Planning tree species diversification in Kenya based on differences in tree species composition between farms. II. Analysis of tree niches.
Article Received: 13 May 2004 Accepted: 30 September 2005 Abstract
Concerns exist about the limited diversity of tree species in agricultural landscapes. Complete tree inventories were carried out on 201 farms from four villages in western Kenya to establish whether significant differences in tree species composition existed between farms, and if so their magnitude and implications for new introductions and plantings. Novel types of ordination using the Hellinger ecological distance and polynomial Redundancy Analysis indicated wide heterogeneity between farms with respect to tree species composition of five niches, including homestead, cropland, fallow, woodlot, and external boundary (
p ≤ 0.05). Multiple regression analysis confirmed the ordination results using the abundance of dominant species as the response variable. The relationship between location and species composition differed with those of two previous surveys. Methodological differences in sampling intensity, locations and time of sampling between these surveys could have caused the difference. The maps of spatial distribution of compositional types provided in the previous surveys were not confirmed, whereas villages were found to contain several farms with a species composition that was not typical of their village. Meaningful results about the species composition of a landscape should include several farms per village and use a sampling grid finer than 5×5 km 2. Keyword Diversification Domestication Hellinger distance Landscape Ordination Redundancy analysis References Asner, G.P., Vitousek, P.M. 2005 Remote analysis of biological invasion and biogeochemical change Proc. Natl. Acad. Sci. 102 4383 4386 PubMed CrossRef Google Scholar Atta-Krah, K., Kindt, R., Skilton, J.N., Amaral, W. 2004 Managing biological and genetic diversity in tropical agroforestry Agroforest. Syst. 61 183 194 CrossRef Google Scholar Beentje, H.J. 1994Kenya Trees, Shrubs and Lianas National Museums of Kenya Nairobi 722 Google Scholar Bradley, P.N. 1991Woodfuel, Women and Woodlots Macmillan Education Ltd London and Basingstoke 338 Google Scholar Bradley, P.N., Chavangi, N., Gelder, A. 1985 Development research and energy planning in Kenya Ambio 14 228 236 Google Scholar Di Falco, S., Perrings, C. 2003 Crop genetic diversity, productivity and stability of agroecosystems. A theoretical and empirical investigation Scot. J. Polit. Econ. 50 207 216 CrossRef Google Scholar Dorward, A., Poole, N., Morrison, J., Kydd, J., Urey, I. 2003 Markets, institutions and technology: missing links in livelihoods analysis Dev. Policy Rev. 21 319 332 CrossRef Google Scholar Garrity, D.P. 2004 Agroforestry and the achievement of the Millennium Development Goals Agroforest. Syst. 61 5 17 CrossRef Google Scholar Harmand, J.M., Donfack, P., Njiti, C.F. 2003 Tree-root systems and herbaceous species-characteristics under tree species introduced into grazing lands in subhumid Cameroon Agroforest. Syst. 59 131 140 CrossRef Google Scholar Harvey, C.A., Haber, W.A. 1999 Remnant trees and the conservation of biodiversity in Costa Rican pastures Agroforest. Syst. 44 37 68 CrossRef Google Scholar
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