Trees with
"Altitude"

Travelling in Mexico involves a lot of altitude adjustment. Getting from point A to point B can mean a journey on tortuous roads, up and down mountains, or a more gentle ascent on straight highways across the plateaus.

Altitude change gives opportunity for micro

ecosystems to exist that support some unusual vegetation. Going south from Torreon to Zacatecas, the elevation rises from 3700' to 8200'. Between 6500' and 7500', Joshua trees (Yucca brevifolia) stand as sentinels in the desert, tall and dramatic compared to the cactus and mesquite scrub. Going from Zacatecas to Aguascalientes, the road descends from 8200' to 6100' and once again you pass several miles of Joshua tree "forest" at the specified altitude. These trees grow exceedingly slowly. They require cold winter temperatures that dip below freezing, and hot, dry summers. If these conditions are not met, the tree will not grow or bloom that year. The Yucca moth is essential for pollinating the flowers and the sharp, spiny leaves provide protective havens for several species of birds and lizards.

In a previous post, I described a hike we took to the top of the Ceboruco Volcano in the

southwest Mexican province of Nayarit. At the base of the mountain, mango and avocado groves flourish. Sugar cane and cactus grow in cultivated fields. On the mountain top (7600'), close to the active crater, the temperature is 10-15 C cooler and pine trees grow on the fertile volcanic soil. Large pine cones up to 10" in height were plentiful on the ground. It was a far different world than at the base...a refreshing change from the heat for my northern acclimatized body!