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Update:July 31, 2019

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Changes in the forest distribution under future population decline


Article title

High-resolution national land use scenarios under a shrinking population in Japan

Author (affiliation)

Haruka Ohashi (a), Keita Fukasawa (b), Toshinori Ariga (b), Tetsuya Matsui (a), Yasuaki Hijioka (b)

(a) Center for International Partnerships and Research on Climate Change, FFPRI, Tsukuba, Ibaraki, Japan.

(b) National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan

Publication Journal

Transactions in GIS, March 2019 DOI:10.1111/tgis.12525( External link )

Content introduction

The population of Japan has been decreasing since 2010. By 2060, the population is expected to drop to 2/3rd of its current size. Future population decline may cause changes in land use, thereby causing changes in the quality and quantity of ecosystem services and variedly impacting on human well-being. However, these changes can also provide a new opportunity for regional development by enhancing multifaceted ecosystem functions, e.g., promoting reforestation on abandoned farmland or building sites. To consider the guidelines for such land use in advance, predicting the changes in the land use resulting from future declines in the population is essential.

In the present study, we developed a machine-learning model that predicts land use on a grid with a 1-km2 resolution using spatially explicit information such as population density and topography. Using this model, we estimated the land use changes under two future population scenarios: centralization and decentralization. The result showed that under the centralization scenario, built-up areas become compact in urban centers; simultaneously, forests and wastelands expand in current agricultural areas. Conversely, under the decentralization scenario, a mosaic-like landscape structure with a mixture of forest and farmland is widely maintained in agricultural areas.

The result of this study will provide fundamental information for predicting future changes in ecosystem services and planning measures for climate change adaptation under the declining population in the future.

Figure. Predicted change in the proportion of forest

Figure. Predicted change in the proportion of forest and wasteland from 2010 to 2050 predicted using the land use model developed in this study. Under the centralization scenario, there are many grid cells with increasing area of forest and wasteland (left), and under the decentralization scenario, there are more grid cells with a decreasing area of forest and wasteland near the urban centers (right).