Towards effective reforestation: growth and commercial value of four commonly planted tropical timber species on infertile soils in Panama

Abstract

Finding suitable tree species that not only grow well on nutrient poor soils but are also safe financial investments is one of the major obstacles to successful reforestation efforts in the tropics. Our study compared the financial viability and growth of valuable timber species in monocultures and mixtures on infertile soils. Our work shows the extraordinary growth in volume and value of Dalbergia retusa and Terminalia amazonia while underscoring the poor financial viability of Tectona grandis and Pachira quinata, all commonly planted timber species in Panama and much of Central and South America. Using Bayesian statistics, our predictions show that T. amazonia monocultures could reach nearly 200 m3 ha−1 of merchantable volume after 30 years compared to the ~ 40 m3 ha−1 that T. grandis could accumulate in the same time frame. While D. retusa monocultures did not have the highest predicted merchantable volumes of all the species, it did have the highest predicted net present value (NPV), with a predicted mean NPV of > US$97,000 ha−1, quadrupling the species with the next highest monoculture’s NPV, T. amazonia monocultures (~ US$20,000 ha−1). Our work emphasizes that reforestation can be financially viable on low nutrient soils, even in the absence of fertilization or other silvicultural manipulations, if species selection and site are carefully considered and matched.

Mapping a conservation research network to the Sustainable Development Goals

“…These include increased climate resilience (Hall et al, 2022), with a focus on reduced flooding (Ogden et al, 2013) (SDGs 1.5, 11.5, 13.1, 13.2), improved water quality (Chavarria et al, 2021) and security (dos Reis Oliveira et al, 2019) (SDGs 6.3, 6.5), and natural heritage protection (SDG 11.4). This research is designed to improve the efficient use of natural resources (SDG 12.2), reinforce land tenure claims and provide economic benefits to landowners through carbon credits and sustainable forest management (Adamowicz et al, 2019; Hall, Kirn, et al, 2015; Sinacore et al, 2022) (SDG 1.4).…”

Species selection and plantation management in enrichment planting with native timber species in the Panama Canal watershed

“…The growth of teak in the Agua Salud plantations is classified as well below average, based on site index curves established for Central American teak (Keogh, 1982;Hall, 2013), and observations from the more fertile soils of the Panama Este and Darien provinces (Fennica et al, 2020). Given low growth rates, teak at Aqua Salud are not projected to be financially profitable within a 20-year rotation (Hall, 2013; Sinacore et al, 2022). In the private plantations, teak growth is similarly poor, though trees are older and thus, on-average, slightly larger (Table 2).…”

“…Given the high value and cultural importance of this species, Panamanian farmers have expressed especially strong interest in cultivation of D. retusa (Garen et al, 2011;Hall et al, 2011a). In a study comparing plantations of native timber species to teak in the PCW, D. retusa was far more productive than teak by all measures (Sinacore, 2018;Sinacore et al, 2022). The species consistently achieves high growth and survival across a range of environmental conditions including dry and infertile sites (Craven et al, 2013;Hall and Ashton, 2016;Soderlund, 2016), but in full-sun conditions D. retusa tends to have a wide-spreading, multi-stemmed growth form that is not ideal for timber; identifying strategies for improving growth form is a management priority (Mayoral et al, 2017).…”

“…Plantation forestry has been heralded as a "win-win" that both provides opportunity for rural landowners to generate income and also preserves the ecosystem services of natural forest cover (FSC, 2012;Kissinger et al, 2012), but these potential benefits are not always realized. Factors that limit the socio-economic benefits of plantations for low-resource producers include insecure land rights and long return times on initial financial investments (Brown et al, 2008;Brancalion et al, 2012;Sinacore et al, 2022), as well lack of technical support and access to markets (Shyamsundar et al, 2018). Ecologically, plantations can contribute to a heterogeneous landscape (Barlow et al, 2007) and increase per-area productivity to facilitate conservation and minimize over-harvesting of natural forests in other areas (Parrotta et al, 1997;Paquette and Messier, 2010), as well as enhancing benefits of natural forests by buffering edges and increasing connectivity amongst forest fragments (Brockerhoff et al, 2008).…”

“…Studies in Central America (e.g., Piotto et al, 2010;Griess and Knoke, 2011;Sinacore et al, 2022) suggest that using native species in PCW FLR efforts can provide greater economic and ecological benefits, but more information is needed to guide implementation and management. Toward this end, this study contributes to a small but growing body of literature (e.g., Piotto et al, 2010;Hall et al, 2011a;Plath et al, 2011;Schneider et al, 2014) that seeks to evaluate the survivorship and growth performance of valuable native species in plantations.…”