|| 要旨トップ | 本企画の概要 |||日本生態学会第61回全国大会 (2014年3月、広島) 講演要旨
シンポジウム S10-2 (Lecture in Symposium/Workshop)
In stream ecosystems, it has been pointed out that estimating the contribution of resources to an organism and its trophic level are difficult because the δ13C of periphytic algae greatly varies with spatio-temporal variation. Recently, estimation of the trophic levels based on δ15N of individual amino acids has been developed to resolve those problems. However, there are few applications of this tool to actual food webs.
We investigated macroinvertebrates in headwater streams in Mt. Gomadan Experiment Forest. In this area, the clear cutting is usually operated within small catchments. Therefore, it is possible to clarify the long-term effects of the clear cutting on ecosystems. We measured the bulk δ13C, δ15N and δ15N of amino acids of organisms in six headwater streams of stand ages ranging from 5 to >90 yr.
A dual isotope plot of δ13C and δ15N values showed that most of macroinvertebrates depended on both terrestrial litter and periphytic algae. The mean δ13C values of macroinvertebrates decreased with increasing stand ages. The result indicates that the macroinvertebrates in old stand ages depended more on allochthonous resources rather than on autochthonous resources. In the presentation, we will also discuss the results of the trophic levels using δ15N values of amino acids.