PARENT SESSION
Oral Session #40: Carbon sequestration and flux.
Presiding: G. Koch
Tuesday, August 6. 1:00 PM to 4:45 PM. Gila Meeting Room, TCC.

Ecosystem C pools of primary tropical forests along climatic and elevation gradients in Costa Rica .

Kauffman, J. Boone^*,1, Hughes, Flint², Watson, Vicente³, Jobse, Judith¹, Tosi, Joseph³, ¹ Oregon State University, Corvallis, OR² USDA Forest Servoce - Institute of Pacific Islands Forestry, Hilo, HA³ Centro Cientifico Tropical, San Jose, Costa Rica

ABSTRACT- Tropical forests are significant terrestrial C sinks yet the variation in pool size between different forest types is little studied. We determined total aboveground biomass (TAGB) and C pools as well as soil C pools (to 1m) in 34 Costa Rican primary forests encompassing 6 life zones along a gradient from lowland tropical dry and moist forests, to lower montane rain forest (0 to ~1600 m asl). While there was tremendous variation within zones, mean TAGB was lowest in dry forest (184 Mg/ha) and highest in lower montane rain forest (414 Mg/ha). Patterns of aboveground C storage varied by the different forest types; a few large trees were important pools in tropical moist and wet forests while high tree densities accounted for high biomass in the pre and low-montane forests. Soil C pools were lowest in tropical moist and dry forest (111-131 Mg/ha) and highest in the pre and lower montane forests (~269 Mg/ha). Mean total ecosystem C pools ranged from 219 Mg/ha, (dry forest) to 477 Mg/ha (lower montane rainforest). Climate and soils have strong effects on the size and structure of ecosystem C pools; important considerations in determining the potential for landscapes to sequester C.

KEY WORDS: Tropical forests, Ecosystem C pools, Soil C, Tropical Forest Biomass