Graduate School of Science and Engineering Science of Environment and Mathematical Modeling

<1> Mechanisms for maintaining diversity and function for soil fauna in forest ecosystem

To establish a sustainable management method to keep healthiness of forest ecosystems, we need to make the function in ecosystem to work effectively the mechanisms nutrient cycling. For the sake, we must investigate the decomposition process precisely and make clear the ecology of soil fauna and microorganisms relating with the structure and function of the soil organisms contributing the decomposition process.
We investigate the weight, nutrient, fungal length and structure of soil faunal community during the decomposition of needles. As a result, at the early stage of decomposition fungal lengths suddenly increased and content of nitrogen and phosphorus also increased. At that stage, fungal selective feeder (some species of Collembola) dominated in the litter. At the late stage of decomposition, the growth of fungi decreased and animal species feeding on feces or humus materials increased. The diversity of soil fauna was supported by the succession process with species turnover. We also investigated the importance of the composition of leaves and twigs in the litter layer to determine the structure of soil faunal communities. As a result, the representative species responded differently to the species of leaf or weight of litter. From this result, the weight and composition of litter layer is suggested to be an important factor to determine the soil faunal community. From these achievements, we could take the knowledge about the decomposition process and maintenance for the diversity of soil fauna.

<2> Study for the effects of the various environmental disturbance on the soil biodiversity

Various group of organisms could be used for the indicator to the various environmental disturbance. However, the response of soil faunal community to the change of forest environment as a soil indicator was rarely studied. So, I investigated the influence of the forest management, resource amount, change of altitude, invasive species and road construction on the soil animal communities, and present the way to avoid or reduce disturbance effects.
For example, we studied the effects of tree harvesting methods on soil fauna in Borneo Island, Malaysia. We found that the reduced impact logging methods reduced the damage of logging for soil fauna compared with the conventional logging method. This tendency was common to the other decomposer organisms, trees and mammals. Therefore, this method of logging suggested to be useful method for sustainable use of forest and reducing the greenhouse gas emission