- Feb 28, 2022
- 16 min read

REFORESTATION – AN IN-DEPTH INTRODUCTION

Updated: Mar 2, 2022

This is the online version of an NFT that is owned by SeedBomb ASA Limited. The text comprising this article was minted as an NFT, which you can see here.

Natural ecosystems are comprised of a staggeringly complex network of interacting animals, fungi, and plants, which also respond to environmental phenomena. Trees, and by extension, forests are perhaps one of the most quintessential images of nature and wild spaces, yet they are not only beneficial for their aesthetic or recreational value. Trees can also serve as sources of consumable materials like food, building materials and medicine, and provide beneficial services to humans and wildlife, such as reduced risks of flooding, pollution filtration, and vital shade (Díaz et al., 2018). Perhaps most importantly given the environmental and climate challenges facing us today, trees and forests provide critical reservoirs of carbon and water (Di Sacco et al., 2021). The Paris Agreement of COP21, seeking to limit global temperature rises to 1.5-2.0 °C, noted the importance of forests and natural carbon sinks in achieving this goal (UNFCCC, 2018). Exemplifying this importance in mitigating climate change is the fact that 12.42% of greenhouse gas emissions in the United States (US) are already offset by US forests (US Environmental Protection Agency, 2022). Surprisingly, the majority of carbon stored is not contained in the biomass of the trees themselves but is in fact sequestered in the soils, highlighting the importance of soil monitoring and soil health with regard to forestry (Nave et al., 2018).

Despite the many tangible values provided by forests, deforestation rates have generally increased across the world (Rosa et al., 2016) to the extent that an extensive section of the eastern Amazon is now known as the ‘arc of deforestation’ (Fearnside, 2000; Numata et al., 2011; Nunes et al., 2020). Yet hope remains, with the announcement of the UN Decade on Ecosystem Restoration explicitly calling for increases in reforestation and ecological restoration between 2021 and 2030 to combat deforestation, drastic ecosystem collapse and climate change (United Nations, 2019). Indeed, restoration of deteriorated forests (reforestation), as well as conversion of cultivated land to forested areas (afforestation), have the potential to draw massive quantities of carbon out of the atmosphere and store it in both biomass and topsoils (Nave et al., 2018; Santos et al., 2019).

The primary rationale for large-scale reforestation, the potential for the removal of CO2 from the atmosphere, has a relatively long history of research (e.g. Dixon et al., 1994; Silver et al., 2000; Griscom et al., 2017; Fuss et al., 2018; Hawes, 2018; Mitchard, 2018; Busch et al., 2019) relative to the encouragement of reforestation actions by global institutions as a source of negative emissions (the earliest mention being in 2007; UNFCCC, 2008)… Recent analyses evidence the efficacy of reforestation for this purpose – an estimated 9.5 GtCO2 were removed from the atmosphere by reforested tropical areas between 2000 and 2010, with these same forests projected to draw down a total of 31.3 GtCO2 by 2050 (Busch et al. 2019). In the US, reforestation could draw enough carbon into topsoils to offset 0.8-1.3% of yearly emissions, with significant potential upside in the future (Nave et al. 2018). In fact, estimates of the potential for restoration for carbon sequestration may have been drastically underestimated until recently (Cook-Patton et al., 2020) hinting at even greater potential. It is vital that proper planning and implementation of reforestation is undertaken however, as inadequate consideration of the specific localised strategy required to maximise carbon sequestration (and other beneficial aspects of reforestation) can actually result in a net increase in carbon emissions (Di Sacco et al., 2021). Promising new research is also showing that reforestation need not be limited to ‘wild’, rural locations. Teo et al. (2021) model the possibility for urban reforestation to sequester 82.4 MtCO2 a year, in addition other localised benefits (flood protection, mitigation of urban heat island effects and pollution, and benefits to residents’ mental health; Song et al., 2018; Richards et al., 2020).

Reforestation can also stem biodiversity loss, arguably one of the most urgent environmental issues of the present day (Ceballos et al., 2017; Rull, 2022). With a collective decline of 68% in the populations of bird, mammal, fish, reptile, and amphibian species since 1970 (WWF, 2020; see also McCallum, 2021) and even greater losses of invertebrates (e.g. Hallman et al., 2017; Sánchez-Bayo and Wyckhuys, 2019; Cowie et al., 2022). In large part, these declines are a consequence of habitat loss or degradation (IUCN, 2015; Maxwell et al., 2016), and so restoration of habitats may be crucial to ensure that entire populations and species are not eradicated (Possingham et al., 2015; Venteret et al., 2016; Whitworth et al., 2018; Kemppinen et al., 2020). Efforts to aid conservation and stem biodiversity loss through reforestation must be planned correctly however, to avoid unforeseen detrimental impacts (e.g. Heilmayr et al., 2020; Seddon et al., 2020). Most importantly, reforesting with vast monoculture plantations where previously there was natural forest has a whole host of problematic impacts (Di Sacco et al., 2021). Instead of restoring biodiversity, monoculture strategies can actually introduce invasive species (Kull et al., 2019) and decrease diversity (Hua et al., 2016; Wang et al., 2019; Wu et al., 2021). Furthermore, selecting species to sustain or regenerate biodiversity long-term is more complex than simply maximising the number of species (Di Sacco et al., 2021). Given the intricacy of natural ecosystems, careful consideration must be given to the promotion of healthy, mutualistic relationships between species that are being targeted for reintroduction as part of reforestation. Maximal biodiversity requires a resilient, stable ecosystem – it is not simply about reforesting with as many tree species as possible. Fungi and animals which facilitate healthy natural processes, such as the breakdown of organic matter, pollination and seed-dispersal, are crucial (McAlpine et al., 2016; Steidinger et al., 2019). A long-term, patient approach is also necessary in the establishment of a biodiverse reforested (or afforested) area.

The potential for carbon sequestration and enhancement of biodiversity through reforestation is clearly well-documented, however there are many other potential benefits of reforestation. For example, reforestation can provide significant cooling effects at both ground level (Zhang et al., 2020) and in the air (Novick and Katul, 2020), as well as influencing cloud dynamics that result in reduce cooling due to cloud-albedo (Cerasoli et al., 2021). Increasing the stability of soils and the avoidance of desertification is another important service that reforestation can provide (e.g. Hooke and Sandercock, 2012; Song et al., 2022), however benefits are not always necessarily indirect. Reforestation can have significant direct socio-economic benefits to local communities. New reforestation projects can provide employment opportunities in the direct involvement of the work (Di Sacco et al., 2021), while reforested areas can be designed to generate monetisable non-timber forest products (NTFPs) (de Souza et al., 2016). A diversity of NTFPs (and therefore of tree species) provide additional resilience and security by ensuring farmers are not tied to a single asset (as would be the case in a monoculture plantation (Di Sacco et al., 2021). Ecotourism is an emerging industry that has great potential as another source of employment and revenue, although reforested regions need to be at a reasonably mature stage (Almeyda et al., 2010). For reforestation projects to be successful however, local communities should be included at every stage of the development, implementation and ongoing management (Bloomfield et al., 2019). Particularly in the planning stage indigenous local knowledge can be essential in ensuring that the best strategy is chosen (Wangpakapattanawong et al., 2010).

A major decision that factors into any reforestation programme is the level of human intervention that is necessary or required, which can be dependent on the goals or situation of the project. For example, active tree planting and seeding will be necessary in certain areas that would not naturally return to the ecosystem that was present prior to disturbance or degradation (Román-Dañobeytia et al., 2015; Howe, 2016), such as southwestern Australia, coastal forest in Eastern Africa, and Amazonian uplands (for comprehensive lists of similar regions and more information, see Hopper, 2009; Chazdon and Guariguata, 2016; Hopper et al., 2016; and Hopper et al., 2021). This method has been proven to work (e.g. Koch and Hobbs, 2007, see also Stanturf and Mansourian, 2020), however in regions where it is possible, natural regeneration may in fact be preferable. Natural regeneration of forests can result in greater biodiversity (Chazdon et al., 2009; Rozendaal et al., 2019) and carbon sequestration (Poorter et al., 2016; Lewis et al., 2019) than actively planted attempts (but see César et al. 2018). Nonetheless, the choice between active planting and natural regeneration is not necessarily as binary as it initially seems (Di Sacco et al., 2021) – there are varying degrees of intervention which form a gradient from a largely hands-off approach (e.g. Chazdon and Uriate, 2016; Perino et al., 2019) through mild intervention strategies (e.g. Shono et al., 2007, 2020; Philipson et al., 2020) to very active methods (e.g. Zahawi et al., 2013; Bechara et al., 2016; Uebel et al., 2017). However, the timeframe for these benefits to come to fruition can vary (Brancalion et al., 2016). Similarly, the financial investment required with each level of intervention changes in complex ways, costs do not simply increase with the amount of intervention required. Some studies note potentially greater costs in low intervention methods (Zahawi et al., 2014), though the majority of research pointed towards increases in costs with more intervention (Prach and Moral, 2015; Molin et al., 2018; Crouzeilles et al., 2019; Prach et al., 2019).

Despite the mounting evidence pointing towards the multitudinous benefits of reforestation, a reduction in rates of deforestation is undoubtedly a better way to protect the environment; reforestation cannot compensate for the destruction of existing forests (Wheeler et al., 2016; Brancalion and Chazdon, 2017; Meli et al., 2017; Cook-Patton et al., 2020). Mature, natural forests contain huge amounts of carbon that is released into the atmosphere upon deforestation (Seymour and Busch, 2016; Busch et al., 2019; Maxwell et al., 2019), they also store and recycle massive quantities of water, prevent erosion (Veldkamp et al., 2020) and are highly biodiverse (Deere et al., 2020). Yet the reality is that logging and land clearing (the majority of which is attributable to animal agriculture; Barona et al., 2010; Alves-Pinto et al., 2017) are resulting in increasing rates of deforestation of mature natural forests, particularly in the tropics (Busch et al., 2019). In many regions, reforestation is therefore a necessary strategy to restore healthy natural ecosystems.

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REFORESTATION – AN IN-DEPTH INTRODUCTION

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