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.
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.
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.