Variation of vegetation incidence by installation of a slit-type erosion control dam -a study based on mesh data and variation of substrata of habitats-

Abstract

This paper summarizes a field survey on physical features of and vegetation on a dry riverbed around a slit-type erosion control dam in Ozo river. Field surveys cover the range 130m to upstream and 200m to downstream of the dam and were performed in 2001 before the construction, and 2008 and 2009 after the construction. We developed a relationship between physical property of substrata and incidence of species of vegetation on the same property of substrata for each species. This incidence ratio is obtained from the observed data in 2001.Predicted mesh numbers and observed mesh numbers for all species observed in three years were shown in one figure. An estimation line between prediction and observation which is developed by Generalized Linear Mixed Model can give reliable relationship even for cases of sparse incidence of vegetation. It is shown that variation of vegetation incidence can be predicted by physical property of substrata. However, it is also shown that substrata and vegetation in studied area are still under succession stage in short period after the impact of construction.