Thursday, August 6, 2009 - 10:15 AM

SYMP 16-6: The long ecological view:  Unravelling trends, confounding effects, and complex responses at Archbold Biological Station

Hilary Swain, Archbold Biological Station

Background/Question/Methods

Joseph Grinnell, renowned researcher, teacher, field biologist and collector in the forty years before World War Two, pictured a biological field station (the Hastings Reservation in northern California) as "a recognized 'Mecca' to which will come, for periods of undistracted research, advanced students of ornithology, mammalogy, botany, entomology, ecology, etc., using the local flora and fauna as source of the living materials to be studied, with aid from the station records and the authentically identified reference collections - a pleasant picture, truly".  Biological field stations continue to be much-loved, pleasant Meccas for field biologists, but field station records serve increasingly as vital biological barometers, witnesses to changes in biodiversity and ecosystem responses over the long-term. The length of field station records, the "long ecological view", is key to unraveling long-term trends, but demands frequent re-interpretation, particularly as we uncover confounding effects and interactions among ecosystem stressors.   I use here four examples drawn from Archbold Biological Station, Florida, to illustrate how understanding biological responses to climatic variability evolves over the course of long-term studies.

Results/Conclusions

1)  Lake Annie was described in 1979 as a stable, high-transparency monomictic lake, the most pristine in Florida.  But 25 years of monthly limnological sampling, in conjunction with 75-year climate and lake level records, have unravelled a complex story:  the lake exhibits large shifts in transparency driven by long-term rainfall cycles associated with the Atlantic Multi-decadal Oscillation.  2)  The seminal study of Florida scrub jays conducted at Archbold for four decades shows that the timing of breeding is associated with the Southern Oscillation Index, but this trend was revealed only by removing the confounding effect of the availability of supplementary human-provided food.  3)  Population viability analyses of several Florida scrub plants can be best explained by combining fire cycles with climate records.  4)  In contrast to commonly held predictions, the 40-year fire history from Archbold does not show strong correlation with drought conditions, largely because social conditions-permits for prescribed burns-lead to fire suppression in drought years. 

Biological field stations can serve as ecologists' fine wine cellars, laying down new bottles of data every year, enabling judicious sampling of vintage data for decades to come.  But field stations can provide this long view only if they have the resources to secure and archive data, such that data can be readily retrieved, reviewed, and re-analyzed.