ICT International

Advancing soil, plant and environmental decision making

Measuring how Kauri trees share water

OVERVIEW

When two trees of the same species are close to one another, they are able to undertake Hydraulic Coupling​ which allows the sharing of water between the trees. This was evident from the experiment that investigated the sap flow movement between a leafless Kauri tree remnant and conspecific hosts in Newland.

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LOCATION

New Zealand

How the SFM1 Sap Flow Meter was used

When two trees of the same species are close to one another, they are able to undertake Hydraulic Coupling. The use and applications of the SFM1 evidently provided​ data that detects there is water movement or flow between a Leafless Kauri Tree Remnant to Conspecific Hosts. The ICT international SFM1 (heat ratio method) was used to measure sap flow. Two sensors installed at 35 cm (vertical) and 40 cm height (horizontal) in the living stump and one sensor each at breast height in two neighbouring adult trees.

About the research

Given that the experiment was conducted to assess only the water sharing that would happen between neighboring trees, the results could only implicate physiological significance rather than ecological nature. Therefore, replications of similar pattern of measurements would improve the understanding of the hydraulic coupling of neighboring trees.

How does a tree without green foliage keep itself alive?

Dr Martin Bader and Assoc. Prof. Sebastian Leuzinger from Auckland University of Technology have found that when two trees of the same species are close to one another, they are able to undertake Hydraulic Coupling – that is share water, carbon, minerals and microorganisms.

To prove this, they attached ICT International SFM1 Sap Flow Meters and PSY1 Stem Psychrometers to a Kauri Tree and an adjacent stump with no leaves.

From the data that these instruments captured, Bader and Leuzinger were able to observe the movement of the sap between the stump and the tree.

The SFM1 Sap Flow Meter can measure very low sap flow and reverse sap flow. This enabled measurement of sap flow toward the tree in day time and reversal of flow toward the stump at night. The hydraulic gradient as measured by the PSY1 Stem Psychrometer reversed from day to night and hence the direction of flow reversed from day to night in relationship to this measured hydraulic gradient.

Sample Data

Read the full article (open access) from Bader and Leuzinger below:

Bader, M. K.-F., & Leuzinger, S. (2019). Hydraulic Coupling of a Leafless Kauri Tree Remnant to Conspecific Hosts. iScience, 19, 1238–1247. https://doi.org/10.1016/j.isci.2019.05.009