Silvopastoral systems and remnant forests enhance carbon storage in livestock-dominated landscapes in Mexico.

A large area of the terrestrial land surface is used for livestock grazing. Trees on grazing lands provide and can enhance multiple ecosystem services such as provisioning, cultural and regulating, that include carbon sequestration. In this study, we assessed the above- and belowground carbon stocks across six different land-uses in livestock-dominated landscapes of Mexico. We measured tree biomass and soil organic carbon (SOC) stocks in fodder banks, live fences, pasturelands with dispersed trees, secondary forests, and primary forests from three different geographical regions and compared them with conventional open pasturelands respectively. We also calculated tree diversity indices for each land-use and their similarity with native primary forests. The aboveground woody biomass stocks differed significantly between land-uses and followed the gradient from less diverse conventional open pasturelands to silvopastoral systems and ecologically complex primary forests. The SOC stocks showed a differential response to the land-use gradient dependent on the study region. Multivariate analyses showed that woody biomass, fine root biomass, and SOC concentrations were positively related, while land-use history and soil bulk density showed an inverse relationship to these variables. Silvopastoral systems and forest remnants stored 27-163% more carbon compared to open pasturelands. Our results demonstrate the importance of promoting appropriate silvopastoral systems and conserving forest remnants within livestock-dominated landscapes as a land-based carbon mitigation strategy. Furthermore, our findings also have important implications to help better manage livestock-dominated landscapes and minimize pressures on natural protected areas and biodiversity in the hotspots of deforestation for grassland expansion.

Efecto de inoculantes y aditivos sobre fracciones de fermentación ruminal y degradación in vitro en ensilaje de sorgo (Sorghum sp) / Effect of inoculants and additives on fractions of ruminal fermentation and in vitro degradation in sorghum silage (Sorghum sp)

Resumen La acción de inoculantes y aditivos sobre la composición química y degradación ruminal de la materia seca (MS) de ensilaje de sorgo ya ha sido reportada. Sin embargo, se desconoce el efecto que estos tienen sobre la actividad microbiana, y por lo tanto, sobre su potencial de asimilación a nivel ruminal. El objetivo de este estudio fue evaluar el efecto de la adición de inoculantes y aditivos en ensilaje de la planta completa de Sorghum sp. sobre las fracciones de fermentación ruminal y degradación in vitro. Se utilizó un diseño experimental completamente al azar, con 7 tratamientos (control, 3 inoculantes, 2 aditivos y una combinación de inoculante con aditivo) y 21 repeticiones por tratamiento. Se usaron diferentes tipos de inoculantes y aditivos en el proceso de ensilaje de sorgo: lactosuero, yogur, ácido fosfórico, Lactobacillus plantarum y mezcla mineral. Después de 60 d de fermentación, se cuantificaron MS, pH, proteína cruda (PC), degradación in vitro de la MS a 24 h (DIVMS), parámetros de la cinética de fermentación (Vmáx = volumen máximo, L = fase lag, S = tasa de fermentación) y volumen fraccional (fermentación rápida = 0 h a 8 h, media = 8 h a 24 h y lenta = 24 h a 72 h) por producción de gas in vitro. El análisis estadístico indicó que los inoculantes y aditivos modificaron la composición química, los parámetros L, Vmáx, DIVMS y las fracciones de fermentación rápida y media (P < 0.05). El uso de lactosuero y L. plantarum como inoculantes en ensilaje de sorgo redujo la pérdida de PC y, en general, los inoculantes y aditivos mejoraron el pH de los ensilajes; no obstante, disminuyeron el aprovechamiento de las fracciones de fermentación rápida y media, modificaron el potencial de fermentación y provocaron efecto negativo en la DIVMS.

Abstract The action of inoculants and additives on the chemical composition and ruminal degradation of sorghum silage dry matter (DM) has already been reported. However, the effect that these have on the microbial activity and, therefore, on its potential for assimilation at the ruminal level is unknown. For that reason, the objective of this study was to evaluate the effect of the addition of inoculants and additisves in silage of the entire plant of Sorghum sp. on fractions of ruminal fermentation and in vitro degradation. The experimental design was completely random, with 7 treatments (3 inoculants, 2 additives and a combination of inoculate with additive) and 21 repetitions per treatment. Different types of inoculants and additives were used in the process of sorghum silage: cheese whey, yogurt, phosphoric acid, Lactobacillus plantarum and mineral mixture. After 60 d of fermentation, dry matter (DM), hydrogen potential (Hp), crude protein (CP), in vitro dry matter degradation to 24 h (IVDMD), parameters of fermentation kinetics (Vmax= maximum volume L = lag phase, S = fermentation rate) and fractional volume (rapid fermentation = 0 h to 8 h, intermediate = 8 h to 24 h and slow = 24 h to 72 h) were quantified through the in vitro gas production technique. The results indicated that the inoculants and additives modified the chemical composition, the L parameters, Vmax, IVDMD and the rapid and intermediate fermentation fractions (P < 0.05). The use of cheese whey and L. plantarum as inoculants in sorghum silage reduced the loss of CP. Overall, the use of inoculants and additives improved silage Hp; however, it decreased the use of rapid and intermediate fermentation fractions, modified the fermentation potential of the silage and provoked a negative effect on the IVDMD.