Tag Archives: Desert

Disturbance and Invasive Plants

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By Garry Rogers

Disturbance and Invasive Plants:  Introduction

Wild Horses and Weeds

Wild Horses on a Former Great Basin Shrubland Destroyed by Livestock Grazing, Invasive Plants, and Fire.

In the invasive plant literature, disturbance refers to an event that removes plants and alters the soil surface.  “Disturbance is believed to be the major factor favoring plant introductions” (Radosevich et al. 2007:  58).  Without disturbance, invasive plants would find no openings to become established and begin to spread and replace native species.

It is important to understand the nature and origin of disturbance that leads to plant invasions, because, as with global warming, it is often profitable to deny human responsibility for invasions so that a disturbance activity can continue. Continue reading →

Desert Habitat: Soil Microorganisms

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By Garry Rogers

The Role of Soil Microorganisms in Desert Ecosystems

There would be no life on the land if there was no soil.

“When you thrust a shovel into the soil or tear off a piece of coral, you are, godlike, cutting through an entire world. You have crossed a hidden frontier known to very few. Immediately close at hand, around and beneath our feet, lies the least explored part of the planet’s surface. It is also the most vital place on Earth for human existence” (Wilson, 2010).

Biological Soil Crusts

1-Gt Basin Lower Valleys-003

Biological Soil Crust (Brown stipplescale) growing in a rocky area in the Great Basin Desert.

In sunny desert environments, various species of algae, cyanobacteria, microfungi, lichens, and bryophytes form thin crusts over the surface of the ground.  The crusts protect the soil from erosion, enrich its composition, and enhance plant growth.  The crusts are among the most important components of desert ecosystems.

Biological soil crusts (BSCs) are quite fragile.  If they are damaged, soils lose moisture and nutrients and become susceptible to erosion and invasion by alien plants.  BSCs are susceptible to considerable damage by livestock (e.g., Brotherson et al. 1983). Recovery of BSCs at some sites can occur within 20 years (Anderson et al. 1982), but most studies have concluded that longer periods are required (e.g., Jeffries and Klopatec 1987), and that full recovery can require centuries (Belnap 1993). Continue reading →