Nisikawa Usio

Current studies

１．Ecological restoration of farmland

Paddy fields are known to serve as alternative wetland habitats for a range of wildlife that once inhabited floodplain habitats. However, biodiversity in paddy fields are threatened worldwide, due to the overuse of agrochemicals, land consolidation or abandonment of management following depopulated and ageing rural communities.

To restore biodiversity of paddy-dominated landscapes and to revitilise depopulated and ageing rural communities, wildlife-friendly farming practices are implemented in many places of Japan. However, the effectiveness of wildlife-friendly farming has rarely been reported from paddy-dominated landscapes.

Through field surveys and manipulative experiments, I have studied the effectiveness of wildlife-friendly farming practices on paddy field biodiversity on Sado Island, one of the Globally Important Agricultural Heritage System (GIAHS) site in Japan. I am considering of experimentally implementing wildlife-friendly farming practices in rural areas of Noto Peninsula, where such a farming practices are less popular. By collaborating with economists, I will also explore sustainable ecological restoration in paddy-dominated landscapes.

Related articles

Usio N & Miyashita T eds. (2015) Social-ecological restoration in paddy-dominated landscapes. Ecological Research Monographs, Springer, Tokyo

Nakamura S, Tsuge T, Okubo S, Takeuchi K, Usio N (2014) Exploring factors affecting farmers' implementation of wildlife-friendly farming on Sado Island, Japan. Journal of Resources and Ecology 5: 370-380.

２．Farm pond conservation and management

Farm ponds have high conservation value because they are often comprised of unique or rare aquatic biota. However, farm pond ecosystems are degraded due to invasion of nonnative species, water pollution, land consolidation or abandonment of management. Through field surveys and interviews, we evaluated whether pond draining, a traditional management method, was effective in managing biodiversity and water quality of farm ponds. Through a collaboration with an economist, we calculated willingness to pay (WTP) of farm pond managers against management of nonnative species.

Related articles

Usio N, Imada M, Nakagawa M, Akasaka M, Takamura N (2013) Effects of pond draining on biodiversity and water quality of farm ponds. Conservation Biology 6: 1429-1438.

Usio N & Miyashita T eds (2011) "Biological and human dimensions of species invasions", Syokabo Publishing, Tokyo. (In Japanese)

3. Ecology and management of crayfish

Crayfish can play important roles as keystone species in freshwater biodiversity and ecosystem functioning. We have studied ecology, biogeography and management of Japanese (Cambaroides japonicus) and American crayfishes (Pacifastacus leniusculus and Procambarus clarkii).

To explore the invasion success of the signal crayfish (P. leniusculus), we are currently studying morphological, behavioural and genetic variations in its native and nonnative range.

Related articles

Larson ER, Abbott CL, Usio N, Azuma N, Wood KA, Herborg L-M & Olden JD (2012) The signal crayfish is not a single species: cryptic diversity and invasions in the Pacific Northwest range of Pacifastacus leniusculus. Freshwater Biology 57: 1823-1838.

Koizumi I, Usio N, Kawai T, Azuma N, Masuda R. (2012) Loss of genetic diversity means loss of geological information: the endangered Japanese crayfish exhibits remarkable historical footprint. PLoSONE 7: e33986.

Larson ER, Olden JD & Usio N (2010) Decoupled conservatism of Grinnelian and Eltonian niches in an invasive arthropod. Ecosphere 1: Article 16.

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