Canopy transpiration and water fluxes in the xylem of the trunk of Larix and Picea trees - a comparison of xylem flow, porometer and cuvette measurements

摘要: Leaf gas exchange, transpiration, water potential and xylem flow measurements were used in order to investigate the daily balance of intact, naturally growing, adult Larix Picea trees without major injury. The total use tree was very similar when measured as at breast height or trunk top below shade branches, canopy transpiration by a porometer exchange chamber different crown positions. average is about 12% lower than single twig sun Picea. Despite similarity flows there are larger differences actual course. Transpiration started 2 3 h earlier decreased noon before maximum reached, stopped evening though stem. course base lowest branches with needles. difference efflux from via influx caused stored water. specific capacitance wood estimated be 4.7 x 10-8 6.3 kg kg-1 Pa-1 amount available storage 17.8 8.7 kg, which 24% 14% respectively. Very little main trunk. With increasing crown, foliage decreases. Plant status recovers decrease refilling sites. liquid conductance 0.45 10-9 0.36 mol m-2s-1 role stomata their control environmental internal plant factors discussed.