Reforestation plans in Africa could go awry

October 28, 2020

The state of mature ecosystems must be taken into account before launching massive reforestation plans in sub-Saharan Africa, according to geo-ecologist Julie Aleman, a visiting researcher in the geography department of Université de Montréal.

"The biomes of the region we studied, which includes all the countries south of the Sahara, are divided into two fairly distinct types: savannah at about 70 per cent and tropical forest for the rest," said Aleman, co-author of a major new study on African biomes.

Involving some 30 researchers, several from Africa itself, the study is published this week in the Proceedings of the National Academy of Science.

"When we analyze the assemblage of tree species in each biome, we find that each is extremely different," Aleman said. "Moreover, if we look closely at the history of these biomes, we realize that they have been fairly stable for 2,000 years. Reforestation with tropical forest species in areas that are more associated with savannahs would therefore be a mistake."

Without wanting to point the finger at countries that might make this mistake, Aleman pointed out that reforestation plans include the planting of billions of trees. Even the intention is good, countries must try to avoid artificially creating tropical forests where savannahs have dominated for several millennia, she said.

Moreover, the choice of species selected is decisive. Acacias are more associated with open environments, for example, whereas celtis trees are specific to forests. In some cases, eucalyptus plantations have proved to be "ecological disasters," according to Aleman.

Tracing the past

She does her work at UdeM's paleoecology laboratory, whose mission under director Olivier Barquez is to retrace the past of biomes. Aleman's main collaborator, Adeline Fayolle, a professor at the University of Liege, in Belgium, assembled the floristic data (lists of tree species) for the new study.

"To do this, we conducted a kind of old-fashioned data mining, in the sense that we analyzed a large amount of existing data, published and sometimes archived in forgotten documents, buried in dust, as well as data recently acquired in the field, to try to understand the history of the region," said Aleman.

The study takes taken equal account floristic, environmental and paleoecological data to better understand the ecological functioning of forests and savannas, helped by analysing 753 sites in both environments. The environmental factors having the greatest impact on these environments are rainfall and its seasonality, as well as temperature, the researchers found.

One of the most remarkable phenomena in the savannah is the frequency of disturbances that affect them. Brushwoods can flare up to three times a year in some places, for example. To protect public health, local governments sometimes want to limit these fires. These decisions are legitimate, but can have significant ecological consequences, the co-authors say.

That's because, for the most part, large trees are unaffected by the flames, and the ashes regenerate the soil.

Almost devoid of wildlife

The impact of human activity can be seen wherever the researchers carried out their research, but mainly in Tanzania, Congo and the Central African Republic. In some cases, some areas are almost devoid of wildlife.

As early as 2017, when she published an article in the African edition of the online platform The Conversation, Aleman has been steadily trying to alert public opinion to the threats to African ecosystems. The Conversation.

She believes that the situation is not desperate but that governments must be careful in how they intervene so as to not makes things worse. Aleman hopes that the new study will lead to a better understanding of the biological reality of the African continent.

"This is a rather theoretical contribution,: she said, "but I believe that we can use it to inform reforestation policies."
-end-
About this study

"Floristic evidence for alternative biome states in tropical Africa", by Julie Aleman et al, was published Oct. 27, 2020 in the Proceedings of the National Academy of Science.

University of Montreal

Related Reforestation Articles from Brightsurf:

Reforestation plans in Africa could go awry
An international team led by an UdeM researcher publishes the findings of a study on the biogeographical history of sub-Saharan Africa.

Surprised researchers: Number of leopards in northern China on the rise
Most of the world's leopards are endangered and generally, the number of these shy and stunning cats is decreasing.

Reforestation can only partially restore tropical soils
Tropical forest soils play a crucial role in providing vital ecosystem functions.

UVA-led team warns negative emissions technologies may not solve climate crisis
A multidisciplinary team led by University of Virginia researchers used the Global Change Assessment Model developed at the University of Maryland to compare the effects of three negative emissions technologies on global food supply, water use and energy demand.

NUS-led study considers potential and constraints of reforestation for climate mitigation
A recent study led by NUS researchers showed that practical considerations, beyond where trees could be planted, may limit the climate change mitigation potential of reforestation.

Native trees thrive in teak plantations and may protect the Panama Canal
Teak often underperforms on poor soils. By planting valuable native trees in existing teak plantations, researchers will evaluate the potential increase in timber value, biodiversity value and ecosystem services provided.

The geological record of mud deposits
The UPV/EHU's HAREA: Coastal Geology research group has conducted a study into how human activities may have influenced the mud depocentres on the Basque shelf, in other words, in the area of the Basque Mud Patch (BMP) on the coast of Gipuzkoa down the ages.

Papers concludes that incentives to afforestation can be harmful to the environment
'Through a counterfactual analysis, we showed that between 1986 and 2011 the incentives to afforestation in Chile caused an increase in forest plantations, but reduced the extent of native forests', explains the main conclusions of the paper Impacts of Chilean forest subsidies on forest cover, carbon and biodiversity, published by the journal Nature Sustainability.

Countries must work together on CO2 removal to avoid dangerous climate change
The Paris Agreement lays out national quotas on CO2 emissions but not removal, and that must be urgently addressed, say the authors of a new study.

Nitrogen-fixing trees help tropical forests grow faster and store more carbon
New research published in Nature Communications shows that the ability of tropical forests to lock up carbon depends critically upon a group of trees that possess a unique talent -- the ability to fix nitrogen from the atmosphere.

Read More: Reforestation News and Reforestation Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.