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Belowground hydraulic conductance in a mature boreal Scots pine tree

Lintunen, A., Paljakka, T., Salmon, Y., Hölttä, T.
Acta horticulturae 2018 no.1222 pp. 103-108
Pinus sylvestris, autumn, dendrometers, growing season, sap flow, soil temperature, soil water, soil water content, soil water potential, spring, summer, trees, water content, xylem
We studied the dynamics of belowground hydraulic conductance (k(bg)) of a mature Scots pine tree in field conditions using continuous xylem diameter change and sap flow measurements over a full growing season in a boreal environment. Our aim was to analyze how k(bg) is linked to soil temperature and soil water content. k(bg) was calculated as the ratio of daily maximum sap flow rate to the difference between stem and soil water potential estimated from daily diameter variations of xylem measured with point dendrometers. k(bg) increased with increasing soil temperature in spring and autumn when soil temperatures were below +8°C. k(bg) also increased with increasing soil water content if soil temperature was high enough as was the case in summer. The results suggest that k(bg) in the studied tree was more limited by soil temperature than water content.