Contrasting responses to drought of forest floor CO 2 efflux in a Loblolly pine plantation and a nearby Oak‐Hickory forest
Abstract Forest floor CO 2 efflux ( F ff ) depends on vegetation type, climate, and soil physical properties. We assessed the effects of biological factors on F ff by comparing a maturing pine plantation (PP) and a nearby mature Oak‐Hickory‐type hardwood forest (HW). F ff was measured continuously w...
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Published in | Global change biology Vol. 11; no. 3; pp. 421 - 434 |
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Main Authors | , , , , , , , |
Format | Journal Article |
Language | English |
Published |
01.03.2005
|
Online Access | Get full text |
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Summary: | Abstract
Forest floor CO
2
efflux (
F
ff
) depends on vegetation type, climate, and soil physical properties. We assessed the effects of biological factors on
F
ff
by comparing a maturing pine plantation (PP) and a nearby mature Oak‐Hickory‐type hardwood forest (HW).
F
ff
was measured continuously with soil chambers connected to an IRGA during 2001–2002. At both sites,
F
ff
depended on soil temperature at 5 cm (
T
5
) when soil was moist (soil moisture,
θ
>0.20 m
3
m
−3
), and on both
T
5
and
θ
when soil was drier. A model (
F
ff
(
T
5
,
θ
)) explained 92% of the variation in the daily mean
F
ff
at both sites. Higher radiation reaching the ground during the leafless period, and a thinner litter layer because of faster decomposition, probably caused higher soil temperature at HW compared with PP. The annual
F
ff
was estimated at 1330 and 1464 g C m
−2
yr
−1
for a year with mild drought (2001) at PP and HW, respectively, and 1231 and 1557 g C m
−2
yr
−1
for a year with severe drought (2002). In the wetter year, higher soil temperature and moisture at HW compared with PP compensated for the negative effect on
F
ff
of the response to these variables resulting in similar annual
F
ff
at both stands. In the drier year, however, the response to soil temperature and moisture was more similar at the two stands causing the difference in the state variables to impel a higher
F
ff
at HW. A simple mass balance indicated that in the wetter year, C in the litter–soil system was at steady state at HW, and was accruing at PP. However, HW was probably losing C from the mineral soil during the severe drought year of 2002, while PP was accumulating C at a lower rate because of a loss of C from the litter layer. Such contrasting behavior of two forest types in close proximity might frustrate attempts to estimate regional carbon (C) fluxes and net C exchange. |
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ISSN: | 1354-1013 1365-2486 |
DOI: | 10.1111/j.1365-2486.2005.00915.x |