By Tom Oberbauer, President CNPS-San Diego
It is fascinating to contemplate the appearance and distribution of biological natural resources in San Diego County at the time of the first European contact. Because San Diego County is now one of the more populous counties in the U.S., it is sometimes difficult to imagine what it looked like a mere 500 years ago. All the land that is now covered by urbanization and agriculture was originally natural and inhabited by a wide array of plants and animals and what is more interesting is that our ever present Mediterranean weeds were not here. Just imagine land without Avena fatua (wild oats) and brome grasses (Bromus madritensis, B. hordeadeus and B. diandrus) and the ever present Red-stem filaree (Erodium cicutarium). Their absence means that other species already existed in the areas that they now inhabit. When considering the combination of land that is converted to urban and agricultural lands and the land that is inhabited by non-native weeds, a very large area of San Diego has very different land cover than what originally occurred here.