Diversity, abundance, and structure of tree communities in the Uluguru forests in the Morogoro region, Tanzania

Abstract

Uluguru forests are globally recognized as important biodiversity hotspots, but anthropogenic pressure threatens their value. This study examined species diversity, abundance, and structure of trees in the Uluguru forests. All trees of diameter at breast height (DBH) ≥ 10 cm were inventoried in seven forests ranging from 3 to 995 ha in area. A total of 900 stems, 101 species and 34 families were inventoried. Fabaceae was the most speciose family. Ehretia amoena Klotzsch was the most abundant species with relative abundance of 9.22 %. The forests differed significantly in species richness (26–93 species ha⁻¹), tree density (85–390 stems ha⁻¹), basal area (3–24 m² ha⁻¹) and Shannon-Wiener diversity (2.50–4.02). Forest area was significantly and positively correlated with species richness (r = 0.92) and species diversity (r = 0.95). Tree density showed significant positive correlation with species richness (r = 0.80) and basal area (r = 0.85). Milawilila and Nemele forests had highest floristic similarity (0.55) followed by Kimboza and Kilengwe (0.54) while the rest had similarity coefficients of less than 0.50. Despite legislative protection, many forests remain at risk and therefore the possibility to conserve highly valuable tree species via enhanced protection or cultivation must be considered.

Keywords

Eastern arc / Biodiversity / Disturbance / Hotspots / Similarity

References

[1] Addo-Fordjour P, Obeng S, Anning K, Add MG. Floristic composition, structure and natural regeneration in a moist-semi deciduous forest following anthropogenic disturbances and plant invasion. Int J Biodivers Conserv, 2009, 1: 021-037.

[2] Ahrends A (2005) Patterns of degradation in lowland coastal forests in coastal region Tanzania M.Sc. Dissertation, Germany: Ernst-Moritz-Arndt University of Greifswald, p 150

[3] Burgess ND, Clarke GP. The coastal forests of Eastern Africa. 2000, Cambridge: IUCN, 443.

[4] Burgess ND, Muir C (1994) Coastal forests of Eastern Africa: Biodiversity and Conservation. In: Proceedings of a workshop held at the University of Dar es Salaam, August 9–11, 1993. London (UK): Society for Environmental Exploration/Royal society for the protection of birds, United Kingdom, p 112

[5] Burgess N, Dorggart N, Lovett JC. The Uluguru Mountains of eastern Tanzania: the effects of forest loss on biodiversity. Oryx, 2002, 36: 140-152.

[6] Burgess ND, Butynski TM, Cordeiro NJ, Doggart NH, Fjeldsa J, Howell KM, Kilahama FB, Loader SP, Lovett JC, Mbilinyi B, Menegon M, Moyer DC, Nashanda E, Perkin A, Rovero F, Stanley WT, Stuart SN. The biological importance of the Eastern African Mountains of Tanzania and Kenya. Biol Conserv, 2007, 134: 209-231.

[7] Echeverria C, Newton AC, Lara A, Benayas JMR, Coomes DA. Impacts of forest fragmentation on species composition and forest structure in the temperate landscape of southern Chile. Glob Ecol Biogeogr, 2007, 16: 426-439.

[8] Gentry A. Changes in plant community diversity and floristic composition on environmental and geographical gradients. Ann Mo Botan Gard, 1988, 75: 1-34.

[9] Gotelli NJ, Colwell RK. Magurran AE, McGill BJ. Estimating species richness. Biological diversity: frontiers and measurement and assessment. 2011, New York: Oxford University Press, 39 54

[10] Hill JL, Curran PJ. Species composition in fragmented forests: conservation implications of changing forest area. Appl Geogr, 2001, 21: 157-174.

[11] Ingram JC, Dawson TP, Whittaker RJ. Mapping tropical forest structure in southern Madagascar using remote sensing and artificial neural networks. Remote Sens Environ, 2005, 94: 491-507.

[12] Kacholi DS (2013) Effects of habitat fragmentation on biodiversity of Uluguru Mountain forests in Morogoro region, Tanzania. Ph.D Dissertation, Georg-August University, Goettingen, Cuvillier Verlag, Germany, p 150

[13] Kent M, Coker P. Vegetation description and analysis. 1992, London: CRC Belhaven Press, 363.

[14] Madoffe S, Hertel GD, Paul R, Connell BO, Killenga R. Monitoring health of selected Eastern Arc Forests in Tanzania. Afr J Ecol, 2006, 44: 171-177.

[15] Magurran AN. Measuring biological diversity. 2004, Melden: A Blackwell Publishing Company

[16] Malimbwi RE, Shemweta DTK, Zahabu E, Kingazi SP, Katani JZ, Silayo DA (2005) Forest inventory for Mvomero district, Morogoro Tanzania: Forconsult Report

[17] Mittermeier RA, Myers N, Thompsen JB, da Fonesca GAB, Olivieri S. Global biodiversity hotspots and major tropical wilderness areas. Conserv Biol, 1998, 12: 516-520.

[18] Modest RB, Maganga SLS, Hassan SN, Mariki SB, Muganda M. Population structure and extraction of three commercial trees in Nguru ya Ndege forest reserve, Morogoro-Tanzania. Ethiop J Environ Studies Manag, 2010, 3: 41-48.

[19] Mwavu EN (2007) Human impact, plant communities, diversity and regeneration in Budongo forest reserve, North-Western Uganda. Ph.D Thesis, University of Witwatersrand, South Africa, p 197

[20] Myers N, Mittermeier RA, Mittermeier CG, da Fonseca GAB, Kent J. Biodiversity hotspots for conservation priorities. Nature, 2000, 403: 853-858.

[21] Newmark WD. Forest area, fragmentation, and loss in the Eastern Arc Mountains: implications for the conservation of biological diversity. J East Afr Natural Hist, 1998, 87: 29-36.

[22] Richards PW. The tropical rain forests. 1952, Cambridge: Cambridge University Press, 450.

[23] Rwamugira SP (2008) Impact of mining on forest ecosystems and adjacent communities of Eastern Arc Mountains. A case study of Ruvu catchment forest reserve. M.Sc. Dissertation, Sokoine University of Agriculture, Morogoro, Tanzania, p 134

[24] Seaby RM, Henderson PA. Species diversity and richness 4. 2006, Lymington: Pisces Conservation Ltd, 123.

[25] Seaby RM, Henderson PA. Community analysis package 4. 2006, Lymington: Pisces Conservation Ltd, 123.

[26] Stattersfield AJ, Crosby MJ, Long AJ, Wege DC (1998) Endemic bird areas of the world: priorities for biodiversity conservation. BirdLife conservation series No 7, BirdLife International, Cambridge, p 846

[27] Temu RPC, Andrew SM. Endemism of plants in the Uluguru Mountains, Morogoro, Tanzania. For Ecol Manag, 2008, 255: 2858-2869.

[28] Top N, Mizoue N, Ito S, Kai S, Nakao T, Ty S. Effects of population density on tree structure and species richness and diversity of trees in Kampong Thom Province, Cambodia. Biodivers Conserv, 2009, 18: 717-738.

[29] Tuomisto H, Ruokolainen K. Environmental heterogeneity and the diversity of pteridophytes and Melastomataceae in Western Amazonia. Biol Skr, 2005, 55: 37-56.

[30] Valencia R, Balslev H, Pay YM. High tree alpha-diversity in Amazonian Ecuador. Biodivers Conserv, 1994, 3: 21-28.

[31] Mrema JP (2006) Conservation of Brachylaena huillensis O. Hoffm (Asteraceae) in Dindili Forest Reserve Morogoro. MSc Thesis, Addis Ababa University, Ethiopia, p 86

[32] Whitmore TC (1989) Southeast Asia tropical forests. In: H Lieth and MJH. Werger (eds), Ecosystems of the World. Tropical rainforests ecosystems, Elsevier, Amsterdam, 195–218

[33] Zegeye H, Teketay D, Kelbessa E. Diversity, regeneration status and socio-economic importance of vegetation in the islands of Lake Ziway, South-Central Ethiopia. Flora, 2006, 201: 483-498.