Academic literature on the topic 'Trees – Ethiopia – Growth'

Acacia seyal is one of the multipurpose parkland agroforestry tree species in eastern and southern Africa. It is a common on-farm tree in the Rift Valley of Ethiopia, but information is limited on its effect on soil properties and sorghum growth and yield. The study was conducted to evaluate its effect on selected soil properties and sorghum growth and yield in Guba Lafto district of northern Ethiopia. Six isolated and closely comparable Acacia seyal trees growing on sorghum farms were purposely selected, and plots were marked under the canopy of trees with three radial distances (0–2 m, 2–4 m, and 4–6 m) and one outside of the tree canopy (10 m away from any tree). Soil samples from each distance zone were taken between 0–20 cm and 20–40 cm soil depths for soil property analysis. Four quadrates with 1 m2 at each distance zone in four directions were laid for sorghum growth and yield attribute valuation. The results showed that only total nitrogen (TN) was significantly higher ( P < 0.05 ) at the subsoil layer under the canopy compared to an open area, while other selected soil parameters were not affected by the tree species. Sorghum biomass yield ( P = 0.006 ) and grain yield ( P = 0.025 ) were significantly lower under the canopy of the trees than in the open area. Generally, Acacia seyal had little effect in improving soil properties and showed a negative effect on sorghum yield and growth. Further research on its effect under wide area coverage of parkland system should be performed to bring a radical shift on the intercropping farming system.

Acacia seyal is one of the multipurpose parkland agroforestry tree species in eastern and southern Africa. It is a common on-farm tree in the Rift Valley of Ethiopia, but information is limited on its effect on soil properties and sorghum growth and yield. The study was conducted to evaluate its effect on selected soil properties and sorghum growth and yield in Guba Lafto district of northern Ethiopia. Six isolated and closely comparable Acacia seyal trees growing on sorghum farms were purposely selected, and plots were marked under the canopy of trees with three radial distances (0–2 m, 2–4 m, and 4–6 m) and one outside of the tree canopy (10 m away from any tree). Soil samples from each distance zone were taken between 0–20 cm and 20–40 cm soil depths for soil property analysis. Four quadrates with 1 m2 at each distance zone in four directions were laid for sorghum growth and yield attribute valuation. The results showed that only total nitrogen (TN) was significantly higher ( P < 0.05 ) at the subsoil layer under the canopy compared to an open area, while other selected soil parameters were not affected by the tree species. Sorghum biomass yield ( P = 0.006 ) and grain yield ( P = 0.025 ) were significantly lower under the canopy of the trees than in the open area. Generally, Acacia seyal had little effect in improving soil properties and showed a negative effect on sorghum yield and growth. Further research on its effect under wide area coverage of parkland system should be performed to bring a radical shift on the intercropping farming system.

The important ecosystem services of the high altitude tropical afro-alpine Erica arborea L. forests are under increasing environmental and human pressure. The Erica treeline ecotone in the Ethiopian highlands forms a temperature-responsive vegetation boundary that is potentially affected by climate change. The cambium of 10 Erica arborea trees in Lib Amba Mountain and Ferrah Amba Mountain in the North Ethiopian highlands was marked in 2012, and corresponding tree disks were sampled after 498 days. Microphotographs of these cambial marks confirmed the formation of annual growth rings (0.76 ± 0.24 mm) with higher vessel density in earlywood and radially flattened fibers in the last layers of the latewood. In-continuum measurements of vessel size and density on microphotographs indicated the formation of inter-annual density fluctuations (IADFs) related to early rainfall in March-May. The same stem disks and 40 increment cores were used for detailed tree-ring analyses—a tree-ring chronology with 18 trees spanning from 1966 to 2014 could be derived. A significant (p < 0.1) positive correlation with minimum temperature in the growing season (August) and a negative correlation with minimum temperature in the spring season (March) were indicated as the most important climate factors regulating tree growth of Erica trees in the afro-alpine forest. The existence of annual tree rings and the proven potential for chronology building encourages further tree-ring analyses of Erica arborea in the afro-alpine tropical highlands in order to link it with climate variability and climate change.

Poor agricultural productivity has led to food shortages for smallholder farmers in Ethiopia. Agroforestry may improve food security by increasing soil fertility, crop production, and livelihoods. Agroforestry simulation models can be useful for predicting the effects of tree management on crop growth when designing modifications to these systems. The Agricultural Production Systems sIMulator (APSIM) agroforestry tree-proxy model was used to simulate the response of maize yield to N fertilizer applications and tree pruning practices in the parkland agroforestry system in the Central Rift Valley, Ethiopia. The model was parameterized and tested using data collected from an experiment conducted under trees and in crop-only plots during the 2015 and 2016 growing seasons. The treatments contained three levels of tree pruning (100% pruned, 50% pruned, and unpruned) as the main plots, and N fertilizers were applied to maize at two rates (9 or 78 kg N ha−1) as sub-plots. Maize yield predictions across two years in response to tree pruning and N applications under tree canopies were satisfactorily simulated (NSE = 0.72, RSR = 0.51, R2 = 0.8). Virtual experiments for different rates of N, pruning levels, sowing dates, and cultivars suggest that maize yield could be improved by applying fertilizers (particularly on crop-only plots) and by at least 50% pruning of trees. Optimal maize yield can be obtained at a higher rate of fertilization under trees than away from them due to better water relations, and there is scope for improving the sowing date and cultivar. Across a 34-year range of recent climate, small increases in yields due to optimum N-fertilizing and pruning were probably limited by nutrient limitations other than N, but the highest yields were consistently in the 2–4 m zone under trees. These virtual experiments helped to form hypotheses regarding fertilizers, pruning, and the effects of trees on soil that warrant further field evaluation.

Abstract: Coffee production with shade trees is important to improve growth and quality of coffee, sustain and restore agroecology and nature based agroforestry practices. The trial was conducted at Mechara Agricultural Research Center (on station) in DaroLebu District of West Hararghe Zone, Oromia, Ethiopia. The study was intended to evaluate the influence of coffee shade trees on growth performance, yield and quality of coffee (Coffea arabica L.) under the canopy of Erytherina absinica, Cordia africana and Acacia sieberiana. The design was Randomized complete block design with three replications. The outcome had been observed a significant value at (p<0.05) probability level, non- significant value at (p>0.05) probability level and highly significance value at (p<0.01) probability level between treatments. Statistically significant and non- significant differences were observed between shaded and unshaded as well as within shaded effect based on the given parameters. Integration of shade in coffee farming system created creditable promising in producing organic coffee. Shade utility could be confirmed as to be ecologically sustainable, economically viable and socially acceptable practice. In so doing that, the effect of Erytherina absinica, Cordia africana shade trees illustrated the highest mean value in most parameters, while the least one is under the Acacia sieberiana shade tree. So the effect of Erytherina absinica mean observed with the highest value on total bearing plants 60%, thousand seed weight 59% and yield in Quintal per hectare 47.4% greater than the least treatments’ mean value based on growth parameters. On the other hand, the effect of Erytherina absinica mean observed with the higher value on aromatic intensity 46.4%, aromatic quality 87.2%, acidity 92.4%, body 93.5%, flavors 88.6% and overall quality 88.6% than the least treatments’ mean value, and also the effect of un-shade mean observed with the higher value on astringency 68.8% and bitterness 93.5% than the least treatments’ mean value based on organoleptic parameters. The highest mean value of Erytherina absinica observed on total bearing plants 12.1, thousand seed weight 130 gram and yield in Quintal per hectare 5.7 based on growth parameters, while based on organoleptic parameters, the highest mean value observed under the effect of Erytherina absinica shade tree on aromatic intensity 4.5, aromatic quality 3.9, acidity 7.9, body 7.7, flavors 7.9 and overall quality 7.9. Therefore, based on the most treatments’ parameters, to be the best shade tree was Erythrina abyssinica followed by cordia africana. Commonly, the dynamic indication of the treatment’s means difference were indicated between shaded and unshaded rather than within shaded means variation at most treatments’ parameters.

Dissertation (PhD (Bosb))--University of Stellenbosch, 2003.
ENGLISH ABSTRACT: This study was conducted to evaluate and compare the water and nutrient relations of three indigenous deciduous tree species, viz., Cordia africana Lam., Croton macrostachyus Del., Millettia ferruginea (Hochst.) Baker and two widely planted eucalypts, viz., Eucalyptus camaldulensis Dehnh and Eucalyptus globulus Labill from Ethiopia. The study was organized as glasshouse and field observations in Ethiopia. Owing to the lack of baseline studies on the water and nutrient relations of the deciduous tree species, the glasshouse experiments involved a wide range of water and nutrient applications. Seedlings were grown with the supply of various levels of water and nutrients during which gas exchange, water potential, relative water content, tissue nutrient content and biomass production were measured. The field observations were limited to the study of surface root distribution and leaf nutrient composition of mature trees and their effects on soil nutrient pool. The observations were made on isolated trees and mixed or pure stands of trees in Badessa area, Eastern Ethiopia. The field site was selected because of the availability of the study species and suitability of the trees for the study. In the glasshouse, increased water deficit significantly reduced predawn leaf water potential, relative water content, stomatal conductance, photosynthetic rate, whole plant water use efficiency, plant height, diameter, leaf area and biomass production. Both of the eucalypts did not grow faster than the deciduous species under well-watered conditions unlike under water stress conditions. C. macrostachyus and C. africana had higher transpiration rates and tissue nutrient accumulations than the other species. They also demonstrated higher biomass allocation to roots than all the other species to support the intensive water and nutrient uptake rate. Due to the ability to re-orient its leaves to avoid direct solar irradiance, M. ferruginea maintained higher tissue water potential and relative water content than all the other species under water stress regimes. The impact of imposed drought was quick and more damaging to the eucalypts compared to the deciduous tree species indicating that the eucalypts may not survive extreme drought conditions unlike the deciduous species that drop their leaves and may remain dormant for weeks. The current study gave new experimental proof that E. globulus was more vulnerable to drought than E. camaldulensis. Soil N stress resulted in an overall reduction of tissue N concentration, N:P ratio, photosynthetic rate, stomatal conductance and photosynthetic water use efficiency in all the species studied. Pants with high foliar nitrogen concentration had higher photosynthetic capacities indicating that N plays a key role in photosynthesis and growth of all the studied species. The current study showed that for all the tree species, more attention has to be given to soil N than to P as soil P had minor effects on the photosynthetic activities of plants of all species compared to N.The investigation on tissue nutrient composition confirmed that N:P ratio could be used to detect Plimitation in plants. However, N:P ratio could not distinguish between N-limitation and combined limitations of N and P. The study of isolated C. africana and C. macrostachyus trees on soils in Badessa, Eastern Ethiopia indicated improved soil N, P and K under tree canopies whereas no effects were observed on the other soil nutrients studied. Similar to glasshouse conditions, C. macrostachyus and C. africana produced extensive surface roots, interfering with crops grown in association. Due to their high nutrient cycling potential the net effect on soil was positive. Comparison of E. camaldulensis woodlot and a mixed stand composed of deciduous species indicated that the fine root biomass in the surface soil under E. camaldulensis was about three times that under the mixed stand. The fine root biomass of E. camaldulensis inside the stand and 10 meters away from the stand were comparable in the surface soils showing the presence of root competition with adjacent crops. Therefore, planting of E. camaldulensis in association or adjacent to croplands should be avoided. Nutrient and carbon pool of soil inside the mixed stand was generally higher than that of E. camaldulensis indicating that trees of the mixed stand recycled more nutrients to the soil.
AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die verskille tussen water- en voedingstofverhoudings van drie inheemse blaarwisselemde boomsoorte te vergelyk, viz., Cordia africana Lam., Croton macrostachyus Del., Millettia ferruginea (Hochst.) Baker en twee bekende eucalyptus spesies, viz., Eucalyptus camaldulensis Dehnh en Eucalyptus globulus Labil van Etiopië. Die studie het bestaan uit kweekhuis- en veldobservasies in Etiopië. As gevolg van beperkte navorsing ten opsigte van water- en voedingstofverhoudings in bladwisselende boomsoorte, het die kweekhuis-eksperimente bestaan uit 'n wye verkeidenheid water- en voedingstoftoetse. Saailinge is gegroei deur verskillende vlakke van water- en voedingstowwe by te voeg. Gaswisseling, waterpotensiaal, relatiewe hoeveelheid water, hoeveelheid voedingstowwe en produksie van biomassa is gemeet. Die veldobservasies was beperk tot oppervlak-wortelverspreiding en blaarvoedingstof hoeveelhede van volwasse bome, sowel as die effek op grondvoedingstowwe. Observasies was beperk tot geïsoleerde, gemengde en een spesie opstande, in die Badessa area, Oos Etiopië. Die studiearea was gekies op grond van die voorkoms van die gekose boomsoorte, sowel as die toepaslikheid van die bome vir die studie. In die kweekhuis is gevind dat die verhoogte watertekort die pre-sonop blaarwaterpotensiaal, relatiewe hoeveelheid water, stomatiese geleiding, fotosintetiese tempo, heelplant water-gebruikseffektiwiteit, plant hoogte, diameter, blaararea en biomassa produksie beduidend verminder het. Nie een van die eucalyptus spesies het vinniger as die bladwisselende spesies onder voldoende hidrasie gegroei nie. Dit was egter nie die geval onder die waterbeperkte toestande nie. C. macrostachyus en C. africana het ‘n hoër transpirasie tempo sowel as weefselvoedingstof waardes gehad as die ander spesies. Hierdie boomsoorte se wortelbiomassa was ook meer as die ander spesies, om vir die tempo van water- en voedingstofopname te akkomodeer. As gevolg van die vermoë om blare te kan oriënteer om direkte sonlig te vookom, het M. ferruginea ‘n hoër water-weefselpotensiaal en relatiewe waterinname gehad in vergelyking met die ander boomsoorte in beperkte water toestande. Die impak van gëinisieerde droogte het vinnig voorgekom en het meer skade aan die eucalyptus aangerig in vergelyking met die bladwisselende boomsoorte. Dit dui aan dat die eucalyptus-spesie nie ekstreme droogte kan oorleef nie, waar bladwisselende spesies hul blare laat afval en vir weke aan een dormant kan bly. Hierdie studie gee eksperimentele bewyse dat E. globulus minder bestand is teen droogte as E. camaldulensis. Beperkte N in die grond het veroorsaak dat daar ‘n algemene vermindering van weefsel Nkonsentrasie, N:P ratio, fotosintetiese tempo, stomatiese geleiding en fotosintetiese watergebruiks effektiwiteit in al die bestudeerde spesies was. Plante wat oor hoër blaar-stikstofkonsentrasiesbeskik, het hoër fotosintetiese kapasiteite wat aandui dat N ‘n belangrike rol in fotosintese en die groei van al die bestudeerde spesies speel. Die oorhoofse bevindings van die studie was, dat daar meer aandag gegee moet word aan grond-N as P omdat grond-P net ‘n kleiner rol speel in die fotosintetiese aktiwiteite van plante van al die spesies in vergelyking met N. Die ondersoek na weefselvoedingstof hoeveelhede het bewys dat die N:P ratio gebruik kan word om P-tekorte in plante aan te dui. Die N:P ratio kan egter nie die verskil in N-tekorte en gekombineerde tekorte van N en P aandui nie. Die studie van die geïsoleerde C. africana en C. macrostachyus bome op grondtipes in Badessa, Oos Etiopië het verbeterde grond-N, P en K onder kroondak gebiede getoon, daar was egter geen verskille in die ander grondvoedingstowwe wat bestudeer is nie. In toestande gelykstaande aan die van die kweekhuis, het C. macrostachyus en C. africana meer oppervlaksswortels ontwikkel. Die toename aan oppervlakswortels het ingedring op gewasse wat in assosiasie gegroei is, dit het egter ‘n positiewe effek op die grond gehad as gevolg van die hoë voedingstof-siklus-potensiaal. Die E. camaldulensis opstand is gevergelyk met ‘n gemengde opstand van bladwisselende spesies waar daar gevind is dat die fynwortel biomassa in die oppervlak grond onder die E. camaldulensis ongeveer drie keer soveel was as die van onder die gemengde opstand. Kompetisie met aangrensende gewasse is aangeui deurdat die fynwortel biomassa van E. camaldulensis binne die opstand en 10 meter weg van die opstand vergelykbaar was in die oppervlakgronde. Dit dui dus aan dat die plant van E. camaldulensis in assosiasie of aangrensend aan gewasse vermy moet word. Die teenwoordigheid van voedingstowwe en koolstof in die grond van die gemengde opstand was oor die algemeen hoër as die van die E. camaldulensis. Dit is ‘n aanduiding dat die bome van die gemengde opstand meer voedingstowwe aan die grond verskaf.