Large woody plants often represent a valuable resource in arid regions, with heavy human use for fuel, for construction and for carving purposes. The harvesting of trees from portions of the Sonoran desert has been suggested as the culprit responsible for failure of recruitment in some giant saguaro and other perennial populations. Gutierrez et at. (1993) observed that the removal of shrubs from a Chilean desert apparently resulted in the disappearance of native annual plants associated with shrubs and a concomitant increase in non-native species.
Because biotic mediation of the environment is so critical in harsh arid ecosystems, changes in species composition are likely to have direct effects on ecosystem processes and thus indirectly on the diversity of other groups. For example, the introduction of Tamarix spp. to desert springs and riparian areas in both Australia and the US has caused dramatic changes in hydrology, soil chemistry, the light environment, and so on; these in turn affect native plants and animals. Here the strongest feedback appears to be the change in ecosystem function driving a change in biodiversity.
Was this article helpful?