Around 1900 temperate and semidesert grassland productivity declined, soil erosion incrensed, and drought destabllixed the live stock industry in the northern and southern hemispheres. As government leaders throughout the world began to recognize the importwee of grassiaad productivity nnd soil conservation, a massive experiment began to evolve. Government and private hrdividurls collected seed from every continent, and planted seed at experimental stations and ranches in their respective countries. Hundreds of individuals who conducted thousands of seeding trials observed that buffelgrass (Cenekrur c&u& L.), weeping lovegrass [Erugrostts curv& (Schrad.) Neesl, kleingrass (Pun&urn coiivatwn L.), and Lehmann lovegrass (Eragrostts l&mum&no Nees) plants from seed coiiected in Africa were easier to establish and persisted longer than other grasses. Uetween 1930 and 1986 scientists in many countries evaluated the estabiishment and persistence of these grasses, but no attempt was made to syntbesixe the data base and determine the effects of climate and soil on piant estab-Ushment and persistence. Our objective was to: (1) determine the climatic and edapbic characteristics of areas where the seed of each grass was collected in Africa, and where each grass has been successfuliy established in both hemispheres, and (2) identify characteristics which infiuence long-term persistence. Where buffelgrass predominates and spreads, summer rainfall varies from 150 to 550 mm, winter rainfall is less than 400 mm, mean miminum winter temperatures rarely fall below 50 C, and soil texture is loamy. Weeping lovegrass can be established and plants persist when spring, summer, and fail rainfall varies from 400 to 1,000 mm on deep sandy soil end mean minimum winter temperrtures rarely fall below -50 C. The invesion of adjacent nonplanted sites occurs only in Africa where growing season reinfall infrequently cycles between 750 and 1,000 mm and soils remahr wet in mid-summer. Kleingrass can be established where mean maximum daily summer temperatures are above 300 C, mean minimum daily winter temperatures rarely fall below 00 C, summer growing season rainfall vuies from 400 to 999 mm, and soils are clayey or silty. Kleingrass, like weeping lovegrass, spreads to nonplanted sites only in Africa where a mid-summer drought does not occur. Lehmann lovegrass predominates and spreads only in southern Africa, southeastern Arizona, and northern Mexico when summer r&fail in 30 to 40 days exceeds 150 mm, and soil textures are sandy or sandy loam.

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.

Thii research was designed to identify relationships between T-4464 buffelgrass (Ce&zrus ciliaris L.) survival and climatic and soil characteristics. At 167 buffelgrass seeding sites in North America we collected climatic and soils data where the grass: 1) persisted over time and increased in area covered (spreads), 2) persisted over time but does not increase in area covered (persists), and 3) declined over time and all plants eventually died (dies). At 30 sites in Kenya we collected climatic and soils data in the area where T4464 seed was originally collected. Only total soil nitrogen and organic carbon differed among survival regimes. Total soil nitrogen and organic carbon concentrations were least where buffelgrass spreads, intermediate where the grass persists and greatest where the grass dies. To predict buffelgrass survival among the 3 survival regimes, and between areas where the grass spreads or dies, we used discriminant function analyses. A model including organic carbon, total soil nitrogen, sand, clay, potassium and cation exchange capacity correctly classified 78% (13=0.8) of the seeding sites in the 3 survival regimes. A model including sand, total soil nitrogen, calcium, mean minimum temperature in the coldest month, annual pre-The authors acknowledge the financial suppon provided by USDA-Agricultural Research Service (Drs. Plowman. Knipling and Child). We thank Dr. N.J. Chatterton (USDA-ARS) for laboratory f&ilitk. Drs. Gary Richardson (USDA-ARS) and D.V. Sisson (Utah State University) for statistical advice. We also appreciate support and financial assistance provided by Consejo National de Ciencia y Tecnologia,

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.