Keep an eye out for this potential problem weed in southern California: Stipa capensis. First reported in 1995 in Riverside, this species is native to the Mediterranean and has established in the Coachella Valley of the Sonoran Desert. It is spreading rapidly in the Palm Springs area, forming dense monocultures. Confirmed reports have recently been made in Borrego Springs and Point Mugu. It has the potential to promote fire in California desert ecosystems and may also suppress native wildflower abundance in the areas it invades.

How to spot...

Roadsides are often a very difficult place to control weeds. Weeds thrive on roadsides and roadsides and rights of way are obviously long and narrow. Weeds along the edge of the shoulder need to be cleared to reduce fuels to prevent wildfires, and to ensure safety for drivers and also so that weeds do not damage the road surface or shoulder structure.

Herbicide applications on roadsides are often conducted at large scales where several acres to many acres are treated in a day. Roadside equipment can also be highly specialized ensuring large stretches of public roads and adjacent lands are better protected.

Herbicide applications on roadsides should be calibrated to ensure the amount of herbicide applied is the amount...

Wildfire is an important ecological process that shapes patterns of plant diversity in many Mediterranean ecosystems, including California. In coastal sage scrub and chaparral, for example, plant diversity is often highest in the growing seasons immediately after a site burns, with many fire-following species emerging from the soil seed bank and bud bank. This often results in spectacular displays of wildflowers when sufficient rainfall occurs following fire.

In a recent study published in Global Change Biology, however, we found that persistence of these unique, fire-following wildflowers may be threatened by invasive plant species as well as nitrogen...

A recent article in the LA Times argued that California native plants should not be the only option for drought-tolerant landscaping. Missing from this perspective was a discussion of the severe threat that many non-native plants pose to California's unique and biodiverse ecosystems including reduced native plant establishment and increased fire risk. Additionally, we know that the nursery trade plays an important role in driving these invasions. For example, a recent study by researchers at the...