Performing gas-exchange measurements on excised branches - evaluation and recommendations

In forest canopies, it is common to perform leaf-level gas-exchange measurements on recently excised branches, often without testing for excision-related biases. We conducted a formal test of excision effects using gas-exchange measurements from cut and uncut canopy branches of three deciduous hardw...

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Bibliographic Details
Published in:	Photosynthetica Vol. 59; no. 1; pp. 61 - 73
Main Authors:	MISSIK, J.E.C., OISHI, A.C., BENSON, M.C., MERETSKY, V.J., PHILLIPS, R.P., NOVICK, K.A.
Format:	Journal Article
Language:	English
Published:	Academy of Sciences of the Czech Republic, Institute of Experimental Botany 01-01-2021
Subjects:	canopy physiology cut branch hydraulics isohydricity measurement bias methodology
Online Access:	Get full text
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Summary:	In forest canopies, it is common to perform leaf-level gas-exchange measurements on recently excised branches, often without testing for excision-related biases. We conducted a formal test of excision effects using gas-exchange measurements from cut and uncut canopy branches of three deciduous hardwoods - sugar maple (Acer saccharum Marsh.), tulip poplar (Liriodendron tulipifera L.), and white oak (Quercus alba L.). Across all species, excision immediately reduced photosynthesis and stomatal conductance by 27-62% relative to pre-excision rates. In white oak, which had particularly long (> 100 cm) vessels, gas exchange was more impaired for shorter (~ 30 cm) as compared to longer (~ 100 cm) branches. Additional hypotheses linking branch height and species water-use strategy to excision bias were tested but not confirmed. A survey of 23 previously published studies confirms that our results are not without precedent. Excision-related biases should be considered when interpreting measurements performed on excised branches.
ISSN:	0300-3604 1573-9058
DOI:	10.32615/ps.2020.079