Navigating the Complexity of Forest Landscape Restoration: Beyond Tree Planting 

African landscape at sunset
In the endeavour to restore degraded landscapes, the focus often turns to planting trees as a solution. However, a complexity lies in the potential misclassification of ecosystems and the potential unintended consequences of well-meaning restoration efforts.

Recent research published in Science has revealed that ill-judged tree planting in Africa threatens ecosystems. The authors of the paper raise concerns over schemes that plan to plant trees in non-forest ecosystems – such as savannahs and grasslands – which could potentially disrupt or destroy intact ecosystems.

Whilst the Bonn Challenge aims to restore forests, this study identifies possible unintended consequences if tree planting is occurring extensively in non-forest areas.

Although there is an acknowledgement that forest landscape restoration should not cause the loss or conversion of open, nonforested ecosystems, concerns have been raised that the focus on tree-based restoration could lead to misplaced restoration and destruction of intact, ancient ecosystems. This occurs because those ecosystems are frequently misclassified as forest, or because tree cover levels are deemed below potential given the climate and soils. However, increasing tree cover can degrade non-forest ecosystems, leading to biodiversity loss.

The FAO definition of forest is not helpful for most of these degradation examples, because it does not adequately differentiate natural and plantation forest, and is based solely on vegetation structure, meaning that open systems with trees, such as savannas, can be misclassified as forest. Vegetation definitions that only consider tree cover are problematic for tropical grassy biomes because they fail to recognize the grassy layer under the canopy which is a defining feature of these systems. The authors of this study suggest that using biome maps would help to identify true forests more accurately.

It is essential to recognise the differing characteristics of forest and nonforest degradation, as this will determine restoration actions and enable genuinely degraded systems to be restored with greater sensitivity. By recognising the unique characteristics of different ecosystems and landscapes, we can tailor restoration efforts to their specific needs. Biome maps offer a more nuanced understanding, allowing us to differentiate between true forests and other ecosystems like grasslands and savannas.

Restoration actions must be differentiated based on the nature of degradation. What works for a degraded forest may not necessarily be suitable for a grassy biome. It’s imperative to adopt restoration approaches that respect the integrity of each ecosystem, minimising unintended consequences and maximising positive outcomes.

Furthermore, in some cases the study identifies a concerning disparity between reforestation commitments and the actual restoration needs. Many countries pledge to restore areas exceeding their available forest cover, raising questions about resource allocation and the efficacy of restoration planning.

“The urgency of implementing large-scale tree planting is prompting funding of inadequately assessed projects that will most likely have negligible sequestration benefits and cause potential social and ecological harm.” – Dr Nicola Stevens, a researcher in African environments at the University of Oxford and co-author of the paper

This study examined restoration projects taking place in AFR100 countries to determine if savannas and other nonforest ecosystems are the target of on-the-ground tree-planting restoration projects. Across Africa, 133.6 million ha has been pledged toward AFR100 in 35 countries, exceeding the original target of 100 million ha by a third. Of this, only 25.0 million ha is earmarked for restoration in nonforest systems, with many countries making forest cover pledges covering an area greater than forest area available.

This could lead to a failure to meet UN Restoration Principles in nonforest ecosystems, as biodiversity outcomes can be poor and increasing woody cover in open ecosystems is itself a cause of degradation. The research also found that 52% of tree-planting projects in Africa are occurring in savannahs, with almost 60% using non-native tree species, which also brings the risk of introducing invasive species.

“Restoration of ecosystems is needed and important, but it must be done in a way that is appropriate to each system. Non-forest systems such as savannahs are misclassified as forest and therefore considered in need of restoration with trees. There is an urgent need to revise definitions so that savannahs are not confused with forest because increasing trees is a threat to the integrity and persistence of savannahs and grasslands.” – Kate Parr, a professor of tropical ecology at the University of Liverpool and co-author of the study.

Read the paper here.