Landscape Diversity in the Floodplain of the Tama River

Abstract

The landscape diversity in the floodplain of the Tama River and that of the Tokyo area were analysed using published vagetation maps. Four diversity indices were calculated; community richness, patch richness, H'(Shanon-Weaver's diversity index), J'(Pielou's evenness index). Generally speaking, the four indices are signficantly correlated with one another.
The floodplain of the Tama River was devided into 62 segments with the space of one kilometer from the mouth of the river. Two factors, area and alteration of land by human activities, were extracted from the characteristics of these segments by factor analysis. It is found that landscape diversity is negatively correlated with alteration of land by human activities.
Landscape diversity indices were calculated in 65 quadrats (1×1km) sampled at random in Tokyo. Landscape diversity increases as the land undergoes changes by human activities, reaching the maximum where urban and agricultural areas account for 50%, but decreases in the quadrats subjected to heavy alteration by human activities.
The findings in the floodplain of the Tama River are similar to those in the quadrats subjected to heavy alteration by human activities in the Tokyo area.