Last article discussed the importance of biodiversity and how ecosystems with abundant biodiversity were considered healthy and sustainable.

The Sonoran Desert, because of its location, size, rainfall, and elevation changes is the most biodiverse desert in the world. Covering 120,000 square miles, this luxurious habitat is home to more than 100 species of reptiles, 60 mammals, 350 birds and 2,000 plants. This enviable status is rapidly approaching a tipping point that threatens the deserts ability to maintain this high biodiversity. As more and more people come to enjoy the warm climate and diverse ecosystems the human caused stressors tend to degrade the natural beauty that drew them here in the first place. When climate change is mixed with pressure from an ever-expanding human population a delicate ecosystem such as the Sonoran Desert will suffer.

“Fragmentation caused by urbanization is now considered the number one threat to biodiversity in the region and is not expected to diminish during our lifetimes.” 1

A rouges gallery of environmental stressors contributing to biodiversity loss follows.

  • Direct human impact
    • Ground water depletion occurs when more water is pumped out of an aquifer than is replenished by rainfall. The result is failing rivers; when rivers fail trees and under-story plants die and biodiversity shrinks to unsustainability. This has happened on the Rio Grande, the San Pedro, the Santa Cruz [Tucson], the Gila, Salt [Phoenix], and Verde. Many of these lifegiving riparian areas have been suffering for decades.
    • Development and agriculture have led to widespread fragmentation of biomes by blading the desert, replacing it with manicured tracts of walled homes, huge fields and non-native landscapes.

 

  • Invasive species can be plant, animal or insects. An invasive species is “an alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health” Often these organisms have few competitors to keep them in control.

 

  • A hotter and drier climate is a reality no matter what the cause and is playing havoc with our global biome. Climate change predictions for the Sonoran Desert are for higher temperatures, less precipitation, and greater weather extremes. These weather extremes include severe freeze events that get colder and last longer, long enough to cause widespread damage to native plants.

This all sounds pretty grim but stay tuned, next month; What you / we can do to improve the biodiversity of the Sonoran Desert?

1 A Natural History of the Sonoran Desert [Arizona – Sonoran Desert Museum]