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Stem respiration in a closed-canopy upland oak forest.
1Oak Ridge National Laboratory, Environmental Sciences Division, Oak Ridge, TN 37831-6034, USA.
Tree Physiology
|April 1, 1996
Summary
Tree stem respiration varies with season and drought, with maintenance respiration comprising a significant portion of total respiration. Woody tissue respiration contributes substantially to carbon cycling at the ecosystem level.
Area of Science:
- Forest Ecology
- Plant Physiology
- Biogeochemistry
Background:
- Stem respiration is a key component of forest carbon cycling.
- Understanding seasonal variations and environmental influences on respiration is crucial for accurate ecosystem modeling.
- Maintenance respiration (R(m)) represents a significant energy cost for trees.
Purpose of the Study:
- To quantify stem respiration rates in mature oak and red maple trees.
- To investigate the relationship between respiration, growth, temperature, and water availability.
- To estimate the contribution of maintenance respiration to total stem respiration and its ecosystem-level implications.
Main Methods:
- Measured stem respiration (R(t)) on 56 trees across three species over two years.
- Monitored diameter increments, stem temperatures, and soil water content.
- Utilized Q(10) values and baseline respiration to predict seasonal maintenance respiration (R(m)).
Main Results:
- Respiration tracked growth, but increased during drought.
- Dormant season respiration correlated with sapwood thickness, while growing season respiration did not.
- Maintenance respiration constituted 47-65% of total stem respiration annually.
- Woody tissue respiration contributed 149-204 g C m(-2) soil surface year(-1) to ecosystem carbon flux.
Conclusions:
- Stem respiration is dynamic, influenced by growth, drought, and temperature.
- Maintenance respiration is a substantial carbon sink in forest ecosystems.
- Accurate estimation of woody tissue respiration is vital for understanding forest carbon budgets.