Mwangi James Kinyanjui^*, Chris A. Shisanya, Ondimu Ken Nyabuti, Wargute Patrick Waqo, Merceline Awuor Ojwala

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Department of Resource Surveys and Remote Sensing, Nairobi, Kenya.
Department of Geography, Kenyatta University, Nairobi, Kenya.
Department of Geography, Egerton University, Njoro, Kenya.
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Abstract: Species relative dominance by basal area was assessed along an agro ecological gradient in the Mau Forest Complex (MFC). Trees were recorded per species and diameter at breast height (D1.3) for size class D1.3 ≥ 10 cm in 60 quarter hectare plots distributed in 7 agro ecological zones (AEZ) namely LH1, LH2, LH3, LH4, UH0, UH1 and UH2. Basal area per species was used to calculate species relative dominance i.e. the proportion of basal area by a species to the total basal area of the AEZ. Species associations were analysed as the group of highly ranked species in each AEZ. Sorensons similarity index was used to calculate the proportion of similar species among AEZ. Analysis of variance compared basal area among AEZ and Tukey’s multiple comparison test used to identify specific AEZ with differences. Tabernaemontana stapfiana (Britten) was ranked first in LH1, UH1 and UH0 with relative dominance values of 22.66%, 22.89% and 30.73% respectively. It was however not recorded in any other AEZs. Dombeya goetzenii (K. Schum) occurred in 6 of the 7 AEZs but had moderate dominance values in each of the 6 AEZs. The sum of dominance values per species in all AEZs indicated no species mono-dominance and different species dominated at different AEZs. Co-dominance resulted in species associations like Tabernaemontana-Allophylus-Eke-bergia-Albizia in LH1, Juniperus-Dombeya-Casearia-Prunus in LH2, Acokanthera-Cussonia-Olea-Teclea in LH4 and Tabernaemontana-Syzygium-Podocarpus-Neoboutonia in UH1. Species richness was highest in UH1 and had the highest similarity indices with those of other AEZs. The UH1 had a species similarity of 67% with LH1, 63% with LH2 and 56% with LH4. However, species in the very humid zone UH0 differed with those of the drier lower highland zones (UH0 vs LH3 and vs LH4 = 31% and 37% respectively). Basal area differed significantly among AEZ ( = 3.76) showing that they differ in stocking levels. Tukeys test showed that high potential zones of LH1, LH2, UH0, UH1 did not differ and similarly the lower potential zones; LH3 and LH4. The results show that the variation of species and forest stocking in the MFC is strongly influenced by AEZ and proposes future biomass mapping to be done along AEZ.

Keywords: Species Dominance, Basal Area, Agro Ecological Zoning

Cite this paper: Kinyanjui, M. , Shisanya, C. , Nyabuti, O. , Waqo, W. and Ojwala, M. (2014) Assessing Tree Species Dominance along an Agro Ecological Gradient in the Mau Forest Complex, Kenya. Open Journal of Ecology, 4, 662-670. doi: 10.4236/oje.2014.411056.

References

[1]   Lohbeck, M., Poorter, L., Martínez-Ramos, M., Rodriguez-Velázquez, J., van Breugel, M. and Bongers, F. (2014) Changing Drivers of Species Dominance during Tropical Forest Succession. Functional Ecology, 28, 1052-1058.
http://dx.doi.org/10.1111/1365-2435.12240

[2]   Priya, D., Jean, P.P. and Egbert, G.L. (2005) Changes in Rain Forest Tree Diversity, Dominance and Rarity across a Seasonality Gradient in the Western Ghats. Indian Journal of Biogeography, 32, 493-501.
http://dx.doi.org/10.1111/j.1365-2699.2005.01165.x

[3]   Chase, J.M. and Leibold, M.A. (2003) Ecological Niches: Linking Classical and Contemporary Approaches. University of Chicago Press, Chicago.
http://dx.doi.org/10.7208/chicago/ 9780226101811.001.0001

[4]   Burak, K.P., Roy, S.W., Matthias, M.B., Craig, M. and Pauline, F.G. (2011) Response of Plant Species and Life Form Diversity to Variable Fire Histories and Biomass in the Jarrah Forest of South-West Australia. Austral Ecology, 37, 330-338.

[5]   Magurran, A.E. (1988) Ecological Diversity and Its Measurement. Chapman and Hall, London.
http://dx.doi.org/10.1007/978-94-015-7358-0

[6]   Tania, U.H., Paul, M.D. and Carlos, A.P. (2007) Regional Scale Variation in Forest Structure and Biomass in the Yucatan Peninsula, Mexico: Effects of Forest Disturbance. Forest Ecology and Management, 247, 80-90.
http://dx.doi.org/10.1016/j.foreco.2007.04.015

[7]   Bohlman, S. and Pacala, S. (2012) A Forest Structure Model that Determines Crown Layers and Partitions Growth and Mortality Rates for Landscape-Scale Applications of Tropical Forests. Journal of Ecology, 100, 508-518.
http://dx.doi.org/10.1111/j.1365-2745.2011.01935.x

[8]   Philip, M.S. (1994) Measuring Trees and Forests. 2nd Edition, Aberdeen University Press, Aberdeen.

[9]   Leigh, D., Puyravaud, D., Terborgh, S. and Wright, S.J., et al. (2004) Why Do Some Tropical Forests Have So Many Species of Trees? Biotropica, 36, 447-473.

[10]   Nigel, C.A. Pitman, J.W.T., Miles, R.S., Percy, N.V., David, A.N., Carlos, E.C., Walter, A.P. and Milton, A. (2001) Dominance and Distribution of Tree Species in Upper Amazonian Terra Firme Forests. Ecology, 82, 2101-2117.
http://dx.doi.org/10.1890/0012-9658(2001)082[2101:DADOTS]2.0.CO;2

[11]   Schroeder, T.A., Hamann, A., Wang, T.L. and Coops, N.C. (2010) Occurrence and Dominance of Six Pacific Northwest Conifer Species. Journal of Vegetation Science, 21, 586-596.
http://dx.doi.org/10.1111/j.1654-1103.2009.01163.x

[12]   Beentje, H.J. (1994) Kenya Trees, Shrubs and Lianas. National Museums of Kenya, Nairobi.

[13]   Kinyanjui, J.M. (2009) The Effect of Human Encroachment on Forest Cover, Structure and Composition in the Western Blocks of the Mau Forest Complex. PhD Thesis, Egerton University, Njoro.

[14]   Kinyanjui, J.M. (2011) NDVI Based Vegetation Monitoring in the Mau Forest Complex, Kenya. African Journal of Ecology, 49, 165-174.
http://dx.doi.org/10.1111/j.1365-2028.2010.01251.x

[15]   Kinyanjui, J.M., Karachi, M. and Nyabuti, K.N. (2013) Natural Regeneration and Ecological Recovery in Mau Forest Complex, Kenya. Open Journal of Ecology, 3, 417-422.
http://dx.doi.org/10.4236/ oje.2013.36047

[16]   Kinyanjui, M.J., Latva-Kayra, P., Bhuwneshwar, P.S., Kariuki, P., Gichu, A. and Wamichwe, K. (2014) An Inventory of the Above Ground Biomass in the Mau Forest Ecosystem, Kenya. Open Journal of Ecology, 4, 619-627.
http://dx.doi.org/10.4236/oje.2014.410052

[17]   Prance, G.T. (1984) The Vegetation of Africa. By F. White. Brittonia, 36, 273.
http://dx.doi.org/10.2307/2806524

[18]   Mutangah, J.G., Mwangangi, O.M. and Mwaura, P.K. (1993) Mau Forest Complex Vegetation Survey. KIFCON Report, Nairobi.

[19]   Fischer, G., Velthuizen, H., Shah, M. and Nachtergaele, F. (2002) Global Agro-Ecological Assessment for Agriculture in the 21st Century: Methodology and Results. International Institute for Applied Systems Analysis, Laxenburg.

[20]   Quiroz, R., Zorogastúa, P., Baigorria, G., Barreda, C., Valdivia, R., Cruz, M. and Reinoso, J. (2000) Toward a Dynamic Definition of Agroecological Zones Using Modern Information Technology Tools. CIP Program Report 1999- 2000.

[21]   Sombroek, W.G., Braun, H.M.H. and van der Pouw, B.J.A. (1982) Exploratory Soil Map and Agro-Climatic Zone Map of Kenya, 1980. Scale: 1:1,000,000. Exploratory Soil Survey Report No. E1. Kenya Soil Survey Ministry of Agriculture, National Agricultural Laboratories, Nairobi.

[22]   Sehgal, J., Mandal, D.K., Mandal, C. and Vadivelu, S. (1992) Agro-Ecological Regions of India. 2nd Edition, Technical Bulletin No. 24, NBSS and LUP, 130 p.

[23]   Coops, N.C., Gaulton, R. and Waring, R.H. (2011) Mapping Site Indices for Five Pacific Northwest Conifers Using a Physiologically Based Model. Applied Vegetation Science, 14, 268-276.
http://dx.doi.org/10.1111/j.1654-109X.2010.01109.x

[24]   Kinyanjui, J.M., Karachi, M. and Ondimu, K.N. (2012) Documenting the Carbon Content of the Mau Forest Complex. Journal of Environment, Natural Resources Management and Society, 1, 70-81.

[25]   Henry, M., Picard, N., Trotta, C., Manlay, R.J., Valentini, R., Bernoux, M. and Saint-André, L. (2011) Estimating Tree Biomass of Sub-Saharan African Forests: A Review of Available Allometric Equations. Silva Fennica, 45, 477-569.
http://dx.doi.org/10.14214/sf.38

[26]   Jaetzold, R., Schmidt, H., Hornet, Z.B. and Shisanya, C.A. (2007) Farm Management Handbook of Kenya. Natural Conditions and Farm Information. 2nd Edition, Vol. 11/C. Central Province, Ministry of Agriculture/GTZ, Nairobi.

[27]   Kent, M. and Coker, P. (1992) Vegetation Description and Analysis. John Wiley and Sons, New York.

[28]   Zar, J.H. (2010) Biostatistical Analysis. 5th Edition, Prentice-Hall, Englewood Cliffs, NJ, 944.

[29]   Borghesio, L., Giannetti, F., Ndang’ang’a, K. and Shimelis, A. (2004) The Present Conservation Status of Juniperus Forests in the South Ethiopian Endemic Bird Area. African Journal of Ecology, 42, 137-143.
http://dx.doi.org/10.1111/j.1365-2028.2004.00511.x

[30]   Blackett, H.L. (1994) Forest Inventory Reports for Kenya’s Indigenous Forests. KIFCON Report, Nairobi.