Land use change from forests to grazing lands is one of the important sources of greenhouse gas emissions in many parts of the tropics. The objective of this study was to analyze the extent of soil organic carbon (SOC) loss from the conversion of native forests to pasturelands in Mexico. We analyzed 66 sets of published research data with simultaneous measurements of soil organic carbon stocks between native forests and pasturelands in Mexico. We used a generalized linear mixed effect model to evaluate the effect of land use change (forest versus pasture), soil depth, and original native forest types. The model showed that there was a significant reduction in SOC stocks due to the conversion of native forests to pasturelands. The median loss of SOC ranged from 31.6% to 52.0% depending upon the soil depth. The highest loss was observed in tropical mangrove forests followed by highland tropical forests and humid tropical forests. Higher loss was detected in upper soil horizon (0–30 cm) compared to deeper horizons. The emissions of CO2 from SOC loss ranged from 46.7 to 165.5 Mg CO2 eq. ha−1 depending upon the type of original native forests. In this paper, we also discuss the effect that agroforestry practices such as silvopastoral arrangements and other management practices like rotational grazing, soil erosion control, and soil nutrient management can have in enhancing SOC stocks in tropical grasslands. The results on the degree of carbon loss can have strong implications in adopting appropriate management decisions that recover or retain carbon stocks in biomass and soils of tropical livestock production systems.

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This study analyzes the mean, maximum, and minimum temperatures and precipitation trends in southeast Mexico-Yucatan Peninsula, Central America and the Caribbean regions. The Climate Research Unit (CRU) TS 4.01, with a spatial resolution of 0.5° × 0.5°, was the database used in this research. The trends of the four selected climate variables cover the period from 1960 to 2016. The results obtained show a clear and consistent warming trend, at a rate of about 0.01 °C/year for the entire study region. These results are consistent with some previous studies and the IPCC reports. While the trends of precipitation anomalies are slightly positive (~0.1 mm/year) for southeast Mexico-Yucatan Peninsula and almost the entire Caribbean, for Central America (CA) the trends are negative. The study also presents the correlation between temperatures and precipitation versus El Niño Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and Atlantic Multidecadal Oscillation (AMO) drivers, indicating global warming and frequency signals from the climate drivers. In terms of the near future (2015–2039), three Representative Concentration Pathways (RPC) show the same trend of temperature increase as the historical record. The RCP 6.0 has trends similar to the historical records for CA and southeast Mexico-Yucatan Peninsula, while the Caribbean corresponds to RCP 4.5. In terms of the far-future (2075–2099), RCP 6.0 is more ad-hoc for southeastern Mexico-Yucatan Peninsula, and RCP 8.5 corresponds to Central America. These results could help to focus actions and measures against the impacts of climate change in the entire study region.

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Silvopastoral systems have great potential for storing carbon because of carbon assimilation in tree woody biomass, carbon input through litterfall and below‐ground carbon turnover. In this study, we quantified and compared the carbon stocks at livestock ranches in Tabasco, Mexico, containing either scattered trees in grazing pastures (STP) or grass monocultures. Sampling plots were randomly established at each ranch where the above‐ and below‐ground carbon stocks, carbon input from litterfall, grass production and arboreal biomass growth were measured. We found that silvopastoral systems stored an average of 257.45 Mg ha−1 of soil organic carbon (SOC) compared to 119.17 Mg SOC ha−1 at grass monoculture ranches (to 30 cm depth); silvopastoral systems also stored 44.64 Mg C ha−1 in wood biomass; and, grass monocultures had greater cumulative grass biomass production. Overall, it is concluded that livestock ranches in Tabasco, Mexico, with scattered trees in grazing pastures stored 58.8% more carbon than those grass monocultures, with carbon stocks of 327.01 Mg C ha−1and 134.47 Mg C ha−1, respectively. The results are useful for land management decision making for sustainable livestock systems framed in the Sustainable Development Goals (SDGs).

Fire has been an integral part of ecosystem functioning in many biomes for a long time, but the increased intensity and frequency of wildfires often affect plant diversity and carbon storage. Prescribed burning is one of the alternatives to forest fuel management where the fire is controlled and carried out under a determined set of weather conditions and objectives. The effect of prescribed burning on plant diversity and carbon (C) storage has not been studied widely. The objective of this study was to evaluate the effect of prescribed burning on plant diversity indices, biomass stocks, and soil C storage in the tropical highland forests of Southern Mexico. We assessed plant diversity and carbon stocks at 21 sampling sites: seven with prescribed burning, seven non-burning, and seven with wildfires. We calculated tree biodiversity indices, stand structural properties, and species composition among burning treatments. We quantified C stocks in vegetation biomass by using an allometric equation and forest litter by direct sampling. We analyzed 252 soil samples for soil organic C content and other properties. The results showed that the biodiversity index was higher in sites with prescribed burning (Shannon index, H = 1.26) and non-burning (H = 1.14) than in wildfire sites (H = 0.36). There was a greater similarity in plant species composition between non-burning and prescribed burning sites compared to wildfire sites. Prescribed burning showed a positive effect on soil carbon storage (183.9 Mg C ha−1) when compared to wildfire (144.3 Mg C ha−1), but the difference was not statistically significant (p > 0.05) in biomass stocks. Prescribed burning in this study conserved plant diversity as well as soil carbon stocks compared to non-burning, the opposite of what we found in wildfires.

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<p class="Abstract">Estimates of biomass in homegardens are primarily based on the tree component and few studies quantify the perennial herbaceous component. This component is of importance in the humid tropics of Mesoamerica, where distinct varieties and species of banana (<em>Musa</em> spp) are cultivated. This crop represents a dynamically stable biomass within homegardens and provides owners with continual production for alimentation and cash income. The aim of this study was to produce an allometric model for estimating the biomass of banana plants using dasonomic data, compare it to other models and estimate the biomass of cultivated banana plants from homegardens in the state of Tabasco, Mexico. This was based on the hypothesis that 1) the formulation of specific allometric models results in more precise estimations of the standing biomass of banana plants; and 2) banana plants contribute a significant proportion of the total biomass in homegardens. Dasonomic data and the dry weight of the above and below ground components of 30 individual plants of the most abundant species of banana (<em>Musa balbisiana</em> Colla) were collected in homegardens of the Los Rios region in Tabasco, Mexico. The mean biomass of the total plants of <em>M. balbisiana</em> harvested from homegardens was 5.85 kg plant^-1, with a range of 0.52 – 13.32 kg plant^-1. The above-ground and corm biomass represent 87.6% and 12.4% of total biomass respectively. The above-ground biomass (AGB) was strongly correlated with pseudostem diameter (DBH) and to a lesser degree with height data. The Husch and Schumacher – Hall models, with the variables pseudostem diameter at a height of 30cm (d₃₀), height of the pseudostem (HF) and total height (HT), performed best statistically; however, based on the crossed validation, the best model was that proposed by Kopezky, with the equation AGB= -0.0927+0.0203*DBH². In homegardens with banana plants, the banana biomass was between 0.1 and 1 t ha^-1, and in some cases between 2 and 5 t ha^-1. The mean density of the total biomass of the banana plants, in a sample of 69 homegardens where bananas were present, was 688 kg ha^-1, corresponding to 2% of above-ground biomass in the homegardens of the region of study. </p>