Evaluation of rangelands under two ecological zones in North Kordofam, Sudan

This study was conducted in North Kordofan State under two ecological zones( semi desert and low rainfall savanna on sand zones). The objectives were to evaluate the natural rangelands and to study their attributes, condition and trends in order to suggest appropriate measures for their sustainable utilization. Both quantitative and qualitative measurements were used. The quantitative measurements included ground measurements and remote sensing. For the ground measurements range condition, plant composition, plant density, vegetation cover, biodiversity, biomass production, stocking rate, proper use factor (PUF) and carrying capacity were calculated. The total production for the two ecological zones was defined using remote sensing technique and geographical information system (GIS). For qualitative measurements chemical analysis was done for some plants and trees to define the nutritional and mineral content. In vitro Dry and organic matter digestibility were also determined for some range plants and ten rams were reared on natural rangelands for three consecutive grazing periods (30, 60 and90 days) to study the performance. Data were arranged in split-plot design, taking ecological zone as main plot and the season as subplot. Chemical composition and digestibility data were analyzed as a randomized complete block design. SPSS software was used in statistical analysis. The majority of range attributes and parameters were higher for Low Rainfall Savanna compared with the semi desert. Range condition differed from year to another at the two ecological zones, being good at 2003 and 2004 for the low rainfall savannah on sand and poor for the semi desert one, while it was good for both ecological zones during 2005. This variation was accompanied by high variability in plant density, cover and diversity. To mention few examples the overall respective mean %live plants for the two zones were 47.44 and 69.67%, respective range productivity (ton/ha) for the 2003 were 1.09 and 2.163, for 2004 were 0.62 and 0.819 and for 2005 were 0.90 and 0.96. The estimated productivity (tons) for the whole semi desert (7,715,459 ha) and low rainfall savannah (894,966 ha) zones were 3,086,183.6 and 626476.2 tons, with respective grazing capacities 5.7 and 6.1 ha/AU for 2005 as an example, and respective PUE of 163.9 and 175.4 AU/1000ha. The chemical analysis for selected range plants showed that CP, CF, ash, EE and NFS were in the range from 6-10, 35-45, 7-10, 1.1-2.1 and 36.7-46.7% respectively. The chemical analysis for selected browse trees were CP5.1%, CF 31-33%, EE 0.4-0.9%, ash 7-8.1 % and NFE 53-56.9%. Mineral contents ranged from 0.0144-0.075 p.p.m for P, 0.002-0.063 p.p.m for K and 1-2.9 p.p.m for Iodine. In vitro DM and OM digestibility ranged from 52-59 and 52-62%, respectively. Rams grazing on natural rangelands recorded weight gains during the first grazing period (December), and then they lost weight at the second period (January) and recorded a high weight loss during the third period (February). The study concluded that rangelands of low rainfall savannah on Sand zone were better than at the semi desert zone. However, both zones were deteriorating in both quality and quantity which negatively affects livestock performance particularly during the long dry season (January-July). There is a high need for introducing protection measures to improve range condition and reverse the downward trend. Furthermore, there is also a high need for studying the effects of protection, reseeding, range harvesting on range management and sustainable utilization