Changes in duration of reproductive phases and lagged phenological response to experimental climate warming

Abstract

Background : Climate manipulation experiments have found lagged responses in biomass and community composition.

Aims : To look for lagged responses of flowering phenology and effects on duration of reproductive phases.

Methods: Treatment and post-treatment year phenological data from 12 species in a 1-year step warming and double precipitation experiment was examined.

Results: Changes in phenology due to the previous year's warming were in the opposite direction to those observed during the treatment year. Six species responded to warming in 2004, delaying flowering 6.2 days and fruiting 7.9 days. Unlike 2003, no species advanced flowering phenology in 2004. Delays resulted from a soil moisture deficit in formerly warmed plots that lasted 3 months or more after warming ended. Increased precipitation altered phenology in one species but did not affect duration of reproductive phases. While 10 of 11 responsive species entered bud phase earlier under warming than in controls in 2003, in only two species showed a phenological delay at the beginning of the bud phase in 2004. Warming tended to shorten flowering and fruiting stages and total duration in spring annuals.

Conclusions: Together, these results suggest that climate anomalies can influence phenology in the following year, here due to a lag in soil moisture recharge.

Keywords:

• climate change
• climate warming
• flowering duration
• flowering phenology
• increased precipitation
• lagged effects
• lagged response

Acknowledgements

Field assistance was provided by Nancy Zerhbach and Melissa Talley. Financial support provided by NSF IRCEB grant no. DEB 0078325.