Guest Post by Jessa Ata, 2021-2022 Sustainability Leadership Fellow, and Ph.D. Candidate in the Department of Agricultural Biology at Colorado State University

I. In for the hype

The popular notion of trees as a means to solve global environmental problems has fueled the recent spike in tree planting initiatives and people’s interest in tree planting. In the hopes of restoring nature, big investments have been funneled toward ambitious large-scale reforestation programs especially in regions highly vulnerable to forest degradation. This has caused considerable stir among scientists and environmentalists for several reasons. Well-intentioned as they may be, tree planting schemes can easily fail with serious consequences for generations to come. Here, I explore the technical and social complexities of tree planting, and the best (and worst) practices to achieve a successful massive tree planting program.

II. The ideal vs. reality

Some would say the best moments happen when unplanned. But in the case of tree planting, you might want to think twice. To quote Brancalion & Holl (2020), “Well-planned tree planting projects can be a valuable intervention to address some of the most critical challenges of our time, such as mitigating climate change, conserving biodiversity and providing food, wood and income to small landowners.” Unfortunately, there have been many cases of tree planting projects missing the mark.

Successful tree planting requires an appropriate mix of species planted in areas that match their growth requirements. The right species are most often those that are native to the area. Being well-adapted to the landscape means native species require less inputs (e.g., fertilizers) to establish, are less vulnerable to pests and diseases, and are more likely to enhance biodiversity. When this principle is not adhered to, the results can be catastrophic. Aside from the displacement of native vegetation which occurred with the planting of the aggressive exotic Prosopsis sp. in Africa, one can’t overlook the potential unintentional tragedy that exotics can inflict.  For example, the entire population of native American chestnut trees was wiped out by an exotic disease brought into the country attached to non-native trees planted indiscriminately. Non-native reforestation also sparks fears of hybridization in the Andes, making invasion even more complex as novel, physically indistinguishable hybrids can genetically pollute native populations and propagate without control in sight (Gaskin, 2016).

Poor understanding and assessment of where to grow your trees could only lead to ecological harm, tree death and millions of dollars going down the drain. Tree planting efforts in arid and semiarid regions often have extremely low survival rates, increased disease incidence as trees become highly stressed, and intense desertification due to planting fast-growing trees with low water efficiency (Cao et al., 2010). We are now seeing this effect as we watch South Africa axe hectares of water-loving non-native trees to reclaim billions of liters of lost water. This of course comes with a huge bill to cover the cost of operation. Poor site-species matching also leads to botched mangrove reforestation efforts in many coastal areas worldwide, characterized by stunted or dead mangrove seedlings and reduced diversity of natural seagrass communities (Mendoza et al., 2019). Sadly, one can only mourn the reported demise of millions of seedlings (and the millions of dollars lost!) in various countries from such ill-advised reforestation programs.

One key aspect that tends to be left out of reforestation programs is people. Collaboration is critical for success in implementing tree planting initiatives. It is essential that local people be involved from the get-go not only to resolve land tenure issues (Brancalion & Holl, 2020) but also to “elect among several options of tree species and tree-growing technologies” (Warner, 1994). Many tree plantation efforts were unsuccessful when they failed to acknowledge and work with local communities and other stakeholders. The news is sprawled with many low-intensity conflicts that escalated to violence stemming from planting trees in disputed lands. Planting the wrong kind of trees in some tree planting programs were also met with resistance as they were deemed undesirable by the locals. In many cases, such discontent has led to planted seedlings being pulled out or burned by dissatisfied local people.

Lastly, tree planting activities need to be regularly assessed to determine whether short and long-term goals have been met. Unfortunately, poor and inconsistent reporting of reforestation programs (e.g., species planted, survival rates, and seed/seedling sources) and questionable claims of reforestation success currently plague many nations and tree-planting organizations. While the uncoordinated tree planting initiatives in multiple scales (local, regional and international) makes tree planting success rather sporadic, the success stories of other million-dollar reforestation programs have lost credibility with allegations of financial fraud.

III. So, what now?

Nature has its ways of healing itself but it does not mean humans can’t help. We can assist and enrich forest restoration in natural forests by protecting and nurturing natural regeneration and by transplanting seedlings in forest understories, a system proven to be effective especially when combined with local indigenous knowledge. When exotics are the only viable option – as in some large areas of denuded forests – a clear set of policies and management strategies need to be in place to mitigate the risk of invasiveness and the negative impacts that may, directly or indirectly, come along with it.

This also means supporting science and local communities to help identify key species and sites for forest rehabilitation. Scientific research will guide decisions on where and what to plant with better chances of sustainability and long-term survival of rehabilitated ecosystems. Establishing dialogue between local communities, other stakeholders, and project implementers will also unify goals, optimize resources, resolve conflicts, minimize tradeoffs, and maximize benefits to people and nature. At the end of the day, honest reporting is critical not only to assess our progress in the biophysical, socio-economic, institutional and financial aspects of reforestation but also to serve as a benchmark for future tree planting programs. Of course, all these cannot be achieved in just a blink!

Rebuilding a forest takes adaptive strategies from careful planning and collaboration to a great deal of patience and dedication. Take it from the Republic of Korea. Its lush forests that stretch across vast horizons are a product of decades of institutional changes to prioritize a greener nation. Apart from Korea’s values embedded in their religion and culture, the Korean government has instilled in their people the act of tree planting as an “act of patriotism” (Rivera, 2011). And no doubt, science played a huge part in identifying the right technologies to ensure tree planting success.

Tree planting is not the silver bullet to the global environmental issues we are facing today. It is, however, still “one of the best options to offset a portion of anthropogenic carbon emissions” (Holl & Brancalion, 2020). But before embarking on massive tree planting efforts, we should reflect on the basics and the complexities to make them a success.

References 

Brancalion, P. H. S., & Holl, K. D. (2020). Guidance for successful tree planting initiatives. Journal of Applied Ecology, 57(12), 2349–2361. https://doi.org/10.1111/1365-2664.13725

Cao, S., Tian, T., Chen, L., Dong, X., Yu, X., & Wang, G. (2010). Damage Caused to the Environment by Reforestation Policies in Arid and Semi-Arid Areas of China. AMBIO, 39(4), 279–283. https://doi.org/10.1007/s13280-010-0038-z

Gaskin, J. F. (2016). The role of hybridization in facilitating tree invasion. AoB Plants, plw079. https://doi.org/10.1093/aobpla/plw079

Holl, K. D., & Brancalion, P. H. S. (2020). Tree planting is not a simple solution. Science, 368(6491), 580–581. https://doi.org/10.1126/science.aba8232

Mendoza, A. R. R., Patalinghug, J. M. R., & Divinagracia, J. Y. (2019). The benefit of one cannot replace the other: Seagrass and mangrove ecosystems at Santa Fe, Bantayan Island. Journal of Ecology and Environment, 43(1), 18. https://doi.org/10.1186/s41610-019-0114-7

Rivera, R. (2011). “Turning bare land into a green nation”: How South Korea recovered its degraded forests. CIFOR Forests News. https://forestsnews.cifor.org/4723/turning-bare-land-into-a-green-nation-how-south-korea-recovered-its-degraded-forests?fnl=en

Warner, K. (1994). Selecting tree species on the basis of community needs. Food and Agriculture Organization of the United Nations.