While I’m doing New Mexico nature writing, let’s consider the creosote.
A friend at work asked me this afternoon why creosote survived in Isleta, the pueblo south of Albuquerque, which my friend rightly thought was far north of its natural range.
As it happens, I had a paper on my desk that offers a bit of an answer.
Creosote is a spindly desert shrub that has always been dear to my heart. It’s the dominant species on the landscapes of the big deserts of southeastern California, where we used to camp winters when I was a kid. They arrange themselves spatially with a sort of rhythm that dominates the landscape.
My friend was right. Isleta, up around 5,000 feet in elevation (1600 meters) is pretty much at the top of their range, and they’re a very recent arrival. Farther south, packrat middens at the Sevilleta National Wildlife Refuge, north of Socorro, show they’ve been in residence for something like 2,500 years. But up the road at Isleta, they’re a more recent arrival, maybe less than 200 years.
Why? In part, us. To quote from the Duran et al. paper:
Rangeland overgrazing resulting from high stocking rates of cattle, sheep and horses in the late 19th century coupled with extended drought periods have created conditions conducive to desert shrub invasions into formerly grassland habitats.
Creasote bush – Larrea tridentata – is one of the first species to move in, followed by cactus (Opuntia) and Yucca.