is the case for the Asiatic black bear and the brown bear in Japan. The idea is that bears' home ranges are large and, consequently, that the conservation of bears would result in the conservation of other sympatric plants and animals. Buskirk (1999), however, stated that since large carnivores are habitat generalists, they cannot serve as umbrellas. In fact, in the Sierra Nevada, most martens, fishers and wolverines, which are habitat specialists, are extinct or nearly so, while American black bears are common or abundant (Buskirk pers, comm. 2009). Buskirk's opinion is important for the following reasons. 1) Although the concept of an umbrella species has merit, unless a species' habitat and resource requirements are known, the conservation of other species is not assured. 2) If a conservation initiative is enacted under this slogan and some animals disappear, while bears are abundant, as happened in the Sierra Nevada, then the logic underpinning the initiative is flawed. 3) The proposition of "the more, the better" can be unpopular, even with people who have an understanding of conservation efforts, because such a proposition may be difficult to accept, particularly in a small country like Japan. 4) The concept that bears are umbrella species stems from the idea that not only bears but also other organisms should be conserved; however, the term can be misconstrued to imply that, "Bears live here and thus other animals must also be OK." Thus, the slogan can function in a manner contrary to its intent. We should be cautious not to use this concept without confirming the true meaning of umbrella species.

View full abstract