climatic change scenarios is shown in Fig. 5A.
The short-rotation plantation expansion rate
under dierent climatic change scenarios is given
in Fig. 5B. The response of yields and area of
short-rotation plantations to the percent of precipitation
decline from climatic change by the
year 2050 is shown in Fig. 6A in absolute
amounts, and in Fig. 6B as percent dierence
from the no climatic change scenario. Projections
over the 1990±2050 period for a reference calculation
with no change in climate (Fig. 5B) are
compared in Fig. 6A and B with the situation in
the year 2050 assuming climatic change (precipitation
reduction) ranging from 0±50%. The likely
pattern of the eect of climatic change is apparent,
with disproportionate increases in plantation
areas needed to supply demand when yields
decline due to climatic change.
Assuming no technological change, if there
were a 10% drop in rainfall, a 3.5% drop in
marginal yield would result, leading to a 5%
increase in the area of short-rotation plantations
required. A 50% drop in rainfall would produce
a 17% drop in marginal yields and a 38%
increase in short-rotation area requirements
(Fig. 6B). Conversely, any improvements, such as
genetic breeding advances that increase yield by a
given percentage, decrease area requirements by
more than the same percentage. While technological
improvements are likely to occur, the
assumption of constant technology is appropriate
as the reference case for interpreting the impacts
of climatic change.
It is important to realize that positive changes,
such as technological advance in tree breeding,
could be equal in magnitude to negative changes
such as yield decline from climatic change, but
that such a conclusion would not be a neutral in
terms of its policy implications. This is because
negative impacts such as climatic change should