砂州景観の生態的機能における生元素の表層貯留の役割

抄録

The ecosystem conservation of river environment is the key for land management. Through cooperated research among river hydraulics, ecology and limnology more than ten years, we have accumulated a lot of fragmentary information, and the problem is how to organize them properly to apply to the ecosystem assessment.

A segment with alternate sand bars is focused on. The information about habitat of typical organisms with their life cycles and bioelement cycle (nutrients-organic matters) are concentrated on the “typical micro-landscapes” as ecological function in a river with alternate bars. These micro-landscapes are classified by frequency of inundation and surface materials as terrestrial part are formed as fluvial process during floods which occur a few times in a year, while alternate sand bars are governed by floods which occur once a few years. The results indicate an ecological function is a role of bioelement storage on substratum of respective micro-landscapes. In addition, by using aerial photos taken since 1967 with the data of cross-section surveys, GIS techniques makes a map of micro-landscapes for each sand bar and it provides the area proportion of respective micro-landscapes. For the Kizu river as an example, we have showed comparison of 10 bars at present and historical change of two typical bars from 60’s to today.