We're all captives of our preconceptions. Living in the West, cattle and sheep immediately come to mind when we think of grazing. Range managers have long recognized that grazers shape grasslands, for better or worse. This is a result not only of the quantity of grasses utilized as food, but also of the selectivity of grazers. Put bluntly, some plants taste good, while others are the Brussel sprouts of the rangelands.
But looking only at our traditional conception of grazers omits a
variety of important animals. Grasshoppers easily come to mind, but a recent study in
England showed that even as unlikely a creature as the lowly slug can have major
effects. Fenced plots with and without slugs were followed for 3 years. Feeding
especially on seedlings, the slugs left fewer kinds of plants during the first 2 years,
but species richness surged to 23% higher in year 3. Harvesting the faster growing
kinds ultimately allowed survival of less competitive species. But relax; Chihuahuan
Desert slugboys yelling, "Herd them up and move them out" just isn't
going to happen.
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.