Living on the Edge

Living on the Edge……

Rainforests in West Africa are quite different from rainforests anywhere else for two very good reasons………..one, that their existence depends on a unique weather pattern known as the Intertropical Convergence Zone (ITC) …….and two, because the region has dried out and cooled down a number of times in the past.

West African rainforests can be likened to a filling between two slices of bread – the Atlantic to the south and the Sahara to the north – which produce a soggy or dry sandwich depending on pressure from the ITC.  During the course of the year the ITC moves, shifting north and bringing warm moist air from the ocean – the rainy season - and then moving back again, pushed by cool dry winds from the desert – a phenomenon known as the Harmattan which fills the air with a mist of dust and coats every surface, including your lungs, with the finest airborne particles of sand.  Before it changes direction in July or August, the ITC may reach as far as 20˚N of the equator, which can bring rain into the Sahara itself.

 Any rainforest close to the equator is guaranteed to be hot and wet all year round, but West Africa is not quite close enough to bring this guarantee.  Instead, it has four different kinds of rainforest depending on how far they are from the equator and to what extent they are affected by  the huge mass of the Sahara.  Rainforest closest to the equator is termed wet evergreen forest (annual rainfall 1750-2000mm) and in West Africa it occurs only in southernmost parts – in Nigeria from around Lagos to Benin City and down to Port Harcourt and Calabar.  Next come areas of moist evergreen forest (1500-1750mm) and after this there is moist semi-deciduous forest (1250-1750mm), which is the largest single type in West Africa and the one with the tallest trees. In this kind of rainforest,  diminishing rainfall and a pronounced dry season cause many trees to lose their leaves for months on end.

But most extreme of all is the dry semi-deciduous forest we have at IITA in Ibadan  where three or four months of the year are bone dry and with average annual rainfall hovering around 1250mm, a high proportion of trees, climbers and other plants become dormant and leafless in order to survive.  We are in fact in the transition zone, midway between 7 and 8˚N of the equator where forest meets savanna. Further south there is little concern about when it might next rain but here we are on a tightrope between wet and dry.  Like the ancient Roman deity Janus, god of doorways and gates who is depicted with two faces so that he can look both backwards and forwards, this area could go either way with global warming.

Mind the Gap…….

Another reason that IITA in Ibadan is so uniquely positioned is that it is in the far west of Nigeria and close by another major phenomenon – the Dahomey Gap.  Situated largely in neighboring Benin, this startling geographical feature is a massive intrusion of savanna which reaches almost to the coast, cutting a vertical swathe through the West African rainforest. This creates a formidable barrier that many species of rainforest plants and animals cannot cross, which results in two different kinds of forest.  To the west of the Dahomey Gap, from Ghana to Senegal, there is what is known as Upper Guinea Forest, and on the other side is Guinea-Congo forest which has closer affinities to forests in Central Africa. This puts the IITA Forest Reserve literally in a unique position as one of the few remaining forest fragments in the transition zone and an increasingly rare example of westernmost dry, semi-deciduous Guinea-Congo forest.  Given that it is also well protected, there is perhaps no better place to monitor changes in climate and biodiversity.

Against the odds……

Human-induced climate change has never happened before and by definition is therefore unpredictable. Becoming drier is nothing new though. Indeed it would appear that this has happened several times to West African forests in the geological past, leaving pockets of rainforest only in the warmest wettest places and driving all else to extinction.  This is another reason that West African rainforests are different from those in the Americas, Asia and Australasia. Everyone knows that rainforests have the greatest diversity of living things anywhere on earth and a high degree of endemism – species found in one area and nowhere else. In general you expect the highest endemism in very complex terrain – rugged mountains, diverse watersheds and varied rocks and soils - which creates innumerable niches and physically separates species which then evolve differently. Endemism in West Africa seems to be for a different reason though.  For one thing, West Africa has no high mountain ranges like Central America, Borneo or New Guinea and is more uniform in its geology. The high numbers of endemic species in West Africa may therefore have more to do with survival against the odds in small pockets of rainforest when all the surrounding forest dried out.

In general……

These are big generalizations of course, but they serve to give an idea of why rainforests in West Africa are the way they are, and why the last few remaining areas are so very special.  At present rates of deforestation, they will more or less be gone by 2020, and mostly before they have been studied in any detail or assessed in terms of their contribution to the environment and life in the region. That’s why even a small fragment like the 350-ha IITA Forest Reserve can have a big impact if actively managed for research, conservation and education as well as for the diversity of plants and animals that live there. 

The End……

Deni Bown © 2012

Naming names OR how to get more fun from downloading checklists

Have you ever wondered how some plants and animals get their names? Obviously they are given names so that we can tell them apart and communicate with other people.  This sounds simple enough – a green-headed sunbird differs from a blue-throated sunbird and a scarlet-chested sunbird. But what about an African spirit, a friendly sapphire, blue policeman, western fairy playboy or gaudy commodore?   You could never tell from the names that these are butterflies.  In fact if you look through the Forest Project checklists of birds and butterflies (see Downloads), you have to conclude that ornithologists are practical and to-the-point with their names, while lepidopterists are imaginative to say the least.  Perhaps this is because we don’t catch and eat butterflies.  After all, the right whale got its name because it was the right one to go after for its meat and oil.  You can’t have a much more direct name than that.

blue policeman (Coeliades chalybe)

Plants come somewhere in between.  The sandpaper tree has leaves that feel like sandpaper and can be used for polishing, a dose of the worm bush gets rid of  worms, pigweed is good for feeding pigs and bitter leaf is exactly that.  These are useful names for describing practical purposes but then some plants have names like “morning glory’, “woman’s tongue” and “passionflower”.  Names like these tell you more about the observer than the plant.  They reflect our feelings and interests.

In fact we often use our names for the wildlife around us to describe ourselves or others – ‘eagle-eyed’ or having a ‘bee in your bonnet’.  If you take the time and trouble to find out, you will discover that common names in any language can say a lot about people and culture. The Igbo name for Pararistolochia goldieana, the largest flower in Africa, is ekommili, describing the unopened flower which is similar in shape to the local blacksmith’s bellows (eko) but very fragile (mmili).  

Pararistolochia goldieana, buds and open flowers

Which brings us to scientific names.  Every organism on earth which has been classified by a scientist has a two-part scientific name.  They are based on Latin or Greek words, or on Latinised versions, and provide a common scientific language worldwide.  The scientist who first identifies and describes the organism gets to name it, following internationally accepted rules.  This may sound dull but some scientific names are every bit as interesting as common names.  If you learnt Latin at school, you would know that Pararistolochia means distinct from but similar to (para-) Aristolochia (another group of related plants).  The second part, goldieana, describes this plant specifically, in this case that it was brought to the attention of scientists by the Reverend Hugh Goldie, a missionary who lived in Calabar in the 1880s. 

Next time you find out the name of a bird or butterfly or plant, check what the name means or how it got its name.  You may find out something very interesting and it may also help you to remember the name.

Deni Bown 21 March 2012

 

Beekeeping at IITA

Bees are very interesting social insects. Like most - OK some of us - they are highly disciplined and stick to a rigorous routine. When handled properly by a trained beekeeper, their products – honey, propolis and wax - can provide healthy products and a valuable source of income.

Beekeeping is not new to IITA Ibadan - there are reports of abandoned hives in and around the campus – but this project is the first joint venture between IITA and a local company, Earthly Produce Limited (EPL).  The idea for the project was inspired by IITA International School’s December 2010 production, Fern Gully, a play based on the theme of biodiversity.  The objective is to demonstrate the vital role forests play in providing sustainable natural resources which can generate earnings with very little investment or effort, especially for rural communities.

An area approximately 2,500 sq. m. in size, located in the IITA forest has been selected as the site of the apiary.  It has a wide variety of trees and will provide shade and excellent sources of nectar and pollen for the bees.  Ten Kenyan Top Bar hives, each with 20 top bars were installed on 20 February 2012. The choice of hive was based on the cost and ease of construction and also the low level of management required compared to other types of hives. The wood used to construct the hives is from locally grown Gmelina arborea trees, chosen for its strength and durability. Installing the hives at this time of the year is ideal as it falls within the honey flow season and there is also a high possibility of catching bee swarms.

Idris Olaniyan, Femi Kesington, Deni Bown (IITA), Jubril Abanikanda and Abdul Wahid Ibrahim at installation of EPL beehives in IITA forest.

In addition to developing the apiary, EPL will organise training seminars on beekeeping which will include both theoretical and practical sessions. The seminars will cover the basics of beekeeping such as hive construction, managing hives, beekeeping equipment and other topics necessary for the beginner.  They will also highlight the importance of beekeeping to farmers and the vital role that bees plays in pollinating crops.

So when next you see a bee foraging on a flower take a closer look and observe what it is doing. As long as you don’t touch it, the chances of getting stung are quite slim. But BEE careful  near a beehive or the nest of a wild colony.  Without proper protective clothing and know-how this could BEE quite dangerous!

Femi Kesington, Earthly Produce Limited  femikesington@yahoo.co.uk

Deni Bown, IITA Forest Project  d.bown@cgiar.org