Pattern of functional diversity along the elevation gradient in the dry evergreen Afromontane forest of Hararghe Highland, Southeast Ethiopia

  • M. Teshome Oda Bultum University
  • Z. Asfaw Wondo Genet College of Forestry and Natural Resources
  • M. Mohammed Oda Bultum University
Keywords: environmental filters; community weight mean; mixed effect model; wood density; specific leaf area.


Understanding plant species distribution patterns along environmental gradients is fundamental to managing ecosystems, particularly when habitats are fragmented due to intensive human land use pressure. The variation pattern of functional diversity of plant communities along the elevation gradient in the Dindin dry evergreen Afromontane forest was tested. Fifty four plots of 20 x 20 m (400 m2) were established at 200 m intervals starting 2,300–2,900 m a. s. l. and woody species composition, and environmental variables were recorded. Nine functional diversity indices based on functional distances were employed to esimate functional diversity. The mixed effect model was used to determine the effect of elevation, aspect and slope on functional diversity indices. The results showed that functional diversity in communities varied greatly; functional diversity revealed a decrease with increasing elevation and a‘‘humped’’ pattern, with peak diversity appearing at middle elevation. Functional diversity was significantly correlated with elevation, slope, and aspect. Functional diversity was significantly correlated with species richness and evenness. Environmental filtering was important to the functional diversity pattern; the nine indices were all successful in the analysis of functional diversity in the plant community with different effectiveness, and modified functional attribute diversity, plot-based functional diversity, community based functional diversity, functional richness, and community weight mean of woody density performed better than the other four indices in this study.


Abiem, I., Arellano, G., Kenfack, D., & Chapman, H. (2020). Afromontane forest diversity and the role of grassland-forest transition in tree species distribution. Diversity, 12, 30.

Arellano, G., Cala, V., Fuentes, A., Cayola, L., Jørgensen, P. M., & Macía, M. J. (2016). A standard protocol for woody plant inventories and soil characterisation using temporary 0.1-ha plots in tropical forests. Journal of Tropical Forest Science, 28(4), 508–516.

Austrheim, G. (2002). Plant diversity patterns in semi-natural grasslands along an elevational gradient in southern Norway. Plant Ecology, 161(2), 193–205.

Aynekulu, E., Gebrehiwot, K., Boehmer, H. J., Aerts, R., Moonen, P., Vagen, T. G., Denich, M., & Mekuria, W. (2012). Altitudinal variation and conservation prio­rities of vegetation along the Great Rift Valley escarpment, northern Ethiopia. Biodiversity Conservation, 21, 2691–2707.

Bates, D, Mächler, M, Bolker, B., & Walker, S. (2015). Fitting linear mixed-effects models using lme4. Journal of Statistical Software, 67(1), 1–48.

Bu, W., Zang, R., & Ding, Y. (2014). Functional diversity increases with species diversity along successional gradient in a secondary tropical lowland rainforest. Tropical Ecology, 55(3), 393–401.

Burgess, N. D., Balmford, A., Cordeiro, N. J., Fjeldsa, J., Küper, W., Rahbek, C., Sanderson, E. W., Scharlemann, J. P., Sommer, J. H., & Williams, P. H. (2007). Correlations among species distributions, human density and human infrastructure across the high biodiversity tropical mountains of Africa. Jornal of Biological Conservation, 134, 164–177.

Caddotte, M. W., Carscadden, K., & Mirotchnick, N. (2011). Beyond species: Functional diversity and the maintenance of ecological processes and services: Review. Journal of Applied Ecology, 48, 1079–1087.

Casanoves, F., Pla, L., Di Rienzo, J. A., & Díaz, S. (2011). FDiversity: A software package for the integrated analysis of functional diversity. Methods in Ecology and Evolution, 2, 233–237.

Cavanaugh, K. C., Gosnell, J. S., Davis, S. L., Ahumada, J., Boundja, P., Clark, D. B., & Andelman, S. (2014). Carbon storage in tropical forests correlates with taxonomic diversity and functional dominance on a global scale. Global Ecology and Biogeography, 23, 563–573.

Chave, J., Coomes, D., Jansen, S., Lewis, S. L., Swenson, N. G., & Zanne, A. E. (2009). Towards a worldwide wood economics spectrum. Ecology Letters, 12, 351–366.

Chun, J. H., & Lee, C. B. (2017). Disentangling the local-scale drivers of taxonomic, phylogenetic and functional diversity in woody plant assemblages along elevational gradients in South Korea. PLoS One, 12(10), e0185763.

Conti, G., & Díaz, S. (2013). Plant functional diversity and carbon storage-an empirical test in semi-arid forest ecosystems. Journal of Ecology, 101, 18–28.

Cordeiro, N. J., Burgess, N. D., Dovie, D. B., Kaplin, B. A., Plumptre, A. J., & Marrs, R. (2007). Conservation in areas of high population density in sub-Saharan Africa. Biological Conservation, 134(2), 155–163.

Costa, S. D., Gerschlauer, F., & Pabst, H.,Kuhnel, A., Huwe, B., Kiese, R., Kuzyakov, Y., & Kleyer, M. (2017). Community-weighted means and functional dispersion of plant functional traits along environmental gradients on Mount Kilimanjaro. Journal of Vegitation Science, 28, 684–695.

de Bello, F., Carmona, C. P., Mason, N. W. H., Sebastia, M. T., & Leps, J. (2012). Which trait dissimilarity for functional diversity: Trait means or trait overlap? Journal of Vegetation Science, 24(5), 807–819.

de Bello, F., Lavorel, S., Lavergne, S., Albert, C. H., Boulangeat, I., Mazel, F., & Thuiller, W. (2013). Hierarchical effects of environmental filters on the functional structure of plant communities: A case study in the French Alps. Ecography, 36, 393–402.

Elias, E. (2016). Soils of the Ethiopian Highlands: Geomormology and proporties. CASCAPE Project, ALTERA, Wageningen University and Research Centre (Wageningen UR), The Netherlands.

Elliott, G. P., & Kipfmueller, K. F. (2010). Multi-scale influences of slope aspect and spatial pattern on ecotonal dynamics at upper treeline in the Southern Rocky Mountains, U.S.A. Arctic, Antarctic, and Alpine Research, 42(1), 45–56.

FAO (2005). New_LocClim: local climate estimator (version 1.10). Environment and natural resources, working paper number 20 (CD-ROM). FAO, Rome.

Friis, I. B., Demissew, S., & Breugel, P. (2010). Atlas of the potential vegetation of Ethiopia. Det Kongelige Danske Videnskabernes Selskab.

Gazol, A., Moiseev, P., & Camarero, J. J. (2017). Changes in plant taxonomic and functional diversity patterns following treeline advances in the South Urals. Plant Ecology and Diversity, 10, 283–292.

Grieser, J., Gommes, R., & Bernardi, M. (2006). New LocClim-the local climate estimator of FAO. Geophysical Research Abstracts, 8, 2.

Kattge, J., Diaz, S., & Lavore, S. et al. (2011). TRY – a global database of plant traits. Global Change Biology, 17, 2905–2935.

Kebede, M., Yirdaw, E., Luukkanen, O., & Lemenih, M. (2013). Plant community analysis and effect of environmental factors on the diversity of woody species in the moist Afromontane forest of Wondo Genet, South Central Ethiopia. Biodiversity Research and Conservation, 29, 63–80.

Klimeš, L. (2003). Life-forms and clonality of vascular plants along an altitudinal gra­dient in E Ladakh (NW Himalayas). Basic and Applied Ecology, 4, 317–328.

Kluge, J., & Kessler, M. (2011). Phylogenetic diversity, trait diversity and niches: Species assembly of ferns along a tropical elevational gradient. Journal of Biogeography, 38, 394–405.

Kraft, N. J. B., Valencia, R., & Ackerly, D. D. (2008). Functional traits and niche-ba­sed tree community assembly in an Amazonian forest. Science, 322, 580–582.

Kuznetsova, A., Brockhoff, P. B., & Christensen, R. H. B. (2017). lmerTest Package: Tests in linear mixed effects models. Journal of Statistical Software, 82(13), 1–26.

Linder, H. P. (2014). The evolution of African plant diversity. Frontier Ecology and Evolution, 2, 38.

Magurran, A. E. (2004). Measuring biological diversity. Blackwell Science Ltd., Australia.

Maire, V., Wright, I. J., Prentice, I. C., Batjes, N. H., Bhaskar, R., van Bodegom, P. M., Cornwell, W. K., Ellsworth, D., Niinemets, U., Ordonez, A., Reich, P. B., & Santiago, L. S. (2015). Global effects of soil and climate on leaf photosynthetic traits and rates. Global Ecology and Biogeography, 24(6), 706–717.

Mason, N. W. H., Mouillot, D., Lee, W. G., Wilson, J. B., & Setälä, H. (2005). Func­tional richness, functional evenness and functional divergence: The primary components of functional diversity. Oikos, 111(1), 112–118.

Mason, N. W., & de Bello, F. (2013). Functional diversity: A tool for answering challenging ecological questions. Journal of Vegetation Science, 24, 777–780.

Mouchet, M. A., Villéger, S., Mason, N. W. H., & Mouillot, D. (2010). Functional diversity measures: An overview of their redundancy and their ability to discriminate community assembly rules. Functional Ecology, 24, 867–876.

Muller-Landau, H. C. (2004). Interspecific and intersite variation in wood specific gravity of tropical trees. Biotropica, 36, 20–32.

Papanikolaou, A. D., Fyllas, N. M., Mazaris, A. D., Dimitrakopoulos, P. G., Kallima­nis, A. S., & Pantis, J. D. (2011). Grazing effects on plant functional group diversity in Mediterranean shrublands. Biodiversity Conservation, 20, 2831–2843.

Pavoine, S., & Bonsall, M. B. (2011). Measuring biodiversity to explain community assembly: A unified approach. Biological Reviews, 86, 792–812.

Petchey, O. L., & Gaston, K. J. (2006). Functional diversity: Back to basics and looking forward. Ecological Letter, 9, 741–758.

Pla, L., Casanoves, F., & Rienzo, J. D. (2012). Quantifying functional biodiversity. Springer, Dordrecht, Heidelberg, London, New York.

Podani, J., & Schmera, D. (2006). On dendrogram-based measures of functional diversity. Oikos, 115, 179–185.

Ricotta, C., & Moretti, M. (2008). Quantifying functional diversity with graph-theo­retical measures: Advantages and pitfalls. Community Ecololgy, 9(1), 11–16.

Rutten, G., Ensslin, A., Hemp, A., & Fischer, M. (2015). Vertical and horizontal vegetation structure across natural and modified habitat types at Mount Kilimanjaro. PLoS One, 10(9), e0138822.

Schmera, D., Eros, T., & Podani, J. (2009). A measure for assessing functional diver­sity in ecological communities. Aquatic Ecology, 43, 157–167.

Schröter, D., Cramer, W., Leemans, R., Prentice, I. C., Araújo, M. B., Arnell, N. W., Bondeau, A., Bugmann, H., Carter, T. R., & Gracia, C. A. (2005). Ecosystem service supply and vulnerability to global change in Europe. Science, 310, 1333–1337.

Solefack, M. C. M., Fedoung, E. F., & Temgoua, L. F. (2018). Factors determining floristic composition and functional diversity of plant communities of Mount Oku forests, Cameroon. Journal of Asia-Pacific Biodiversity, 11, 284–293.

Spasojevic, M. J., Copeland, S., & Suding, K. N. (2014). Using functional diversity patterns to explore metacommunity dynamics: A framework for understanding local and regional influences on community structure. Ecography, 37, 939–949.

Spracklen, D., & Righelato, R. (2014). Tropical montane forests are a larger than ex­pected global carbon store. Biogeosciences, 11, 2741–2754.

Swenson, N. G., & Enquist, B. J. (2007). Ecological and evolutionary determinants of a key plant functional trait: Wood wensity and its community wide variation across latitude and elevation. American Journal of Botany, 94(3), 451–459.

Swenson, N. G., Anglada-Cordero, P., & Barone, J. A. (2011). Deterministic tro­pical tree community turnover: Evidence from patterns of functional beta diversity along an elevational gradient. Proceedings of the Royal Society B, 278, 877–884.

Tefera, M., Chernet, T., & Haro, W. (1996). Explanation of the geological map of Ethiopia (1:2000,000 scale). Second edition. Ethiopian Institute of Geological Survey, Addis Ababa.

Tesfaye, G., Teketay, D., Fetene, M., & Beck, E. (2010). Regeneration of seven indigenous tree species in a dry afromontane forest, Southern Ethiopia. Flora, 205, 135–143.

Thakur, D., & Chawla, A. (2019). Functional diversity along elevational gradients in the high altitude vegetation of the Western Himalaya. Biodiversity and Conservation, 8–9, 1–20.

Villéger, S., Mason, N. W. H., & Mouillot, D. (2008). New multidimensional functional diversity indices for a multifaceted framework in functional ecology. Eco­logy, 89, 2290–2301.

Wana, D. (2009). Plant species and functional diversity along altitudinal gradients, Southwest Ethiopian Highlands. Bayreuth.

Zanne, A. E., Lopez-Gonzalez, G., Coomes, D. A., Ilic, J., Jansen, S., Lewis, S. L., Miller, R. B., Swenson, N. G., Wiemann, M. C., & Chave, J. (2009). Global wood density database. Dryad.

Zhang, J. T., Bai, X., & Shao, D. (2017). Functional diversity and its attribute factors in the Yunmeng Mountain National Forest Park in Beijing, China. Cerne, 23(1), 75–84.

Zhang, J. T., Li, M., & Nie, E. (2014). Pattern of functional diversity along an altitudinal gradient in the Baihua Mountain Reserve of Beijing, China. Brasilian Journal of Botany, 37, 37–45.

Zhang, J.-T., Zhang, B., Li, M., & Zhu, X. (2013). Functional diversity and conservation of Phellodendron amurense communities in the Dongling Mountain of Beijing, China. Botanical Sciences, 91(4), 505–513.

Zhang, Q. P., Wang, J., Gu, H. L., Zhang, Z.-G., & Wang, Q. (2018). Effects of continuous slope gradient on the dominance characteristics of plant functional groups and plant diversity in alpine meadows. Sustainability, 10, 4805.

Zhou, Y., Chen, S., Hu, G., Mwachala, G., Yan, X., & Wang, Q. (2018). Species richness and phylogenetic diversity of seed plants across vegetation zones of Mount Kenya, East Africa. Ecology and Evolution, 8, 8930–8939.