Ecological situation of acacia tortilis subspecies raddiana. Case study: In white nile state, Sudan

This study conducted during the season 2017 at ED-Duem Locality which is laid at Northern White Nile State of Sudan, the main objectives of this study was measurement, listing of all acacia raddiana tree sites their assessed the physical characteristics of the height, diameter at breast height and were account the abundance, dominance, and survival % of natural regeneration of acacia raddiana tree as the main species. The researcher used the systematic circular sampling plots methodology which established with total number of 130 sample plots. The sample plots were circular in shape with a radius of 17.84 m (0.1 ha in area.). In these sample plots all trees with diameter at breast height (dbh) equal to or greater than seven centimeters were measured for tree species, and the regeneration survey in each sample plot (10) quadrats ( subplots) of 1mx1m (1m2), the regeneration survey in each sample plot (10) quadrats ( subplots) of 1mx1m (1m2) were calculated. The results showed no signifi cant different for acacia raddiana tree in eight sites, and the survival rate of Acacia raddiana regeneration are (20.4 -23.9%). Research Article Ecological situation of acacia tortilis subspecies raddiana. Case study: In white nile state, Sudan Goda MMB1, Dosougi MA2, Osman A3 and A Musa Ibrahim4* 1Forest Extension, Forest National Corporation, Sudan 2Dean of Forest Colleges, Sudan University for Science and Technology, Khartoum, Sudan 3Forest Colleges, Sudan University for Science and Technology, Sudan 4Livestock Marketing and Resilience Programme, (LMRP)/IFAD, Sudan Received: 08 July, 2020 Accepted: 27 January, 2021 Published: 28 January, 2021 *Corresponding author: Abdelsami Musa Ibrahim Adam, Livestock Marketing and Resilience Programme, (LMRP)/IFAD, Sudan, E-mail:


Introduction
The total forest cover in the Sudan  of its forest covers [1]. White Nile State rich with vegetation types and many fl ora in natural forests, and as forest covers.
Acacia raddiana tree is one of the fl ora in natural stands. The genus Acacia belongs to the family fabacease, and subfamily Mimosaceae. Acacia raddiana is synonyms Acacia raddiana. It is a gregarious tree and between 7 -21 m in length [2]. The genus occurs in Sudan. The known species of the Sudan is Acacia raddiana, and the Arabic name of the tree is "Sayal".
Eventually, Acacia species considered as one of the most important species in arid and semiarid areas and used widely in all the zones where it is ecologically adapted, water found in areas with maximum average rain < 600 mm Mustafa [3], Acacia tortilis subspecies raddiana occurs in the White Nile State in aggregates areas, it is the highest as it occurs in different area at Eldouim locality. Lamprey [4] found 7 percent natural germination from seed collected from faecal pellets. He obtained no regeneration of seed from fallen pods. At present, it regenerates in area frequented by animals (night holding grounds, round ponds and wells and in the neighborhood of villages), and also in areas newly opened to cultivation on which animals roam freely after harvest. Natural regeneration rates of 19-27% were obtained in Eritrea [5], considered as poor. The disadvantages of the natural regenerations are: Less control over initial stocking and spacing, generally lower commercial yield, no generic improvement or the introduction of disease resistant stock, possible delays in regeneration due to drought or inadequate ingested seeds and the possible need for precommercial thinning to ensure good growth. It is classifi ed Citation: Goda  Abundance, domance, and the survival rate for natural regeneration on Acacia raddiana tree.
Assessment of tree species and natural regeneration:

Layout of sample plots
The systematic circular sampleplots [8] were used in this study. The area covered in this study was 258 hectares. 8 sites (camps) were selected and established with a total number of 130 sampleplots. The sampleplots were circular in shape with a radius of 17.84 m (0.1 ha in area)., in these sampleplots all acacia raddiana trees, and their natural regeneration which were measured and analyzed as follow:

T-test: Acacia raddiana tree
In each sampleplot tree were measured in different parameters., and data recorded for each tree.

Natural regeneration
For assessment of natural regeneration in the study area, plots need to be small. These may be based on separate sampling or sub plots within conventional forest inventory plots [9].
The regenerating species (R.S.) were calculated and analyzed as follow Abundance, domance, and the survival rate for natural regeneration on Acacia raddiana tree.

Results and discussion
Effect of Site on the average density /ha of Acacia tortilis subspecies raddiana Table 1  Elsefory [10] mentioned that the wood species was 19.3 stem/ ha at the three sites in the same study areas, which signalize the declination. Goda [11] calculated that the average of Acacia albida tree about 11 trees/ha in four sites at the study area, which point out retrogradation. as a multipurpose tree, used as a browse tree for fattening animals during dry season, shade, green wall, energy, poles, popular medicine and pharmaceutical, one of groups of nontimber forest product like Gum is edible and can be used like Gum Arabic [6].

Study area
Study was carried out at White Nile State. The position between (13 58 09.9 and 14 30 22.5 North 32 03 07.2 and 32 02 15.8 East). The area of the White Nile State is almost 34567 ha. The total population of the state in 2009 was around 1730588, out of which 1149292 (66.4%) live in rural areas. The main tribes living in the area are Hassania, Kowahalla, hussunate, Kababish, Magadai, and Galieen. The soil habitats are loamy or gravely soils as was indicated by Elamin [2]. The water resources include the White Nile River which is representing the main water source in the area, the underground water and the surface water including khors, wadies. The vegetation coverage is available according to the climatic zones. The study area is generally characterized by high temperatures for most of the year, with means of 37 ° C and 21 ° C for maximum and minimum summer temperatures respectively [7]. The rainy season extends from June to October and most of the rains fall during July to August. The average annual rain falls for Eldouim had declined from 330 mm  to 239 mm (1990-2012).

Assessment of tree species and natural regeneration
Layout of sample plots: The systematic circular sampleplots [8] were used in this study. The area covered in this study was 258 hectares. 8 sites (camps) were selected and established with a total number of 130 sampleplots. The sampleplots were circular in shape with a radius of 17.84 m (0.1 ha in area). In these sample plots all acacia raddiana trees, and their natural regeneration which were measured and analyzed as follow:

T-test at Acacia raddiana tree.
Parameter assessment of the area: In each sampleplot tree were measured in different parameters, and data recorded for each tree. Acacia raddiana species identifi ed (size and number); tree height in m and diameter at breast height (d.b.h), cm. data for each sampleplot recorded in a sheet. In each sampleplot the natural regeneration counted and recorded Acacia raddiana tree. Further the trees height was also classifi ed into the height classes. Diameters were also classifi ed in to the diameter classes., and in each sampleplot the natural regeneration was counted and recorded of acacia raddiana tree.

Natural regeneration
For assessment of natural regeneration in the study area, plots need to be small. These may be based on separate sampling or sub plots within conventional forest inventory plots [9].
The regenerating species (R.S.) were calculated and analyzed as follow: Citation: Goda Table 2.

Diameter classes distribution of Acacia tortilis subspecies raddiana
The diameter classes' distribution always not follows the trend of species distribution according to height classes by sorting diameter classes into three ranges as height classes.

Natural regeneration of Acacia tortilis subspecies raddiana at eight sites
The natural regeneration seeds at Acacia raddiana tree it is the matter of adequate conditions nearly in all Acacia raddiana     24-31. sites. Natural regeneration of acacia raddiana were found in all sites with exception of site eight which were zero into the abundance , and also dominance per ha of July 2011, and survival rate in the same year were zero of acacia raddiana, Table 4. This site is unprotected after seed ripening and dispersal and the reasons may be the absence of guards and communal settlement "waara". The natural regeneration is quite promising in case of ingested seeds into "waara" ecology. The survival rate of natural regeneration of the species are (20.4-23.9%), and Lamprey [4] found in Tarangere Game Reserve in Tanzania 7 percent germination from seed collected from faecal pellets. He obtained no germination of seed from fallen pods thus natural regeneration is very poor. Seedlings survival rates of 19-27% were obtained in Eritrea [5], considered as poor. This numbers of natural regeneration values are low as shown in Table 4. This is due to the seed losses their embryo , and inadequate ingested seed. Rainfall plays a vital role in natural regeneration in the Sudan. The density and occurrence of trees decreased northwards similar to pattern of rain fall. The natural regeneration from seeds is diffi cult on sites that receive less than 600 mm, unless the seeds were ingested by animals or placed on fl ow sites. Mustafa [3] However, the natural regeneration number in 2011 was lower than in 2012. The reason may be due to the delay of rainfall in 30th of June in season 2011 while in 2012 than the rainfall started in the 13 the of June. And above all the total rains of 2011 to 210.8 mm at Eldouim Station compared to 385 mm in 2012 at the same station. But, in spite of all natural regenerations survival rate was almost similar in two seasons. It fi nds that high percentage of people poor as nomads in areas without guard, also no "waara" , and where nomads settle, with their livestock for a while, and after the rainy season the area is almost subjected to heavy grazing which causes by the intensive number of animals, which deteriorates the areas. Where there is Acacia raddiana regenerations, and a bit of regenerations (saplings) founds in the seven sites. Those locations are the only ones with guards, and "waara". Therefore, regenerations has chance to becomes mature trees if the sites are acceptable to the local community, and to be involved in the management and improvement of "waara" areas, which near to their villages, for their the natural benefi ts, and reforestation as the natural forest.

Conclusion and recommends
Conclusion * The study indicates that there is no signifi cant difference of Acacia raddiana tree in eight sites.
* The mature trees (in the height, and the diameter), probably disappeared.
* Acacia raddiana consider very low which indicates the deterioration.
* The highest number of trees in some sites resulted of regenerations through "waara" environments, and the continuous presence of forest guards.
* Acacia raddiana could regenerate naturally on "waara" area or in area frequented by animals.
* Natural regeneration rates of Abundance (Sep.2011. 6.75%-Sep.2012. 9.13%) were obtained in study areas, which is considered as very few and poor percentage.
* Sites of no the "waara" , and no guards, the Natural regeneration is diffi cultly.
* Some factors affecting regeneration are; trampling, rodents, children, fi re regenerating and seeds harvesting by ants.
* The seeds are of three type's infested, empty and viable ones.

Recommendation
* Improves the management of forest programs.
* Grazing, and cultivation at Acacia raddiana sites, and as were always should be banned or at least regulated.
* There is a need for Forests National Corporation, integrated with local Communities and United Nation on rehabilitation the study area and other degraded lands.
* There is a need for Community Based Capacity Mechanism for awareness programs considering the importance of the trees species at the study areas, and other sites.
* Trees with diameter at breast height more than 23 cm can be used for harvesting seeds.