Modeling Watershed-scale Stream Metabolism in Subtropical Small Mountainous Rivers, Taiwan
Abstract
Stream metabolism, closely linked to net ecosystem productivity (NEP), is one of important routes of carbon cycle and aquatic ecosystem functions. Stream metabolism can be described as the diurnal variation of dissolved O2 (DO) concentration, in which photosynthetic active radiation (PAR), landscape setting, hydrologic regime, biome, nutrient concentrations and temperature regulate. However, few studies focused on stream metabolism in subtropical small mountainous rivers (SMRs), where the change of stream metabolism along river continuum is unclear. Our study used the hourly DO records to estimate the local stream metabolism. Further the controlling factors supplementary with landscape metrics was introduced to Spatial Stream Network (SSN) models for simulating stream metabolism along rivers. Results showed that the monthly mean NEPs in each study sites vary from -1.4 g O2 m-2 d-1 to 2 g O2 m-2 d-1 with strong seasonal variation. The mean of daily NEP in the whole study area appears the lowest value on March (-0.16 g O2 m-2 d-1) and reach the peak on July (0.97 g O2 m-2 d-1). Meanwhile, the pH and building area likely affect stream metabolism significantly. The low and negative NEP indicates the headwater rivers are heterotrophic-dominated or phytoplankton-limited, but changes toward autotrophic-dominated downstream. The identification of controlling factors to stream metabolism is an essential step for further spatial estimation along river continuum.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.H15P0988H