The Role of Managed Forest Ecosystem: An Inventory Approach - The Greenhouse Gas Balance of Italy - page 64

While waiting for the results from the repetition of the INFC field plot survey
in the year 2015, an estimate of the annual change in carbon stock, only for the
above ground living biomass carbon pool, has been provided by Tabacchi et al.
( 2010 ) on the basis of the so-called default method (IPCC 2003 ) applied to INFC
data taken at the year 2005.
The carbon stock change is calculated as difference between gains and losses in
the stem volume of living trees, based on the Eq. 4.2 :

C DEFAULT = I C + M IN + M NEWFOR − M HARV − M FIRES − M DISTURB − M OUT

(4.2)

where: I c = net annual increment of the stem volume of living trees; M in = stem
volume of living trees that at time t 1 are below the minimum dbh threshold, but
contribute to a total stem volume at time t 2 (ingrowth); M newfor = stem volume of
living trees in areas converted to forest from time t1 to t2; M harv = stem volume
of trees harvested from time t1 to t2; M ires = losses of stem volume in forest land
due to forest fires; M disturb = losses of stem volume due to natural disturbances;
M out = stem volume of living trees in forest land converted to non-forest land
from time t1 to t2.
Table 4.4 summarizes the results of the carbon stock change balance in forest
lands in Italy for the reference year 2005. Overall, the annual change in above-
ground living tree biomass in forest land is estimated as high as + 14.7 Mt, with an
uncertainty (95 % conidence interval) of 2.8 Mt.
A comparison with the range of NPP values provided by model-based
approaches (see Chap. 5 ) can be drawn on the basis of the annual carbon gain in
the above ground living tree biomass pool as estimated by the net annual incre-
ment: this value falls in the 95 % confidence interval from 1.35 t C ha − 1 y − 1 to
1.45 t C ha − 1 y − 1 ; such estimates are both lower than the simulated NPP values
for main Italian forest types (i.e. from 3 to 4.5 t C ha − 1 y − 1 , see Chap. 5 ) , but such
a difference is likely to be explained by the fact that the simulated NPP quantifies
carbon stock change for all of the forest carbon pools.

Table 4.4 Estimates and
associated 95 % confidence
interval (uncertainty)
of the annual change of
aboveground living tree
biomass in the forest land
in Italy at the year 2005
(adapted from Tabacchi
et al. 2010 )

Variable Estimated value

(Mt y

Uncertainty
(%)

Uncertainty
(Mt y

− 1 ) − 1 )

3.7 0.914

24.7

I c

2.4 30.0 0.723

M in

30.0 0.133

M newfor 0.4

9.5 26.2 2.493

M harv

0.9 30.0 0.272

M ires

30.0 0.672

M disturb 2.2

0.2 30.0 0.063

M out

14.7 19.4 2.849

Stock change