| East Usambara Mountains
05° 00’ S - 38°50’ E 12,916
ha sub-montane forest Region - Tanga. District - Muheza |
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Back to Main Page____________________________________________________________________________________________The East Usambara range is a steeply scared plateau with the main ridges running north to south. They cover less than 130,000 ha and are one of the smallest ranges in Tanzania. They are separated from the much larger West Usambara Mts. to the north-west by the wide valley of the Lwengera River which flows southwards to join the Pangani River. The mountains themselves are drained internally by the catchment of the Sigi River, entering the sea at Tanga, the principle town in the region. The forests became fragmented long ago. The early German colonists created coffee plantations which have been replaced by an ever expanding tea industry. Some of the better quality lowland forest has been replaced with plantations of teak Tectis grandis. The 19 main forest reserves are in the process of being reorganised into larger blocks with the inclusion of important lowland forest that has survived on public land. The establishment of the Amani Nature Forest Reserve (Hakkinen and Wambura 1992), gazetted in May 1997 to offer both better protection and public access is to be welcomed, with some reservations that core areas are large enough and access is limited.
The altitudinal range of the mountains is only 150 m to 1,506 m but being within 35 km of the coast they receive significant rainfall (typically 2,000 mm/annum) in all months and are cloaked in rich forest. While there are no endemic bird species (the Usambara Hyliota Hyliota (australis) usambarae has recently been elevated to specific status (Urban et al. 1997) but this is not yet universally recognised) endemism in other forms is high. Montane forest exists at lower altitudes in the East Usambara than any other comparable mountain block in Tanzania. To the north of the highland block there are extensive areas of Brachylaena woodland which are of some ornithological importance.
There is a rich bibliography of the natural resources of these mountains, some of the more recent works are listed at the end of this account. Among the most important are "A Synecological Study of Usambara, Tanganyika Territory, with particular reference to birds" (Moreau 1935). A useful history and summary of the area is given in Iversen (1991) which also contains an extensive bibliography.
Birds
The East Usambara have always been the most studied of the various mountain blocks in Tanzania yet they have continued to provide exciting discoveries. R.E. Moreau, one of Africa’s greatest biologists, was resident in Amani from 1928 until 1946. He employed observers to watch nests and obtain other useful information and inherited Loveridge’s experienced collector, Salimu Asumani. Despite this concentration of effort so long ago and the thousands of field days by various ornithologists between 1950 and 1990 no less than three globally threatened species (Sokoke Scops Owl, East Coast Akalat and Swynnerton’s Robin) have been discovered as residents in the East Usambara forests during the last seven years. Already a highly significant area these recent findings suggest that the East Usambara Mts. are one of the two most important sites on the African mainland for globally threatened birds.
Given the extent of human pressure and subsequent fragmentation
of these forests this century the avifauna has survived well in terms of species and it
seems likely that no modern species has yet been lost. The population size of some bird
species is undoubtedly small and can only give cause for concern. Numbers of Usambara
Eagle Owl, Sokoke Scops Owl, Long-billed Tailorbird, Dappled Mountain Robin,
Swynnerton’s Robin and Usambara Weaver are low and only just viable given the growth
of human populations and gradual attrition of the forest resource. The endemic races of
Southern Hyliota Hyliota australis usambarae and Red-headed Bluebill Spermophaga
ruficapilla cana occur at low densities in few localities. Other important species in
an East African content are such forest edge specialists as Pallid Honeyguide and Magpie
Mannikin while the local race of Golden-tailed Woodpecker Campethera (abingoni)
mombassica (which has recently returned to the status of a full species) is locally
common. The Green Ibis, another rare bird of the forest interior must be at exceptionally
low densities. The most recent assesment of the forest birds is that of Evans (1997).
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Category 1 - globally threatened species
Critical
Long-billed Tailorbird Not described until 1931 and still a little known species, its status is discussed more (Long-billed Apalis) fully on page #.
Vulnerable
Sokoke Scops Owl Discovered as late as 1965 in the Arabuko-Sokoke forest in coastal Kenya it was considered endemic to that forest until a population was found in lowland East Usambara in August 1992 (Cambridge Tanzania Rainforest Project 1994).
Usambara Eagle Owl Previously known only as a low density bird from higher altitude forest it was discovered in Kambai and Kwamgumi lowland forests in August 1992 (CTRP 1994).
Swynnerton’s Robin The finding of this species in Mtai F.R. during August 1990 (Evans et al. 199#) was a major discovery. It has since been located in other lowland forests (CTRP 1994) but appears to be a low density species at all sites.
East Coast Akalat During a 1992 expedition to the lowland forests this small thrush was the second most common species to be caught in mist nets (ref #) That it had not been discovered earlier is a clear indication that all previous fieldwork had been undertaken close to and on the approach to Amani in the south.
Dappled Mountain Robin Known from very few specimens and captures in the forests close to Amani. It would appear that it does not occur in the lower altitude forests. Its rarity in the East Usambara is cause for concern and probably relates to fragmentation of the forests.
Amani Sunbird A low density bird throughout the altitude range of the forest. This contrasts strongly with its status in the Arabuko-Sokoke forest in coastal Kenya where this species has adapted to Brachystegia woodland and is reasonably common.
Banded Sunbird Frequently seen at higher altitudes but with few records from lowland forest. It nests on horizontal branches just below the canopy of the tallest trees and will congregate at favoured feeding sites, including exotic Eucalyptus, when these are in flower.
Usambara Weaver Known from very few previous records but recently discovered on Mt. Nilo ( N. (Tanzania Mountain Weaver) Cordeiro in lit.) which suggests it has always been a higher altitude low density species that is on the edge of its range in the East Usambara.
Near-threatened
Southern-banded Snake Eagle A low density resident in lower altitude forest, hunts from a perch, often at the forest edge and is likely to be under recorded unless calling.
Fischer’s Turaco Locally common throughout the forest, perhaps less common at lower elevations. Seriously threatened by the international trade in wild caught birds.
Plain-backed Sunbird Reasonably common at lower elevations. More strictly a coastal forest species. Recently discovered in the Brachylaena woodlands to the north of the East Usambara Mts. where it may be locally common (Cordeiro 1998).
Category 2 - restricted range species
Endemic Bird Area 105 - Tanzania-Malawi mountains
Fischer’s Turaco see category 1
Sokoke Scops Owl see category 1
Usambara Eagle Owl see category 1
Swynnerton’s Robin see category 1
Sharpe’s Akalat an often common species in the higher altitude forest
Spot-throat less common here than in the Udzungwa Mts.
Dappled Mountain Robin see category 1
African Tailorbird (Red-capped F. W.) a locally common species in the higher altitude forest
Long-billed Tailorbird (Apalis) see category 1
Amani Sunbird see category 1
Banded Sunbird see category 1
Usambara Weaver (Tanzania Mountain) see category 1
Kenrick’s Starling an uncommon bird of the forest canopy at higher elevations
Endemic Bird Area 111 - Coastal forests
Fischer’s Turaco see category 1
Sokoke Scops Owl see category 1
Amani Sunbird see category 1
Category 3 - biome restricted assemblages
African Highlands # species out of a country total of 80 (#%).
East African Coast 17 species out of a country total of 29 (59%).
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Other threatened / endemic wildlife
There are many endemic and near endemic forms associated with these forests. Seven African Violets Saintpaulia spp. are endemic and have formed the base of a multi-million dollar horticultural business. 3.1% of the plants are strict endemics, 22% are near endemics (IUCN Plant Conservation Programme).
Howell (1993) lists 15 Amphibia and 13 Reptilia from the East Usambara that are endemic to Tanzania. There are 41 species of millipede, 85% of which are endemic, 45% of the molluscs (Gastropoda) are endemic and 40% of the butterflies (Kurikka pers. comm.).
There are four mammal species classified as Globally Threatened. Abbot’s Duiker, Black and Rufous Elephant Shrew, Bush-tailed Mongoose and Collared Fruit Bat. Most of the larger mammals would have been extirpated long ago but Leopard probably remain, albeit at very low densities.
Conservation issues
Human pressures on these forests have been high since the Germans first arrived and began to establish estates and farms. Severe fragmentation was enhanced by the development of commercial coffee and tea estates on the plateau and replacement of lowland forest with plantations of exotic tree species and even sisal. Fragmentation is especially threatening for forest interior species and is being documented in the East Usambara (Newmark 1991). An effort is being made to reverse the long term effects of forest fragmentation by joining nearby forests with corridors (Newmark 1993). It is still possible to achieve this without disrupting the lives of too many people and incurring unbearable compensation costs but the time is now, within a few years the opportunity will have been lost, probably forever.
During the early 1980’s much remaining forest was put at risk by uncontrolled commercial logging that targeted key commercially viable trees at the expense of everything else including the protection of riverbanks. Fortunately this policy was reversed and the Finnish Government is to be congratulated for supporting the East Usambara Catchment Forestry Project which offers a long term future for these forests and their biological diversity (Johansson and Katigula 1994).
A project under the auspices of the International Union for Conservation of Nature (IUCN) was endeavouring to bring local people into the conservation of the remaining forests (Tye 1993) but had been abandoned as unsuccessful by 1997 (Kurikka pers. comm.).
There are small scale NGO initiatives being developed in specific areas of interest such as Kambai where the Tanzania Forest Conservation Group is working with village communities.
The warm and wet conditions are well suited to plant growth as witnessed by the many fine specimens in the old arboretum at Amani Botanical Garden. Unfortunately these climatic conditions are also suitable for non-indigenous invasive species. One of these Maesopsis eminii, a native of north-western Tanzania, has caused considerable problems throughout the area (Hamilton 1989). The virtual eradication of this tree should be given serious consideration although recent research suggests that indigenous trees are regenerating well under Maesopsis and that given time they will out compete it providing disturbance to the forest soils is kept to an absolute minimum.
The commercial growing of Cardamom inside forest reserves has been a major problem that only continued monitoring by forest guards can eliminate (Hermansen et al. 1985, Rodgers and Homewood 1982).
The expansion of the tea industry and a dramatic increase in the use of inorganic fertilizers due to an increase in foreign investment creates some concerns for long term damage to the soils and water. Already there have been examples of degredation and damage to streamside habitats and valley bottoms seen as a source of cheap soil high in organic matter. Eucalyptus plantations will no doubt be expanded to feed the increase in tea production and these will cause significant damage to soil fertility and structure in the future unless they are rotated with less environmentally damaging tree species.
The lowland forest is arguably most at risk and is also globally the most important for birds. With so many defunct Sisal Estates between the East Usambara and the sea there is an opportunity to plant them with indigenous hardwoods such as Milicia excelsa that produces timber known commercially as Mvule (Iroko in West Africa). This species can be grown commercially if anyone is prepared to make the long term investment of around 40 years prior to any significant financial returns. The sandy soils are too poor to produce viable stands of exotic teak and may be given over to plantations of Eucalyptus to supply other nations with a cheap source of pulpwood. Such schemes would totally destroy the natural environment of the area and would provide little long term investment in either the nation or its people. Mvule already grows well in the area as witnessed by the large number of isolated trees that are too disfigured to remove for timber. Data from experimental plots at Mombo at the base of the West Usambara suggests a similar return to the dreaded exotic teak Tectis grandis (REF # ). Mvule grows slowly but the value of sustainably logged tropical hardwoods can only increase above and beyond dollar inflation rates. Plantation planting of Mvule would allow use of the land for agriculture during the first phase of development (7 years) and provide fuelwood during the second phase of management (a further 7 years). From year 15 natural invasion and enrichment planting of the rarer indigenous trees would create a semi-natural forest similar to that on the Rondo Plateau in southern Tanzania (IBA 48 page #). From year 40 careful commercial logging would provide valuable hardwood for established furniture factories in Tanga and other urban centres as well as a continued refuge for many of the rare and endemic life forms for which Tanzania has ultimate responsibility. Taken a stage further such plantations could expand along the entire length of the Tanga-Dar es Salaam railway providing a long term source of income to coastal villages and urban centres as well as having enormous tourist potential.
Such long term views and commitments must be taken if anyone is going to do anything about real sustainable forestry that is environmentally friendly. If donor nations had started such projects when they first arrived in Tanzania during the mid sixties vast stands of commercially viable forests would be floureshing where now onlyenviromentally dead sisal grows and furniture factories would already be beyond the planning stage.
While climatic change on a global scale is a cause for concern there have already been significant local changes in precipitation within the East Usambara range. Data from the thirties suggests far more cloud cover than exists today and a shorter dry season. Should this trend continue many plants that adapted to the previous wet conditions may be out grown by invasive species better suited to a dryer microclimate. It is difficult to quantify the benefits to global climate from planting forest but the carbon sink component is real as is the increased stability to local conditions. Protecting both local people and the water supply to Tanga from extreme weather conditions.
Recommendations
References
Cambridge Tanzania Rainforest Project. 1994. A biological and human impact survey of the lowland forests, East Usambara Mountains, Tanzania. BirdLife Study Report No. 59. BirdLife International. Cambridge. UK.
Cordeiro, N.J. 1997. Final report on a survey of the fauna and threats to the forests and Brachyaena woodlands in the East Usambara lowlands, Tanzania.
Evans, T.D. 1997. Records of birds from the forests of the East Usambara lowlands, Tanzania, August 1994-February 1995. Scopus 19: 92-108.
Hakkinen, I. and Wambura, M. 1992. A frame plan for the Amani Nature Reserve. Project technical paper 5. Forest and Bee-keeping Division & Finnish Forests and Park Service. Dar es Salaam & Vantaa.
Hamilton, A.C. and Bensted-Smith, R. (eds.). 1989. Forest Conservation in the East Usambara Mountains, Tanzania. International Union for Conservation of Nature: Gland. Switzerland.
Hermansen, J.E., Benedict, F., Corneliussen, T., Hofsten, J. and Venvik, H. 1985. Catchment forestry in Tanzania. Status and Management. - (Consultancy report for NORAD, Oslo.).
Howell, K.M. 1993. Herpetofauna of the Eastern Arc forests: in Lovett, J.C. and Wasser, S.K. Biogeography and ecology of the rain forests of eastern Africa. Cambridge University Press.
Iversen, S.T. 1991. The Usambara Mountains, NE Tanzania: History, Vegetation and Conservation. Uppsala University. Sweden.
Johansson, S.G. and Katigula, M.I.L. 1994. East Usambaras, Tanzania - A Galapagos in Africa: in KIFCON, Natural forest conservation in East Africa: Experiences, lessons and future strategies. Proceedings of a workshop, Nyeri, Kenya, May 1994. Kenya Indigenous Forest Conservation Project (KIFCON) and Forest Department. Karura. Kenya.
Moreau, R.E. 1935. A synecological study of Usambara, Tanganyika Territory, with particular reference to birds. Journal of Ecology 23: 1-43.
Newmark, W.D. 1991. Tropical Forest Fragmentation and the Local Extinction of Understory Birds in the Eastern Usambara Mountains, Tanzania. Conservation Biology Vol. 5 (1): 67-78.
Newmark, W.D. 1993. The role and design of wildlife corridors with examples from Tanzania. Ambio 22: 500-504.
Rodgers, W.A. and Homewood, K.M. 1982. Species richness and endemism in the Usambara mountain forests. Biological Journal of the Linnean Society. 18: 197-242.
Tye, A. 1993. Forest and bird conservation in the East Usambara mountains, north-east Tanzania. Proc. VIII Pan-Afr. Orn. Congr. 287-292.
Urban, E.K., Fry, C.H. and Keith,S. 1997. The Birds of Africa. Vol. V. Academic Press. London.
Further reading
Johansson, S.G. and Sandy, R. 1996. Protected areas and public lands - land use in the East Usambaras. East Usambara Catchment Forest Project. Technical paper 28. Forest and Bee-keeping Division & Finnish Forests and Park Service. Dar es Salaam & Vantaa.
Lovett, J.C. and Wasser, S.K. 1993. Biogeography and ecology of the rain forests of eastern Africa. Cambridge University Press.
Moreau, R.E. 1935. A critical analysis of the distribution of birds in a tropical African area. Journal of Animal Ecology, Vol. 4: 167-191.