EDITORIAL

Special feature: effects of anthropogenic habitat changeson plant and animal populationsKoji Nakamura

Preface

Published online: 20 June 2006� The Society of Population Ecology and Springer-Verlag Tokyo 2006

The 22nd Symposium of the Society of PopulationEcology was held October 28–30, 2005, at KatayamazuOnsen, Ishikawa, hosted by society members fromKanazawa University. For the symposium, we orga-nized two sessions, one on the population ecology ofbiological invasion and the other on the effects ofanthropogenic habitat changes on plant and animalpopulations. In this issue and the following issue ofPopulation Ecology, selected papers from the sympo-sium’s second and first sessions, respectively, are beingpublished. As the organizer, I take this opportunity tointroduce the presentations from the second session.

As mentioned in The National Biodiversity Strategyof Japan act of 2002, there are three types of biodiversitycrises: crisis 1 is development and other human activitiescausing species loss and extinction as well as thedestruction and fragmentation of ecosystems. Crisis 2 ischange in some habitats where natural environmentshave experienced human interference, as in satoyama,but, unlike the change in crisis 1, the human interferencein those environments has been reduced. Human activ-ities, including agriculture and forestry, have kept thebiodiversity of satoyama in balance for centuries, butnow free from human interference, about half of thesatoyama sites suffer the risk of extinction of manyendangered species in Japan. Crisis 3 is alien species (atopic dealt with in session 1) and chemical materials.

In session 2, six speakers presented the results oncrises 1 and 2 in an isolated urban forest, old-growthforests, and satoyama areas. These studies were carriedout by using quantitative methods of population ecol-ogy, such as mark-recapture of individuals, life tables,and metapopulation models. We also discussed mea-

sures for biodiversity management on the basis of thosestudies.

Habitat fragmentation often reduces plant repro-duction and recruitment, and is hypothesized to be adeterministic cause of population decline. To date, onlya few studies have quantified temporal variability offragmentation effects, and very few have conducteddemographic analyses of fragmented populations.Hiroshi Tomimatsu (Tokyo Metropolitan University),the first speaker, evaluated the consequences of habitatfragmentation in the common forest herb Trilliumcamschatcense in northern Japan. He carried out com-parative studies of populations with different sizes andfound evidence that seedling recruitment was reducedwith fragmentation because of pollen limitation andmicroclimatic edge effects. However, the effect onfecundity varied widely across years, with no clear effectof population size. He discussed these results withimplications for conservation and future research.

Daisuke Utsunomiya (Kanazawa University), thesecond speaker, reported the recent deterioration ofbiodiversity and disturbance in the pollination system inKanazawa Castle Park, where an isolated natural habi-tat with mature forest patches and grasslands wasmaintained until the late 1990s. Destruction of naturalhabitats by deforestation and construction of largeflower gardens, which took over native bees and waspsfrom native plants growing in the park, caused thechanges. He carried out a quantitative census byrecording the abundance of flowers of all plant speciesand all insect visitors to them in the study area. Toobtain the baseline data in this region, he also executed acomparative study in a satoyama area, located 6 kmaway, using the same methods.

The next two studies dealt with endangered aquaticinsects in satoyama environments, using mark-recaptureof adults for estimating population size and dispersalrate among habitats. Shogo Nishihara (The Universityof Tokyo), the third speaker, studied five endangereddiving beetles, including Dytiscus sharpi (Coleoptera:Ditiscidae), in the Noto Peninsula, Ishikawa Prefecture,

K. NakamuraInstitute of Nature and Environmental Technology,Kanazawa University,Kakuma, Kanazawa 920-1192, JapanE-mail: koji@kenroku.kanazawa-u.ac.jpTel.: +81-76-2646211Fax: +81-76-2646212

Popul Ecol (2006) 48:175–176DOI 10.1007/s10144-006-0270-3

and found that the beetles tended to remain in the samepond, and that the maximum life span of some specieswas as long as 3 years. He also found that populationsize of these beetles had sharply declined recently, al-though the reason was unclear.

Kazumasa Hidaka (Ehime University), the fourthspeaker, talked about endangered aquatic insects, thegiant water bug Lethocerus deyrolloi, and the divingbeetles Cybister spp. in the rice-paddy ecosystem. Thetwo speakers maintained that habitat degradation due toconcreting in agriculture practices and the increased rateof abandonment of paddies threaten hot spots of rareaquatic species.

Thomas Ranius (Swedish University of Agriculture),the fifth speaker, reported metapopulation dynamicsand conservation of a beetle, Osmoderma eremita,associated with hollow trees that has received muchattention among European conservationists. He usedcapture–recapture and telemetry of adult beetles. Indi-viduals in a stand of trees together form a metapopu-lation, connected by dispersal among trees. He alsostudied stands of different size, connectivity, and phys-ical characteristics and examined the colonization–extinction processes. Ongoing research aims at modelingthe extinction risk of O. eremita, as related to changes inthe density and spatial structure of the habitat.

Finally, Yoshihiro Natuhara (Osaka Prefecture Uni-versity) reported extinction and conservation of theclouded salamander, Hynobius nebulosus, at the meta-population level through landscape changes in satoy-ama. The species needs a site where both water andforest are present together. There are three threats forH.nebulosus: urbanization, land reform of paddy-fields,and abandonment of rice paddies. He built a habitatmodel on the regional scale and a metapopulation modelfor conservation and examined the efficacy of meta-population viability analysis for evaluation of develop-mental impact and its mitigation.

This special feature includes two review articles basedon the presentations by Ranius and Tomimatsu. Otherpresentations, based largely on unpublished or ongoingstudies, will be published elsewhere in the future.

Reference

Nature Conservation Bureau, Ministry of the Environment, Gov-ernment of Japan (2002) Living with nature—the nationalbiodiversity strategy of Japan. Nature Conservation Bureau,Tokyo

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