• Climatic effects on buffelgrass productivity in the Sonoran Desert

      Martin, M. H.; Cox, J. R.; Ibarra-F, F. (Society for Range Management, 1995-01-01)
      Buffelgrass (Cenchrus cilaris L.), a perennial bunchgrass from northcentral Kenya has been successfully seeded on 400,000 ha in northwest Mexico. To determine if carrying capacity increased after buffelgrass introduction we measured live, recent-dead standing, old-dead standing and litter at 2-week intervals for three years. Live biomass was produced throughout the year but peak production, over the 3 years was in August. Peak live biomass production varied from 46S kg/ha in a summer of below-average precipitation to 3,045 kg/ha in a summer of above-average precipitation. Recent- and old-dead standing quantities were highly variable among years and transfers among components were dependent on temperature and precipitation. Buffelgrass annually produces about 3 times more green forage than native grasses.
    • Predicting buffelgrass survival across a geographical and environmental gradient

      Ibarra-F, F. A.; Cox, J. R.; Martin-R, M. H.; Crowl, T. A.; Call, C. A. (Society for Range Management, 1995-01-01)
      This research was designed to identify relationships between T4464 buffelgrass (Cenchrus 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% (r2=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 precipitation and winter precipitation correctly classified 88% (r2 = 0.8) of the seedling sites between spreads and dies. Survival regime selection prior to brush control, seedbed preparation and sowing will reduce planting failure probabilities, soil erosion and economic losses, and enhance long-term beef production.