Influence of climatic and edaphic factors on the distribution oferagrostis lehmanniananees in Arizona, USA

Abstract

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.

Epidermal conductance as a component of dehydration avoidance in Digitaria californica and Eragrostis lehmanniana, two perennial desert grasses

“…lehmanniana is native to arid savanna communities in the North Cape Region of South Africa (Cox and Ruyle, 1986). This C 4 species is also caespitose and suffrutescent, and tillers may survive on plants for more than 1 year producing new leaves from axillary buds along their length when soil water is adequate (Angell and McClaran, 2001).…”

“…lehmanniana in southern Arizona is represented by descendants of a single accession ('A-68') that was collected in the Griqualand West region, North Table 1 Mean monthly precipitation and temperature (NOOA, 2004) Cape Province, South Africa (Crider, 1945;Cox and Ruyle, 1986). Precipitation in this region of South Africa (mean: 250-500 mm yr À1 , 414 mm yr À1 at Kimberley, RSA) occurs primarily as thunderstorms during a 6-month summer rainy season (75-85% of annual precipitation) when mean temperatures may be above 20 1C.…”

Insect assemblages change along a gradient of invasion by a nonnative grass

“…Since its introduction in the 1930s, dominance and distribution of this nonnative grass have increased rapidly throughout the southwestern United States and Mexico, with predictions for its potential distribution to exceed 71,000 km 2 in southern Arizona and New Mexico alone (Cox and Ruyle 1986;Anable et al 1992;Schussman et al 2006). Invasion by E. lehmanniana has strong implications for the structure of these grassland plant communities because it grows rapidly and produces up to four times more aboveground biomass than native grass species (Crider 1945;Cable 1971;Cox et al 1990).…”

The effect of dominance by an alien grass species, Lehmann lovegrass, Eragrostis lehmanniana, on faunalpedoturbation patterns in North American Desert grasslands

“…Lehmann lovegrass (Eragrostis lehmanniana) is a short-lived, small seeded grass native to the semiarid lands in the Northern Cape of South Africa. Lehmann lovegrass is found in many different soil and moisture conditions in most of South Africa (Cox and Ruyle, 1986). In South Africa, E. lehmanniana replaces large seeded perennial grasses which have been reduced by grazing (Milton et al, 1999).…”