Conservation vs Reforestation: Protecting Old-Growth Forests or Planting New Trees

Forests are one of nature’s most potent weapons in the battle against climate change. These towering, complex ecosystems act as carbon vaults, absorbing and storing greenhouse gases from the atmosphere through the magic of photosynthesis. Beyond just carbon, forests provide irreplaceable biodiversity value and essential ecosystem services like water filtration, soil conservation, and nutrient cycling. With human activities driving alarming rates of deforestation and forest degradation over the past century, restoring the world’s forests is more critical than ever. 

However, in a world of limited conservation resources and capacity, a debate rages around strategy –

 Should the priority be preserving ancient old-growth forests or actively replanting young trees worldwide? 

As with many polarized debates, the truth lies somewhere in the middle. Both saving the last intact stands of primeval nature and creatively planting new native forests have crucial roles to play in climate change adaptation and biodiversity preservation. With smart policies and balanced action, the world’s remaining carbon- and species-rich old-growth forests can be protected for centuries to come, even while scaling up young forest cover elsewhere.

The Carbon and Biodiversity Value of Old-Growth Forests

In the carbon storage battle, mature forests have a secret weapon: time. Forests accumulate carbon as they age, with the largest concentrations found in primeval stands dominated by elderly trees. A single tree over 500 years old can contain over 900 tons of CO2, equivalent to the emissions from driving 200 cars for a year. In primary forests, like the Amazon rainforest, about a fifth of all the carbon is locked in just 1-2% of hyper-mature trees. Extrapolated worldwide to remaining old-growth forests, these senior trees hoard huge reservoirs of carbon that would be released if cut down. Preserving these natural carbon vaults locks away greenhouse gases that would otherwise be heating the planet.

old growth forests tree

However, the benefits of old forests extend far beyond just carbon sequestration. Half of the forest biodiversity worldwide is dependent exclusively on the microclimates and habitats found in mature, multi-aged stands. Features like large snags, accumulations of decaying woody debris, and canopy gaps provide specialized environments not found anywhere else. Species from tiny lichens to majestic spotted owls rely on the biodiversity riches of old forests for survival. 

The complex interdependent ecosystems of primeval forests, like mycorrhizal networks, can take centuries to re-establish if disturbed. Protecting remaining old-growth stands and allowing them to expand free from human pressures thus provides lifesaving support for thousands of threatened forest species. Simply put, nothing on Earth can replace a naturally evolved old-growth forest.

The Potential Scale of Reforestation Efforts

At first glance, it may seem that actively planting trees could capture more carbon and do more good for the planet than just cordoning off patches of old-growth forests. After all, CO2 emissions are accumulating rapidly, and too much pristine nature would limit economic development, right? 

Wrong, actually. Recent research suggests there are a staggering 900 million hectares worldwide suitable for active reforestation without compromising food production or urban development. That is over twice the size of Alaska! Restoring even a third of this land area back to natural forests could capture a whopping 205 billion tons of CO2 from the atmosphere. For context, that is nearly two-thirds of all the carbon pollution humans have released since the start of the Industrial Revolution. Talk about making a dent…


Strategically planted forests also provide connectivity between fragmented wildlife habitats, benefiting biodiversity too. Planting native trees as buffers around protected old-growth reserves prevents damaging edge effects like fire and invasive species. Reforesting degraded habitats better supports vulnerable species; for example, planting corridors of oak forest allows endangered squirrels to expand beyond isolated pockets. Intelligently executed worldwide, massive tree planting could start reversing climate change while also allowing species room to migrate and thrive.

Comparing the potential benefits of old-growth forest vs reforested land. 

  • Old Growth Primary Rainforests:

When it comes to carbon storage and biodiversity values, primary old-growth rainforests are virtually irreplaceable, even with well-meaning reforestation efforts.

  • Research shows that a significant amount (over 50%) of all carbon is stored in just 1-2% of ancient trees over 1,500 years old. The Amazon for example, contains lots of these ancient rainforests that have been growing and accumulating carbon for over 2 million uninterrupted years
  • Old-growth forests have coevolved with complex interdependencies between 40,000+ plant species per acre, fungi networks, and terrestrial and aquatic wildlife developed over millennia. 
  • Scientists warn that losing more than 20% of primary rainforest cover leads to catastrophic tipping points for both climate and biodiversity values. Preserving the remaining old-growth rainforests is critical to preventing climate change and mass extinction tipping points.
  • Reforestation:

Reforestation does show potential for partial carbon and habitat recovery, however, albeit over centuries rather than millennia.

  • 10–20 years of undisturbed regrowth of cleared rainforest lands can achieve ≤50% original biomass and species diversity.
  • Latent root structures and residual seed banks facilitate partial forest succession and carbon recovery long-term, however, with a much longer timeline. 
  • Research shows limited recovery potential for some endemic birds, lizards over decades in regenerating areas.
  • Connecting secondary forest habitat corridors facilitates more wildlife recolonization over centuries.

Fragmented patches of secondary or planted forests simply cannot mimic such rich, interconnected ecosystems. There is simply no substitute for irreplaceable old growth bounty, but any secondary regrowth is a viable environmental option. 

The Current Reality of Forest Loss

However, the sad reality remains that, despite reforestation rhetoric, net global forest cover continues to decline. For every tree planted, an estimated 5 trees are still being destroyed worldwide by deforestation and land conversion. Most critically, what remains of ancient carbon and species-rich old growth such as the Amazon rainforest, is increasingly under threat. In the Congo and Canada, only 10% and 8% of the original old-growth primary forests are still intact.

deforestation in Amazon Forests

Even supposedly “protected” forests are being steadily fragmented into smaller patches; the proportion of tropical forests in fragments less than 1 square kilometer has doubled to over 20% just since the 1990s. As small forest fragments lose their core habitat area, prevention of fires and hunting becomes impossible, degrading carbon stores and biodiversity. Clearly, despite global pledges of carbon neutrality and conservation support, business-as-usual economic interests continue bulldozing irreplaceable old-growth while mostly planting timber concessions rather than natural forest.

What are the most effective and efficient ways to eliminate CO2 with minimal resources?

While reforestation is an ideal option, it may not be the most efficient in terms of time, amount of CO2 sequestered per year, and associated financial cost, among other factors. More efficient alternatives would be preserving existing forest ecosystems, while improving the management of existing forests would be more efficient. These approaches, in addition to reforestation, provide a healthy CO2 sequestration strategy.

  • Preserving existing forest ecosystems.

As previously stated, older and dense forest trees store a considerably higher amount of CO2 when compared to younger trees, providing a high rate of carbon emission removal per hectare at a relatively lower cost. Protecting existing forests appears to be one of the cheapest and fastest strategies to combat rising CO2 emissions. Protecting the rainforest compensates for any emissions that may have resulted from changes in land use, conserves habitat for wildlife animals, and limits deforestation.

  • Improving management means lowering emissions while absorbing CO2 from the atmosphere.

Improving management includes preserving current forest ecosystems and biomes while looking for solutions to reduce CO2 emissions. It offers a significantly lower relative cost than reforestation and related restoration processes. A more complex but effective solution investigates regenerative agricultural practices such as tree planting in croplands, fertilizer management, and cover crop planting to increase soil fertility. These practices are integrated with existing practices and do not have the problem of leakage, as is the case with forests. Leakage occurs when individuals leave one protected area to continue their environmentally unfriendly practices in another, resulting in a net loss. Improved management tackles these issues by focusing on cutting emissions while simultaneously removing CO2 from the atmosphere.

  • Reforestation efforts are pivotal to the existence of the planet.

One of the most crucial tasks in protecting our world is reforestation. However, as previously stated, reforestation as a stand-alone approach may be ineffective. According to one study, replanting is far more beneficial than avoiding deforestation. Younger trees, as they grow, tend to absorb more CO2 than older trees over time. In general, protecting rainforests is good, but protecting forests while also developing new forests is even better.

Takeaways: One step closer to a healthier and more sustainable climate.

In summary, society faces two parallel forest crises: protecting the last irreplaceable biologically rich old growth while also urgently needing more tree cover worldwide to stabilize the climate. Thankfully, these goals need not compete but can rather synergize to mutual benefit. Reframing forests as more than just carbon stockpiles, but as the planet’s life support systems, housing over 80% of terrestrial biodiversity, is key. With balanced policy and voluntary action from governments, corporations, and communities, Earth’s remaining old forests can provide their lifesaving gifts for centuries more, even as next-generation forests mature to aid in the climate fight. Our planet’s beating heart depends on it. 

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Picture of David Imolore

David Imolore

David Imolore is a content writer with FundThePlanet, with a passion for writing on crucial topics such as rainforest conservation, climate change, and sustainability for people and businesses. His passion lies in raising awareness about the importance of preserving our planet's vital ecosystems. Through his writing, he strives to inspire positive climate action and foster a deeper connection between individuals, communities, and the environment.
Picture of David Imolore

David Imolore

David Imolore is a content writer with FundThePlanet, with a passion for writing on crucial topics such as rainforest conservation, climate change, and sustainability for people and businesses. His passion lies in raising awareness about the importance of preserving our planet's vital ecosystems. Through his writing, he strives to inspire positive climate action and foster a deeper connection between individuals, communities, and the environment.
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