Print PageThere is general scientific consensus that human-induced climate change will have significant impacts on global ecology without reductions in CO2 emissions and mitigation programs. Agroforestry systems and forest habitat restoration can contribute to climate change mitigation by sequestrating atmospheric carbon and fixing it in the biomass pools. Coffee in the Tarrazú region of Costa Rica is farmed in low tree specie diversity agroforestry systems. These agroecosystems are embedded in a landscape characterized by the occurrence of different land uses. Community stakeholders are deeply interested in exploring the potential for carbon sequestration in this agricultural landscape.
This research aims to estimate above ground biomass and soil carbon in three land uses in a gradient of elevation of the terrain. It also explores the tradeoffs between two agroecological functions in coffee agroecosystems: carbon sequestration and coffee production. In 2008 and 2009, plots were chosen and visited following a stratified random sampling using a Geographical Information System (GIS). The strata consisted of four of Holdrige’s life zones and three land covers. Varying radius circular in forest and pasture sites, and square plots in coffee were used. Tree and coffee plant dimensions and diversity were recorded, and soil samples to estimate organic matter contents were collected.
Results/Conclusions
From the 34,544 ha of the study site, 30.9%, 39.6%, and 26% are under pasture, coffee, and forest cover respectively. Forests trees are characterized by an abundance of two species of Quercus. Two tree species Erythrina, and members of Musa composed most of the shade canopy in coffee plots. Preliminary results indicate that the median diameter at breast height (DBH) was: 15.7 cm with a range of 5 to 130.5 cm for forest trees, and 15.5 cm with a range of 1 to 54 cm for trees found in coffee plots. The mean tree density in coffee plots was 0.224 ± 0.032 trees m-2 (N=39). Mean and standard deviation for soil carbon (%) were 4.89 (1.86), 5.08 (1.36), and 4.91 (2.53), for the forest, coffee, and pasture sites respectively. Soil Carbon was higher in coffee plots, probably due to the regular pruning of trees, which also limits above ground biomass in coffee growing areas. Consequently, pruning and soil management practices may be an important determinant of C-storage in coffee landscapes. Incentives to restore pasture and improve coffee shade management may provide significant potential to increase C-sequestration in Costa Rica’s coffee growing regions.
