The importance of agroforestry systems as carbon sinks has recently been recognized due to the need of climate change mitigation. The objective of this study was to compare the carbon content in living biomass, soil (0-10, 10-20, 20-30 cm in depth), dead organic matter between a set of non-agroforestry and agroforestry prototypes in Chiapas, Mexico where the carbon sequestration programme called Scolel'te has been carried out. The prototypes compared were: traditional maize (rotational prototype with pioneer native trees evaluated in the crop period), Taungya (maize with timber trees), improved fallow, traditional fallow (the last three rotational prototypes in the crop-free period), Inga-shade-organic coffee, polyculture-shade organic coffee, polyculturenon-organic coffee, pasture without trees, pasture with live fences, and pasture with scattered trees. Taungya and improved fallow were designed agroforestry prototypes, while the others were reproduced traditional systems. Seventy-nine plots were selected in three agro-climatic zones. Carbon in living biomass, dead biomass, and soil organic matter was measured in each plot. Results showed that carbon in living biomass and dead organic matter were different according to prototype; while soil organic carbon and total carbon were influenced mostly by the agro-climatic zone (P \ 0.01). Carbon density in the high tropical agro-climatic zone (1,000 m) was higher compared to the intermediate and low tropical agro-climatic zones (600 and 200 m, respectively, P \ 0.01). All the systems contained more carbon than traditional maize and pastures without trees. Silvopastoral systems, improved fallow, Taungya and coffee systems (especially polyculture-shade coffee and organic coffee) have the potential to sequester carbon via growing trees. Agroforestry systems could also contribute to carbon sequestration and reducing emissions when burning is avoided. The potential of organic coffee to maintain carbon in soil and to reduce emissions from deforestation and ecosystem degradation (REDD) is discussed.

This research explores interactions between farmers' knowledge and socioeconomic circumstances and the floristic composition of multistrata coffee plantations in Chiapas, Mexico. Interviews with 24 individual farmers with accompanying vegetation transects and two community level participatory workshops were carried out. The frequency, density, dominance, utility and importance value for all tree species surveyed were obtained. Farmers were grouped by cluster analysis on the basis of their land area, time producing coffee and the age of their coffee farms but the dominant shade species in their coffee plantations was not influenced by socioeconomic status ( p < 0.05). A total of 74 shade species were recorded and classified as temporary, suitable, or unsuitable as shade species by farmers, based on attributes such as leaf phenology, foliage density, crown shape and the amount and timing of litter decomposition, as well as their overall impact on coffee yield. Principal component and cluster analysis using these attributes confirmed the consistency of the farmers' classification system. A group of preferred species was identified, but less than half the trees recorded on farms were of these species, showing that farmers retained a wide range of trees and shrubs in their plantations, taking into account not only commercial interests but also their contribution to ecosystem functions. Farmers harnessed the forces of secondary succession by retaining pioneers as temporary shade, knowing that they would naturally be succeeded, while at the same time promoting and tolerating other longer living native species that they considered more suitable as coffee shade. Managing diverse secondary succession instead of establishing monospecific shade was an efficient way for farmers to achieve acceptable coffee yields while contributing to biodiversity and landscape conservation that could allow them access to niche markets.

We assessed wildlife predation on livestock and poultry and the implications for predator conservation in the most important rainforest areas of south-east Mexico. We estimated the economic impact of predation and identified variables correlated to predation frequency in four communities adjacent to Calakmul and Montes Azules Biosphere Reserves. We did participant observation and interviews with 161 residents during January-September 2010. We recorded 2,861 deaths of livestock and poultry from predation by wild carnivores over the previous 3 years. Opossums (n 5 677 predation events), raptors (n 5 676) and ocelots (n 5 539) were responsible for the highest numbers of killings. Poultry constituted the main target of wild predators (n 5 2,548 deaths). Sheep (n 5 201 events) and cattle (167) were the most affected by large predators such as jaguar Panthera onca and puma Puma concolor. Economic losses from predation were estimated to be USD 55,600 over the 3 years in the four communities. Predation frequency was positively correlated with livestock numbers (r 2 5 0.87, P , 0.05) but negatively associated with wild prey abundance (r 2 5 0.96, P , 0.05). Better husbandry practices focused on the safety and location of livestock enclosures and on reducing overabundance of dogs and regulating hunting on wild prey in rural areas may help mitigating conflict between wild predators and residents in the rainforests of south-east Mexico.

ObjectiveThe aim of the experiment was to assess the effect of increasing amounts of Leucaena leucocephala forage on dry matter intake (DMI), organic matter intake (OMI), enteric methane production, rumen fermentation pattern and protozoa population in cattle fed Pennisetum purpureum and housed in respiration chambers.MethodsFive crossbred heifers (Bos taurus×Bos indicus) (BW: 295±6 kg) were fed chopped P. purpureum grass and increasing levels of L. leucocephala (0%, 20%, 40%, 60%, and 80% of dry matter [DM]) in a 5×5 Latin square design.ResultsThe voluntary intake and methane production were measured for 23 h per day in respiration chambers; molar proportions of volatile fatty acids (VFAs) were determined at 6 h postprandial period. Molar concentration of VFAs in rumen liquor were similar (p>0.05) between treatments. However, methane production decreased linearly (p<0.005), recording a maximum reduction of up to ~61% with 80% of DM incorporation of L. leucocephala in the ration and no changes (p>0.05) in rumen protozoa population were found.ConclusionInclusion of 80% of L. leucocephala in the diet of heifers fed low-quality tropical forages has the capacity to reduce up to 61.3% enteric methane emission without affecting DMI, OMI, and protozoa population in rumen liquor.

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