Chlorophyll Index and Photosynthetic Carbon Sequestration in Northern Eurasia Forests

An infrared gas analyzer was operated in an open-circuit differential mode to measure CO₂ gas exchange in intact leafy and leafless parts of skeletal branches of Pinus sylvestris L. throughout the summer daylight period. The photosynthetic carbon sequestration in major types of forest phytocenoses in northern Eurasia was assessed for middle-aged and moderately dense stands. The estimates were corrected for carbon losses associated with phloem transport of photosynthetic products per each meter of transport pathway (14 kg C/(kg chlorophyll m)), as well as for respiratory losses of heterotrophic phytomass. A high correlation (R² = 0.82) was found between this component of production process in the current growth season and the chlorophyll index for major forest associations of northern Eurasia. It is concluded that the transport-related carbon losses of photosynthetic products in the phloem over the current growth period (1100 h) enlarge significantly as the mean stand height increases during the tree growth and upon the regional shift from north to south.