N and P Fertilization on Rangeland Production in Midwest Argentina

Rangeland degradation in a semi-arid South Africa—I: influence on seasonal root distribution, root/shoot ratios and water-use efficiency

“…The average WUE values of 3 kg ha À1 mm À1 for rangeland in good condition obtained in this study, are within recorded ranges like South Africa (2.0-3.5: Snyman and Fouche´, 1991;Snyman, 1998Snyman, , 1999bO'Connor et al, 2001), Argentina (2-4: Guevara et al, 2000), Australia (2.7: Ingram, 2002;3.4: Holm et al, 2002), North American grassland (6: Sala et al, 1988;Lane et al, 1998), while the increase of WUE from poor to good condition rangeland is consistent with recorded relationships of WUE with degradation (Le Houe´rou, 1984;Pickup, 1995;Snyman, 1988Snyman, , 1998Snyman, , 1999aO'Connor, et al, 2001;Holm et al, 2002). The fact that all rangeland conditions used water more efficient during the first half of the growing season is also supported by Snyman (1988) on the same rangeland type.…”

Structure and growth rate of Prosopis flexuosa woodlands in two contrasting environments of the central Monte desert

“…an could be attributed to different water availability and land use histories. Water availability is the major limiting factor in arid lands (Noy-Meir, 1973), like the Monte desert (Guevara et al, 2000). Therefore the higher number of tall trees with larger basal areas and the faster rates of radial growth in Telteca may reflect a more abundant and/or stable water supply at this site.…”

Atmospheric dust in modern soil on aeolian sandstone, Colorado Plateau (USA): Variation with landscape position and contribution to potential plant nutrients

“…The role of aeolian dust in ecosystem nutrient dynamics in these semi-arid ecosystems is likely to be significant. Phosphorus can co-limit productivity (with N) in semi-arid environments (Guevara et al, 2000;Snyman, 2002), particularly when water availability is high. Despite uncertainty regarding the total contribution of dust to surface P, our results show that this contribution is significant.…”