Dealing with global climate change - Ecological Applications: Toward a Sustainable World - page 317

(a)

9.5
9.0
8.5
8.0
7.5
7.0
6.5
6. 1960

1970 1980 1990 2000 2010 2020 2030

(b) (c)

250,000

250,000

Best-case scenario
Intermediate
Worst-case scenario

0 0

0 1,250,000 0 1,250,000

Spawning stock biomass (tonnes) Spawning stock biomass (tonnes)

Fig. 11.10 (a) Historical sea surface temperatures in the North Sea and the scenarios assumed to affect the future of the cod
fi shery. The best-case scenario assumes no change to mean temperature beyond 2001, the worst case assumes a constant
increase to a rise of 1˚C and the intermediate case assumes a rise of 0.2˚C by 2040. (b) Stock recruitment curves for each
scenario, assuming that increased temperature affects cod population dynamics by reducing juvenile survival. (c) Stock
recruitment curves that assume increased temperature reduces the size of the habitable area of cod. Vertical lines in (b) and
(c) show, for each scenario, the standing stock biomass that provides the maximum sustainable yield. (From Kell et al.,
2005.)

11.3.4 Forestry - a
boost for developing
countries?

Global climate change can also be expected to cause considerable change to forest
harvests around the world. This will occur partly because of positive or negative
effects on tree growth and forestry yields (both because of changes to temperature
and moisture, but also through a direct fertilization effect of increased atmospheric
CO 2 ). But in addition there will be potential losses as 'dieback', caused by increases
to forest fi res, storm damage or pest outbreaks. And fi nally, we can expect changes
to the habitable areas of forest species. Table 11.1 shows the predicted responses to
climate change in different parts of the world during the twenty fi rst century.
Of course, it would be silly to imagine that foresters will fail to respond to climate
change - in due course they will plant more appropriate trees. And, in fact, it is
developing countries in tropical and subtropical regions that are expected to be best
able to adapt, because their trees grow faster and their forest rotations are therefore
shorter. Taken overall, forestry in many parts of the world is predicted to show
long-term gains in production, particularly through increased growth rates, increases
to forested areas and switches to more appropriate species. However, dieback can
reduce these gains. North America, Russia and China seem particularly susceptible
to the negative effects of dieback, at least for the fi rst decade or two (Figure 11.11).
South America, on the other hand, is predicted to perform strongly in this period
because of low dieback and rapid adaptation by switching to more appropriate
plantation trees. In the longer term, China and Russia catch up because of signifi cant
increases in forested land area and good increases in yield.