Dealing with global climate change - Ecological Applications: Toward a Sustainable World - page 322

(a) (b) (c) (d)

Branchinecta
conservatio
Branchinecta
longlantenna
Branchinecta
mesovallensis

Fmax (days)
0-35

Fmax
7%

Fmax
33%

36-75
76-122
123

1% 1.0%

Fig. 11.14 (a) Distribution of biological reserves (black shading) in the Central Valley region of
California, USA (inset). The current set of protected areas only includes a small proportion of
locations where vernal pools are found. Thus, temporary pond dwellers, such as fairy shrimps
( Branchinecta spp.), are at risk. (b) The current distribution of F max - the annual average number
of days of continuous inundation of ponds . F max is a key factor determining the success of fairy
shrimps. The current ranges of three fairy shrimp species are shown in outline. (c) Predicted
changes to F max under a cooler and drier scenario ( − 1˚C, − 10% precipitation). (d) Predicted

changes to F max under a warmer and wetter scenario ( 30% precipitation). The manager's

objective will be to maintain shrimp biodiversity by adding new protected areas that incorporate
the necessary future range of F max values. (From Pyke, 2005.) (This fi gure also reproduced as
color plate 11.14.)

+ 3˚C, +

Dávila-Aranda (2003) predicted future species distributions in relation to the loca-
tion of the reserve.
Table 11.2 shows how the predicted ranges of species contract or expand under
the various scenarios. Focusing on the most extreme scenario (an average tempera-
ture increase of 2.0˚C and a 15% reduction in rainfall), you can see that more than
half the species that are currently restricted to the reserve are expected to go extinct.
Managers can use this information to make a case for setting aside new reserve areas.
The second category of cacti, whose current ranges are almost equally inside and
outside the reserve, will contract, but in such a way that their distributions become
almost completely confi ned to the reserve. The fi nal category, whose current distri-
butions are much more widespread, also contract but are expected to be distributed
both within and outside the reserve. In the case of these latter classes of cacti, then,
the location of the reserve seems to cater adequately for potential range changes.

11.5.2 Fairy shrimps
- a temporary
setback

The inhabitants of temporary ponds, such as the ones known as vernal (springtime)
pools, have a particular problem under climate change. Whereas some habitat types
may move to new locations, vernal pools can only exist where there are topographic
depressions underlain by dense, impermeable soil layers. And while the pools
cannot shift, their properties can be altered dramatically by local climate. Thus, the
length of the period during which these temporary ponds hold water will change
with alterations to temperature and rainfall. Figure 11.14a shows the current
distribution of protected areas in California's Central Valley - these only include a