elocation-id: e3999
Climate change today constitutes a substantial threat to living beings. Human activities such as the use of fossil fuels, burning, the use of chemicals, and mainly deforestation contribute to the emission of greenhouse gases. In response to this, in Mexico, governmental, national, and environmental programs have been implemented that establish schemes in conjunction with producers in which various social, economic, and environmental benefits are obtained, and whose main objective is to reduce the environmental impact, as is the case with the Sowing Life Program. Agroforestry systems are considered a relevant system to face climate change through the biomass and carbon content of the different plant strata in these agroecosystems. The research estimated the indirect carbon storage in the agroforestry system, with a total of 15 sites measuring 4 x 25 m; the plot is a participant in the Sowing Life Program in the locality of San José El Amate (Huehuetán, Chiapas); once these data have been collected, biomass, carbon, and carbon dioxide were obtained through allometric equations. The agroforestry plot studied has a reserve of 22.6 t ha-1 of aboveground biomass, 8.75 t ha-1 of carbon and 32.14 t ha-1 of carbon dioxide.
aboveground biomass, allometric models, climate change, mitigation.
High concentrations of greenhouse gases, such as carbon dioxide (CO2), have driven the search for strategies to mitigate them through natural absorption and storage mechanisms (González-Abrego et al., 2023). Agroforestry systems play an essential role in this process. The amount of carbon sequestered is linked to the characteristics of the agroforestry system present in situ, including tree species and system management (Podong et al., 2023).
Mexico is among the 15 countries with the highest greenhouse gas emissions worldwide, with approximately 444 million tons of net emissions per year, which represents 2% of global emissions (Casanova et al., 2011). In Mexico, a series of social and productive programs have been created to promote the development of small-scale producers; among them, the Sembrando Vida (Sowing Life) Program stands out, the purpose of which is to increase agroforestry productivity based on sustainability criteria, considering the mitigation of climate change and the reduction of greenhouse gases (Baca et al., 2021).
In the state of Chiapas, from 2001 to 2018, 327 753 ha were deforested, equivalent to 18 209 ha year-1 of deforested land; in 2023, 10 694 ha were deforested (CONAFOR 2022). Due to the loss of cover and soil degradation, the Sowing Life Program has been implemented, with the primary objective of reducing environmental degradation.
The plots established under this production scheme meet conditions that allow their carbon sequestration potential to be evaluated from the early stages, because it incorporates forest species (cedars and mahogany), fruit species (citrus), and traditional crops (coffee and cocoa) in various agroforestry arrangements (INECC, 2021). Despite the program’s socioenvironmental importance, most research has focused on social and economic aspects (Tapia-Alba and Chiatchoua, 2025), and studies on ecological impacts are limited, leaving an important gap to investigate the carbon dynamics in these agroecosystems (Cortez et al., 2022).
Therefore, this study aims to estimate the carbon content stored in the aboveground biomass of forest species in plots under the Sowing Life agroforestry scheme in Huehuetán, Chiapas.
The research was conducted in the locality of San José El Amate, in the municipality of Huehuetán, Chiapas. The UTM coordinates are 1 657 449 on the Y-axis and 559 120 on the X-axis, located in zone 15, with an altitude of 50 m. The study plot has an area of 2.5 ha enrolled in the Sowing Life Program (Figure 1).
The plot was established in 2019 within the Sowing Life Program and was evaluated in the fourth year. The plantation design consists of a mixed agroforestry system that combines agricultural and forestry activities with the association of seven species. Agricultural species include Musa paradisiaca L. and Theobroma cacao L., with average diameters at breast height (DBH) of 12.36 cm and 4.79 cm (2 m high), respectively. The main forest species (fruit and timber) are: Annona muricata L., Bixa orellana L., Cedrela odorata L., Tabebuia rosea L., and Cocos nucifera L.; these have an average DBH of 3.5 cm, 5.57 cm, 5.56 cm, 6.76 cm and 0.95 cm, respectively, with a mean height of 1.7 m.
The research was conducted under a simple random design, primarily using 15 sites, each with an area of 100 m2 (4 x 25 m). For data collection, plant species were stratified; small-sized species were recorded first, followed by the inventory of forest species. In each plot, the species present were identified and quantified, and the variables diameter at breast height (DBH) and total height (h) were measured.
To estimate aboveground biomass, the indirect method was employed, using allometric equations specific to each species or functional group (Table 1).
| Model | Species | Equation | Author |
|---|---|---|---|
| 1 | Annona muricata L. | LogBA= -1.716+2.413*Log(DBH) | Nogueira et al. (2008) |
| 2 | Bixa orellana L. | LogBA= -1.716+2.413*Log(DBH) | Nogueira et al. (2008) |
| 3 | Cedrela odorata L. | B= 0.00341*DBH3.38248 | Benavides-Solorio et al. (2021) |
| 4 | Cocos nucifera L. | B= 4.5+7.7*H | Frangí and Lugo (1985) |
| 5 | Musa paradisiaca L. | B= 0.0303*DBH2.1345 | Danarto and Hapsari (2016) |
| 6 | Tabebuia rosea L. | B= 0.1959*D2.1206 | Sáenz-Reyes et al. (2021) |
| 7 | Theobroma cacao L. | LnB= -4.2+1.19*Ln(DBH)+2.34*Ln(H) | Morán-Villa et al. (2024) |
From these equations, individual biomass values were calculated and then integrated to obtain the total biomass by site. Each model was applied to a specific species according to its suitability and previous validation in studies related to its physiology and growth.
The carbon concentration of the plant species recorded in the study area was obtained from the average factors reported in the literature (Table 2).
| Species | Carbon concentration | Author |
|---|---|---|
| Annona muricata L. | 0.5 | Elías and Potvin (2003) |
| Bixa orellana L. | 0.5 | Elías and Potvin (2003) |
| Cedrela odorata L. | 0.45 | Mendizábal-Hernández et al. (2011) |
| Cocos nucifera L. | 0.5 | IPCC (2003) |
| Musa paradisiaca L. | 0.37 | Arias et al. (2014) |
| Tabebuia rosea L. | 0.5 | Hamburg (2000) |
| Theobroma cacao L. | 0.47 | Hernández-Núñez (2021) |
To obtain the carbon content, the total aboveground biomass of each individual was quantified through allometric models. Subsequently, the biomass value was multiplied by the corresponding carbon concentration factor to convert the results into tonnes per hectare (t ha-1).
To estimate carbon dioxide equivalent (CO2e), a stoichiometric factor was used to convert the mass of carbon (C) into its equivalent in CO2. Therefore, the CO2e content was calculated using the following expression: CO2e = net C content × 3.67.
To assess differences in carbon dioxide (CO2) concentrations between study sites, data were grouped with location as a factor. First, the assumption of normality was verified by the Shapiro-Wilk test (Shapiro and Wilk, 1965). When normality was rejected (p < 0.05), the nonparametric Kruskal-Wallis test (Kruskal and Wallis, 1952) was used to compare the groups. Subsequently, Dunn’s test was applied to determine significant differences (p < 0.05). All analyses were run in R Studio (version 4.3.0; R Core Team, 2023).
The species present in the 15 sites established in the Sowing Life plot were Annona muricata L. (soursop), Bixa orellana L. (achiote), Cedrela odorata L. (Spanish cedar), Cocos nucifera L. (coconut), Musa x paradisiaca L. (banana), Tabebuia rosea (Bertol.) D.C. (pink poui), and Theobroma cacao L. (cocoa). Within the plot, the plantation is designed in rows alternating agricultural crops and forest crops.
The estimated biomass (B) had its maximum value at site 13 (33.2 t ha-1) and its minimum value at site 1 (12.5 t ha-1); the average value was 22.6 t ha-1 (Figure 2).
Some studies demonstrate greater biomass in cocoa agroforestry systems, such as the case of Pocomucha et al. (2016), who recorded a biomass of 65.62 t ha-1. For their part, Andrade et al. (2013) calculated an average biomass of 28.8 and 33.6 t ha-1, which is also higher than that found in this research.
The carbon stored by agricultural activity (cocoa-banana) was 8.4 t C ha-1; specifically at the species level, Musa paradisiaca (banana) obtained more carbon stored in the present sites than Theobroma cacao (cocoa); these accumulations were low compared to those provided by M. paradisiaca. This is attributed to the higher density of M. paradisiaca plants at the sites, whereas T. cacao has a lower presence, so C capture was minimal (Figure 3).
The study by Ganeshamurthy (2023) estimated that the carbon stocks of the banana plant contribute between 2.573 and 6.407 t ha-1; in contrast, the cocoa plant, according to Bermello et al. (2024), has an average aboveground biomass ranging from 0.056 t C ha-1 to no more than 4.064 t C ha-1 per tree. For their part, Avellán et al. (2020) report stocks of 2.95 t C ha-1 with the same species of T. cacao, stating that it is the number of individuals that determines the result.
Carbon stocks include the shade perennials Annona muricata (soursop), Bixa orellana (achiote), Cedrela odorata (Spanish cedar), Cocos nucifera (coconut), and Tabebuia rosea (pink poui). Some sites showed no presence of any of the perennial species, and only in some sites were one or a few individuals of one or more species recorded.
More specifically, at sites 1 and 2, no timber or woody trees were found; at site 3, 0.841 t C ha-1 was quantified, with C. nucifera being the only forest species inventoried. Site 4 shows the presence of B. orellana (1.148 t C ha-1) and T. rosea (1.508 t C ha-1). At site 5, only A. muricata is distributed with 0.436 t C ha-1. Site 6 (0.101 t C ha-1), site 7 (1.239 t C ha-1), and site 8 (2.859 t C ha-1) have only one forest species: C. odorata. Site 9 reports T. rosea with 0.796 t C ha-1; at site 10, A. muricata is again distributed with 0.528 t C ha-1. At sites 11 to 14, no timber species were found; only at site 15, with C. odorata (0.080 t C ha-1) being the species present. These results are shown in the same order in Figure 4.
Some studies, such as that of Mendizábal-Hernández et al. (2012), report captures of up to 3.11 t C ha-1 for the species C. odorata, which is slightly higher than the value calculated for this species in the present research.
As a general result for all the species inventoried, regardless of activity, the average carbon is 8.75 t C ha-1; therefore, the total carbon estimated for 2.5 ha will be 21.87 t C ha-1 (considering that this is the area required within the Sowing Life Program). The average value obtained is within the parameters of what a model Sowing Life plot can store in an agroforestry system, given that agroforestry systems generally store approximately 9, 21, 50 and 63 t C ha-1 in aboveground biomass (Espinoza et al., 2012).
Similar studies, such as the one carried out by Ortiz et al. (2008), found that a laurel-cacao system stored between 43 and 62 t C ha-1, which are much higher values than those obtained in the present research, which may be due to the type of species and associations present in that system. For their part, Espinoza et al. (2012) found stores of 12 to 228 t C ha-1 in an agroforestry system, which is still higher than the 8.75 t C ha-1 found in the present research; however, compared to the study by Ortiz et al. (2008), it obtained higher carbon sequestration results. Although both studies have results with greater C capture, they align and agree with the carbon sequestration standard for an agroforestry system, which, according to Andrade et al. (2013), is 28.8 and 33.6 t C ha-1.
The analyzed carbon dioxide data did not follow a normal distribution, registering a p-value < 0.001. Since the data are not normally distributed, when using the nonparametric Kruskal-Wallis test, a p-value < 0.001 was obtained, indicating significant differences between the sites. Therefore, when applying Dunn’s test, it is observed that the pairs of sites 1-13, 1-14, 14-2, 1-5 and 2-5 present differences in their carbon dioxide (CO2) values between these sites (Table 3). The remaining comparisons do not show significant differences between the sites.
| Comparison | Z | P. adj. | t C ha-1 |
|---|---|---|---|
| 1-13 | -3.523509 | 0.0447166 | 4.8-12.6 |
| 1-14 | -3.927671 | 0.0090061 | 4.8-9.8 |
| 14-2 | 3.68284 | 0.0242182 | 9.8-5.9 |
| 1-5 | -3.800792 | 0.0151446 | 4.8-7.1 |
| 2-5 | -3.554287 | 0.0397956 | 5.9-7.1 |
In the design of an economic valuation model for agroforestry systems in cocoa, Fernández and Mora (2016) quantified CO2 removal up to their fourth year, obtaining 24.42 t ha-1 of CO2; in another sampling in their ninth year, they found up to 65.32 t ha-1 of CO2. In this regard, in their research titled Carbon storage and fixation, and valuation of environmental services in agroforestry systems in Costa Rica, Ávila et al. (2001) determined an average value of 8.9 t C ha-1 as the highest capture of the agroforestry system; that same result, when analyzed with the carbon dioxide factor, results in an average of 32.66 t ha-1 of CO2.
For their part, Zavala et al. (2018), when estimating the biomass and carbon stored in a coffee plantation agroforestry system, obtained 33.59 t C ha-1, equivalent to 123.27 t ha-1 of CO2, in a research that determines the age of the crop as a factor that influences carbon sequestration and storage, where the agroforestry system stores the most significant amount of CO2 during the 8-16 year age range.
The biomass estimate for the Sowing Life plot in the locality of San José El Amate was 22.6 t ha-1; the total carbon corresponds to 8.75 t ha-1. Regarding CO2 emissions, there are differences between some evaluated sites. The data obtained are dissimilar to those reported in other agroforestry systems in which the number of individuals and their associations have an impact.
Nevertheless, it should be noted that AFSs are part of a fundamental strategy to mitigate climate change; unlike monoculture, this environmental service is of higher quality in an agroecosystem. Sowing Life plots are an option to increase carbon storage and reduce climate change; therefore, it is important that agroforestry systems are considered as a strategy to buffer CO2.
We thank Mr. Jaime Rodríguez, owner of the plot on which this research was conducted.
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