Soil processes dominate the long-term response of forest net primary productivity to increased temperature and atmospheric CO2 concentration

B. E. Medlyn*, R. E. McMurtrie, R. C. Dewar, M. P. Jeffreys

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

64 Citations (Scopus)

Abstract

Predicting the responses of forest growth to elevated temperature (T) and atmospheric CO2 concentration ([CO2]) on decadal time scales presents a formidable challenge because of the many interacting processes involved. A key uncertainty concerns the relative importance of plant and soil processes to the overall long-term response. In this study, the plant-soil model G'DAY was used to simulate forest growth responses to T and [CO2] on different time scales for forests in cool and warm climates. An equilibrium-based graphical analysis was used to distinguish the roles played by plant and soil processes in determining the response. Doubled [CO2] caused a large initial increase (~20%) in net primary productivity (NPP), but this did not persist in the long term. By contrast, a 2°C increase in T caused a persistent long-term increase in NPP of approximately 10-15%. These responses were similar at cool and warm sites. The equilibrium analysis indicated that soil processes dominated the long-term responses predicted by the model. In particular, the predicted long-term increase in NPP under elevated T reflected an increase in predicted N mineralization and plant N uptake, assuming that a constant fraction of mineralized N is taken up by plants. The analysis highlights key uncertainties for future research.

Original languageEnglish
Pages (from-to)873-888
Number of pages16
JournalCanadian Journal of Forest Research
Volume30
Issue number6
Publication statusPublished - 2000
Externally publishedYes

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