Extinction threat of EA coastal ecosystem with Anne Outwater

By Mahali Infrastructure TZ

If you grew up in the city of Dar like me, it could be you truly believe Ashoka trees have been in the East African coast for ever more. Well as it turns out these trees are from India even the beloved Neem tree.
When the infrastructure in a city or region doesn't respect the natural Eco system, you can have dire effects like floods and temperature fluctuations which defunct the purpose of proper infrastructure. It’s important thus that the ecosystem flora be allowed to flourish alongside the man made infrastructure in order for a sustainable co-existence.

A typical skyline in residential Dar es Salaam 
with alien trees the Neem (left) 
and the Ashoka (right)

Today we have the pleasure of talking with Dr. Anne Outwater Senior Lecturer at the School of Nursing in Muhimbili University of Health and Allied Sciences and a columnist with Sunday News in her weekly ‘Nature Notebook’. She’s currently working on a book with Ilana Locker and Roy Gereau of the Missouri Botanic Garden.

It will be in both Swahili and English to be published later in the year by Mkuki na Nyota titled ‘Plants of Coastal East Africa: A guide to protection and planting. It highlights the indigenous species, particularly plants that belong to the ecosystem around the coast of East Africa which stretches from the countries Mozambique, Tanzania, Kenya to Somalia.

“The ecosystem of coastal East Africa is highly unusual in that about 1,750 plants are found in these forests and nowhere else…Satellite data shows that these  forests are more than 95% destroyed and the pieces that still exist are fragmented and many are highly degraded. Many of the plants that live in them are therefore rare and highly vulnerable to extinction.” Explains Anne Outwater.

The truth of the matter is that our web of life depends on plants. As through photosynthesis, plants convert the sun’s energy into food for many insects, amphibians, birds, and mammals. . The plant feeders in turn sustain a whole range of wildlife that feed upon them, and so forth, all the way up the food chain to us humans.

However when you introduce exotic plants to an ecosystem it’s better to not have planted them at all; as various local herbivores to include livestock (cows, goats) are especially adapted to feeding on native plants.
The intrusion of exotic plants can negatively affect native plants by bringing foreign species like weeds and microorganisms. Which can destroy and cause diseases to the native plants; resulting in loss of food for the local herbivores (including livestock) which finally affects the livelihoods of humans who depend on these animals.

Mvule (Militia Excelsa) native to East Africa

There are NGO’s like Commonwealth Agricultural Bureau International (CABI) working in East Africa who are bringing awareness to this threat through research and aid for rural communities.

‘Invasive plants pose a significant threat to biodiversity and agricultural productivity in Africa and unless action is taken to mitigate the threat, countries are unlikely to meet the challenges of the Millennium Development Goals of poverty eradication and accelerated human development.

Human development, especially in Africa, is closely coupled to the health of natural ecosystems since 80% of the population largely relies on natural resources for its survival.’ Impacts of Invasive Plants and their sustainable Management in Agro-Ecosystems in Africa. A review-Arne Witt

It’s not only farmers and those who live in the rural community that are affected by the loss of our natural ecosystem. Dar es Salaam a city in this coastal region is a prime example of the side effects of this loss. From the recent floods which are causing major water pollution derived from runoff soil that has clogged and overwhelmed our local river and streams banks. This accelerated by the fact that there’s not enough vegetation to hold the sop soil compact (a fact aggravated by the loss of 95% of our natural ecosystem in this area). To the uncomfortable humidity with high temperatures during the summer which wouldn't be the case if the natural ecosystem was more alive.

The Ficus Sycamore (Mkungu) of East Africa 
only about 15 years old in Dr Anne's backyard

The other benefit of growing native trees or flora is that some of them such as timber trees like Milicia excelsis Mvule and Khaya anthoteca (Mkangazi) grow very fast.

When trees and flora are native to the region they have little problem growing as they’re adapted to the local climate and landscape; here a complex set of checks and balances enables the ecosystem to function creating the greatest bio diversity possible.  For example all plants native to coastal East Africa are drought tolerant because they are used to five months without rain every year.

So why have we destroyed 95% of this ecosystem indeed if it’s so beneficial? The truth is this knowledge is lost to many of us. “People haven’t thought about it much…When they get their plot they clear it. And then they can’t find replacements as nobody knows anymore, what are the natural trees of coastal East Africa. Of course a few people know like academics but that’s all; so that’s why we’re doing this book so that this knowledge can come back to people…” Dr. Outwater

Leaves of Hymenaea verrucosa (Sandarusi) 
or Gum copal now almost extinct 
in coastal East Africa

The book ‘Plants of Coastal East Africa’ goes to highlight the native trees of this ecosystem which include Acacia nilotica (Mkunga), Afzelia quanzensis (Mkongo), Albizia amara (Mujogolo), Baphia Kirkii (Mkuruti), Brachystigia spiciformis (Mtundu), Khaya anthotheca (Mkanganzi), Lannea schweinfurthi (Mpwipwi), Milicia excels (Mvule), Salvadora persica (Mswaki), Sclerocarya caffra (Morula), Sterculia Africana (Mluze), Tamarindus Indicus (Mkwaju), Adansonia digitata (Mbuyu) or Ficus sycamorus (Mkuyu-mkungu tree).

It also highlights the non native trees of coastal east Africa which are unfortunately rampant in cities like Dar es Salaam. The alien trees include the ‘Ashoka’, the ‘Neem, Flamboyant or Christmas tree, Leucena, Prickly Pear, Jacaranda, Lantana, and Eucalyptus.

So the next time you’re looking to get more green in your backyard or if you’re in City Planning please bear in mind our precarious ecosystem and make efforts to sustain it by  planting and protecting native plants. And you can look for ‘Plants of Coastal East Africa’ in book stores of Mkuki na Nyota and other bookstores in the cities of East Africa towards the end of the year.