Ecosystem metabolism and trophic models of Miaoli lowland streams

• Main Authors: Han-Ni Tsai, 蔡函霓
• Other Authors: Hsing-Juh Lin
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/68155602435772436911

碩士 === 國立中興大學 === 生命科學系所 === 103 === An ecosystem is composed of organisms and surrounding environment. Study on specific organism will exclude the interactions between organisms and abiotic factors. When we perform an ecological study, the basic unit for research should be “ecosystem”. In this study, we determined the system metabolism and constructed trophic models of Miaoli lowland streams, in order to examine ecosystem structure and functioning. We also tried to determine main factors that regulate ecosystem structure. System metabolism represents the rates of production and consumption of organic matter, which is an integrated measure of a system. During the research period, system metabolism was higher in spring and summer, and all the study sites were heterotrophic. Energy supplied from adjacent riparian zones help to maintain the system functioning. Factors regulate system metabolism were different in the two streams. Velocity, and phosphate concentration were main factors for the Fei Fong Stream’s GPP. Coverage significantly regulated the GPP of the Hou Long Stream. The regulators of ER in the Fei Fong Stream were velocity and the concentrations of phosphate. Main impacted factor significantly impacted on the ER in the Hou Long Stream was the concentrations of organic matter and DIN. The driving forces for Miaoli lowland streams’s GPP were velocity, nutrient concentrations and coverage. The driving forces for Miaoli lowland streams’s ER were organic matter, velocity and nutrient concentrations. Trophic models simplify complex diet relationships between organisms, and summarize ecosystem structure and functioning. As result, the effective trophic levels at all the study sites were between 2-3, and there were few consumers with higher trophic levels, indicating that ecosystem structures were simple. Combined stream with riparian ecosystems into an entire ecosystem, the ecosystem maturity and stability would become higher. According to ecosystem indices, two streams belong to developing ecosystems. At the two sites in the Fei Fong Stream, the net primary production:respiration ratios approached 1, and the higher biomass:throughput ratios indicate that the ecosystems of the Fei Fong Stream were more mature. Our results were also supported by higher Finn’s mean path length. The linkage between stream and riparian ecosystems were strong for the two lowland streams in Miaoli. This suggests that we have to take them into a whole ecosystem for research or exploitation.