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Lehmann lovegrass (Eragrostis lehmanniana Nees) was introduced into Arizona, USA, from South Africa in 1932 and has since been sown throughout the southwestern USA and Northern Mexico. The species is well adapted in southeastern Arizona where it has been sown on over 69 115 ha and has spread by seed to an additional 76 040 ha. Where Lehmann lovegrass predominates and spreads, surface soils are sandy, summer rainfall is greater than or equal to 200 mm and winter temperatures rarely fall below 0° C. Factors contributing to the spread of Lehmann lovegrass in southeastern Arizona include fire, cattle grazing and drought. UITTREKSEL Eragrostis lehmanniana Nees is in 1932 in Arizona, VSA, aangeplant deur middel van saad afkomstig vanuit Suid-Afrika, en is sedertdien ook oral in die suid-westelike VSA en Noordelike Meksiko gesaai. Die spesie is goed aangepas in die suid-oostelike gedeeltes van Arizona waar dit ingesaai is op 69 115 ha en het reeds deur middel van saad versprei tot 'n addisionele 76 040 ha.Die gras domineer en versprei veral in gebiede waar die gronde sanderig is, somer reënval hoër is as 200 mm en winter temperature nie onder 0°C daal nie. Ander faktore wat bydrae tot die verspreiding van E. lehmanniana in Arizona, sluit vuur, beweiding en droogte in.Additional index words: Cattle grazing; fire; plant invasion; rangeland revegetation and seed germination.

Lehmann lovegrass (Erapost& lehmanniana Nees), II perennial bunchgrass from southern Africa, has recently replaced native grasses on 200,000 ha in southeastern Arizona. Hence the need to determine annual iluctuations in live and dead biomass in wet and dry years. This information is necessary if we wish to determine (1) potential plant productivity changes on Arizona rangelands after the Lehmann lovegrass invasion, and (2) how the presence of Lehmann lovegrass has affected animal utilization and grazing management. Live biomass was present throughout the year but August peaks were almost 2,000 kg/ha in 1 wet summer, 1,430 kg/ha in 2 normal summers, and 960 kg/ha in 1 dry summer. Recent-dead approached zero in August when live peaked, and slowly accumulated in fall and winter. Old-dead peaked before the summer rains when temperature peaked and rapidly disappeared following snow accumulations in winter. Litter was highly variable among sampling areas, plots, and sampling dates but amounts usually peaked before the summer rains and decreased in winter and spring. Lehmann lovegrass annually produces 3 to 4 times more green forage than native grasses, but cattle prefer native grasses more than Lehmann lovegrass.