| Energy-based indicators have been proposed as measures for assessing the state of ecosystems. The objectives of this study were: (1) to provide a conceptual framework for the application of the energy dissipation principles in small scale ecosystems at low height (2) to determine if by viewing living forms as energy degrading structures a relationship can be found between successional stage (i.e. complexity) and disturbance, surface canopy temperature and caloric equivalent of non-agricultural and agricultural plant communities. The non-agricultural sites were chosen to represent varying successional stages. At the agricultural site corn was grown under six levels of nitrogen in no-till and conventional tillage systems. A positive relationship was found to exist between surface canopy-air temperature differential (plant canopy temperature minus air temperature at 50 cm above the canopy) and successional stage and/or level of input. In the younger non-agricultural sites surface canopy was warmer and caloric equivalents were lower. At the agricultural site, as nitrogen levels increased surface canopy became cooler. No evidence was found to support the hypothesis that caloric equivalence would increase with increasing level of nitrogen. |
