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The cocoa tree (Theobroma cacao L.), widely distributed in southern and central Mexico, has many economic and ecological functions. However, there is a lack of data and information regarding the aboveground biomass (AGB) of this species in Mexico, which hampers understanding of its carbon sequestration potential. The objectives of this study were (1) to develop allometric equations to estimate AGB and (2) to determine the relationships of AGB components in cacao trees. Twenty-one trees were destructively sampled and separated into components (trunk, branches, leaves) at the Chontalpa subregion of Tabasco, a large cocoa production area. Samples of biomass cocoa trees were used to determine their carbon content. A typical cacao tree in our study area is 6.64 m in height, with a diameter at breast height (dbh) of 13.29 cm and with dry aboveground biomass of 37.02 kg. We found that about 50% of the biomass of a cacao tree is concentrated in the trunk while stems of different sizes, leaves, and fruits account for the other 50%. Seven AGB models were designed using dbh, basal diameter at 30 cm (d30), total height (h), canopy area (Ac), canopy height (Ch), and crown width (Cw) as biomass predictors. The dbh was the best-correlated independent variable with all AGB components. Selected models showed adequate fit and performance with high R2 (ca. 95%) in estimating AGB, but the most appropriate allometric equation was Ln (TB) = − 4.20 + 1.19 * ln(dbh) + 2.34 * ln(h) because this model had higher R2, lower Akaike criterion, and Mallow’s cp values. We recommend the use of this model to calculate aboveground biomass and carbon content for cacao trees in agroforestry systems similar to those of our study area. [ABSTRACT FROM AUTHOR]

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Ecological restoration of many arid zones is a pressing issue because of recurrent loss of plant cover. Here, we conducted a germination and growth study of three framework plant species, native to the Chihuahuan Desert in Northern Mexico, to optimize the establishment for arid zone restoration. The plant species were Zinnia grandiflora Nutt., Menodora scabra A. Gray, and Yucca elata (Engelm.) Engelm, which were selected for their potential for restoration as drought tolerant species. We evaluated seed germination, survival, and biomass allocation of seedlings under four (high, medium, low, and very low) simulated rainfall sequences as irrigation treatments. Rainfall sequences were obtained from a previous study that considered 35 years of precipitation records. Each sequence is accounted for 20% of probability of a wet, normal, low, or very low year in terms of precipitation occurring in the study area. Germination was conducted in controlled greenhouse conditions and seeding was done in pots containing soil mix. Sequences produced soil moisture fluctuations in which germination percent was higher for M. scabra (88%) and Z. grandiflora (31%) on the high sequence compared to the other sequences. Survival at the end of the treatments was above 80% of all the three species, and seedlings allocated more aboveground biomass as the moisture increased and more belowground biomass as moisture decreased. Implications under our study conditions include that germination of Y. elata would not be negatively affected by low soil moisture, and the best germinative results for Z. grandiflora and M. scabra would be achieved under higher soil moisture. [ABSTRACT FROM AUTHOR]

Copyright of Revista Chapingo Serie Horticultura is the property of Universidad Autonoma Chapingo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)