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

Grasslands of central North America 237
Nebraska and Kansas, but only 1 million hectares of state and Indian land
and 1.4 million hectares of federal land. There are National Forest lands in
the Dakotas, Nebraska, Arkansas and Missouri, but most of these are forest
or woodlands (Mitchell, 2000). Some Forest Service Land is in National
Grasslands, but these are relatively small compared with non-federal land.
Licht (1997) lists 15 separate National Grasslands in the Plains states. These
vary in size from less than 600 ha for McClelland Creek National Grassland ,
to over 400 000 ha in the Little Missouri National Grassland in North Dakota.
The Bureau of Land Management (BLM) has mineral rights to considerable
areas outside the West, but little surface rights in the Great Plains (Holechek,
Pieper and Herbel, 2001). Most of the BLM holdings in the Plains grassland is
in Montana and Wyoming, but there are also a few allotments in South Dakota
(Licht, 1997; Wester and Bakken, 1992).
Major crops in tall-grass regions are maize and soybeans (Lauenroth, Burke
and Gutmann, 1999), with maize more important in the north and soybean in
the central and southern portions of the grasslands. Wheat is the other major
cereal crop, with higher yields in eastern portions, but greater areas in the west
and north in locations with less than 500 mm/yr precipitation (Lauenroth,
Burke and Gutmann, 1999). Cotton is important in eastern New Mexico, western
Oklahoma and northern Texas.
Grazing management
Livestock production
Several types of enterprises constitute the livestock production systems of
Central North America. In the drier portions of the region (short-grass
and mixed -grass ), extensive range grazing operations are the norm. These
operations are typically cow-calf operations with the young animal sold for
finishing in feedlots (Neumann and Lusby, 1986). In other cases, stocker
programmes – whereby weaned animals are retained and maintained by
feeding roughages to ensure growth but not improvement in condition – are
practised (Neumann and Lusby, 1986; Wagnon, Albaugh and Hart, 1960).
Stocking rates on native short-grass prairie vary considerably depending on
precipitation , range condition and other environmental factors. Klipple and
Costello (1960) reported that moderate stocking in eastern Colorado was
about 21 ha per animal unit year (AUY), while Bement (1969) recommended
19.4 ha to support 1 AUY. In the panhandle of Nebraska, Burzlaff and Harris
(1969) reported that moderate stocking was 14 ha per AUY. These stocking
rates were based on summer grazing from May through October. In mixedgrass
regions, stocking rates are normally higher, e.g. 9.3 ha AUY in North
Dakota (Rogler, 1951). In tall-grass prairie , stocking rates are much higher:
4 ha AUY in Oklahoma (Harlan, 1960). In the Prairie Provinces of Canada
(see Plates 6.15, 6.16 and 6.17), Smoliak et al. (1976) reported that carrying
capacities ranged from 21.6 to 10.9 ha AUY depending on range type and