Data for: Using a demographic model to project the long-term effects of fire management on tree biomass in Australian savannas

Tropical savannas are characterised by high primary productivity and high
fire frequency, such that much of the carbon captured by vegetation is
rapidly returned to the atmosphere. Hence, there have been suggestions
that management-driven reductions in savanna fire frequency and/or
severity could significantly reduce greenhouse gas emissions and sequester
carbon in tree biomass. However, a key knowledge gap is the extent to
which savanna tree biomass will respond to modest shifts in fire regimes
due to plausible, large-scale management interventions. Here, we: (1)
characterise relationships between the frequency and severity of fires and
key demographic rates of savanna trees, based on long-term observations in
vegetation monitoring plots across northern Australia; (2) use these
relationships to develop a process-explicit demographic model describing
the effects of fire on savanna tree populations; and (3) use the
demographic model to address the question: to what extent is it feasible,
through the strategic application of prescribed burning, to increase tree
biomass in Australian tropical savannas? Our long-term tree monitoring
dataset included observations of 12,344 tagged trees in 236 plots,
monitored for between 3 and 24 years. Analysis of this dataset showed that
frequent high-severity fires significantly reduced savanna tree
recruitment, survival and growth. Our demographic model suggested that:
(1) despite the negative effects of frequent high-severity fires on
demographic rates, savanna tree biomass appears to be suppressed by only a
relatively small amount by contemporary fire regimes, characterised by a
mix of low- to high-severity fires; and (2) plausible, management-driven
reductions in the frequency of high-severity fires are likely to lead to
increases in tree biomass of about 11.0 t DM ha–1 (95% confidence
interval: -1.2–20.8) over a century. Accounting for this increase in
carbon storage could generate significant carbon credits, worth on average
three times those generated annually by current greenhouse gas (methane
and nitrous oxide) abatement projects, and has the potential to
significantly increase the economic viability of fire/carbon projects,
thereby promoting ecologically sustainable management of tropical savannas
in Australia and elsewhere. This growing industry has the potential to
bring much-needed economic activity to savanna landscapes, without
compromising important natural and cultural values.