Using Isotope Ratios of Respired CO2 in Small Watersheds as Indicators of Ecosystem Function: a Pilot Study

碳有两种稳定形态，12C和13C。这两种形式都用于光合作用，但植物对12C略有偏好，因此与大气中的二氧化碳相比，植物富含12C。此外，富集度还表明了植物生理的变化。这一知识长期以来一直被用于研究单个植物的生理学；我们的研究将这些概念应用于整个生态系统的研究。通过在夜间对定义明确的小流域入海口的空气进行采样，并分析呼吸二氧化碳中的碳同位素，我们相信我们可以监测流域内生态系统对环境变化的生理反应。我们将在两个小流域测试这一概念，并将设计和测试自动采样空气进行同位素分析的设备。每个田野季节至少有两名本科生参与这项研究。

Carbon has two stable forms, 12C and 13C. Both forms are used in photosynthesis, but plants have a slight preference for 12C, so plants are ENRICHED in 12C compared with atmospheric CO2. Furthermore, the degree of enrichment indicates variations in plant physiology. This knowledge has long been used to study physiology of individual plants; our study applies these concepts to studies of WHOLE ECOSYSTEMS. By sampling air at night at the mouth of small, well-defined watersheds, and analyzing carbon isotopes in respired CO2, we believe we can monitor the physiological responses of the ecosystems within the watersheds to environmental change. We will test this concept in two small watersheds, and will also design and test equipment to automatically sample air for the isotope analyses. At least two undergraduates will be involved in this study each field season.