Tropical forests are losing their carbon storage capacity

Although they occupy only seven percent of our planet’s land area, tropical rainforests are the Earth’s largest carbon sinks, storing between 25 and 40 percent of global soil carbon and thus mitigating to a certain extent some of climate change’s most severe impacts. 

According to a new study led by Colorado State University (CSU) and supported by the National Science Foundation, climate change will significantly affect the carbon storage capacities of tropical rainforests, with persistent drying caused by reductions in rainfall leading to carbon loss from the most fertile soils.

“Tropical forests can be really sensitive to reductions in rainfall and they have some of the largest stores of carbon on Earth. As climate is drying, that carbon is vulnerable,” said study lead author Daniela Cusack, an associate professor of Ecosystem Science and Sustainability at CSU.

“All that carbon that’s stored in rainforests right now is like a bank. We’re banking all that carbon and anything that releases that carbon is going to exacerbate climate change and impact everybody.”

By assessing the effects of natural seasonal drying and persistent reductions in rainfall on carbon fluxes in tropical forests, the experts discovered that these phenomena suppress the release of carbon dioxide. 

“There was some resilience at first, which makes sense because these are seasonal forests, so they’re used to a dry season,” Cusack explained. “But it seems like after that initial resilience, we’re hitting a threshold where things are shifting more rapidly in some tropical forests.”

The ecosystem model that the experts used predicted that chronic drying would increase the release of carbon dioxide from wetter and more fertile tropical forests, while decreasing carbon dioxide fluxes from drier forests. 

“We had predicted that the wettest site would be most sensitive to drying. It’s the least adapted to drier conditions,” Cusack said.

The scientists expected that, as the wettest sites dry down, they would become more favorable for microbes that decompose carbon in soil and turn it into carbon dioxide. Surprisingly though, the investigation revealed that the wettest sites lost the least carbon, while the most fertile ones lost the most. 

These findings suggest that different tropical forests will respond differently – and on different time frames – to climate change, and that the most fertile soils across the tropics could be the first to lose high amounts of carbon as the planet keeps warming.

“This research adds to our understanding of the relationship between tropical forest conditions and carbon sequestration,” said NSF’s program director Tom Evans. “Tropical rainforests are an important carbon sink, and this research documents that different types of tropical forest regimes exhibit different responses to changing climate conditions.”

The study is published in the journal Global Geochemical Cycles. 

The future of tropical rainforests 

The future of tropical rainforests is a topic of concern and interest due to their critical importance for biodiversity, climate regulation, and human well-being. Here are some key aspects that are currently being discussed and addressed by scientists, environmentalists, and policymakers:

Deforestation

Deforestation remains a significant threat to tropical rainforests. The expansion of agriculture, logging, and infrastructure development, driven by economic interests, poses a severe risk to these ecosystems. Efforts are being made to promote sustainable land-use practices, increase protected areas, and enforce stricter regulations to combat deforestation.

Climate Change

Climate change is expected to impact tropical rainforests in multiple ways. Rising temperatures, altered rainfall patterns, and increased frequency and intensity of extreme weather events can affect the distribution and health of rainforest ecosystems. Mitigating climate change through global efforts to reduce greenhouse gas emissions is crucial for the long-term survival of these forests.

Biodiversity Loss

Tropical rainforests are home to an incredible array of plant and animal species. However, deforestation and habitat fragmentation threaten biodiversity by reducing available habitats and disrupting ecological processes. Conservation initiatives, such as the creation of protected areas, habitat restoration, and species conservation programs, are vital for preserving biodiversity in rainforest regions.

Indigenous Rights and Local Communities

Recognizing and respecting the rights of indigenous peoples and local communities who live in or depend on rainforest ecosystems is crucial. Their traditional knowledge and sustainable practices can contribute to the conservation and sustainable management of these forests. Empowering these communities to participate in decision-making processes and supporting their livelihoods are important for the future of rainforest conservation.

Technology and Innovation

Technology can play a significant role in monitoring and managing tropical rainforests. Advances in remote sensing, satellite imagery, and data analysis enable more accurate monitoring of deforestation and forest health. Additionally, sustainable practices such as agroforestry, which combines agriculture and forestry, can provide alternative livelihoods while conserving forested areas.

International Collaboration

Addressing the challenges facing tropical rainforests requires global collaboration. Governments, organizations, and individuals need to work together to implement effective policies, share knowledge and resources, and support initiatives that prioritize rainforest conservation. International agreements like the Paris Agreement and initiatives like REDD+ (Reducing Emissions from Deforestation and Forest Degradation) aim to address these issues.

It is important to note that the future of tropical rainforests depends on the collective efforts of governments, organizations, and individuals to protect and sustainably manage these invaluable ecosystems. By promoting sustainable practices, reducing deforestation, combating climate change, and supporting local communities, we can contribute to a more positive future for tropical rainforests.

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By Andrei Ionescu, Earth.com Staff Writer

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