Excision increases branch water potential but generally reduces leaf gas exchange
Marcella Cross1,2, Sean T Michaletz1,2
1Department of Botany, The University of British Columbia, 6270 University Blvd., Vancouver, British Columbia V6T 1Z4, Canada.
Tree Physiology
|April 20, 2026
Summary
Branch excision for plant gas exchange measurements affects water potential and photosynthesis differently across species. Understanding these species-specific impacts is crucial for accurate data interpretation in plant science.
Area of Science:
- Plant Physiology
- Forest Ecology
- Environmental Science
Background:
- Measuring leaf gas exchange in inaccessible trees is challenging.
- Branch excision is a common method, but its effects on plant physiology are not fully understood.
- Variability in water potential and gas exchange responses to excision exists across species.
Purpose of the Study:
- To quantify the effects of branch excision on water potential and gas exchange in diverse tree species.
- To investigate species- and trait-dependent variations in these effects.
- To provide guidance for interpreting gas exchange data from excised branches.
Main Methods:
- Measured branch water potential, stomatal conductance, photosynthesis, and stomatal behavior (g1) in five tree species.
- Conducted a meta-analysis of 26 species to assess generality.
- Compared effects across different hydraulic traits and water-use strategies.
Main Results:
- Excision consistently increased branch water potential across all species.
- Angiosperms showed reduced stomatal conductance and photosynthesis post-excision.
- The gymnosperm exhibited increased stomatal conductance and photosynthesis; meta-analysis confirmed general decreases in gas exchange.
- Effect sizes varied significantly based on species, water-use strategy, and hydraulic traits.
Conclusions:
- Branch excision significantly impacts plant water relations and gas exchange.
- Responses are highly species- and trait-dependent, necessitating careful interpretation of data.
- Study-specific corrections are essential when using excised branches for physiological measurements.
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