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Journal of Arid Land  2020, Vol. 12 Issue (4): 609-617    DOI: 10.1007/s40333-020-0076-8
Research article     
Exploring tree diversity and stand structure of savanna woodlands in southeastern Sudan
M M HASOBA Ahmed1,*(), A H SIDDIG Ahmed2,3, E YAGOUB Yousif2
1 Faculty of Forest Sciences and Technology, University of Gezira, Madani 22212, Sudan
2 Faculty of Forestry, University of Khartoum, Khartoum North 13314, Sudan
3 Department of Environmental Conservation, University of Massachusetts Amherst, Amherst 01003, USA
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Savanna woodlands in Sudan host great biodiversity, provide a plethora of ecosystem goods and services to local communities, and sustain numerous ecological functions. Although the importance of the Acacia trees in these areas is well known, up-to-date information about these woodlands' diversity is limited and changes in their woody vegetation composition, density, diversity and relative frequency are not monitored over time. This study explored tree diversity and stand stage structure in Nuara Reserved Forest, a typical savanna woodland ecosystem in southeastern Sudan. A total of 638 circular sample plots (1000 m2 for each) were established using a systematic sampling grid method. The distance between plots was 200 m. In each plot, all living trees with diameter at breast height (DBH) ≥5.00 cm were identified and counted, and their DBH values were recorded. From these data, tree composition, diversity, density and stage structure were assessed. There were 12,259 individual trees representing four species (Acacia seyal, Balanites aegyptiaca, Acacia Senegal and Acacia mellifera) that belong to two families. The dominant species was Acacia seyal. Average tree density was 191 trees/hm2 and the Shannon-Weiner index for trees diversity was 0.204. Overall, young trees comprised 86.30% of the forest. The state of tree richness and density in the study area was low compared to other similar environments in the region and around the world. We recommended adoption of a proper management system that includes monitoring of woody vegetation diversity in this forest, and management actions to enhance tree diversity and sustain ecosystem services to local communities. In addition to care for the dominant Acacia seyal stands, more attention and conservation should be devoted to reestablishing Acacia senegal and Acacia mellifera trees because of their high ecological and economic values for local communities.

Key wordsspecies diversity      stand structure      savanna woodland ecosystem      forest monitoring      forest management      ecosystem services      Nuara Reserved Forest     
Received: 02 September 2019      Published: 10 July 2020
Corresponding Authors: M M HASOBA Ahmed     E-mail:
About author: *Corresponding author: Ahmed M M HASOBA (E-mail:
Cite this article:

Ahmed M M HASOBA, Ahmed A H SIDDIG, Yousif E YAGOUB. Exploring tree diversity and stand structure of savanna woodlands in southeastern Sudan. Journal of Arid Land, 2020, 12(4): 609-617.

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Fig. 1 Sketch maps for the location of Sennar State in southeastern Sudan (a) and the location of Nuara Reserved Forest (study area) in Sennar State (b), as well as the overview of Nuara Reserved Forest (c)
Fig. 2 Distribution of sample plots in Nuara Reserved Forest
No. Species name Number of plotsa Relative frequency (%) Number of individuals Relative density
1 Acacia seyal 533 84.20 11,638 218.34
2 Balanites aegyptiaca 176 27.80 577 32.78
3 Acacia senegal 15 2.36 40 26.60
4 Acacia mellifera 2 0.31 4 20.00
Total 638b 100.00 12,259
Table 1 Estimates of trees species composition, relative frequency, number of individuals and relative density in Nuara Reserved Forest
Fig. 3 Photo showing very dense sample plot dominated by Acacia seyal trees in Nuara Reserved Forest
Fig. 4 Spatial distribution of average tree density in Nuara Reserved Forest. The black lines within the figure represent the boundaries of forest compartments.
No. Species Number of trees Percentage of species in the stage (%)
(5.00-14.99 cm)
(15.00-24.99 cm)
(≥25.00 cm)
1 Acacia seyal 11,638 93.10 6.40 0.42
2 Balanites aegyptiaca 577 56.49 36.56 6.93
3 Acacia Senegal 40 90.00 10.00 0.00
4 Acacia mellifera 4 100.00 0.00 0.00
Total 12,259 86.30 13.35 0.34
Table 2 Percentage of each species in the three tree stand stages in Nuara Reserved Forest
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