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Published on: November 21, 2015
Recent widespread tree growth decline despite increasing atmospheric CO2
Lucas C R Silva1, Madhur Anand, Mark D Leithead
1Global Ecological Change Laboratory, School of Environmental Sciences, University of Guelph, Guelph, Ontario, Canada.
Plos One
|July 27, 2010
Summary
Rising atmospheric CO2 has increased tree water use efficiency (WUE) but not prevented widespread forest growth declines. Warming-induced stress is a key factor, but other stressors may also impact tree health and forest carbon stocks.
Area of Science:
- Forest Ecology
- Climate Change Biology
- Dendrochronology
Background:
- Rising atmospheric CO2 and temperature are expected to enhance boreal and temperate forest growth.
- However, dendrochronological studies show varied tree growth responses, with unclear physiological bases.
- The impact of atmospheric changes on tree growth remains a critical research question.
Purpose of the Study:
- To investigate the effects of atmospheric changes on water use efficiency (WUE) and tree growth.
- To assess these impacts across different tree species and latitudes in Canadian forests.
- To clarify the physiological mechanisms behind observed tree growth trends.
Main Methods:
- Combined dendrochronological methods with carbon isotopic analysis.
- Analyzed tree growth (basal area increment - BAI) and WUE over a latitudinal gradient.
- Correlated growth and WUE with climate variables (temperature, precipitation).
Main Results:
- Trees exhibited a 53% increase in WUE over the past century.
- Widespread tree growth decline (BAI) was observed in recent decades.
- Warming temperatures correlated negatively with BAI, suggesting water stress.
- Where climate didn't explain declines, WUE and BAI were positively correlated, indicating additional stressors.
Conclusions:
- Temperate and boreal forests show widespread growth declines, primarily due to warming-induced stress.
- Increased WUE from rising CO2 did not prevent growth decline, challenging carbon stock predictions.
- Findings suggest the existence of additional stressors impacting forest health beyond climate change.
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