Variation in ages and growth rates of trees in Amazonian tropical forests: consequences for carbon and forest management Simone Vieira, Plínio Camargo, Luiz Martinelli (CENA) Susan Trumbore (UCI), Jeff Chambers (Tulane), Niro Higuchi (INPA) Diogo Selhorst, Foster Brown (SETEM)

Our questions – CD-08 What is the capacity for these forests to store C? Where could it be stored and for how long? Our approach – CD-08 Look at components of C fluxes: This specific work: changes in living tree C stocks, and the environmental variables that control them. Use radiocarbon to determine the residence time of carbon in trees and soils

Manaus ZF2 Reserve Rio Branco - Catuaba Exp. Farm Santarém Tapajos National Forest

Rio Branco Manaus Santarém Field sites All terra firme forest Soils are Oxisols Variation in dry season length Shortest in Manaus, longer in Rio Branco, Santarém

Trees How old are tropical trees? How fast do they grow? How long do they store carbon? How do characteristics vary across the Amazon basin?

Measurement of tree diameter during establishment of permanent plot

Stem frequency in DBH Class (stem ha -1 ) Manaus (626), Rio Branco (467) and Santarém (460)

Biomass (Mg ha -1 ) Tree diameter class (cm) Not all forests in the Amazon are equal Manaus has more biomass overall, in smaller trees, than sites with a more pronounced dry season Manaus Rio Branco Santarém trees ha Mg C ha cm (DBH mean) Vieira et al., 2004

Growth rates from dendrometer bands

Growth rates vary seasonally with rainfall, though not simply Mean annual growth increment – Manaus 1.7 mm yr -1 Rio Branco 3.8 mm yr -1 Santarém 3.1 mm yr -1 Biomass increment in living trees ~ 2 Mg C ha -1 yr -1 all three sites

Radiocarbon Sample

Tree age (radiocarbon)

Radiocarbon and dendrometer based estimates of growth agree mm/yr from dendrometer bands mm/yr from DBH and radiocarbon age >50cm 30-50cm 10-30cm Rio Branco Manaus Santarem 1:1

Big trees grow faster than small trees mm/yr from dendrometer bands mm/yr from DBH and radiocarbon age >50cm 30-50cm 10-30cm Rio Branco Manaus Santarem 1:1

Trees in Manaus (central Amazon) grow much slower than other areas mm/yr from dendrometer bands mm/yr from DBH and radiocarbon age >50cm 30-50cm 10-30cm Rio Branco Manaus Santarem 1:1

Mean age – Manaus 422 years Rio Branco 332 years Santarém 271 years

No Individuals/ ha Manaus SantarémRio Branco Trees can be old Extrapolating growth rates, we estimate >20% of all trees and 15-35% of trees cm diameter are >300 yrs old Age of individuals estimated from diameter/growth rate (yr)

Limited radiocarbon data available agree qualitatively with age structure based on Monte Carlo extrapolation of dendrometer growth rates % of individuals with age >300 years

Trees 45years Basal age (years) from radiocarbon No of individuals

Manaus Santarém Rio Branco Individuals/ha Biomass C MgC/ha Growth MgC/ha/yr Mean age of C (yr)* MRT of C (stock/growth)** * From monte carlo simulations **biomass-weighted Data from Vieira et al C dynamics differ with forest location

Low carbon use efficiency (NPP/GPP ~ 30% at Manaus and Santarém sites) Low carbon use efficiency (NPP/GPP ~ 30% at Manaus and Santarém sites) ~25% of NPP used for wood growth at Manaus (data pending for other sites) ~25% of NPP used for wood growth at Manaus (data pending for other sites) Although biomass may recover quickly through fast-growing pioneer species, slow growing species (therefore biodiversity) will take centuries to recover from disturbance Although biomass may recover quickly through fast-growing pioneer species, slow growing species (therefore biodiversity) will take centuries to recover from disturbance Implications of low growth rates: