PhD (Forest Management), Associate Professor
Seed science and technology, with particular emphasis on forest trees, is my major research interest. I am also equally interested in regeneration/restoration of tropical dry forests. With regard to seed science and technology, I have been working on the development of new, robust and pervasive techniques for upgrading seed lot performance, such as Near Infrared Spectroscopy (NIRS), seed priming and dormancy alleviation in seeds of various forest trees of temperate and tropical origins. Results from my research on the application of NIRS have demonstrated the immense potential of the technology for detecting empty, internally insect-infested and vigorous seeds; thereby replacing the current seed testing methods, such as X-ray and chemical analyses. Putative seed origins and seed parents can also be identified quickly using NIRS, which enables monitoring of seed lot mix up and deployment by genotype. Developing optimal seed priming and dormancy alleviation methods are other areas of my research interest so as to increase the speed and uniformity of germination in nurseries as well as increasing the success of seedling establishment and growth under stressful environmental conditions. Combining these methods and scaling-up to large scale commercial operation so as to enable precision sowing in forest plantation is being pursued.

Concerning tropical dry forests regeneration/restoration, the focus has been on understanding biotic and abiotic factors influencing the regeneration processes in different tropical regions – South America (Nicaragua, Costa Rica, Ecuador), Africa (Burkina Faso, Ethiopia), Asia (Nepal, Laos, Indonesia, China and Iran). Such background information is very vital to design appropriate restoration measures.

On-going research
1. Towards precision sowing in plantation forests in China (Sida)
2. Linking restoration of tropical forests with climate change mitigation (EU-FONASO)
3. The role of pioneer species in recovering tropical forests: understanding the process of natural secondary succession to adapt restoration practices (EU-FONASO)
4. Effects of fire and herb ivory disturbance on the transitional forest vegetation in the Paramo, Ecuador (FORMAS)

Teaching
Organize and teach the following under-graduate and post-graduate course
Forest reproduction and seed handling, 7.5 credits, C-level forest science program
Tropical forest reproduction, 7.5 credits, level C, forest science program
Tropical Forest restoration, 6 credits, PhD-level
Forest Restoration in theory and practice, PhD-level
How to writing and publish scientific papers, 3 credits, PhD-level

Selected peer-reviewed publications
1. Negash Mamo, Diriba Nigusie, Mulualem Tigabu, Demel Teketay, Miftah Fekadu. 2011. Longevity of Juniperus procera seed lots under different storage conditions: implications for ex situ conservation in seed banks. Journal of Forestry Research  22(3): 453−459
2. Sivakumar, V., Gurudevsingh, B., Anandalakshmi, R., Warrier, R.R., Sekaran, S., Mulualem Tigabu, P.C. Odén. 2011. Culling phenotypically inferior trees in seed production area enhances seed and seedling quality of Acacia auriculiformis. Journal of Forestry Research 22(1), 21-26.
3. Pengfei Wu, Xiangqing Ma, Mulualem Tigabu, Chen Wang, Aiqin Liu, Per Christer Odén. 2011. Root morphological plasticity and biomass production of two Chinese fir clones with high phosphorus efficiency under low phosphorus stress. Canadian Journal of Forest Research 41(2), 228-234. 
4. Guillermo Castro-Marín, Mulualem Tigabu, Benigno González-Rivas, Per Christer Odén. 2011. Germination requirements and seedling establishment of four dry forest species from Nicaragua. Tropical Ecology, 52(1), 1-11.
5. Catherine Ky-Dembele, Mulualem Tigabu, Jules Bayala, Patrice Savadogo, Issaka Joseph Boussim, Per Christer Odén. 2010. Clonal propagation of Detarium microcarpum from root cuttings. Silva Fennica 44(5), 775-786.
6. Sovu, Patrice Savadogo, Mulualem Tigabu, Per Christer Odén. 2010. Direct seeding of four native tree species for forest restoration on ex-pasture fields in the highland plateau of Laos: seedling establishment and performance. Mountain Research and Development, 30(3), 232-243.
7. Sovu, Mulualem Tigabu, Patrice Savadogo, Per Christer Odén, Lamphoune Xayvongsa. 2010. Enrichment planting in a logged-over tropical mixed deciduous forest of Laos. Journal of Forestry Research, 21(3), 273-280. 
8. Sidzabda Djibril Dayamba, Louis Sawadogo, Mulualem Tigabu, Patrice Savadogo, Didier Zida, Daniel Tiveau and Per Christer Oden. 2010. Smoke water dilution, heat and seed germination of herbaceous species of the Sudanian savanna-woodland of West Africa. Flora, 205 (5), 291-362. doi:10.1016/j.flora.2009.12.017.
9. Fidèle Bognounou, Mulualem Tigabu, Patrice Savadogo, Adjima Thiombiano, Issaka Joseph Boussim, Per Christer Oden, Sita Guinko. 2010. Regeneration of five Combretaceae species along a latitudinal gradient in Sahelo-Sudanian zone of Burkina Faso. Annals of Forest Science, 67(3), 306.  DOI: 10.1051/forest/2009119
10. Benigno González-Rivas, Mulualem Tigabu, Guillermo Castro-Marín, Per Christer Odén. 2009. Soil seed bank assembly following secondary succession on abandoned agricultural fields in Nicaragua. Journal of Forestry Research, 20(4), 349-354.
11. Sovu, Mulualem Tigabu, Patrice Savadogo, Per Christer Odén, Lamphoune Xayvongsa. 2009. Recovery of secondary forests on swidden cultivation fallows in Laos. Forest Ecology and Management 258(12), 2666-2675.
12. Guillermo Castro Marín, Mulualem Tigabu, Benigno González-Rivas, Per Christer Odén. 2009. A chronosequence Analysis of Forest Recovery on Abandoned Agricultural Fields in Nicaragua. Journal of Forestry Research, 20(3), 213-222.
13. Indra Prasad Sapkota, Mulualem Tigabu, Per Christer Odén. 2009. Spatial distribution, advanced regeneration and stand structure of Nepalese Sal (Shorea robusta) forests subject to disturbances of different intensities. Forest Ecology and Management, 257, 1966-1975.
14. Benigno González-Rivas, Mulualem Tigabu, Guillermo Castro-Marín, Per Christer Odén. 2009. Seed germination and seedling establishment of Neotropical dry forest species in response to temperature and light conditions. Journal of Forestry Research, 20(2), 99-104.
15. Augusto Uasuf, Mulualem Tigabu and Per Christer Odén. 2009. Soil Seed Banks and Regeneration of Neotropical Dry Deciduous and Gallery Forests in Nicaragua. Bois et Forêts des Tropiques, 63(299), 49-62.
16. Abraham Loha, Mulualem Tigabu and Anders Fries. 2009. Genetic variation among and within populations of Cordia africana in seed size and germination responses to constant temperatures. Euphytica, 165 (1), 189-196.
17. Niéyidouba Lamien, Mulualem Tigabu, Ramy Dabiré, Sita Guinko and Per Christer Odén. 2008. Insect (Salebria sp) infestation and impact on Vitellaria paradoxa C.F. Gaertn. fruit production in agroforestry parklands. Agroforestry Systems, 72(1), 15-22.
18. Mulualem Tigabu, Joakim Fjellström, Per Christer Odén and Demel Teketay. 2007. Germination of Juniperus procera seeds in response to stratification and smoke treatments, and detection of insect-damaged seeds with VIS+NIR spectroscopy. New Forests, 33(2), 155-169.
19. Negash Mamo, Mebrate Mihretu, Miftah Fekadu, Mulualem Tigabu and Demel Teketay. 2006. Variation in seed and germination characteristics among Juniperus procera populations in Ethiopia. Forest Ecology and Management, 225(1-3), 320-327.
20. V. Sivakumar, R.R. Warrier, R. Anandalakshmi, Mulualem Tigabu, P.C Odén, S.N. Vijayachandran, S.Geetha and B.G. Singh. 2006. Germination requirements and storage behavior of Myristica dactyloides Gaertn. seeds. Seed Science & Technology, 34(3), 751-755.
21. Mulualem Tigabu, Per Christer Odén and Dag Lindgren. 2005. Identification of seed sources and parents of Pinus sylvestris L. using visible–near infrared reflectance spectra and multivariate analysis. TREES, 19(4), 468-476.
22. Mulualem Tigabu and Per Christer Odén 2004a. Simultaneous detection of filled, empty and insect-infested seeds of three Larix species with single seed near infrared transmittance spectroscopy. New Forests, 27(3), 39-53.
23. Mulualem Tigabu and Per Christer Odén 2004b. Rapid and non-destructive analysis of vigor of Pinus patula seeds using single seed near infrared transmittance spectra and multivariate analysis. Seed Science & Technology, 32(2), 593-606.
24. Mulualem Tigabu, Per Christer Odén, and Tong Yun Shen. 2004. Application of near infrared spectroscopy for the detection of internal insect infestation in Picea abies seed lots. Canadian Journal of Forest Research, 34 (1), 76-84.
25. Leulseged Demelash, Mulualem Tigabu and Per Christer Odén.  2004. Evaluating the relative storability of IDS-treated and untreated Pinus patula Schiede & Deppe seeds by accelerated aging. Journal of Tropical Forest Science, 16 (2), 206-217.
26. Maria Schelin, Mulualem Tigabu, Ingalill Eriksson, Louis Sawadogo and Per Christer Odén. 2004. Predispersal seed predation in Acacia macrostachya, its impact on seed viability, and germination responses to scarification and dry heat treatments. New Forests, 27(2), 251-267.
27. Mulualem Tigabu and Per Christer Odén 2003a. Discrimination of viable and empty seeds of Pinus patula Schiede & Deppe with near infrared spectroscopy. New Forests, 25(3), 163-176.
28. Mulualem Tigabu and Per Christer Odén 2003b. Near Infrared Spectroscopy-based method for separation of sound and insect-damaged Seeds of Albizia schimperiana, a Multipurpose Legume. Seed Science & Technology, 31(2), 317-328.
29. Ali Soltani, Torbjörn Lestander, Mulualem Tigabu and Per Christer Odén 2003. Prediction of viability of oriental beechnuts, Fagus orientalis, using near infrared spectroscopy and partial least squares regression. Journal of Near Infrared spectroscopy, 11(5), 357-364.
30. Mulualem Tigabu and Per Christer Odén. 2002. Multivariate classification of sound and insect-infested seeds of a tropical multipurpose tree, Cordia africana, with near infrared reflectance spectroscopy. Journal of Near Infrared Spectroscopy, 10(1), 45-51.

Conferences and Institutional reports
1. Mulualem Tigabu and Per Christer Odén. 2001. Characterization of tropical forest tree seeds using NIR spectroscopy: Insect infestation. NIR and Calibration in Academic and Industrial Use, 5th NIR NORD Midwinter meeting, 13-14 February 2001, Hällnäs, Sweden (Oral presentation).
2. Mulualem Tigabu and Per Christer Odén. 2002. Near Infrared Spectroscopy as a potential technique to upgrade seed lot quality of conifers. Proc. of IUFRO Research Group for Seed Physiology and Technology. Sep. 11-15, 2002, Chania, Crete, Greece, pp. 185-192 (Oral presentation).
3. Indra Prasad Sapkota, Mulualem Tigabu and Per Christer Odén. 2006. Tree diversity and Regeneration of lowland Bhabar and Hill Sal forests in Central Region of Nepal. “Plant Dynamics: from Molecules to Ecosystems”, 3rd European Plant Science Organization Conference, 28 May – 1 June 2006, Hungary. (Poster)
4. Mulualem Tigabu. 2007. NIR Spectroscopy as a tool for seed orchard management. Seed Orchard Conference. 26-28 September 2007, Umeå, Sweden. (Poster)
5. Didier Zida, Patrice Savadogo, Daniel Tiveau, Djibril Dayamba, Louis Sawadogo, Mulualem Tigabu, Per Christer Odén. 2008. Disturbance in Sudanian Savanna Woodlands and Ecological Responses under Climate Change: The Contribution of Long-term Ecological Research on Fire, Grazing and Selective Cutting. Proc. of IUFRO Forest Adaptation 2008. August 25-28, 2008, Umeå, sweden, p. 277. (Oral presentation)