Buenos Aires National Wildlife Area – An Arid Grassland

Buenos Aires Grassland © 2012 Bo Mackison

Buenos Aires National Wildlife Refuge in southern Arizona is 118,000 acres of grassland, mountain ranges in the background, riparian corridors rippling through the land. The habitat, a semi-arid grassland, is land of the masked bobwhite quail and pronghorn antelope, both of which are being re-introduced in the region. Grasses once filled the Altar Valley, and are now maintained and restored by prescribed burns.

Grasses © 2012 Bo Mackison

In the 1800s, Altar valley was open grassland. Pronghorns had free range, falcons and hawks filled the air with their swooping, gliding, and soaring.  Mexican wolves, black bears and jaguars roamed in the grasses, traveling the corridors between the mountain ranges.

Poppies in the Grasslands © 2012 Bo Mackison

Then the Valley began filling with small towns and ranches in the 1860s, and the delicate balance maintaining the ecosystems gradually suffered. As ranchers expanded and grazing bared much the grasslands and exposed the land to the monsoon rains, erosion of the barren soils quickly followed.

With the grass gone and natural fires suppressed, mesquite gained a foothold. The grassland no longer supported the masked bobwhite quail or aplomado falcon. Pronghorn, wolves, bear, and jaguar were hunted or trapped.  Lehmann’s lovegrass, a non-Native grass, was introduced in the 1970s to help stop erosion. But this poor substitute for native grasses and now considered an invasive species, did nothing of benefit.

Spring in Arivaca Cienega © 2012 Bo Mackison

Buenos Aires National Wildlife Refuge was established in 1982 to re-establish the grasslands habitat and protect the Arivaca Cienga* and the Arivaca Creek and its watershed, and important resource for the several hundreds of kinds of birds that either live in the region, migrate through, or winter over.

The area is again lush with grasses. The wildflowers are abundant — Mexican poppies turn areas golden with bright color, purple bunches of Verbena add contrast.

A beautiful place, an important resource to protect and preserve.

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cienega   pronounced see-en-ay’-ga.  spanish, A cienega usually is a wet, marshy area at the foot of a mountain or on the edge of a grassland where below ground water bubbles to the surface.

Sonoran Desert

Saguaro National Park © 2012 Bo Mackison

The Sonoran Desert covers approximately 100,000 square miles and includes the southern half of Arizona, southeastern California, most of the Baja California peninsula, the islands of the Gulf of California, and much of the state of Sonora, Mexico.

It is lush in comparison to most other deserts. Two visually dominant life forms of plants distinguish the Sonoran Desert from the other North American deserts: legume trees and columnar cacti. It also supports many other life forms encompassing a rich spectrum of some 2,000 species of plants.

Spring in the Sonoran Desert © 2012 Bo Mackison

The amount and seasonality of rainfall are defining characteristics of the Sonoran Desert. Much of the area has a two season rainfall pattern, though even during the rainy seasons most days are sunny. From December to March, storms from the North Pacific Ocean occasionally bring widespread, gentle rain to the northwestern areas. From July to mid-September, the summer monsoon brings surges of wet tropical air and frequent, but localized violent thunderstorms.

Desert Dusk © 2012 Bo Mackison

The Sonoran Desert differs from the other major North American Deserts (Mojave, Chihuahuan, and Great Basin) in that it has mild winters; most of the area rarely experiences frost. About half of the biota is tropical in origin, with life cycles attuned to the brief summer rainy season.