Our planet is in a state of emergency. Wildfires ravage drought-ridden landscapes often spilling over to towns and burning them to dust. Tropical storms and floods submerge our neighbourhoods, destroying the lives of millions. Outbreaks of new tropical diseases are rising, increasing the risk of more future epidemics and pandemics. A million species are on the brink of extinction, and global inequality threatens basic human right. These problems root from global climate change and biodiversity loss, which require urgent solutions and action.
We often talk about high technological solutions to addressing these global challenges. For example, Elon Musk recently announced that he’s awarding a 100 million USD money for the best carbon capture technology. It’s right that we invest in new technologies to curb climate change, but these technologies are still under development. Scaling up and implementing these high-tech solutions will take time, and time isn’t something we have in our struggle against climate change. We need urgent actions now, and our best bet is still in low technological, nature-based solutions that are available for implementation right now.
Trees provide such a natural solution to our biggest problems. They’re great at capturing the carbon from the atmosphere and release oxygen. They create perfect habitats for endangered species and provide a livelihood for those living in poorer regions. Moreover, tree covers in cities also protect urban residents from the effects of global heating. Forests and trees offer us countless ecological, economic, health and social benefits, yet destruction and degradation of forests through deforestation is a global problem, especially in the tropics.
Recognising the importance of forests, governments, and companies worldwide have pledged (many times) to reduce and stop deforestation. One such pledge is the 2014 New York Declaration on Forestry, which aims to reduce deforestation by half by 2020 and end it by 2030. Unsurprisingly, this declaration has already failed its 2020 target! Its own 2019 Progress Assessment concluded: “Tropical deforestation has continued at an unsustainable pace since 2014.” The alarming global deforestation rate means we’ve already lost a significant portion of our forest that needs restoration immediately. Currently, over sixty countries are restoring 210 million hectares of degraded and deforested lands.
But it turns out that forest restoration isn’t as simple as people think. Over simplistic approach to reforestation can lead to catastrophic failure on achieving key objectives. Some of the unintended consequences of a poorly planned reforestation attempt include displacement of native biodiversity by invasive species, reduced croplands and food production, disruption of the water cycle, and decreased carbon storage in biomass and soil. Tree plantations usually go wrong due to monoculture plantations rather than restoration through a mix of native tree species.
That’s why a group of scientists have now come up with ten “golden rules” for reforestation designed to increase carbon fixation, increase biodiversity and provide sustainable livelihoods. Researchers hope that their golden rules act as a useful guide for policymakers, advisors and practitioners of reforestation in avoiding many pitfalls of large-scale tree-planting.
There’s been a lot of coverage on whether tree planting is the most effective way response against climate change. Of course, it’s important to take the greenhouse gases in the atmosphere and return them to where they belong: in the ground — and trees can help us do that. However, research suggests that the most effective way of reducing atmospheric greenhouse gases is to stop using fossil fuels. See my blog: Planting trees is vital, but it won’t stop climate change. We must reduce fossil fuel use.
Still, I believe these aren’t binary options; we must aggressively pursue all strategies to overcome the global crisis that we face. For an effective response against the climate emergency and biodiversity crisis, we must immediately restore forests and degraded land through reforestation and tree planting; prevent any further deforestation; also reduce our dependency on fossil fuels, eventually stop using them.
Anyway, the purpose of this blog is to highlight the best approach to tree planting. See the headings below for my summary of the 10 Golden Rules for Reforestation.
1. Protect existing forest first
Before planning reforestation, always look for ways to protect existing forests, including old- and second-growth, degraded and planted forests.
Despite attempts to prevent deforestation, we’re losing forests rapidly — and reforestation isn’t exactly compensating for the loss of woodlands. Therefore, both national and local level action is needed to protect forests. Often identifying why deforestation is taking place amongst all stakeholders is key to protecting forest at the local level.
Intact, mature forests are significant long-term carbon sinks due to their complexity, large trees, accumulating soils, and resilience to fire and drought. Destruction of such virgin (old-growth) forests may take centuries to recover, especially the rare and vulnerable species. Of course, once extinct, these species will never return. These intact, old-growth forests offer the greatest value in carbon storage and wildlife, so we must prioritise their protection. Forests grown after recent disturbances (second-growth forests), degraded and logged-over forests also need protection.
2. Work together
Involve all stakeholders and make local people integral to the project.
Reforestation projects impact the livelihood of a wide range of individuals. The scale and goals determine who should be involved in the project. There’s no need to engage widely to reforest smallholder farms, whilst large-scale reforestation requires extensive engagement. Stakeholders who are likely to have an interest in reforestation are those that are most likely to be impacted. They include national and local governments, forestry departments, NGOs, civil society, the private sector, landowners, farmers and other land users, as well as universities, botanic gardens, herbaria and other research institutes.
Local communities have the most to gain from forest protection and reforestation projects. Involving the locals from the planning stage through to delivery and monitoring is vital for successful outcomes. Increasing community participation improves positive outcomes, including community wellbeing, equitable distribution of benefits and knowledge. Passive participation can lead to community hostility and disputes over access rights. Before planting any trees, stakeholders should agree on how the costs and benefits will be shared. Reforestation projects are more likely to fail if the priorities differ between local communities and project managers.
3. Maximise biodiversity recovery to meet multiple goals
Restoring biodiversity facilitates other objectives — carbon sequestration, ecosystem services and socio-economic benefits.
Reforestation is not the goal itself but a way to achieve different objectives. Reasons for reforestation include climate change mitigation, biodiversity conservation, socioeconomic benefits (including food security), and soil and water stability. Of course, different priorities of reforestation will involve different strategies and stakeholders. Therefore, knowing the reforestation goals before planting trees will help appropriate project planning, implementation and monitoring success.
Reforestation through native forest approach often allows high levels of biodiversity, making it easier to achieve multiple objectives simultaneously. If the same native species aren’t available for forest restoration, then other native species may be the best bet. Selecting tree species to reinstate forest cover requires using scientific evidence.
A key principle to remember in reforestation projects is to never harm local communities, native ecosystems and vulnerable species.
4. Select appropriate areas for reforestation
Avoid previously non-forested lands, connect or expand existing forest, and be aware of displacing activities that will cause deforestation elsewhere.
Even though there are several tree-planting initiatives globally, reforestations require implementation at a local scale. Therefore, forest restorations require evaluation at the landscape level or below. Selecting areas for reforestation should consider a combination of historical, ecological and socioeconomic factors at different scales. Some tools and resources are available to help guide these decisions, but there’s a need for more. For example, the Restoration Opportunities Assessment Methodology helps quickly identify and analyse areas for reforestation at a national and local level.
In general, it’s more beneficial to re-establish a diversity rich forest in areas that were previous forested but is now degraded. Reforestation should not take place in non-forested areas such as grassland, savanna, wetlands and peatlands. Such areas are rich in biodiversity and store a significant amount of carbon in soils, which would otherwise be lost by planting trees. Therefore, tree planting initiatives need to define “no-go zones”, where restoration should focus on non-forest vegetation.
Ideally, tree planting should expand existing forest. Creating buffer zones and corridors between the restored land to existing natural forests allows native species to migrate and expand their distribution. Finally, it’s vital to consider who is currently using the land, how will they be compensated for income losses, and where will they move their activities? Not considering these factors can result in social conflicts, further deforestation or the user reclaiming the land later. Land tenure and forest governance are vital for the success of reforestation.
5. Use natural regeneration where possible
Natural regeneration can be cheaper and more effective than tree planting, where site and landscape conditions are suitable.
A forest’s natural regeneration offers significant benefits compared to plantations in terms of carbon capture, biodiversity richness and affordability. Natural regeneration ranges from no human intervention to high intervention, where parts of the site undergo intensive plantation to enable the rest of the land’s natural regeneration.
Degree of degradation and previous land use affect regeneration potential. Soil quality, landscape and hydrological features are other factors that determine the level of human intervention required. Sometimes, a single large site may need different levels of intervention within it.
6. Plant the right species to maximise biodiversity
Plant a mix of species, prioritise natives, favour mutualistic interactions and exclude invasive species.
If natural regeneration isn’t possible (Golden Rule 5), trees should be planted after carefully selecting plantation species. Selecting a mix of species (either with native species only or a mix of native and non-native) will make the forest more resilient to disease, fire and extreme weather events. Monoculture plantation and planting invasive species should be avoided.
When selecting tree species for plantation, it’s also important to consider tree species’ adaptability to climate change. If the effect of climate change has an impact on the native species, then non-native species that preserve the ecosystem function may be the best option. Selecting non-native species for reforestation requires carrying out comprehensive risk assessments.
Several tools and database available can help in selecting tree species for plantation. For example, the Global Tree Assessment aims to provide conservation assessment of all tree species. The GlobalTreeSearch database can help identify the distribution of tree species worldwide and generate a list of native species for each country. Local botanical experts and ecologists also offer invaluable knowledge of the local ecosystem, which can help select the native species for plantation and forest recovery.
Scientists recommend a mixture of 20–30 species (mostly native) for plantation for biodiversity recovery. However, maximising biodiversity depends on the mutualistic interaction between the native trees with other species in the ecosystem, such as fungi, seed-dispersing animals, and pollinators. These interactions are vital for ecosystem recovery, but they rarely get the credit they deserve.
In heavily degraded plantation sites, it’s difficult for rare and threatened to establish themselves. Therefore in such cases, it’s effective to plant fewest native trees that can survive and grow in unfavourable conditions first. This approach will complement and promote natural regeneration and recapture the site from weeds in 2–3 years. Once the forest is an appropriate maturity, it’s best to introduce rare and threatened species. Conservation of vulnerable species requires such an approach to protect them and ensure that they have the best survival chance.
7. Use resilient plant material
Obtain seeds or seedlings with appropriate genetic variability and provenance to maximise population resilience.
Selecting genetically diverse species, consistent with local and regional genetic variation, is important for the planted forest’s survival and resilience. Using seeds with low genetic diversity can result in the planted forest being disease-prone and unable to adapt to long-term environmental changes. Therefore, seed collection strategy should include randomly collecting seeds from many individuals across a full extent of the parent population, including rarest species.
8. Plan ahead for infrastructure, capacity and seed supply
From seed collection to tree planting, develop the required infrastructure, capacity and seed supply system well in advance, if not available externally. Always follow seed quality standards.
Whether the reforestation involves planting trees or seeds, they require infrastructure and supply systems. An advanced decision is required to determine whether to get seeds and produce seedlings yourself; subcontract these tasks; or buy plant material from external suppliers. Seeds from a third party, usually by state agencies or commercial suppliers, can come directly from the wild or wild-origin seed orchards.
However, if the seed suppliers fail to meet plant material requirements (Rule 6 and 7), projects need to collect, store and propagate seeds themselves. This requires equipment, storage facilities and specialist knowledge for collection from trained seed collectors. National legislation and local laws on access to biological material and international seed standards must always be followed.
Planting seeds directly requires the seeds to be primed for optimal germination and protected from predators and diseases. Seeding requires a plan, including site preparation and seeding strategy, as well as monitoring after planting. Sapling plantation requires an in-house nursery or equivalent.
No matter what the plan is, it’s important to include infrastructure and expertise requirement right from the start. Often local people can provide a source of labour and expertise and facilitate infrastructure arrangements, so it’s important to engage with them properly.
9. Learn by doing
Base restoration interventions on the best ecological evidence and indigenous knowledge. Perform trials before applying techniques on a large scale. Monitor appropriate success indicators and use results for adaptive management.
Implementation of any intervention should be based on scientific evidence and indigenous knowledge. Where scientific evidence isn’t available or takes time to generate, traditional knowledge acquired over many generations is beneficial. Ideally, large-scale tree planting should follow on from small-scale trials, which confirm the approach’s effectiveness. However, trials take time and aren’t always feasible, so it’s important to monitor progress and adapt the strategy if needed.
Three things are important to monitor forest restoration: (1) the restoration site itself; (2) control site without any intervention; (3) reference forest site (target). Comparing the restoration site with a control site allows seeing the improvement, and comparing the restoration site with the target site allows seeing progress against the end goal. Data should be collected before, just after restoration intervention, and annually thereafter.
Biomass and biodiversity are usually the best indicators to monitor since they provide several ecological and socioeconomic benefits. Biomass is estimated from stocking density and tree sizes in sample plots, whereas plants and birds usually are monitored for biodiversity recovery. Monitoring should also assess progress against reforestation goals, such as the recovery of endangered species, erosion control, or livelihood benefits (jobs created, income and equity). Socioeconomic monitoring is also important to track the benefits to local communities, and that changes in land and resources values have no negative social consequences.
Monitoring generates data for adaptations in the future — of course, if reforestation isn’t achieving key objectives, then changes are required.
10. Generate income for all
Develop diverse, sustainable income streams for a range of stakeholders, including carbon credits, non-timber forest products, ecotourism and marketable watershed services.
Reforestations are more likely to succeed in the longer term if the restoration’s income exceeds those from alternative land uses. Income must be shared fairly amongst all stakeholders, including the poorest.
Biomass accumulation and biodiversity recovery are the two most important indicators of restoration that generates a value of forest ecosystem services. Ecotourism, watershed services (water purification, groundwater, erosion control etc.), non-timber forest products, and carbon credits are examples of ecosystem services that offer ways to monetise forest restoration.
In summary, the guidelines show that reforestation is more complex than many think, and that involving many stakeholders at each stage of the reforestation will generate long-term benefits. Large-scale reforestation and ambitions for a post-COVID green recovery can improve global ecology and improve local livelihoods. However, this will only happen based on sound science, indigenous knowledge, local communities’ support, equitable governance, and the right incentives.
Scientists have proposed these golden rules for reforestation to maximise carbon capture, biodiversity recovery and livelihood benefits. Let’s hope that it will help turn the hope of global forest restoration into reality.
Read the full scientific review “Ten golden rules for reforestation to optimize carbon sequestration, biodiversity recovery and livelihood benefits,” here: https://doi.org/10.1111/gcb.15498