Assessing the carbon sequestration potential of managed forests: a case study from temperate Australia
Roxburgh, SH and Wood, SW and Mackey, BG and Woldendorp, G and Gibbons, P, Assessing the carbon sequestration potential of managed forests: a case study from temperate Australia, Journal of Applied Ecology, 43, (6) pp. 1149-1159. ISSN 0021-8901 (2006) [Refereed Article]
Copyright 2006 the authors. Journal compilation copyright 2006 British Ecological Society.
1. The concept of assessing forests for carbon sequestration is well established.
Operationally, estimating a forests’ potential to sequester carbon requires comparing its
current carbon state with a prediction of its carbon carrying capacity (CCC). Assessment
of CCC is, however, problematic. Mathematical models can be used, although traditional
modelling techniques, where parameters are estimated from empirical measurements,
are usually limited by a lack of ﬁeld data. For example, estimates of carbon residency
times in vegetation and soil are not generally available, nor are they easily measured.
Alternative methods are required.
2. Current carbon stocks in 17 previously logged ﬁeld sites were measured by ﬁeld survey.
CCC for those sites was then predicted using a terrestrial carbon model, calibrated with
measurements from mature, unlogged vegetation of a comparable forest type. Model
parameters were estimated using ‘model–data fusion’ methods, where the model is
inverted and ﬁeld measurements of the carbon stocks (the model outputs) are used
to calibrate the model parameters. Spatial variation was included through functions
deﬁning landscape-scale effects on plant growth relating to topographic inﬂuences on
light and soil water availability.
3. Current above-ground carbon stocks (living plus litter) varied with management
history, averaging 273 ± 30 tC ha−1
(mean ± SE). Model-predicted CCC was 445 ± 13 tC
, yielding a carbon sequestration potential of 172 ± 31 tC ha−1
. Model simulations
predicted the recovery of an average site to take 53 years to reach 75% carrying capacity,
and 152 years to reach 90% carrying capacity. Extrapolation of these results to 7 Mha
of comparable managed forests in the same region suggested a potential carbon sink of
680–895 Mt C.
4. Synthesis and applications. In this study we have demonstrated that forests recovering
from prior logging have the potential to store signiﬁcant amounts of carbon, with current
biomass stocks estimated to be approximately 60% of their predicted carrying capacity,
a value similar to those reported for northern temperate forests. Although sequestration
activities often focus on the aforestation and reforestation of previously cleared land,
our results suggest that, where appropriate, native forest management should also be
considered when developing terrestrial carbon management options, and for terrestrial
carbon accounting more generally