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

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Grasslands of the world
Plate 6.22
Leafy spurge (Euphorbia esula ) infestation on sandy soils in the mixed -grass zone,
Saskatchewan, Canada.
Haferkamp, Heitschmidt and Karl (1997) reported that presence of Japanese
brome reduced yield of western wheatgrass in eastern Montana, but removal
of Japanese brome reduced total standing crop since other species did not completely
replace the brome. In addition to economic consequences, Huenneke
(1995) and Hobbs and Huenneke (1992) listed the following ecological impacts
of plant invasions (for lack of a more appropriate word): spread of toxic substances,
replacement of native species, alteration of hydrological characteristics,
alteration of soil properties, and changed nutrient cycling.
Other suggestions for managing the Great Plains include increasing the
number of national grasslands and developing a “buffalo commons” for certain
portions of the Great Plains (Licht, 1997; Popper and Popper, 1994). Although
such proposals have appeal to some environmental groups, Licht (1997) discusses
several limitations of such proposals.
Riparian areas in the Great Plains are also of concern, as they are in many
other areas of the country (Johnson, 1999). These systems occupy less than one
percent of the land surface, yet are vitally important for catchment processes;
plant and animal diversity; and uses by man, including both industrial and agricultural
purposes (Johnson and McCormick, 1979; Swanson, 1988). Riparian
systems in the Great Plains have been modified by human activities such as
clearing for agriculture, grazing , canalization, damming and water diversion
(Johnson, 1999). Johnson (1999) presents case studies on how these activities
have altered the Missouri River in North Dakota, the Platte River in Nebraska
and Foster Creek in South Dakota.
MAE ELSINGER