Geologic, Hydrologic, and Urban Hazards for Design in Desert Environments - Design with the Desert: Conservation and Sustainable Development - page 117

Part II
The Living Desert
John H. Brock
The “living desert” is the place where the physical environment creates habitats for
organisms and communities to survive. These living communities may be ephemeral
or sustained by the ecosystem they reside, largely due to the fragile balance of climate,
hydrology, and the inherent ability of the land to sustain life. To explore the dynamics of
these relationships, one can gain a deeper understanding of this theme through the field of
ecology, which is the study of the interaction between the biotic and physical worlds, and
can be defined as “the structure and function of nature.”
In ecological terms, a niche is the organism's function, and the morphological varia-
tion among the organisms provides community structure. The assemblages of plants and
animals living in a relatively stable environment are termed communities, and several
communities may comprise ecosystems. For example, a warm-desert ecosystem will have
shrub/grass/succulent plants dominating areas, with variation related to microsites and
drainages, such as riparian communities along perennial streams and washes. Desert eco-
systems are much more diverse and resilient than people give them credit. However, peo-
ple must manage desert ecosystems carefully, because of their unique characteristics, and
need to learn to design and live in human-modified areas based on ecological principles
rather than a self-focused human environment.
The unifying characteristics of the warm deserts, discussed in this topic, are long peri-
ods of dryness during the year and high temperatures, with soils low in nitrogen but often
high in salts. The dominant character of individual desert ecosystems within this biore-
gion is that rainfall is seasonal. In the Sonoran Desert, rainfall is found to fit a bimodal dis-
tribution with some precipitation during the winter season and also in the summer from
convectional thunderstorms driven by monsoon winds from south of the region. In the
Mojave Desert, rainfall comes primarily in the winter, with little summer thunderstorm
activity. The Chihuahuan Desert receives the majority of its rainfall during the warm sum-
mer months during the growing season and little during the winter. The paleohistory