Plant Biology and Biodiversity Management

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Allelopathy in Some Ethiopia Grasses
(Addis Ababa Universty, 1982-06) Medhanie Ghebrehiwot; Berhan Tewolde (PhD)
Investigation for possible chemical interactions among some of the common grass species that grow in and around Addis Ababa was undertaken. The species used were the grasses Alldropogon abyssinicus R. Br. ex Fl:·esen, Hyparrhenia arrhenobasis (Hochst. ex. Steud.) Stapf, Pennisetum glabrum Steud., SnOl"ldenia polystachya (Fre san) Pi Ige1', E leusine jaegeri Pi Iger, &ragrosti8 tenuifolia (A. Rich) Steud. and a legume, ~!edicago polymorpha L. The effects of the extracts of the seven species on the seed germination and plumule and radicle growt'h of the same seven species shoW}d that ~. abyssinicus and ~. polystaohya were the most inhibitory followed by H. arrhenobasis and .!!!... jaegeri in that order. Extracts from!!!... tenuifolia, H. polymorpha and P. glabrum showed less inhibitory effects than the above species. See.d germination inhibition effect Was greatest on ~. polystachya and P. glabrum and that on E. jaegeri and H. arrhenobaaia '"aa the least. Auto-inhibition ,"as found to be as high as allo-inhibition. Extracts from all the species except!!!... tenuifolia ShO\fed auto-inhibitory effecta on germination and plumule growth and/or radicle grovlth. Different experiments Vlere carried out to detect the \fay of release of the inhibitory chemical(s) in ~. abyssinious. The results obtained from these experiments indicate that !. abyssinicus inhibits other speoies when decomposition of its dead .remains takes place and that the live plant doss not re lease any alle lopathic st'bstance into the soil medium
Reaction Studies of a Select Group of Sorghuh Lines to Le; F Streak Disease (Xanthohonas Holcicola)
(Addis Ababa University, 1984-05) Andenow Yeshi; A.Gashe Berhanu (PhD)
From infected sorghum leaves ~ough~ from three different place, 17 yellol'l coloured bacterial coldmies were isolated. After having conducted hypersensitivi.y, morphological, physiological and biochemical tests, including pathogenicity test using sorghum line W8 1297 as a susceptible host, only one isolate was found to be Xanthomonas ~lc~cola. the causal organism of bacterial streak disease of sorghum. Six different inoculation techniques were compared to achieve an effective method of screening together with pathogenicity test. The isolated organism induced typical symptomatic response when the rub and spray method of inoculation was used. Using the rub and spray method, 31 sorghum lines, 7 from highland (about 2000 metres), 8 from intermediate (1600-1900 metres), 15 from lowland (800_1600 metres) and sorghum WS 1297 as s control were examined for resistance to bacterial streak disease caused by .!.holcicola. High resistance to the disease was sho"m by sorghum lines 80 K 6056, Gambella 1107, 80 ~ 6088, 81 ESIP 21, 81 ESIP 25, Melkamash 79, ETS 0601, ETS 4946. Of these 75% are from lowland and 25% are from highland groups. Sorghum lines IS 9294, IS 9302, IS 9379, .81 ESIP 29, Dobbs, IS 8686, Muyra white,IS 9923 nnd'thll control \~S 1297 showed susceptible reactions. Of the susceptible sorghum lines 62,5% are from intermediate, 25% from lowland and 12.5% from highland groups. The reaction of the other lines range from moderately resistant to moderately susceptible.
An Ecological Study of the Vegetation on the Eastern Escarpment of Eritrea Ethiopia
(Addis Ababa Universty, 1984-06) Ghebrekristos Sahle; Berhan Tewolde (PhD)
An ecological study of the vegetation on the Eastern Escarpment of Eritrea from an altitude of 190 meters to an altitude of 2075 meters above sea ;level Vias performed. seventy-seven stands \o[ere selected systematically and all plants found in the stands \o[ere recorded as present. A number of environmental factors including slope, aspect, altitude and percentage of rock cover at the surface \vere measured. Soils sample Vlere also taken from each stand and analysed for texture organic matter, color, conductivity, pH and the cations K, Ca, Mg; Na and Mn. The vegetation data Vlere analysed by tVlo"vIaY indicator species analysis and 10 homogenous groups of stands were formed. The groups of stands Vlere compared for their averaged environmental factors using the t-test. Rank correlation was also computed for the averages of the different environmental factor in each stand grouP. The groups of stands Vlere observed to shoVi the highest number of contrasts in altitude. Altitude in itself does have any effect on the distribution of vegetation, but it is associated with changes in atmospheric pressure, moisture, temperature and other factors. In the study region the amount and distribution 6f moisture was the factor that Vias mostly highly associated with altitude. It can thus be said that the main cause for the variation in vegetation on the Eastern Escarpment of Eritrea was the difference in moisture. Variaticn of moisture betIVeen the stands IVas also accompanied by variations in soil physical and chemical characteristics and topoqraphic factors. Ordination studies IVere also performed using detrended correspondence analysis, reciprocal averaging and IVeightedaverages ordination. The results from these studies confirmed the findings from the classification by the two-way indicator species analysis.
An Ecological Study of The Vegetation of the Ravenna Forest
(Addis Ababa University, 1987-06) Nigatu, Lisanework; Tadesse, Kesfin (PhD)
An ecological study of the vegetation of the Harenna forest was performed from April 1986 to October 1986. Data on the vegetation and environmental factos were collected, i.e. enumeration of tree and shrub species, an estimate of cover abundance value for herbs, epiphytes and lianes, alti~ tude, edaphic factors and topography. The program GROUPAGE \'las used to summarlze -the vef,eta-tion data. The program CHECK \'las employed to analyse species diversity. Five homogeneous clusters of vegetation were re~ cognized using the presence-absence and quantitative data. The clusters obtained were compared for the mean values of the environmental factors using the statistic t-test. The highest number of significant contrasts among the clusters were observed to result from variation in altitude. Analysis of species diversity showed that with increasing al ti tude, tree and shUl'b species decrease \>I11ile herbaceous species, epiphytes and lianes increase in number. As a result, in the area of the Harenna forest, the main vegetation gradient is caused by differences in altitude associated \'lith variation in moisture. The moisture gradient is accompanied by gradients in soil physical and chemical properties and topography.
A Seasonal Study on Phytoplankton Primary Production in Relation to Light and Nutrients in Lake Ziway (Ethiopia)
(Addis Ababa University, 1988-06) Tilahun, Girma; Belay, Amha (PhD)
Primary production by phytoplankton of Lake Ziway, Ethiopia, was st.udied from February. 1987 to Fehruary.1988 by the oxygen light-dark bottle technique. Supporting information included data on thermal characteristics, water chemistry, light penetration and meteorological conditions. Isothermal or near isothermal conditions ~Iere fr~quently observed. These were ensured by ~Iindy condition prevail ing on the large and unsheltered lake surface. I'lell oxygenated water from top to bottom provided evidence for frequent mixing. In all the sampling periods sodium clearly dominated the cations and carbooate-bic~rbD~Nte rlnmi~tQd the anions. The cationic proportion of the lake followed the order Na » Ca > f1g > K \'Ihile its aniont.c proportion fnl..l..owed the order HC03- + C03= » CD S04. The lake \'las found to have a htgh concentratIon of siHca and low concentrations of phosphate ond nitrate. The pattern of underwater light penetration was similar in all the sampling periods. The highest penetration occurred in the red, and the 10~lest in the blue spectral region. Solar irradiance incident on the lake surface di d not va ry markedly except for the 10\'1 va lues record(:d on cloudy days. The maximum photosynthetic rates of bottled phytoplankton varied between 1640 and 4070 mg 02.m-3.h-1 and areal rates ranged from 288 to 1625 mg 02m-2h-l. A principal reason for high rates of photosynthesis WIIS the combined effect of high chlorophyll .i!. content of the euphotic zone (81.1- 191.6 mg ChI lI.m- 2 ) and high photosynthetic capacity 1I1.0 - 22.5 mg 02 (mgChla)-1 h-I ) Efficiency of utilization of photosynthetically available radiation (Ph.A.R), Q, ranged from 2.4 to 9.6 mmol 02 per Einstien Ph.A.R. incident on the lake surface. An inverse relation bet\'leen efficiency and irradiance ~Ias observed. The temporal variation in al gal biomass was more pronounced when measured on a per unit area basis (cv R 23.9%), than when measured on a per unit volume basis (cv = 10.1%). This \'las due to the marked variation in the underwater light climate of the lake. High algal. biomass and sustained product ion seem8d to be maintained more by nutrient recycl ing than by nutrient input as the lake \'las of 10\'1 nutrient status through out the year. Hydrographic (wat2r column structure) factors seemed to play an over riding role in determining the rate of nutrient recycling, the lIndOrl'later light climate, the nxtent of algal gro\'lth in the lake, and subsequently the spatial (vertical) and temporal pattern of phytoplanktonic photosynthesis.
The Microbiology of Tella Fermentation
(Addis Ababa University, 1990-06) Sahlle, Samuel; Gashe, Berhanu (PhD)
Jl'our major phases in Tella fermentation !'rere identified. In each phase, different microorganisms !'iere isolated and enumerated. Six genera of bacteria ~lGJ:'e identified. They \'lere: A!'.thrqbact~er, AcetobacteL, Last;obacilJY2., Baci),.Lu,!'!.. Proteus and l).chromopll.cte:r::. In addition t\oro genera of yeasts I Saccharom.yces and Rhodot orula, ,'rere ident ified, out of these Sacchar~ll!L9_e.§. ~/HS found to be responsible for tella fermentation. In addition to microbiological studies, chomical and physical characteristics of the four phases \'rere studies. In phase I (0-96 hr), the pH droped from 5.2 to Lf.73 at the end of this phase. 'l'here is a slight difference bet~reen temperature of fermonting material and the room temperature"- The total solid content, amount of re.ducing sugar and total carbohydrates ranging from 4.4% to 5. Lf9"lo, 4.04 to 12.0 mg/ml and 18.5-33.4 mg/m:). respectively. In phase II (96-144 hr), the pH decreased from 4.73 to 4.71. Likewise the temperature of the fermenting material increased from 21 00 to 2500 at the end of this phase. The total solid content, amount of reducing sugar,total carbohydrates and ethanol content ranged from 15.22 to 21.1%, 8.75 to 28.37 mg/ml, i}3.16 to <)8.08 mg/ml and o to 3.17% respectively. In phase III (1Lj.Lj. - 192), the pH fell from 4.75 to 4.67 at tho end to this phase. The temperature increased from 240 0 to 2700 at time 192 hr. The amount of total solids, reducing sugar, total carbohydrates and ethanol content ranged from 25.0 to 28.76, 5.2 to 14.83 mg/ml, 98.57 to 118 mg/ml and 2.77 to 5.13% respectively. In phase IV, the pH decreased from 4.58 to 3.34 at the end of this phase. The temp~rature also decroased from 24.600 to 21.6700. The total solid, reducing sugar, total carbohydrate and ethanol contents ranged from 4.3 to 11.73%, 2.35 to 5.2 mg/ml, 34.6 to 78.57 mg.ml and 4,3 to 5.13% respect ively at the ene. of period I ( 192 - 264 hr) of phase IV. In addition a comparison vms made between the laboratory brovred and locally collected tella samples with regard to microbial populations, chemicals and physical characteristics. The microorganisms res,?onsible for its fermentation and spoilage "rcre found to be similar.
Antifungal Metabolites from Submerged Culture of Ganoderna Lucidum (Polypore)
(Addis Ababa University, 1991-06) Bitew Adane; Abate Dawit (PhD)
About 60 different basidiomycete cultures were screened for antimicrobial secondary metabolites in submerged culture grown in four different media. Ten (17%) of them produced antimicrobial secondary metabolites. Production medium, duration of growth, and the most susceptible test organisms for each producing strain were established. Among basidiomycetes screened for antimicrobial activity, the culture filtrate extract of the Ethiopian strain of the polypore, Ganodemw lucidum produced the most effective antifungal compounds. The cu/~lral characteristics, growth in submerged culture of the polypore and isolation methods of the two antifungal antibiotics are described. Medium A (Yeast extract malt extract glucose medium) was a better medium for the production of the two antifungal agents. These compounds were released to the culture fluid and the maximum amount of antifungal compounds is obtained after 12 days of submerged growth at 120 revolution per minute (rpm). TIle two antifungal metabolites (20lA and 201B) isolated from culture filtrated were biologically characterized. TIlese metabolites had a wide spectrum of antifungal activity and affect the growth of several saprophytic as well as pathogenic fungi. The minimal inhibitory concentration (MIG) of 20lA against Candida albicans and Candida pseudotropicalis was less than 1 mcg/ml and 1-5 mcg/ml respectively. Inhibition diameter zone of 36 mm was produced when 10 mcg/disc of 20lA was applied on agar medium seeded with AspergHlus flavus. 20lA was also a potent inhibitor of spore gemlination. No spores of Aspergillus niger were germinated at a concentration of 10 mcg/ml of the antibiotic. Bacteria were affected only at high concentration. Antibiotic 20lA was more active than antibiotic 201B. A comparison of antifungal activity against dennatophytes showed that the efficacy of 20lA was comparable to griseofulvin. Treatment of sheep erythrocytes with the two antifungal antibiotics up to 100 mcg/disc did not show any lytic effect on sheep red blood cel/s. Application of 1 mg/1Ocm' of cn/de extract on a shaved rabbit skin showed no demlatotoxic reactions.
The Ecology of Praomys Albipes (Ruppell, 1842) in the Menagesha State Forest, Ethiopia
(Addis Ababa University, 1992) Bekele Afework; Yalden D.W. (PhD)
The composition, abundance and distribution of the rodent fauna in the Menagesha State Forest, Ethiopia was investigated with particular emphasis on the ecology of the endemic Praomys albipes. Both snap and live-trapping surveys were conducted to assess the species composition, activity patterns, reproduction, embryo sizes, weight and feeding habits of P.albipes. The snap-trapping surveys from November 1991 to July 1993 at different vegetation zones revealed the following rodents: Praomys albipes, Pelomys harringtoni, Lophuromys flavopunctatus, I i Mus mahomet, Arvicanthis dembeensis, Rattus rattus, Otomys typus, Stenocephalemys griseicauda and Dendromus mystacalis. A total of 293 rodents were captured during the snap-trapping surveys. P.albipes comprised 54.3 % of the total catch followed by Pelomys harringtoni ( 15.4 %), L.flavopunctatus ( 11.2%) and M.mahomet ( 10.9%). The remaining five species comprised only 8.2%. P.albipes and L.flavopunctatus were distributed within an altitudinal range from 2200-3300m asl, occurring in bush, forest and Erica scrub. Pelomys harringtoni and M.mahomet were common in Erica scrub and bushy vegetation respectively. P.albipes is exclusively nocturnal. From snap-trapping , live-trapping and captive breeding programmes, reproductively active males with scrotal testes were observed throughout the year and the testes, once scrotal , remained so throughout life. Females breed
An Ecological Study of the Forest Vegetation of Southwestern Ethiopia
(Addis Ababa University, 1997-06) Yeshitela Kumelachew; Bekele Tamrat (PhD)
'DIe floristic composition and stmcnIre of tbe forest vegetation of southwestem Etluopia between altinIdes 1050 to 2500 m are described. Sample plots of 30 m x 30 m were taken for woody plants and 2 m x 2 m for herbaceous and bambeo plants. A total of 101 sample plots were analyzed. The cover-abundance values for trees, shrubs and herbs witltin the sample plots were estimated. All trees and shrubs with diameter at breast height (DBH), i.e, 1.3 m of <0 2 cm were measured for height and diameter. The leaf size of all tree species Witll heights <0 6 m was measured. The presence of epiphytes on each woody individuals and tlle presence of woody climbers (lianas) in tlle sample plot was noted. Altitude, slope, and exposure were measured and soil samples from surface and sub-surface were taken and analyzed for pH, electrical conductivity, soil colour, texture, organic carben, total nitrogen, available phosphorus, exchangeable bases, and cation exchange capacity. A total of 139 species of vascular plants, 15 species of vascular epiphytes, and 12 species of woody climbers (lianas) were recorded. Average linkage clustering procedure was followed to classify the vegetation data and 9 clusters were recognized and tlle clusters were identified as local plant community types and given names after one or two dominating and/or characteristic species. The conl1l1wuty types are: Arulldinaria a/pilla, -Manilikara blltllgi-Coffea arabica, Syzygilllll guineense-Maytelllls gracilipes, IIex lIIitis-Galiniera saxifraga, Celtis' qfi1calla-Dracaella ajrolllolllana, Allop/zylus abyssinicus-JIIsticia schill/periana, Allingeria adolfi:friederici-ChiollClIlthes mildbraedii, Syzygillm gllilleellse-Dracaella ajl'OlIIOlllalla, and Olea lVellVitschii-Oliollallfhes mildbraedii. Analysis of variance (ANOY A) was performed to see if there is any significant variation among the community types with respect to anyone enviromnental parameter. The result obtained shows tltat tlle community types significantly vary for aU the envirol1ll1ental parameters except for slope, exposure, exchangeable sodium and potassium, cation exchange capacity and available phosphorus for subsoil (2()'60 em). Altitude is the enviromnental parameter that differentiate most of the community types. Some of the enVirOll1l1ental perimeter are significantly correlated. The structural 3.ltalysis of the community types showed tltat the density of trees in tlle > 10 cm DBH class is significantly higher than density in the> 20 em DBH class. Forty-seven per cent of the trees in Manilikara blltllgiCoffea arabica community type, and more tltan 60% of the trees in the remaining types belong to the lowest diameter class (5-20 em). More than 50% of the trees in Mallilikara blltllgi-Coffea arabica and SyzygiulIl gllineellse-Maytenus gracilipes community type and over 70% of the trees in the remaining community types raU into the lowest height classes (6-9 & 9-12 m). Mosses are the most abundant epiphytes in all community types 3.lldLando/phia buchananni is the abundant liana in all conununity types except in AllopJzylus abyssiniclIs-JlIsticia schimperiana type. The predominant leaf size class in all conmlwtity types is mesophyll (450()'18,225 mm'), while microphylls (225-2025 mm'), notophyUs (2025-4500 rom'), macrophylls (18,225-164,025 mm'), and megaphylls (> 164,025 mm') leaf sizes are shared by less than 20% of tlle species. Only mesophylls are present in Arundinaria a/pina community type.
A - Comparative Study on the Population Structure, Reproductive Biology and Chromosome Cytology of Two Endemic Aloe Species ( Aloe Pulcherr1ma Sebsebe and Gilbert and Aloe Deep Ana Christian) in Ethiopia
(Addis Ababa Universty, 1999-06) Dessalegn, Fikre; Demissew, Sebsebe (Professor)
A study was carried out to investigate and compare the population structure, reproductive biology and chromosome cytology of two endemic Aloe species, A. pulcherrima (with rare occurence) and A. debrcma (common) on naturally occurring populations around Debre Libanos in central Ethiopia from May 1997 to February 1999. The purpose of the study was to find out the causes for the rare occurrence of A. pulcherrima in comparison to the relative abundance of the sympatric species, A. debrcma with the aim of developing appropriate conservation strategies to conserve these endemic plants. Six plots of (5 x 20 m2) were established at the study site; three of these include the A. pulcherrima and the other three include A. debrcma populations. In each plot, genets and ramets were sorted out and the population structure was described by clone size and rosette diameter of ramets. Size of ramet relationship to flowering and size of ramet and flowering relationship to growth rate were studied. In addition, population flux (dynamics) at genet and ramet level was calculated and compared for the two species. Reproductive success and dispersal efficiency in the two species were estimated and compared based on the extent of vegetative propagation; production of flowers, fruits, seeds and also by pollinator availability and percentage pollen viability in the populations studied. Chromosome cytological studies, i.e., number, pairing and segregation of meiotic chromosomes were conducted in the laboratory from flower buds at appropriate stages of development and comparison made. Environmental factors which influence the development and distribution of the Aloes such as soil, climate, vegetation, herbivory and human oriented activities associated in the study site were obtained and analyzed. The results of the study revealed that A. pulcherrima has very old stagnant “ senile” population with no juvenilization (no recruitment from seed) but entirely depend on vegetative propagation and spread in spite of good seed set, satisfactory pollinatory activity (Sun birds and Bees) and high percentage pollen viability. In addition, it is attacked by a rust fungus parasite (Uromyces aloes) and heavily grazed by goats and baboons. A. debrana on the otherhand has a more viable population with adequate recruitment both from vegetative propagation and sexual reproduction. Moreover, the production of flowers, fruits and seeds were found to be greater than in A. pulcherrima. As in A. pulcherrima, it has satisfactory pollinatory activity (sun birds and bees) and high percentage pollen viability. A. debrana appears to be “ buffered” from rust fungus attack, less often eaten by goats and baboons, and is expanding. The two species also differ in their flower phenology; A. pulcherrima flowering from June to August and A. debrana flowering from December to February. Thus, this avoids competition for pollinators and hybridization between them. Both species also show low mortality at both ramet and genet level. Chromosome cytological study showed that the two species have diploid chromosome number 2n=14; 8 large and 6 small sized. Meiotic activities from pollen mother cells (PMCs) were also found normal with 7 bivalent (711) formation at metaphase I and absence of aberrations such as laggards (univalents and/or separated chromatids), bridges and fragments at anaphase/telophase I and II that ultimately end up in micronuclei formation. These were also evidenced by high percentage pollen viability in the anthers of the species studied. Thus with the need to protect these endemic species, appropriate conservation strategies have to be suggested.
Root Growth Patterns and Plant Adaptability in Three Acacia Species
(Addis Ababa University, 1999-06) Haileselassie, Teklehaimanot; Woldu, Zerihun (PhD); Fetene, Masresha(PhD)
Trees and shmbs screened for desirable properties can play an important role in the rehabilitation of degraded lands. Indigenous species adapted to harsh conditions of degraded sites can reverse degradation processes by stabilizing soils, increasing organic matter and improvements of nutrient status etc. Studies have shown that Acacia species have a potential for use in agroforestry systems and rehabilitation of degraded lands. For proper evaluation of the use of Acacia species in rehabilitation schemes and for agroforestry systems, studies in the root growth patterns and adaptability are essential. The main objective of this study was, therefore, to assess the root growth patterns of some Acacia species namely, A.seyaf Del., A.senegal (L.) Willd. and A.tortilis (Forrsk) Hayne and see the relevance of the results in adaptation to aridity. The study was conducted in Abernosa Ranch and Abiyata Shalla National Park. To investigate rooting patterns of the selected Acacia species, young trees were carefully excavated exposing a representative portion of the root system and quantitative data taken on depth at which the first lateral root starts, radial spreading of lateral roots and the zone of most intense lateral roots. Saplings were completely uprooted and separated for shoot and root palis, and oven-dried for the determination of shoot-root ratio. To see the effect of the Acacia trees on their undergrowth, comparison of herbaceous root biomass was carried out with adjacent open grassland in Abernosa. There was some difference in root growth patterns between species, A.seyal characterized by few but very big lateral root in close proximity to the surface, A.senegal with very dense lateral roots near to the surface and A. tortilis with less prominent lateral roots as compared to the others. The length of the taproots and shootroot ratio of the saplings uprooted indicated that A.tortilis has greater depth penetration. There was no significant difference within species between the two sites for depth of first lateral root, zone of most intense lateral roots and for radius of lateral spread. Depth penetration and ramification of lateral roots seem to be a function of soil and bedrock conditions. The herbaceous root biomass under A.seyal was significantly higher than the adjacent open grassland indicating the influence in increasing productivity.
Status, Ecological Characteristics and Conservation of the Pancake Tortoise, Malacochersus TorniEri in Nguni and Nuu Areas, Kenya
(Addis Ababa University, 1999-06) Kenyatta Patrick; Bekele Afework (Professor)
Pancake tortoise MaiacocherslIs tomieri is a rock crevice-dwelling terrestrial testunid inhabiting rock outcrops and kopjes discontinuously distributed throughout the semi-arid and arid savannas (Somali-Masai floristic zone) of Kenya and Tanzania. Their distribution overlaps with that of Precambrian rocks of the basement complex system. The capture-mark-recapture technique used showed that the species population size in Nguni and Nuu areas is low and declining. Crevice rich rock outcrops with wellvegetated substrates are specifically preferred. Pancake tortoises are thus patchily and discontinuously distributed within their overall range. The species is very specialized in its microhabitat requirements with regard to crevice configuration in which individuals, pairs and occasionally large assemblages reside. The orientation of inhabited rock crevices varies from horizontal to vertical. Suitable crevices that provide protection from predators, overheating and desiccation are limited in number and they may regulate population size. The species pair bonding is seasonal and restricted to breeding season. There was no significant difference (P > 0.05) in mean body weight and straight-line carapace length of males and females. Sexual dimorphism is not well marked. There was a highly significant positive linear correlation (r = 0.964) between straight-line carapace length and body weight. Outside crevice activity is very limited and only some hatchlings were found basking on rock surfaces during the wet season. During the dry season all specimens were within their crevices presumably aestivating. Movement in Pancake tortoises is very limited and centered on their rock crevices as the core areas. Males are more wide ranging than females. Females are relatively sedentary. Age structure of Pancake tortoise shows that adults dominate the population with very few young signifying a declining population. Considerable variation in adult color patterns was observed. The use of growth rings in estimation of age was found to be less reliable as age increases. Habitat alteration by humans in the form of shifting cultivation was identified as the major threat to Pancake tortoise population. Isolation of suitable habitats coupled with limited dispersal abilities of the species and low recruitment rates make , recovery of depleted populations unlikely. In situ conservation through establishment of publicly and/or privately owned nature reserves is recommended over that of tortoise farms. Tortoise farms may provide incentive to manage and conserve the species, although it may in turn encourage illegal off-take.
A Study on the Ecology and Management of the Dess’a Forest in the North Eastern Escarpment of Ethiopia
(Addis Ababa University, 2000-05) Hadera Gebremedhin; Bekele Tamrat (PhD)
This study aims to investigate the potentials and limitations of involving local communities in biodiversity conservation and to propose appropriate development strategies for harnessing such potentials in the Dess'a Forest, Eastern Tigray, North Eastern escarpment of Ethiopia. The Dessa Forest has a high degree of species diversity and endemism that is threatened by increasing human pressure. Conceptually, the research was based on the appreciation of the existence of varying value systems of the local communities in relation to the forest resources. The study further examine the regeneration, and forest structure to obtain information on forest status and to see factors governing the ecology of the forest. Data on the vegetation structure were collected from 59 randomly selected sample plots located at 50 meters altitudinal intervals, ranging from 1500 to 2850 meters above sea level. In the sample plots of the study area 82 species belonging to 33 families were identified. Relative density, Relative frequency, Relative basal area and importance value Index were calculated for each species which showed the overall forest situation. The Importance Value Index (lVI) was analyzed along altitudinal gradient of which five dominant species were identified. These dominant species were Olea europaea, Juniperus procera, Rhus nata/ensis, May tenus arbutifolia and Tarconanthus camphoratus. It was found that in most cases Olea europaea SU~\ m qusp!dfll9 wlVl )he highest , contributor to the relative basal area of the forest area. The general configuration of all species was found to have high density at lower Diameter at Breast Height (Dbh) classes and low density at higher Dbh classes. Shrub and less quality woody species were dominant in the smaller Dbh classes. Horizontal distribution of the species revealed that the number of species increase with the increase in altitude.
The Relative Importance of Three Cabbage Aphid Species (Brevlcqryne Brassicae, Upaphis Erysimi ; Myzus Perslcae) and their Parasitoid Complex in Kenya
(Addis Ababa Universty, 2000-05) Gacil, Peter; Loehr, Bernhard (PhD)
Studies on the relative importance of the three known species of cabbage aphids (8revicory/le brass;cae (Unneaus), Myzus persicae (Sulz) and Upaphis arysim/ (Kaltenbach» and their parasitoid complex in Kenya were carried out. The studies involved farmers' rlelds' surveys and intet"llews and also field experiments conducted at the Jorno Kenyatta University of AgricultLKe and technology (JKUAT) Research and Producti041 Department land and in a farmer's field at Umuru. Gloria Fl hybrid was sown at JKUAT while Copenhagen Market variety was sown at Umuru. The field experiments W&fe conducted In a Completely Randomized Block Design (CRBD) involving three treatmants and a control, with three replicates each. The trealments comprised of applications of: - lambda-Cyhalothrin (Karate; Bacillus /huringiensis Berliner (8t.) var. Kurstaki toxin (Dipel 2x) that selectively kills Diamondback moth (DBM); A combination or the two pesticides (Karate and Bt.) and UnlIeated controls. Parameters included; relative ablXldance of the three species of aphids; their corresponding damage to cabbage; the number of mummies per sample; pereent parasitism and the proportions of the primary- and hyper-parasitoids hatched. The parasiloid complex was constructed from the identified paras ito ids. The results showed aphid counts to be higher in !'1M karate-treated plots than in the karata-treated ones. More hyperparesitoids notably Alloxys/a sp and Pachyneuron sp. than the only primary parasiloid (Diaeraliella rapaa) emerged from non karale-treated plots. This might suggest that karate might have the advantage of repelling hyperparasitolds or inhibiting their emergence. Yield showed some negative correlation with ephid infestations. A combined treatment gave the best ov9(all yield at both sites .
A Taxonomic Study of Blepharis Edulis (Forssk.) Pers. Complex (Acanthaceae)
(Addis Ababa University, 2000-06) Malombe, Ttambo; Kelbessa, Ensermu (PhD)
The species Blepharis edldis (Forssk.) Pel's. has for long been mistaken with B. linaria~folia Pers. and B. ciliaris (L) B. L. Burt or B. boranensis Vol/esen (ined.) and most of the collections identified indiscriminately. While revising the genus, attempt by Vol/esen to separate the species, though with considerable observed morphological variation o.fspecimens, wasfitlile and recommended an in./i"aspecific study based on morphology. This study, ther~fore, employs phenetic techniques on gross morphology, both mature and seedlings characters in conjunction with palynological evidence to disentangle B. edulis complex and related taxa. Cluster analysis segregatedfour groups, which were filrther verified by Principal Component Analysis, Discriminant Analysis and Non-Parametric Analysis. Importantly, vegetative and .floral characters discontinuously or pal"fially separated the accrued cluster groups. These results were fitrther supported by palynology. Subsequently, these taxa were described as B. boranensis Vol/esen (ined.), B. edulis val'. edulis Pers., B. edulis val'. glabra Malombe val'. nov. and B. edulis val'. isabellae Malombe val'. nov. The species B. boranensis, a part./i"om clear separation in the ordination space, it is mOJphological/y discrete from all the other affiliated groups. B. edulis val'. edulis is distinguished discontinuously from B. edlliis val'. isabel/ae and partially from B. edulis val'. glabra byfeatures of cotyledon colour, number and arrangement o.fleafmarginal spines. More so, the three varieties lack a wide geographical variation.
A Study on the Agro-Biodiversity with Special Emphasis on the Relationship Between Distance from Homestead and Crop Diversity on -Farm in Fontanina, Southwelo
(Addis Ababa Universty, 2000-06) Deribe Shewaye; Asfaw Zemede (PhD)
The distribution of crops with distance from the homestead was studied in 324 peasant faIms in Fontanina village (South Welo). Edaphic, climatic and socio-cultural factors play impOliant roles in the distribution of crop species. Farmers categorized their farms into three main classes and each class is located at different distance from the farm house- hold residence, and contains crops of different value. The homegardens are characterized by pere1l1lial plants composed of const11lction and fiuit trees. The nearby farms and main crop fields are fields of annual crops. The nearby farms are characterized by Zea mays L. and other crops planted for immediate use in preharvest periods. The main fields are dominated by Sorghum bie%r (L.) Moench and Eragrostis tef (Zucc.) Trotter. Multivariate statistical analysis of presence I absence data of species in a sample of 65 stands (farms) shows two distinct groups of falms. The fields of annual crops are categorized together and the homegardens formed a separate group. The variation among the homegardens is also detected. Clustering of 50 stands from annual crop fields based on quantitative data of 22 species resulted in three clusters (crop community types) and two plots. Estimation of the frequency of sorghum intraspecific diversity in 123 fields indicated that the frequency of sorghum landraces decreased due to shOliage of rainfall, while that of fast maturing, introduced varieties, of sorghum increased. The discussion undertaken with the interviewed farmers revealed that traditional farmers have accumulated knowledge by which they classify their fanns and crops, distribute crops in their fields and maintain or preserve landrace diversity. This knowledge can fonn the basis for scientific research activities in different branches of conservation and development. For example, it is vital to include farmers' knowledge in the efforts of strengthening the scientific basis of iI/situ conservation of crop genetic resources and in upbringing sustainable agricultural systems.
A Floristic Analysis and Ethnobotanical Study of the Semi-wetland of Cheffa Area, South Welo, Ethiopia
(Addis Ababa University, 2000-06) Tamene Bayafers; Bekele Tamrat (PhD); Kelebesa Ensermu (PhD)
A floristic and ethnoboatnical study was carried out in Chetta plain, South Welo, between 20 November 1999 and 30 February 2000. A total of 74 quadrat were established in semiwetland and relict forest Islands. Cover-abundance values were taken for 115 plant species. From each quadrat one after the other, soil samples were taken at 0-20 cm depth and analyzed for pH, organic carbon and cation exchange capacity. Soil analysis result was computed in one way ANOVA to compare communities in relation with their environment. A significant difference on organic carbon and moisture content was obtained. Vegetation data was classified using computer program named Syn -Tax, multivariate data analysis, Version 5.02 Podani (1994) .Hierarchical clustering, average linkage classificatory technique and the following plant communities .were obtained: Bolhriochloa insculpla - Heleropogon'conlortu.~ Type, Cynodon dacfylon-Xanlhium slrumarium Type, Echinochloa colona-Panicum coloralum Type, Panicum coloralum-Ludwigia slo/onifera Type, Trifolium rueppellianum-/solepis coslala Type, Cyperus alopecuroides-Echinochloa pyramidalis Type, Typha domingensisSchoenopleclus marilimus Type, Isolepis coslala-Schoenopleclus marilimus Type, Cyperus digilalus Type, Lanlana camara-Cordia africana Type. Ethnobotanical information of very important wild plants was obtained from local key informants, mainly based on semi-structured interviews. A total of 206 plant species distributed in 148 genera and 66 families were documented. Of these 54 species are noncultivated food plants, 83 medicinal, 38 forage, 39 cleal',Sing, laundry, tooth brush, fumigation, fragrance and other miscellaneous uses have been recorded. Edible plant parts, eaten fresh, raw, cooked or in combinations, include leaf (4 species), fruit (36), seed (6), flower (2), nectar (1), twig (1), stem (3), bark (2), resin (2), sap (1), above ground part (2), rhizo- me (1) and tuber (1). Depending on food scarcity, non-cultivated food plants were recognized and categorized as snack, seasonal, emergency and famine foods. The Chetta people utilize 79 and 31 medicinal plants for his and ethnoveterinary use respectively. Habit of medicinal plants includes shrubs (38 species), herbs (21), trees (13) and climbers (11). The most frequently used plant parts are leaves (33 species). Remedies are usually prepared by pounding, crushing and squeezing juice (79.69%). The two major routes of administrations are oral (53.60%) and dermal (20.72%). Medicinal plants are used to treat more than 48 human and 20 livestock ailments. Forage and other miscellaneous uses of plants were documented. The wetland is mainly used as a dry season grazing area. Relict forest islands are ritual, belief, religious and traditionalcommunity based in silu conservation sites . . ,. These ,traditional conservation activities and indigenous knowledge of, the people should be strengthened. Traditional community based in situ conservation shoutd be complemented with ex situ conser,ation activities.
Biodiversity Management in Oaaddegoyo (Traditional Home Gardens) by Kaficho People of Bongaarea (Southwestern Ethiopia) : An Ethnobotanic Approach
(Addis Ababa University, 2000-06) Woldeyes, Feleke; Demissew, Prof. Sebsebe
The study was conducted in three villages around 80nga (Southwest Ethiopia) to investigate the role of the local people in managing biological diversity through agricultural activities. The Kafichos, the indigenous people of the study area, are settled farmers who practice traditional home gardening. Their enset based home garden, which consists of a complex mixture of annual and perennial plants, is locally called Oaaddegoyo; and provides them with almost every thing required for subsistence. Data on vegetation (species record, cover-abundance, number of individuals, and plant specimens), and soil samples were collected from sample plots. Ethnobatanic information was gathered by conducting open ended discussions with key informants, owners of home gardens and other family members. The collected plant specimens were identified in the Niational Herbaruim (ETH). The vegetation data was analysed using the computer program SYNTAX and five clusters were recognixed: Ensete·Xanthosoma community, Ensete·Coffea community, Ensete·Brassica community. Ensete·Xanthosoma·Saccharum community and Ensete·Xanthosoma·Nicotiana community. The clusters were compared for the mean values of the soil chemical factors using the ANOVA test. A total of 170 plant species were recorded from the 21 Oaaddegoyo (home gardens) of which 47% were found to be protected or tolerated. Although a decrease in total number of plant species per village with an increase in altitude was observed, the ANOVA (Analysis of Variance) test result indicated no sighificance difference among the three villages in the number of species per garden. The Daaddegoyo whose framework is made by Ensete ventricosum is strongly linked to the other two land·use systems: Kubbo ('managed forest") and Guudo (Inlact forest). It is a stable agroecosystem that harbours a Significant biodiversity. and this has resulted from innovative processes by local farmers over generations. Therefore, the Oaaddegoyo is an in·situ repository of crop germplasm and deserves protection.
An Ecological Study of the Pattern pf Plant Species Diversity Around Lake Manyara, Northern Tanzania.
(Addis Ababa University, 2001-06) Ntalwila Janemary; Bekele Tamrat (PhD)
The plant species diversity and plant communities around Lake Manyara have been described. Soil samples collected from each plot were analysed for soil pH, electric conductivity, cation exchange capacity, organic matter, sodium, calcium, phosphorus, magnesium, total Nitrogen, Soil texture (sand, silt, clay) and Trampling effect. Results obtained show that 84 species representing 40 families were recorded. Classification results using SYNTAX revealed seven plant communities. These include Sporoboboills spicatlls-Cyperus lael'igatlls community type, Cynodon dactyloll-Sporoboills spicatlls community type, Hyphae/1e petersialla-Digitaria l'eillfilla community type, Sporoboills COIlSilllilis community type, Acacia tortilis community type, Hypoestes fOJ'sskalei-Clallsena allisata community type, and Trichilia ellletica- Tabemaemollfalla pachysipholl community type. The distributions of plant community types in relation to the environmental variables have been analyzed. Organic matter, clay content, silt content, soil pH cation exchange capacity, available phosphorus, electrical conductivity and trampling effect are the most important environmental factor that determines community distribution in lake Manyara area. Species diversity and evenness are high in plant community type V (Acacia torfilis community type) and community type VI (Hypoestes forsskalei-Clallsella allisata community type) while plant community type I (Sporoboills spicatlls-Cyperus lael'igatlls) show less species diversity. Vegetation cover and species diversity increased with distance from the lake. Recommendations towards the conservation of species in lake Manyara area are given.
Sjructural, Floristic Composition and Diversity of Vegetation Communities in Mikumi National Park, Tanzania
(Addis Ababa Universty, 2001-06) Mogha, Neema; Woldu, Zeribun (Professor)
Structural and floristic study was calTied out in Mikumi National Park, Tanzania with the objectives of detennine the stlUctural composition of the vegetation communities found in the area; compiling the checklist of plants species found in the area and determination of abundance of vegetation communities in the study area. Data were collected by systematic sampling design, where quadrats were established along transect lines. Nested plot design was used to sample plants of different sizes. The main quadrat for tree and sapling was 25 m x 20 m and within the main quadrat the 5 m x 2 m was used to collect data on shrubs and seedlings. Within a 5 m x 2 m another 0.5 m x 2 m subplot was set for collection of data on herbs and grasses. One hundred seventy four (174) plant species were encountered. Woody species density calculated was 350.67 stem ha-1 and total basal area 17. 76m2ha-. The most abundant tree species recorded in the area were Dalbergia lIIelalloxyloll (23.07%), Acacia lIigrescells (8.42), LOllchocmplis capassa (7.80%), Brachystegia boehlllii (6.72%), combrellllll zeyheri (5.75%), Margaritaria discoidea (4.59%) and Acacia sieberialla (4.18%). The hierarchical cluster analysis using averagelinkage strategy provided six distinct plant communities. I. Flueggea virosa-Pallicllm maximulll-Acacia sieberialla community type 2. Hygrophila auriculata-Sporobolus pyramidalis community type 3. LOllchocmpus capassa-Cassia abbreviata community type 4. Acacia sieberialla-Hyparrhellia mfa community type 5. Acacia IligrescensDalbergia melalloxyloll community type and community type 6. Bracllystegia boehmiiBrachystegia spicifol71lis-Margaritaria disco idea community types. The following tree species; Dalbergia lIlelalloxyloll, Pericopsis allgolellsis Plerocmplls allgolellsis, Brachyslergia spiciformis and Brachyslergia boehmii which are mostly used for carvings, music instlUments, buildings materials and firewood were found highly poached at the edge of the park. The vegetation in this study area were most disturbed by environmental ,animals and human factors which include fire, browsing, grazing, poaching, soil, and water table effects. From this observation, local community pmiicipation on conservation of these valuable tree species is encouraged for near by villages which include,Mikumi town, Doma, Mkata, Kilombero and Kisaki. Futhermore, detailed integrated floristic studies of the area, targeting the unknown ecological area of Malundwe forest which is not covered in this study is recommended

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