Resistance of African tropical forests to an extreme climate anomaly

Please download the Document here below:

e2003169118.full

 

Abstract

 

The responses of tropical forests to environmental change are critical uncertainties in predicting the future impacts of climate change. The positive phase of the 2015–2016 El Niño Southern Oscillation resulted in unprecedented heat and low precipitation in the tropics with substantial impacts on the global carbon cycle.

 

The role of African tropical forests is uncertain as their responses to short-term drought and temperature anomalies have yet to be determined using on-the-ground measurements. African tropical forests may be particularly sensitive because they exist in relatively dry conditions compared with Amazonian or Asian forests, or they may be more resistant because of an abundance of drought-adapted species.

 

Here, we report responses of structurally intact old-growth lowland tropical forests inventoried within the African Tropical Rainforest Observatory Network (AfriTRON). We use 100 long-term inventory plots from six countries each measured at least twice prior to and once following the 2015–2016 El Niño event.

 

These plots experienced the highest temperatures and driest conditions on record. The record temperature did not significantly reduce carbon gains from tree growth or significantly increase carbon losses from tree mortality, but the record drought did significantly decrease net carbon uptake. Overall, the long-term biomass increase of these forests was reduced due to the El Niño event, but these plots remained a live biomass carbon sink (0.51 ± 0.40 Mg C ha−1 y−1) despite extreme environmental conditions. Our analyses, while limited to African tropical forests, suggest they may be more resistant to climatic extremes than Amazonian and Asian forests.

 

Tropical forests are a critical component of the global carbon cycle because they are extensive (1), carbon dense (2), and highly productive (3). Therefore, consistent impacts on these forests can have global consequences. Their global importance is seen via atmospheric measurements of CO2, showing a near-neutral exchange of carbon across the terrestrial tropics; hence, the large carbon losses from deforestation and degradation are offset by the significant carbon uptake from intact tropical forests and tropical forest regrowth (4). Independently, ground observations of structurally intact old-growth tropical forests also show this uptake, with forest biomass carbon increasing across remaining African (5, 6), Amazonian (7), and Asian (8) forests. Yet, unlike in Amazonia (9, 10) and Asia (8), the impact of a severe drought or a drought and high-temperature event in African tropical forests has never been documented using ground data.

 

High temperatures test the physiological tolerance of tropical trees. Above optimal temperatures, plants reduce their carbon uptake (11). This includes closing stomata to avoid water loss, reducing internal CO2 concentrations, and reducing carbon assimilation in the leaf. Higher temperatures increase vapor pressure deficits (12) and alongside reduced precipitation, increase the chance of hydraulic failure (13). Individually or in combination, these impacts can slow growth and may eventually kill trees (14), although tropical seedling growth can increase with experimental warming (15). As well as reduced carbon uptake, plants use more carbon under higher temperatures; respiration rates tend to increase with short-term increases in temperature both at the leaf (16) and forest stand (17) scales, again reducing tree growth and potentially leading to tree death via carbon starvation (18). Recent analyses of tropical forest plot data showed increased temperatures over the prior 5 y were associated with lower levels of carbon uptake from tree growth and higher levels of carbon loss from tree mortality (6). Furthermore, biome-wide spatial analyses suggest the existence of a temperature threshold above which carbon uptake from tree growth declines rapidly (19). Thus, with high temperature anomalies, we expect reduced tree growth and increased tree mortality.

 

Drought also impacts trees as water deficits can slow tree growth and if of sufficient strength or duration, can kill trees, either via hydraulic failure or carbon starvation. Hydraulic failure of the xylem has been found across species and biomes in response to drought, while carbon starvation has been documented in some locations including one tropical site (20). Inventory plot observations before, during, and after droughts show the impacts of drought in Asia and Amazonia. In Asia, the 1997 to 1998 El Niño temporarily halted the carbon sink in live biomass in Bornean forests by increasing tree mortality (8, 21). In Amazonia, severe droughts in 2005 and 2010 elevated biomass mortality and in 2010, also significantly reduced tree growth (9, 10). The Amazon biomass carbon sink was reversed by the 2005 drought, and while it rapidly recovered, it is weaker since 2005 (7), potentially due to high-temperature impacts (6). However, while the impacts of short-term drought in their long-term context have been investigated in Amazonia and Asia, in Africa we so far lack any ground-based assessment of large-scale drought impacts due to a paucity of observations.

 

Although the broad responses of African tropical forests to temperature and drought anomalies might be hypothesized from first principles and the responses of other continents, there are considerable uncertainties. On the one hand, there are grounds for expecting African forests to be especially vulnerable. African forests are already remarkably dry compared with Amazonian and Asian tropical forests, with almost 90% receiving <2,000 mm y−1 precipitation (22), the approximate amount necessary to maintain photosynthesis at high levels throughout the year (23). This low rainfall suggests African tropical forests may already be close to their physiological and ecological limits. Additionally, the lower temperatures African forests tend to experience—as many are situated at slightly higher altitude than forests in Amazonia—could result in limited species tolerace of high temperatures. African forests are also much less species rich than forests in Amazonia and Asia (2, 24), with a relative lack of species in high-temperature African forests (25), and this lower diversity could conceivably drive lower resistance to climate anomalies (26).

 

Alternatively, the relatively dry conditions of African tropical forests may, perhaps counterintuitively, confer drought resistance. African climate has oscillated between wetter conditions in interglacial periods and cooler and drier conditions in glacial periods (27), so the African pool of species present today may be more drought tolerant because some of the most mesic-adapted biodiversity has been lost over time (28, 29). Drier African tropical forest tree diversity is similar to that of the Amazon or Asia, but tree diversity does not increase with shorter dry seasons in Africa as it does in Amazonia (25), suggesting that most wet-adapted species have been lost and either the dry-adapted species remained or these lineages have diversified more, potentially conferring drought resistance. Indeed, a 40-y drought in West Africa led to an increased abundance of deciduous species in tropical forests in Ghana (30, 31). The relatively cool conditions of African tropical forests might also imply resistance as these forests are further from a potential high-temperature threshold that may limit photosynthesis. Overall, African tropical forests could plausibly be more or less vulnerable to temperature and drought anomalies than Amazonian tropical forests.

 

Understanding how intact African forests respond to climate anomalies is vital, not least because they have been providing a substantial long-term carbon sink, reducing the rate and magnitude of climate change (5, 6). The impacts of environmental change on African tropical forests are also important because of unique aspects of their structure. African forests typically have high aboveground biomass and so, high carbon storage per unit area—on average, one-third more than Amazon forests (2, 32, 33). African forests are composed of a smaller number of stems, ∼425 ha−1 (≥100-mm diameter), compared with ∼600 ha−1 in Amazonia and Asia (32) and so, are more dominated by large trees. Hence, even small decreases in growth of the large dominant trees or modest increases in the mortality of these trees could lead to large carbon stock reductions and a loss of the live biomass carbon sink.

 

The 2015–2016 El Niño event provided a first opportunity to assess the impact of high temperatures and strong water deficits on the ∼450 Mha (6) of African tropical forests. While three very strong El Niño events have occurred in the last 50 y (1982 to 1983, 1997 to 1998, and 2015 to 2016), only the latter occurred after a network of long-term inventory plots had been established in Africa and was poised to capture an El Niño event (5). At the onset of the 2015–2016 El Niño, we organized a specific “emergency” six-nation remeasurement program to capture the impact of the climate anomaly on African tropical forests. We therefore combine climate data with measurements from 100 African Tropical Rainforest Observatory Network (AfriTRON) long-term inventory plots that were remeasured to capture the 2015–2016 El Niño event to address the following questions. 1) Did African tropical forests experience unprecedented temperature anomalies in the 2015–2016 El Niño? 2) Did African tropical forests experience unprecedented drought in the 2015–2016 El Niño? 3) Which climate anomalies drove forest responses to the 2015–2016 El Niño? 4) What were the overall impacts on the monitored old-growth structurally intact tropical forests?

 

Please download the Document here below:

e2003169118.full

Go back

Partners News

CBFP’s side event on cross-border transhumance mobilises and makes waves at the 14th Global Forum on Migration and Development (GFMD) in Geneva

Wednesday, January 24, 2024. Geneva. The Franco-Gabonese Facilitation of the Congo Basin Forest Partnership (CBFP) organised a side event on cross-border transhumance at the14th Global Forum on Migration and Development (GFMD).   At the era of climate change, access to water, agriculture, the fight against desertification, biodiversity, forest preservation and cross-border migration, transhumance is the cross-sectoral prime theme.  This explains the central theme of the event:  “Meeting Between the Sahel and northern equatorial Africa - The challenges of the nexus: cross-border transhumance, survival of protected areas, natural resources, and human lives, development, security and peace.”

Congo Basin Science Initiative the 127 members of CBFP: Welcome to our New Partner!

Kinshasa, DRC, 13 February 2024: The Congo Basin Science Initiative has officially joined the Congo Basin Forest Partnership (CBFP). The Basin Science Initiative is now one of 127 member countries and organizations working together in the Congo Basin Forest Partnership to promote sustainable resource management, combat climate change and its impacts, improve living conditions and protect the unique biodiversity of Central Africa’s tropical forest.

Discussions on the stimulation of the forest sector between the Minister of Forestry Economy and the Associate Manager of the Deliotte Cabinet

The strategic meeting between the Minister of Forest Economy, Rosalie MATONDO and Deliotte consultancy cabinet made way to research collaboration possibilities and share prospects on reforms needed to make forestry attractive.

 

CBFP and COMIFAC discuss the results of the 28th Session of the Conference of the Parties to the United Nations Framework Convention on Climate Change (UNFCCC)

From 22 to 24 January 2024, a sub-regional workshop was held in Douala, Republic of Cameroon, to analyse the results of the 28th Session of the Conference of the Parties to the United Nations Framework Convention on Climate Change (UNFCCC). Her Excellency Dr Aurelie Flore Koumba Pambo, the Gabonese Co-Facilitator of the CBFP, participated in the workshop. Download the  final communiqué of the meeting..

UNEA6 side event – Joint Action Against Nature Crime: A Pathway to Achieving Biodiversity, Climate and Sustainable Development Goals

Ministers and representatives from governments, international organisations, and civil society will explore how multi-sector collaboration in the fight against nature crime can inform wider efforts to tackle the triple planetary crisis during an official side event at the upcoming UN Environment Assembly (UNEA-6) in Nairobi.

Southern Africa Dialogue aims to improve detection and disruption of financial flows linked to nature crime – Nature Crime Alliance

Financial crime analysts, industry experts and law enforcement officers from across Southern Africa assembled in Cape Town last week for the first in a new series of regional meetings aimed at tackling illicit financial flows associated with nature crime.

Second ministerial conference on ‘Transhumance-Protected Areas-Security’ in Central Africa: progress and perspectives

This article by Paul Scholte and Matthew Luizza in Conservation News looks at the progress and prospects for work on transhumance in Central Africa since the second international conference of ministers on transboundary transhumance of July 2023 in Yaoundé.

CAR: The United States reassert their support in forest and fauna protection

Gervais MBATA, the new Minister of Water, Forests, Hunting and Fishing hosted at his Cabinet this February 7, the United States’ ambassador to Central Africa, Mrs Patricia MAHONEY. During this fruitful meeting between government members and American diplomats, several topics were discussed about cooperation reinforcement, the USA’s multiform support and especially the implementation of projects on the protection of CAR wildlife areas.

Sustainable management of protected areas: A key meeting between Rosalie MATONDO and Peter FEARNHEAD

On 7 February 2024, Rosalie MATONDO, Minister for Forest Economy, welcomed Peter FEARNHEAD, Chief Executive Officer of the South African NGO African Parks Network (APN). The meeting provided an opportunity to discuss the management and development of the Odzala-KMassif okoua Forest (MFOK), a UNESCO World Heritage Site. The two parties also discussed the challenges of conserving protected areas.

Cocoa without deforestation: is it possible in Cameroon?

This is the question posed by Development Advocates (GDA) in its new publication: Deforestation-free cocoa in Cameroon: questions, concerns and priorities from smallholder farmers. The document sets out the challenges Cameroon faces in doubling its domestic cocoa production, retaining access to its biggest market (the EU) and reducing the pressure on its forests. Please download the GDA publication...

New body aims to limit pollution’s deadly toll - unep

Pollution is widespread – and often fatal.Dirty air alone is responsible for 6.7 million deaths globally every year, while conservative estimates suggest that in 2019, 5.5 million people died from heart disease linked to lead exposure. To stem the pollution crisis, countries agreed in 2022 to establish a new body that would provide policymakers with robust, independent information on chemicals, waste and pollution.

Press release - Climate Chance Europe 2024 Wallonia summit adaptation to climate change, nature-based solutions and resilience

The Climate Chance Europe 2024 Wallonia Summit "Adaption to climate change, Nature-based Solutions and Resilience" was held at the Palais des Congrès in Liège on 8 and 9 February 2024. Over two days, the Summit brought together nearly 1,000 participants of more than 20 nationalities, from numerous European networks and organisations of non-state actors such as businesses, researchers, civil society and local governments.

Towards UNEA-6: Multilateral solutions to triple planetary crisis - UNEP Speech delivered by Inger Andersen

As the world’s top decision-making body on the environment, UNEA-6 will bring together ministers, intergovernmental organizations, the broader UN system, civil society groups, the scientific community and private sector to shape global environmental policy. This year, we’re expecting more than 70 Ministers and 3,000 delegates to join us in Nairobi. We currently have 20 draft resolutions and two draft decisions submitted for countries to discuss. Ms. Ochalik will share more on this. I will talk about the wider context of UNEA-6, and what it means.

GABON: Mrs Nzoma née Arcadie Svetlana Minguengui Ndomba, new Minister for the Environment, Climate and Human-Wildlife Conflict

Following a ministerial reshuffle yesterday, Wednesday 17 January 2024, the Ministry of Water and Forests, formerly responsible for the Environment, Climate and Human-Wildlife Conflict (CHF), has been split into two separate ministries: one responsible for the Environment, Climate and Human-Wildlife Conflict (CHF), managed by Arcadie Svetlana Minguengui Ndomba épse. Nzoma, and the other in charge of Water and Forests, which remains under its full management.

RELEASE: Landscape Restoration Champions Across Africa Receive USD 17.8 Million in Financing from TerraFund for AFR100 - WRI

This second cohort of investments, named TerraFund for AFR100 Landscapes, is restoring land in three of the continent’s vital landscapes: the Lake Kivu and Rusizi River Basin in Rwanda, Burundi, and the Democratic Republic of Congo; the Ghana Cocoa Belt; and the Greater Rift Valley of Kenya. These landscapes were chosen because they provide food and water for millions of people and protect crucial biodiversity; yet they are suffering from decades of degradation.

Tenure Facility joins Congo Basin Forest Partnership

To bolster its work in the region, Tenure Facility has joined the Congo Basin Forest Partnership (CBFP), a strategic alliance of countries and organisations dedicated to fostering sustainable practices, improving living conditions, and preserving the rich biodiversity of Central Africa’s tropical forest.Tenure Facility will bring its longstanding collaboration with several stakeholders – including Indigenous Peoples, local communities, organisations, and governments – to CBFP as it works toward finding inclusive and equitable solutions to forest-related challenges.

Her Excellency Dr Aurelie Flore Koumba Pambo, Co-Facilitator of the CBFP, takes part in the analysis of the results of COP28

Douala, Cameroon, 22-24 January 2024 - The Central African Forests Commission (COMIFAC), with financial support from the German cooperation via the GIZ support project for COMIFAC and the Wildlife Conservation Society (WCS), organised a sub-regional workshop to analyse the results of the 28th Conference of the Parties to the United Nations Framework Convention on Climate Change (COP28).

Turning the corner on environmental crises in 2024 - UNEP

When it comes to climate, we do have something new to build on. Yes, the Dubai Consensus that emerged from COP28 was not everything everyone had hoped for. But it did signal a global decision to move away from fossil fuels, which is critical, as we all know. And, of course, the Loss & Damage Fund was put into operation. This was an important show of solidarity with vulnerable nations, although there is a long way to go to capitalize the fund. The positives did not stop there. We saw new commitments on sustainable cooling and reducing methane emissions. A tripling of renewable energy targets. Nature breakthroughs. Crucially, there was agreement on the framework for the Global Goal on Adaptation.

Strengthening land rights for women and young people supports fair conflict resolution -Tenure Facility

Cicin Juarsim, 52, smiled with joy when the land she has been cultivating officially became hers. “Now I am holding a private ownership certificate in my land. This is not only important for me. This land is important for my children,” said Cicin Juarsim who lives in Muktisari village, Ciamis District, in Indonesia’s western province of Java.

PRESS RELEASE: CBFP Side Event at the 14th Summit of the Global Forum on Migration and Development (GFMD) in Geneva, Switzerland, Wednesday 24 January 2024, 17:00 - 18:30, Virtual.

Under the aegis of the Co-Facilitator of France, Ambassador Christophe Guilhou, the Congo Basin Forest Partnership (CBFP) is taking part in the GFMD and is organising a side event on Wednesday 24 January 2024, from 5.00 pm to 6.30 pm (virtual), on the theme: Meeting between the Sahel and northern equatorial Africa - The challenges of the nexus: cross-border transhumance, survival of protected areas, natural resources, and human lives, development, security and peace.

What is phosphorus and why are concerns mounting about its environmental impact? - UNEP

For months last year, Florida’s beachgoers were plagued by rotting tangles of decaying seaweed that had washed ashore. Known technically as sargassum, the thick clumps were part of a record-setting 8,000-kilometre-long seaweed belt in the Atlantic Ocean. Sargassum blooms cause a range of environmental problems, including coastal “dead zones” bereft of aquatic life. Past sargassum outbreaks have been linked to the excessive release of phosphorus and other chemical substances known as nutrients.

 

SAVE THE DATE - GEF Technical BBL Series: Taking the lessons from Integrated Approach Pilots to the GEF8 Amazon, Congo, and Critical Forest Biome Integrated Program. Tuesday, January 30, 2024, 12:30 - 14:00 pm EST (hybrid event, in English)

Location: Gustavo Fonseca Meeting room (N 8 – 180) and virtually on Zoom. 3. Speakers: Carlos Manuel Rodríguez. CEO and Chairperson of the Global Environment Facility; Ana Maria Gonzalez Velosa, Senior Environmental Specialist, Coordinator of the Amazon Sustainable Landscapes Program, World Bank Group, Latin America Region; Jean-Marc Sinnassamy, Senior Environmental Specialist, Lead of the CFB IP, GEF Secretariat; Charity Nalyanya, Director, Project Management and Technical Oversight, Conservation International (CI); George Akwah Neba, Team Leader of UNEP’s Congo Basin Team; Yawo Jonky Tenou...

Watch the guardians of the forest - Tenure Facility

Seated by a crackling fire burning during an inky night, community elder Cosmas Murunga shares some advice to his audience of young listeners. “As you grow up, women might get married outside of the community. But they shouldn’t forget where they came from,” he says. “And you young men, as you grow, know that you will inherit the ways of your fathers, grandfathers and those of your ancestors.”

Second International Conference of Ministers on Cross-Border Transhumance - Compendium of Country Investment Plans

In the case of Cameroon, the government established an inter sectoral committee chaired by the prime minister office to facilitate development of the country’s PIP. The methodology adopted for writing of this document, followed a participatory approach. After validation of the draft logical framework by the Expert Committee in Douala, the national Steering Committee which brings together various sectoral ministries met in May 2023 to work on priority sectoral activities of the seven strategic axes of the logical framework. A consultant was hired to technically assist the national steering committee in development process of the PIP. The main tasks of the consultant included further consultation of sectoral ministries to discuss priorities, consultation of strategic partners, desktop review of technical reports and other related documents on transhumance, budgeting and development of 5years investment plan.

Welcome to our New Partner: The Tenure Facility!!

Paris, 10 January 2024: The Tenure Facility has officially joined the Congo Basin Forest Partnership (CBFP). The Tenure Facility is now one of 126 member countries and organizations who work together to promote sustainable resource management, to combat climate change and its impacts, improve living conditions and protect the unique biodiversity of Central Africa’s tropical forest.

Global Report on Sanitation and Wastewater Management in Cities and Human Settlements -unhabitat

The report, prepared by a consortium led by Water & Sanitation for the Urban Poor (WSUP), and supported by Agence Française de Développement and the Bill & Melinda Gates Foundation, aims to provide professionals and policymakers working at the intersections of water, the environment, health, energy, agriculture, spatial planning, and land use with a global cooperative and cross-sectoral reference on the current situation and developments in sanitation and wastewater and fecal sludge management in cities and human settlements.

Population growth and climate change: The 2023 world population data sheet is now available

The 2023 edition of the Population Reference Bureau’s (PRB) World Population Data Sheet explores the role of population data in helping countries prepare for and adapt to climate change. It finds that “[b]y examining the association between population vulnerability and risk of exposure to climate shocks, decisionmakers can allocate resources to areas of greatest need and prepare essential systems to respond effectively to climate change.”

 

Embracing Digital Health in the Face of Climate Crises - IISD

In recent years, climate crises such as floods, wildfires, drought, and extreme heat have disrupted ecosystems and negatively impacted human health. The Global South is often the hardest hit by climate change. Amid these crises, digital health emerges as a beacon of hope given its ability to provide accessible, cost-effective, and resilient healthcare services, which are increasingly necessary in the face of the growing challenges posed by climate change, particularly in hard-to-reach regions.

Partnering with FMAFS to scale innovation for food security in Nigeria - IITA

The Nigeria Ministry for Agriculture and Food Security is set to collaborate with IITA to scale technologies as part of measures to implement the government’s 8-point agenda. During a recent visit to the office of the Minister for Agriculture and Food Security, Honorable Abubakar Kyari, in Abuja, IITA Director General and Regional Director for CGIAR in Africa, Dr Simeon Ehui, said the Institute values the strong support of the Nigerian government and would like to align with the national programs.

Translating SDGs into Public Policies: A Case for Permanent VNRs - IISD

Last September, 193 UN Member States reaffirmed their commitment to the 2030 Agenda for Sustainable Development as a shared roadmap, as well as to accelerate progress towards the SDGs. At the same time, countries gathered at the UN General Assembly’s (UNGA) SDG Summit acknowledged that achieving the Global Goals on time is “in peril” due to major setbacks related to multiple global crises.

Summary of the 2023 Dubai Climate Change Conference: 30 November – 13 December 2023

The 2023 Dubai Climate Change Conference began on a high note. During the opening plenary, parties adopted a decision operationalizing the new loss and damage fund that was established the previous year in Sharm el-Sheikh, Egypt, and a number of parties announced pledges for its initial capitalization. This success was made possible by an agreement reached in the Transitional Committee that was tasked and met throughout 2023 to make a recommendation on the institutional arrangements for the fund.

Ambassador Dr. Aurélie Flore Koumba Pambo and Ambassador Christophe Guilhou, Co-Facilitators of the CBFP, wish you the very best for 2024!

Having just completed the 12th meeting of the Governing Council of the CBFP, we would like to thank you once again for the warm reception you gave the Franco-Gabonese Co-Facilitation, which was set up in July 2023. Six months after the start of our Co-Facilitation, we have spoken out on behalf of the Congo Basin at international meetings including...