Tanzania |
Management Plan for the Botanical Research Institute at Amani |
The CPDU office is currently involved in consulting the East Usambara Catchment Forest Project in Tanzania on specific aspects of the Amani Botanical Research Institution. The following text is an extract from a literature review on material available of Amani. This report was produced by Markus Radscheit
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Introduction |
The area of the station covers some 750 acres, of which about a third remains under the original forest, while a large part of the remainder is occupied by permanent plantations of trees and shrubs collected from all parts of the tropics and each having some economic interest.
The station are bounded in the south by the Sigi River and in the north and east by the Dodwe and Kwamkuyu Rivers. The Sigi Plantations form a long, narrow strip of land running in a north-east direction and are separated from the Amani Plantations by the Kwamkuyu River. These are also bounded in the south by the Sigi River, in the east by the Sengere River which joins the Sigi in the south-eastern corner. There is no clearly defined or natural boundary in the north.
The station is surrounded by tropical evergreen rain forest, very rich in species, many of which are endemic. A few genera are discontinuous in their geographical distribution and are only recorded again in West Tropical Africa.
The plantations occupy the crests and slopes of a series of narrow ridges. In general the slopes are east and south-east facing. The altitudinal range varies from 1,300 feet at Sigi to 3,700 feet at Bomole with the result, that there is very little level ground in the whole area and the majority of the slopes are excessively steep.
Tanzania, formerly knows as Tanganyika, is populated by many Bantu groups, such as the Chagga, Hehe, Gogo, Yao, Nyamwezi and other Nilotic peoples. The recent political country situation was defined by a series of treaties between European states in the decade after 1886. These treaties ignored the claims of the sultan of Zanzibar, giving the Germans control over the vast reaches of Tanganyika and reserving Kenya and Uganda for Britain in 1905. After putting down African resistance to their rule, the Germans invested heavily in Tanganyika, hoping to convert the northern part into profitable coffee and tea plantations. In 1918 Tanganyika became a mandate of the League of Nations under British tutelage.
Climate
Amani enjoys annual rainfall of 1945 mm with recorded
extremes of 1377 mm and 3505 mm, The humidity is very high with
an annual mean temperature of 20.8ºC degrees. The mean daily
maximum is 24.6º C and the minimum is 16.3ºC.
Soils
In his 1934 report Greenway provides a detailed description
of the soils at Amani:
"The soils at Amani at or above the 3,000 feet level are of the type generally found under the rain-forests in Usambara, namely a deeply weathered red loam derived from gneiss, granulite or pegmatite. Though the colour gives a general impression of redness, it is usually a reddish-orange brown, pinkish-brown, often yellow-brown or even yellow. In spite of the high content of organic matter (organic carbon = 3 - 6%) the surface soil is only very slightly less bright in colour than the subsoil. The texture is a light loam; sometimes in the subsoil, a clay-loam; but always sandy and always readily permeable to water owing to the laterised nature of the clay (silica/sesquioxide ratio 1.0 or less). Lateritic concretions are entirely absent. When seen in section, the depth of soil seems impressive, but below 3-4 feet there is usually a large proportion of half weathered rock-brash. The reaction is acid (pH 5.2 to 4.6), sometimes less so in the top few inches, especially where a secondary grassy cover has succeeded the forest in clearing. As the slopes are everywhere steep, sheet erosion occurs if cultivation is mis-timed, but the ready absorption of rain and the rapid growth of weeds prevent the more spectacular forms of erosion, and gullying is rare. Its phosphate status is low.
A variant of the main type, occurring locally on the sharp-face and limited in extend, is neutral or less acid (pH 7.0 - 6.0) and less laterised. The slopes opposite Sigi Station carry a further variant, a yellow, tenacious sandy-clay which has an unusually high content of iron but is entirely non-lateritic. Swampy reaches in the valley contain grey or black-grey mottled clays, acid in reaction."
The Usambaras form part of the Eastern Arc Mountain (EAM) chain. In order to understand the overall vegetation pattern of the Usambaras it is necessary to examine the geology and climatic peculiarities of the EAM.
Geology of the EAM
The volcanoes of Meru and Kilimanjaro are geologically recent, and having been formed within the last million years. In contrast, the crystalline block-faulted mountains of the Eastern Arc are very old with initiation of faulting dating from 290 - 180 M yr. before present.
The EAM block was completely severed in the Miocene period following the uplift of the central African plateau, and were probably limited before then. The EAM are classified by their age and isolation. This is reflected in the unique nature of their flora. From north to south the main mountain blocks are the Taita Hills of Kenya and the Pare, Usambara, Uluguru, Nguru, Rubeho (Usagara), Uzungwa, and Mahenge mountains of Tanzania.
Climate in the EAM
Rainfall and dry season length are important factors that determine the overall vegetation pattern in the EAM. In areas above 1800 m, frost is the determining factor for species occurrence. Forests mainly occur on the east facing slopes where rainfall is over 1000 -1500 mm per year. In the northern parts of the ranges there are two distinct peaks of rainfall. Short rains occur during October to December and the heavier, longer rains are from March to May. Some of the areas, especially the Usambaras, appear to have a per-humid climate with most months receiving more than 100 mm of rain. Further south there is a marked dry season of several months and a single rainy season from June to September
Temperatures in the EAM
The dry season is the coolest time of the year, with frost occurring above 1800 m during July and August. The upper limit of forest is determined by the occurrence of frost which is 2100 - 2450 m in the Ulugurus and just over 2000 m in the Usambaras. However, frost has been recorded as low as 1500 m in the Usambaras.
The temperature lapse rate is relatively high. For the Amani-Sigi region on the east Usambaras a hot season temperature maximum lapse of rate of 1.7º C per 100 m has been recorded. On the West scarp the lapse rate is lower with approx. 1º C per 100 m.
The proximity to the Indian ocean has a cooling effect. The
temperatures in the East Usambaras are 4 - 5º C lower at 700m
than in other parts of Tanzania.
The East Usambaras are a group of low mountains close to the coast (40 km) in north eastern Tanzania. They include a main range 40 km long and 10 km wide, rising abruptly from the lowlands at 150 - 300 m and bound on all sides by steep escarpments which level off at 900 - 1500 m onto a deeply dissected plateau, which is most extensive in the south.
The East Usambaras were probably once more or less entirely forested (except the dry lowlands in the north) and it is the forests which are of special biological value and conservation concern. A 1986/87 inventory by the Tanzanian Forest Division and the Finish Aid Agency (FINNIDA) revealed ca. 231 km2 of forest remaining. Of this total ca. 81 km2 occurred on very steep slopes. Only ca. 30 km2 consist of intact, more or less undisturbed forest (Davis, et al., 1994).
By the 1950's, 25 Forest Reserves had been established, building on the few created earlier by the Germans. These reserves are now Catchment Forest Reserves (CFR) administered by the Forest Division. Although there has been some agricultural encroachment in the Forest Reserves, most of their borders have been respected. Despite the still fairly extensive forests outside the reserves, they are vulnerable and continue to be destroyed (Davis et al., 1994).
One of the Catchment Forest Reserves is the Amani Nature Reserve and covers a total area of 8,380 ha, including 1065 ha owned by tea companies. It forms the basis for the East Usambara Catchment Forest Project (EUCFP). The forest mountain provides resources and livelihood for local communities and is a catchment for the water supply of 200,000 people in the town of Tanga. The EUCFP has worked to protect the forest since 1990. The Finish government has provided US$ 6.1 to support the project from 1991 - 1998.
Historical Background
The original function assigned to the institute by the then German Government was 'to study the flora and fauna of German East Africa'. When the station was officially opened on 4 June 1904 the German Governor of German East Africa, Graf von Götzen outlined the aims and objectives of ARI: 'The Institute shall only conduct such activities that are of direct and practical benefit to those living in German East Africa. Any such activities that have no effect in improvement of standards to the east African culture should not be conducted. The establishment of a botanical garden can be considered at a later date'. The administration of ARI was to focus initially on the following project lines:
Initially, very little work was done to study the local flora of East Africa. Emphasis was primarily directed towards economic botany. Dr. Engler used his stay at Amani (1902, 1905) to gather material which was later incorporated into various publications as part of the Flora of Tropical East Africa.
The Kew Archives list series of letters with reference towards the research activities at Amani. The following is an extract from a private and confidential letter written on the 1 December 1932:
Other research activities included the following:
The work that the Germans had been carrying out on the White
Borer of Coffee (Anthores leuconotus), was further pursued
under English control.
In 1902 the centre had about 300 ha of land between the altitude of 400 m and 1,100m. By 1907 some 650 species had been cultivated. Reference is given by Glendon Hill to a conference (probably the Zanzibar Conference 1908 (?)) at which it was decided that Amani should grow as many economic crops as possible. Subsequently work was carried out in the following fields:
Medicine:
Starch & Oil:
British Queen seed potato
Cassava (Manihot esculenta)
Chinese Water Chestnuts
Rubber
Tropical fruit trees & stimulants:
Herbs:
Timber & Building materials:
various species of bamboo
Dyeing:
Fibre:
Vegetable Crops:
The above list is by no means complete, but represents the enormous range of crops being tested at ARI before the WW1.
For a more complete list for crops grown before WW2 refer to Greenway, 1934.
For a more complete list for crops grown after WW2 refer to Honess, 1963.
The following list of provenance is by no means complete, but provides information on the material obtained from a wide range of sources. The majority of plant material appears to be from:
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Solanum macrocarpum from District Wilhelmstal & Tanga;
In 1934 Greenway published an extensive report on the plants grown at Amani. It appears that since the disappearance of the Germans no proper stock checking had taken place:
Greenway (1934) refers to an earlier card index of all plants being held at the research station. This index was held by the Germans in the herbarium. The index provided information on:
Greenway continued using the card index and kept it updated. The current location of the card index is unknown. Greenway refers to two maps that assisted in his work. We only know of a scale 1:2000 map, that has apparently been being kept at the nursery office. Greenway's survey lists all plants according to their planting sites. It also provides a list of plants being introduced by the Germans, that fail being correctly identified. In 1963 a similar survey of the plantations at Amani was carried out and presented by Honess, the Agricultural Officer at Muheza. This surveys provides detailed accession lists on the various plantations in and around ARI.
Since its beginnings an herbarium has always been on site to assists with the identification of plant species. The main points of contacts for expert advise were the Berlin Herbarium (during the German period) and the Kew Herbarium (during the British period).
but also parts or duplicates of important historical collections like those of:
C. Ehrenberg (1825), Schimper (1837-1863), Peters (1842 - 1848), Steudner (1888 - 1901), Staudt (1895), Scheffler (1899);
In the 1930's a large number of seeds, herbarium specimens, etc., were sent to and from Amani to Kew. The Kew Library holds an exhaustive list of material from Amani in the Plant Determination lists.
In 1914 the Amani library stocked almost 4,000 books and 300 journals. All literature held at Amani was brought to the Berlin Library in 1918. In 1943 the Berlin herbarium was hit by a bomb and all material got destroyed.
The following list of references held at the CPDU off ice at Kew is deliberately presented in chronological rather than alphabetical order. It should assist the reader to find information on Amani relating to a certain period of time.
Pre WW1 - Literature
Pre World War Two Literature
Post World War Two Literature
