Grasslands of the World.pdf - Disasters and Conflicts - UNEP

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Plate 6.3
Pronghorn antelope on mixed grass prairie – North Dakota.
Grasslands of the world
ecosystems (Blocker, 1970; McDaniel, 1971; Risser et al., 1981). Some, such
as grasshoppers, have been studied because of their economic importance
(Hewitt, 1977; Hewitt and Onsager, 1983) while others, such as nematodes,
have only recently been properly assessed as to abundance and importance
(Freckman, Duncan and Larson, 1979; Smolik, 1974).
Central plains grasslands also support diverse populations of birds (Bolen
and Crawford, 1996; Guthery, 1996; Knopf, 1996; Wiens, 1973). However,
within the grassland geographical region, habitats other than grasslands
have higher numbers of avian species. Only 11 percent of the bird species
within the grassland geographic area were actually inhabitants of grassland
per se: 51 percent were associated with woodland and forest habitats and
22 percent with wetland habitats (Bolen and Crawford, 1996). Nevertheless,
birds are abundant in grasslands. Glover (1969) listed over 150 species found
on the Central Plains Experimental Range in short-grass habitat in northcentral
Colorado. These included both primary consumers and secondary
consumers. Common grassland birds include western meadowlark (Sturnella
neglecta), grasshopper sparrow (Ammodramus savannarum), horned lark
(Eremophila aplestris) and chestnut-collared longspur (Calcarius ornatus)
(Wiens, 1973, 1974).
Cattle (Plates 6.4 and 6.5) have largely replaced bison as the dominant large
herbivore on the Great Plains. The importance of Great Plains cattle to the beef
industry in the USA is reflected in data quoted by Holechek, Pieper and Herbel
(2001) indicating that 50 percent of all USA beef cattle are found in the northern
and southern Great Plains. Although Lauenroth et al. (1994) concluded
that vegetation changes resulting from the shift from bison to cattle have been
minimal, there are differences in grazing patterns and behaviour: bison select a
DUANE McCARTNEY