河岸带
环境科学
光合有效辐射
初级生产
昼夜垂直迁移
底栖区
有机质
地中海气候
天蓬
生态系统
大气科学
生态学
水文学(农业)
光合作用
生物
栖息地
地质学
植物
岩土工程
作者
Vicenç Acuña,Adonis Giorgi,Isabel Muñoz,Urs Uehlinger,Sergi Sabater
标识
DOI:10.1111/j.1365-2427.2004.01239.x
摘要
1. Single-station diel oxygen curves were used to monitor the oxygen metabolism of an intermittent, forested third-order stream (Fuirosos) in the Mediterranean area, over a period of 22 months. Ecosystem respiration (ER) and gross primary production (GPP) were estimated and related to organic matter inputs and photosynthetically active radiation (PAR) in order to understand the effect of the riparian forest on stream metabolism. 2. Annual ER was 1690 g O2 m−2 year−1 and annual GPP was 275 g O2 m−2 year−1. Fuirosos was therefore a heterotrophic stream, with P : R ratios averaging 0.16. 3. GPP rates were relatively low, ranging from 0.05 to 1.9 g O2 m−2 day−1. The maximum values of GPP occurred during a few weeks in spring, and ended when the riparian canopy was fully closed. The phenology of the riparian vegetation was an important determinant of light availability, and consequently, of GPP. 4. On a daily scale, light and temperature were the most important factors governing the shape of photosynthesis–irradiance (P–I) curves. Several patterns could be generalised in the P–I relationships. Hysteresis-type curves were characteristic of late autumn and winter. Light saturation responses (that occurred at irradiances higher than 90 μE m−2 s−1) were characteristic of early spring. Linear responses occurred during late spring, summer and early autumn when there was no evidence of light saturation. 5. Rates of ER were high when compared with analogous streams, ranging from 0.4 to 32 g O2 m−2 day−1. ER was highest in autumn 2001, when organic matter accumulations on the streambed were extremely high. By contrast, the higher discharge in autumn 2002 prevented these accumulations and caused lower ER. The Mediterranean climate, and in its effect the hydrological regime, were mainly responsible for the temporal variation in benthic organic matter, and consequently of ER.
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