SREL
Reprint #2629
Abundance,
production and mortality of fine roots under elevated atmospheric
C02 in an oak-scrub ecosystem
John
J. Dilustro a,d, Frank P. Day a,*,
Bert G. Drake b, Charles R. Hinkle c
aDepartment
of Biological Sciences, Old Dominion University, Norfolk,
VA 23529, USA
bSmithsonian Environmental Research Center, P.O.
Box 28, Edgewater, MD 21037, USA
cDynamac Corporation, Mail Code DYN- 1, Kennedy
Space Center, FL 32899, USA
dSavannah River Ecology Laboratory, University
of Georgia, Drawer E, Aiken, SC 29802, USA
Received 18 December
2001; received in revised form 5 March 2002; accepted 6
March 2002
Abstract
Atmospheric carbon
dioxide levels are increasing and are predicted to double
this century. The implications of this rise on vegetation
structure and function are not well understood. Measurement
of root growth response to elevated atmospheric carbon dioxide
is critical to understanding plant responses and soil carbon
input. We investigated the effects of elevated carbon dioxide
on fine root growth using open top chambers with both ambient
and elevated (700 PPM) C02 treatments in an oak-palmetto
scrub ecosystem at Kennedy Space Center, FL. Minirhizotron
tubes installed in each elevated and control chamber were
sampled for root length density (mm cm-2) every
3 months. Carbon dioxide enrichment of the chambers began
May 15, 1996. By December 1997, root length density (RLD)
increased to 7.53 mm cm-2 for the control chambers
and 21.36 mm cm-2 for the enriched chambers in
the top 101-cm of soil. Vertical distribution of fine roots
was unchanged under elevated carbon dioxide. Fine root production
increased with elevated carbon dioxide, and mortality and
turnover were higher in the elevated chambers by the last
sample date in 1997. The increased rates of fine root growth
coupled with no change in decomposition rate suggest a potential
increased rate of carbon input into the soil. However, these
results only represent the first 21 months post-fire and
recovery to root closure could just be faster in the elevated
CO2 atmosphere.
Keywords:
CO2; Minirhizotrons; Root growth; Root length
density; Root mortality; Root turnover
SREL
Reprint #2629
