Photosynthetic activity of coniferous undergrowth after industrial felling

The functioning of coniferous undergrowth of preliminary and subsequent generations after industrial felling was considered in the middle taiga subzone of the Komi Republic. Using spectrophotometric and gasometric methods we analyzed the pigment activity, photosynthetic, and respiratory abilities of the assimilation apparatus of pine (Pinus sylvestris L.) and spruce (Picea obovata Ledeb.) undergrowth at the 3- and 10-year old clearings. The pigment apparatus functional rearrangement of the preliminary generation spruce undergrowth at clearings was found. Needles adapt to environmental conditions at the pigment system level by changing the content and ratio of chlorophylls and carotenoids. Changes in plastids in the spruce undergrowth at the 3-year clearings occurred due to a decrease in chlorophyll and carotenoid concentrations, and at the 10-year clearings due to activation of pigment synthesis which affects the carbon dioxide absorption in chloroplasts. The assimilation apparatus of spruce undergrowth at clearing absorbs CO2 by 1.4 and 1.8 time more actively than that under the forest canopy. The photosynthetic and respiratory abilities of spruce needles at clearings do not differ. This indicates a stable level of important vital processes for the studied undergrowth at clearings during ten years after felling. Pine and spruce undergrowth needles are able to absorb CO2 at a fairly high rate up to 5.73 and 2.7 μmol CO2/(m2 · s) respectively. This rate contributes to the accumulation of assimilates in pine needles and their use for growth which logically increases the productivity of undergrowth at clearings. In general, the functional organization of spruce and pine undergrowth assimilating organs ensures their growth and favors the successful restoration of conifers at clearings in the middle taiga subzone of the European North-East.