Author:
Nyberg Marion,Hovenden Mark J.
Abstract
Abstract. Increases in global temperatures due to climate change threaten to
tip the balance between carbon (C) fluxes, liberating large amounts of C
from soils. Evidence of warming-induced increases in CO2 efflux from
soils has led to suggestions that this response of soil respiration
(RS) will trigger a positive land C–climate feedback cycle, ultimately
warming the Earth further. Currently, there is little consensus about the
mechanisms driving the warming-induced RS response, and there are
relatively few studies from ecosystems with large soil C stores. Here, we
investigate the impacts of experimental warming on RS in the C-rich
soils of a Tasmanian grassy sedgeland and whether alterations of plant
community composition or differences in microbial respiratory potential
could contribute to any effects. In situ, warming increased RS on average by
28 %, and this effect was consistent over time and across plant community
composition treatments. In contrast, warming had no impact on microbial
respiration in incubation experiments. Plant community composition
manipulations did not influence RS or the RS response to warming.
Processes driving the RS response in this experiment were, therefore,
not due to plant community effects and are more likely due to increases in
below-ground autotrophic respiration and the supply of labile substrate
through rhizodeposition and root exudates. CO2 efflux from this
high-C soil increased by more than a quarter in response to warming,
suggesting inputs need to increase by at least this amount if soil C stocks
are to be maintained. These results indicate the need for comprehensive
investigations of both C inputs and losses from C-rich soils if efforts to
model net ecosystem C exchange of these crucial, C-dense systems are to be
successful.
Subject
Earth-Surface Processes,Ecology, Evolution, Behavior and Systematics
Cited by
7 articles.
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