climate change on UAE - Stockholm Environment Institute-US Center

of leaf development, fruiting, and senescence,
or less often, the timing of migration or
breeding success for various fauna. In light
and temperature limited ecosystems (such as
temperate and arctic forests), these models
use long time series or large spatial datasets
to derive a series of <strong>climate</strong> forcing factors
which appear to trigger <strong>change</strong>s in phenology
(see Schwartz, 1998 and Zhang et al., 2003,
respectively). These models may be structured
similarly to the bioclimatic models described
previously, but rather than tracking the spatial
presence or absence of a particular species,
they track the timing of specific phenological
phenomena.
This class of model is widely applied in ecosystems
where a gradient of climatic phenomena
creates a gradient of ecosystem response (such
as in temperate forests in relation to temperature).
However, <strong>climate</strong>-phenology models may
prove to be highly important in determining
the impact of <strong>climate</strong> <strong>change</strong> in the UAE when
examining potential asynchrony between symbiotic
species (i.e. if insects which feed on developing
plants are unavailable as a food source
to migrating birds at the time when the birds
require it, the bird population could be put at
risk; Beaumont et al., 2006).
9.3 Examples of applied ecosystem
models in arid environments
Modeling for <strong>climate</strong> <strong>change</strong>
impact assessment
The arid Great Basin in the southwest United
States supports extensive perennial grasslands
and shrubs, and for decades has provided a rich
grazing resource for cattle ranchers throughout
the country. In the mid-1800’s, Cheatgrass
(Bromus tectorum) was accidentally introduced
from Asia. B. tectorum is an invasive species
in the Great Basin, and the annual is highly
adapted to semi-arid to arid environments. The
grass is not palatable to livestock and is able
to compete effectively with both native grasses
and shrubs. It grows earlier than native grasses,
depriving them of nutrients, water, and light. In
rainy years, B. tectorum can quickly grow several
feet in height, after which it is extremely fire
prone. Raging brush fires through large tracts
Figure 9-1. The adaptive management cycle
Source Frankin et al., 2007.
of B. tectorum destroy most native shrubs
and singe the surface of the soil, inhibiting the
growth of other species. It is not uncommon
to see large tracts of B. tectorum monoculture
throughout the Great Basin.
Bradley and Wilcove (2008) explored the
dynamics of B. tectorum in a bioclimatic
model. Tracts of cheatgrass were identified
using a remote sensing technique, and climatic
information was pulled together from a high
resolution <strong>climate</strong> dataset (4.5 km resolution).
The researchers used an automated mechanism
to determine the smallest set of explanatory
<strong>climate</strong> variables, which ultimately included
average precipitation from June to September
(summer to senescence), annual average
precipitation, precipitation from April to
May (spring), and average temperature from
December to February (winter). Using a <strong>climate</strong>
model (GFDL2.1) with a CO 2
doubling scenario
(720 ppm by 2100, SRESA1B), the researchers
determined how the <strong>climate</strong> variables would
<strong>change</strong> by 2100 and determined if and where B.
tectorum would occur in the future <strong>climate</strong>. The
researchers determined that cheatgrass would
become less viable in 50% of its current area,
but might invade specific new areas north of its
current range. As a result, the team suggested
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Climate Change Impacts, Vulnerability & Adaptation