Atmospheric CO2 increase is the main cause of climate change, likely to have a great impact on the environment and economic development in many parts of the world. Forests have a primal role in absorbing CO2 and storing it as wood or in the soil, reducing its concentration, helping to slow down the greenhouse. Therefore, increasing the number and size of forests through afforestation or reforestation is an alternative to reduce or counteract the amount of CO2 in the atmosphere (Law et al., 2018). Thus, reforestation and afforestation are among the most promising natural climate solutions in terms of carbon sequestration (Bastin et al., 2019), and associated co-benefits (Schulte et al., 2021). Forests, including forest plantations, cover approximately 3,997 Gha worldwide and store large amounts of atmospheric CO2, which according to Harris et al. (2021) were a net carbon sink of -7.6 ± 49 GtCO2 yr− 1.
Although planted forests are primarily intended to produce timber for commercial purposes, they are increasingly recognized for their environmental benefits like mitigation of land degradation, their potential to ameliorate climate change and their ability to enhancement biodiversity (Nambiar, 1999). Thus, fast-growing planted forests represent an interesting alternative for developing carbon sequestration projects, because young forests (in full growth stages) store carbon at very high rates (Wright et al., 2000).
In Chile, the potential of forests planted with fast-growing species in relation to carbon sequestration is interesting. Although the country has a competitive timber market and a Climate Exchange that supports the design and development of greenhouse gas emission reduction projects, there is only an incipient carbon market, which impedes the supply of forest carbon from large private landowners as a climate mitigation tool. At the same time, using fast-growing species is a key component of Chile’s Nationally Determined Contributions (NDC) to limit global warming to well below 2, compared to pre-industrial levels (Gobierno de Chile, 2020).
Currently, forest plantations exceed 2.3 million ha, out of them, Pinus radiata D. Don (PIRA) holds the largest area, with 55.98% coverage, followed by eucalyptus plantations with 36.82%, where Eucalyptus globulus Labill (EUGL) and Eucalyptus nitens (Deane and Maiden) Maiden (EUNI) stand out with 25.02% and 11.79% of the total INFOR (2021). Only 34.4% of plantations area -around 697,579 ha, is managed by small and medium landowners, where 69.3% is maintained by the segment of small owners with 483,831 ha.
Pan et al. (2011) argue that decisions in forest management practices can influence C uptake and storage in woody biomass and soils. Thus, in recent decades, interest has developed in reducing the frequency of forest harvesting (also referred to as “extended rotations”), with the purpose of favoring the maintenance and development of high levels of in situ forest C storage (West et al., 2019; Law et al., 2018; Balboa-Murias et al., 2006).
Most of the existing literature studies are species with longer rotation periods (Kärenlampi, 2021; Harmon and Marks, 2002; Foley et al., 2009; Roberge et al., 2016) and case studies and comparative analyses of fast-growing tree species with short rotation periods are scarcely reported. Examples of the latter are findings by West et al. (2019) on Eucalyptus sp., Acacia sp., Pinus sp. and Tectona sp. showing decreasing carbon sequestration yields with increasing carbon payments and, as well as the study in radiata pine and maritime pine by Balboa-Murias et al. (2006) that showed how increasing rotation age and site quality and decreasing in thinning intensity, resulted in increases in total C stocks of aboveground and aboveground biomass.
In Chile, Eucalyptus spp and PIRA have enormous carbon sink potential, occupying an important position in the forest carbon sink, becoming the main forest carbon sink (Olmedo et al., 2020). The species are planted forests in the center-south of the country, with important timber production and benefits, ecological and social, and play an important role in the national economy (Tricallotis et al., 2018).
Carbon trading realizes the ecological benefits of forests through carbon subsidies and monetizes the ecological functions of forests (Streck, 2020). The comprehensive benefit based on carbon sink benefit has become the main body of carbon sink wood composite management. Analyzing the impact of changes in economic factors on comprehensive benefit, timber benefit and carbon sink benefit has important practical significance for realizing multiple benefit management and optimal forest management.
However, afforestation rates have declined considerably and the willingness of forest producers to afforest has weakened due to the loss of government incentives, which has affected to some extent the sustainable development of existing plantations. Then, the possibility of incorporating new and existing forest owners into carbon trading makes the ecological benefits of forests a reality through carbon stream payment, which monetizes the ecological functions of forests. One way to achieve this is by converting the forest’s benefits into carbon credits under existing standards such as the Verified Carbon Standard (VCS). In the VM0003 methodology, VCS quantifies the greenhouse gas emission reductions and removals generated from improving forest management practices to increase the carbon stock on land by extending the rotation age before harvesting. And in this way, increasing the average carbon stock on the land and removing more emissions from the atmosphere (Ecotrust, 2012).
Estimating the monetary value of carbon stored or fixed can have an impact on the way forests are evaluated for fiscal policies, in order to calculate optimal environmental taxes or subsidies (Ovando et al., 2010). Thus, it is important to analyze the impact of changes in economic factors on integrated benefits, i.e., timber benefits and carbon sink benefits, to achieve optimal forest management with multiple benefits. Thus, the objective of this study was to analyze the effect of extending rotation at the stand level in private landowner of Eucalyptus globulus, Eucalyptus nitens and Pinus radiata established in different productivity zones. The analysis also considers variations in the price per ton of carbon stored and in the discount rate.