PARENT SESSION
Oral Session 19: Agroecology I.
Presiding: C Ribic
Tuesday, August 3, 8:00 AM to 11:30 AM, Meeting Room A 105.
Roles of land-use history, topography and site ecology in determining above- and below-ground biomass of an inhabited landscape in eastern Panama.
Kirby, Kathryn*,1, Potvin, Catherine1, 1 McGill University, Montreal
ABSTRACT- Eastern Panama hosts the largest remaining tract of tropical moist broadleaf forest in Central America; however, these forests are being rapidly replaced by permanent pasture and agriculture. Carbon trading initiatives may provide local communities with an economically viable alternative to cattle pasture while promoting land uses that also maintain environmental services. To test this possibility, we worked with an Embera community in Eastern Panama to quantify the above- and below- ground biomass of three land-use types: pastures, intact forests, and traditional agroforests. We used a stratified random sampling scheme to locate sites throughout the 3,198 ha territory, such that sites with a range of ecological characteristics, topographical positions, and land use histories (measured as years under current land use and management regime) were sampled. We measured above-ground biomass including trees, shrubs, lianas, herbs, downed woody debris and leaf litter in two circular 700 m2 plots at each of 48 sites distributed equally over the land-use types. Soil carbon was measured at two depths in each plot. As expected, total above-ground biomass decreased significantly from intact forest, to agroforest, to pasture sites. Above ground biomass was significantly correlated to years since establishment for agroforests, and to grazing intensity for pasture sites. Belowground biomass, which reflects the effects of soil density and percent organic carbon, was not significantly different between land-use types; forests had significantly higher percent carbon in the top soil layer, but compaction in pastures obscured this effect. However, pastures showed a decrease in carbon with time since deforestation, indicating that differences between land-use types increase with time. Overall, above ground biomass shows predictable patterns with land-use change. Land-use effects on below ground biomass is confounded by physical compaction of the soil and a delay in carbon loss, but ultimately follows similar trends as above ground biomass.
Key words: Carbon, Land use, Biomass, Tropical Forest