The Limbe Botanic Garden and Rainforest Conservation Project – mangrove swamps to alpine senecio’s
By Tim Upson
Standing on the sea front in the town of Limbe in South West Cameroon, the aroma of freshly caught fish fills the air, along with the shouts of the fishermen trying to persuade the ‘rich’ white man he has the best fish in town and to part with an exorbitantly large amount of money. However, nothing can detract from the view as you look out to a peninsula covered in rainforest, the emergent trees silhouetted against the skyline. islands are dotted about in the bay, these being dwarfed by the mighty peak of Fernando Po, an almost perfect volcanic cone rising to 3,090 m, 60 miles out into the Bight of Biafra.
One of the main attractions in town is the Botanic Gardens, founded by the Germans in 1892 and shortly to celebrate its centenary. Originally planted to grow and trial new economic plants it is now the centre of a joint project between the British Overseas Development Administration and the Cameroon Government, with the R.B.G. Kew providing technical assistance. This is not the first time Kew has been involved with the Gardens. It was visited by the Director, Sir Arthur Hill, in 1920 who was impressed by the remains of the German garden. This led to the appointment of a Kew officer, T, D. Maitland, as Superintendent. Following a period of neglect another Kew trained officer, J. T. Swarbrick, was appointed in the 1950s and revived the garden, developing a collection of tropical fruit species.
Around Limbe grows rich Lowland Rainforest, in parts degraded, but still with significant areas in a pristine condition. Along the coast are large tracts of Mangrove swamps, but behind the town rises Mt. Cameroon, the highest mountain in West Africa at 4,090 m. It is unique as it offers an unbroken altitudinal profile of lowland rainforest into montane forest and beyond into savanna grassland and finally afromontane communities, characterised by alpine Senecios. There are 45 endemic species of plants and animals recorded from its slopes. This site is seen as being so biologically important that it is proposed as a World Heritage Site.
These very different habitats are to be conserved by two reserves and along with the garden constitute the main core of the project. importantly this is one of the few projects that puts into practice what many people have been saying for too long – the botanic gardens are ideally placed to play an important ro1e in conservation, particularly in the tropics.
At present the gardens cover an area of 46 hectares, situated on the coast overlooking the Bight of Biafra. The gardens are intended to fulfil several important roles; science, amenity, education and conservation. It will be the public face of the project and abase for visiting scientists.
The western half is dominated by an old volcanic core, Bota Hill Its seaward side is protected by a sea wall offering superb views out into the bay and surrounding headlands. The planting theme will be entirely of Cameroon plants, grown in their natural habitats. Plantings will include Lowland Rainforest, Gallery Forest, Swamp Forest and the creation of a lava flow habitat. The Black Mangrove, Avicennia nitida, has already established itself behind a breach in the sea wall, with its own community of crabs and mud skippers.
The Western half of the gardens consists of an area of flat lawn planted with many palms and trees and a smaller hill called the SDO’s Hill. A fine German colonial house situated on top of
the hill, offers views over the town of Limbe. The hill will be planted with educational displays to show such things as economic plants and animal/plant interactions. A display of Banana’s and Plantains has recently been planted to show genetic diversity within this group. The lawns will each have a theme planting such as a Pan-African Palm collection, exotic fruit species, medicinal plants and amenity plantings of ornamental species.
One of the main features of the garden is a large open air amphitheatre called the Jungle Village, used to hold cultural events. The highlight this year was the visit of the Prince of Wales, the arena being filled with people and traditional dancing taking place in the centre – a truly spectacular site. Offices including a herbarium are situated in the centre of the gardens. The River Limbe, which runs along the northern boundary, offers a superb focal point and occasionally Mt. Cameroon can be seen peering through the clouds.
Much work has now been completed in clearing previously overgrown areas and erecting a fence to secure new plantings. Many of the workers are good farmers but training in many aspects of horticultural practice is required, a role in which I was able to help. Training included planting techniques, plant record keeping and chainsaw use. Many plants were propagated this year for planting new features and this offered a good opportunity to teach new propagation methods. Traditionally cuttings were typically taken from woody stems and branches which could be several inches thick. On introducing the softwood cutting they swore they “would never germinate”. After correcting them on this we ran a trial from which I eventually won several beers!
From a scientific and conservation view the reserves are the most important part of the project. The Etinde Reserve covers about one third of Mt. Cameroon, an area of over 300 sq. km, from the summit of Fako peak at 4,095 metres down to the 200 metre contour. Included in the reserve is Cape Debundscha, the second wettest place on earth, with an annual rainfall between 12 and 15 metres’ Visiting this place is like having a shower and bath at the same time. Unique plant communities can also be found on some of the lava flows that run down the mountain, the reserve encompassing the 1928 and 1982 flows. The summit of the mountain is a desolate place of volcanic lava covered only in mosses and lichens, but just occasionally green patches occur where steam still vents.
The reserve takes its name from an old volcanic core, Mt. Etinde, which rises to a height of 1,713 metres on the western slope of Mt. Cameroon. It also offers one of the most interesting walks in the reserves. Chimpanzees can often be heard as you climb and scramble along a hunters trail that leads to the summit. Thickets of Cyathea manniana make spectacular sights while the bright orange flowers of Scadoxus cinnabarinus brighten the dark forest floor. Impatiens, of which there are numerous species, are common, some of which we now hope to cultivate as ornamentals in the garden. Caulifery is very common in the tropics and perhaps one of the most unusual examples is Omphalocarpum elatum in the Sapotaceae. Fascicles of flowers are borne all the way up its trunk (which can be 30 metres high) and are followed by flat circular fruits 30 em in diameter which clothe the trunk giving it a most bizarre appearance. The rind of the fruit is extremely hard being impregnated with silica. I was able to get numerous sparks when trying to open a fruit with a machete.
Near the summit you enter an enchanted forest of dwarfed trees clothed in ferns and great cushions of mosses and lichens. Amongst the moss can be found exquisite epiphytes such as the tiny Utricularia mannii with yellow flowers and the rare Impatiens grandisepala. This is a tuberous species surviving the dry season buried in the moss, emerging during the rains to flower and fruit. On reaching the summit it is traditional to perform a libation with the local guides. This is a form of communion with their ancestor. You are obliged to bring a spirit of some sort, a drop of which is poured over a stone and the rest passed around everyone. We took gin on this occasion – but forgot the tonic’
To the south of Limbe lies the Mabeta-Moliwe Reserve sandwiched between oil palm and rubber plantations. Although it has been logged over it still contains some areas of pristine forest including Mangrove and Pandanus swamp. One of the few emergent trees to have survived the loggers is Lophira alata, the Ironwood. Fortunately the extremely hard wood proves too much for most chainsaws. The other emergent tree to survive is Ceiba pentandra, the Kapok, partly because its wood is not valued but mainly because they believe the tree contains the spirits of dead people.
It is hoped that the forest can be enriched by replanting with economic timber and fruit species, which would also act as a living gene bank. Already several nurseries have been established to grow the necessary plants to do this.
This project is unique and exciting in both its inception and situation in an area of global importance. To fulfil its great potential it both needs and deserves the support of such institutions as the Royal Botanic Gardens, Kew.