Throughout the Southwest, the Ponderosa Pine rules the mid elevations. This open forest lies above the pinyon-juniper pygmy forest and below the mixed coniferous forest of the higher mountains. Surely, one would think, this forest would have covered the lower elevations during the cooler, damper climates of the last ice age. But one would be wrong.
Strange as it seems, this pine was almost entirely absent from the
northern Chihuahuan Desert region—highland and lowland alike. Study of fossil
packrat middens reveals much of the plant life occurring in the immediate vicinities of
the middens during the times they were occupied. The record of ice age vegetation is
quite consistent in the plants found—and in this case, in the tree not found.
Only one location in southern New Mexico and northern Chihuahua has any sign of ice-age
Ponderosa Pine at all: Rhodes Canyon, in the San Andres Mountains. Various reasons for
its absence and subsequent rapid invasion and dominance have been advanced; none seems
sufficient explanation. This gives a whole new meaning to the term, "to pine
away".
Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.