|Title||Primary productivity in arid lands: myths and realities|
|Publication Type||Journal Article|
|Year of Publication||1987|
We tend to view arid environments as harsh and water-limited, due to low amounts of precipitation. In fact, many sites within desert regions receive considerable amounts of water due to run-on; for example, washes (<i>arroyos, wadis</i>). The productivity of these can be high. However, in reality, their extent is small. We often assume productivity of deserts to be only water-limited. Recent research in arid ecosystems indicates, however, that nutrients can be critical to production. We also think of desert precipitation as being unpredictable, in addition to low in quantity. Nevertheless, many of the major arid lands of the world are characterized by highly seasonal patterns of precipitation. Native plant and animal populations have evolved numerous tactics which capitalized on the predictable timing of precipitation. Humans have learned to exploit this predictability by growing crops and raising livestock that can gain from seasonal patters. Humans also manipulate arid environments by removing the limits of productivity through irrigation and fertilization and, while some cases of agricultural production are noteworthy, the reality is that the cost/benefit ratio is not favorable. Furthermore, extensive arid and semi-arid areas are undergoing rapid desertification. Monitoring desertification is essential to our future understanding of arid and semi-arid land productivity.