Canopy (or crown) projected cover is the proportion of ground area covered
by tree crowns. CPC is estimated by vertically projecting outlines of tree
crowns onto the horizontal plane that represents the forest stand area. It
is also called "crown cover," "canopy closure," "cover closure," or similar
terms such as "polnota." Another term-foliage projected cover (FPC)-is used
occasionally. FPC is the proportion of a forest stand covered by foliage,
which is usually a little less than CPC. FPC should not be confused with leaf
area index (LAI), which is the ratio of the one-sided projection of the area
of leaves (or needles) to the ground area-essentially, the average number
of leaves above a point in the forest stand.
In calculating the Global Warming Potentials (GWPs) of
GHGs, it was assumed that CO2 fertilization
is not anthropogenic. The calculations use models that take into account the
absorption of GHGs into the oceans and, in the case of the reference gas,
CO2, its uptake as a consequence of CO2
fertilization. Thus, if CO2 fertilization were
subtracted from the estimate of total emissions (i.e., on the basis that it
is anthropogenic and is an uptake), the effect of CO2
fertilization would be double-counted. Although this effect could be corrected
by recalculating all of the GWPs, this recalculation would have other policy
repercussions. The main effect of such a recalculation would be to significantly
reduce the GWPs of non-CO2 GHGs.
Carbon sequestration must be distinguished from fossil
fuel substitution, which can also be achieved by some LULUCF options (e.g.,
charcoal substitution for mineral coal). Fossil fuel substitution through
forestry is just as permanent as avoided emissions through measures such as
enhancing energy efficiency.
The approximation of the output of the Bern model version
used (but not published) in the SAR is given by:
= 0.175602 + 0.137467 exp(-t/421.093) + 0.185762 exp(-t/70.5965)
+ 0.242302 exp(-t/21.42165) + 0.258868 exp(-t/3.41537) where
F is the fraction of CO2 remaining in the atmosphere
and t is the time after emission in years.
This Special Report makes no assumption about whether,
or to what extent, LULUCF project activities will be approved for crediting
under the CDM.
The categorization of LULUCF activities in this chapter
differs slightly from the categorization of LULUCF projects in Chapter
6. The primary distinction across activity categories here is the change
in land use, whereas the primary distinction across project categories in
Chapter 6 is the change in carbon.