A comparative study of gum arabic yield trends per tree and picking in relation to stand management ͑by farmers and by researchers͒ and type ͑natural and planted͒ was conducted at two locations in North Kordofan, Sudan, for a three-year period. In addition, eight-year yield trends in relation to rainfall were compared based on the 1993-2000 gum yield data from 1440 trees. Although the gum arabic yield followed the same trend over time in all stands at both locations, the gum yield from farm stands, whether planted or natural, was 47% to 60% lower than that from research stands. Late tapping reduced the gum yield by 40% and 50% at the two different locations, respectively. Yield was highly affected by rainfall, correlating positively with annual rainfall in six of the eight years of the study. These findings can be used for improving gum arabic yield through management interventions and for predicting yield in relation to stand type, management regime and rainfall.

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Comparative studies of gum arabic yield trends in relation to natural and plantation management of Acacia senegal in farmers and researchers fields were conducted in the main production centres of the gum belt in western Sudan. The effect of climate variability, namely rainfall and temperature fluctuations were thoroughly examined for ten years. The objective was to arrive at an improved package that can help in understanding reasons behind variability in gum arabic production in the Sudan. The output is expected to help in controlling, predicting and stabilising gum yield in the light of changing climate, varying social and economic conditions and instability of supplies of gum arabic in the internal and international markets. The outcome of the on-station and on-farm research trials clearly demonstrated the yield trends of the different types of tree stands as well as the effects of management and climate change. The results showed that the management of the different tree stands could be improved to arrive at significant (up to 60%) increase in the yield of gum arabic plus increased value addition due to improvement in the quality. Statistically verifiable models to help understanding instability in gum production and supplies were developed. These models were found to explain much (> 80%) of the current variability in gum yield. Recommendations were set for improving the primary production systems for the smallholder and the large-scale producers of gum arabic as well as ensuring sustainable production. A capacity building programme to improve producers' management skills was also suggested.