Climatic and edaphic conditions at eragrostis lehmanniana nees sites in Arizona, USA and the cape province, RSA and potential seeding sites in Southern Africa

Abstract

Climatic and edaphic conditions at Eragrostis lehmanniana Nees sites in southeastern Arizona, USA were compared with those in the Cape Province, RSA to determine a range of conditions under which the species might be expected to establish and persist in southern Africa. Mean annual precipitation amounts and temperature extremes were highly variable where Lehmann lovegrass predominates, but in most summers precipitation accumulations ranged from 150–220 mm and temperature extremes ranged from 20–35°C in 30–40 days. Soils at Lehmann lovegrass sites in the Cape Province were more coarse textured and nutrient concentrations were usually less than at sites in southeastern Arizona; but trends in particle‐size distributions and measured chemical concentrations were generally equivalent. Climatic and edaphic conditions in central Botswana and northeastern Namibia generally range between those in southeastern Arizona and the Cape Province, RSA and we expect that seeded Lehmann lovegrass stands in these areas would enhance semi‐desert grassland productivity.

Edafiese en klimaatstoestande is gemeet op plekke in die suidelike dele van Arizona (VSA) waar Eragrostis lehmanniana Nees voorgekom het. Dit is vergelyk met die in die Kaapprovinsie (RSA) om ‘n reeks van toestandc te bepaal waar dit verwag word dat die spesie sal vestig en sal oorleef in Suider‐Afrika. Die gemiddelde neerslag en die uiterstes in temperatuur was hoogs verskillend waar knietjicsgras voorgekom het. Die somerneerslae het gevarieer van 150–220 mm en die temperatuuruiterstes het gewissel van 20–35°C in 30–40 dae. In die Kaapprovinsie het die grond by die plekke met knietjiesgras, ‘n meer growwe tekstuur gehad en die voedingstofkonsentrasies was oor die algemeen laer as by die plekke in suidelike Arizona. Die neiging in die partikelgrootte se verspreiding en die chemiese konsentrasies was oor die algemeen dieselfdc. Edafiese en klimaatstoestande in sentraal‐Botswana en noordelike Namibië is gewoonlik tussen dié van suidelike Arizona en die Kaapprovinsie. Daar word dus verwag dat gesaaide knietjiesgrasstande in hierdie dele die produksie van die semi‐woestyngrasveld sal verbeter.

Additional index words:

• Northern and Southern hemispheres
• Sonoran and Kalahari deserts
• climatic and edaphic comparisons