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Partitioning interannual variability in net ecosystem exchange between climatic variability and functional change.
Dafeng Hui1, Yiqi Luo, Gabriel Katul
1Department of Botany and Microbiology, University of Oklahoma, Norman 73019, USA. dafeng@ou.edu
Tree Physiology
|April 3, 2003
Summary
Interannual variability in carbon exchange is driven by climate. A new model reveals that seasonal climate variations significantly impact net ecosystem exchange (NEE) and ecosystem respiration (RE), more than previously thought.
Area of Science:
- Ecology
- Climate Science
- Biogeochemistry
Background:
- Interannual variability (IAV) in net ecosystem exchange of carbon (NEE) is crucial for predicting future ecosystem changes.
- Understanding the drivers of IAV is challenging due to the complexity of isolating causal factors.
Purpose of the Study:
- To investigate the primary causes of IAV in NEE, hypothesizing that climatic variability is the main driver.
- To develop and apply a method to distinguish between direct climatic effects and indirect effects (functional change) on carbon fluxes.
Main Methods:
- Utilized a homogeneity-of-slopes model to analyze NEE and nighttime ecosystem respiration (RE) data.
- Employed multiple regression analysis to relate carbon fluxes with climatic variables on annual and multi-year scales.
- Partitioned observed variations in NEE and RE into functional change, interannual climatic variability, seasonal climatic variation, and random error components.
Main Results:
- Seasonal climatic variation was the largest contributor to NEE variability (59.9%) and RE variability (38.1%).
- Functional change explained 9.9% of NEE variation and 13.1% of RE variation.
- Interannual climatic variability and random error also contributed significantly to the observed variations in both NEE and RE.
Conclusions:
- Seasonal climate variability plays a dominant role in driving interannual fluctuations in ecosystem carbon exchange.
- The developed model effectively partitions the sources of variation in NEE and RE, highlighting the importance of functional changes and climate effects.
- Further research is needed to fully understand the complex interplay between climate and ecosystem carbon dynamics.
