This study aimed to explore the contribution of trees in pastures to climate change mitigation by estimating tree biomass stocks (carbon) in Costa Rica and Nicaragua. Between 2002 and 2003, 17,783 trees were inventoried in pastures of 59 farms located in areas representing three life zones: tropical dry forest, tropical wet forest and transition from tropical dry to tropical wet forest. The average value of biomass stocks of trees in pastures was 10.7 ± 1.1 Mg/ha with a minimum value of 5.3 ± 1 Mg/ha in Rivas and a maximum of 13.5 ± 3.5 Mg/ha in Matiguás. There is a relationship between above ground biomass in the pastureland, tree density and basal area, which allows the development of simple equations. The design of policies that encourage the conservation and management of trees in pastures will be a key aspect to be incorporated into national climate change strategies.

Keywords: greenhouse gases, carbon stocks, ecosystems services, agroforestry systems, silvopastoral systems.