1. Controles dos Processos de Assimilação e Respiração de uma Floresta Amazônica
Estou trablahando em Amonzonia Central para mais ou menos 10 anos com pesquiasadores, alunos, e pessoal do campo que faz parte do INPA. Uma questao que esta interesante para nos e o balanco de carbono em florestas primarias. A questao e basico: se voce poderia quantificar todo carbono na floresta un ano depois da outra, para 10, 20, 50 anos, a floresta iria ser fonte, sumidor, ou balancado no sentido de carbono?
Jeffrey Q. Chambers, Edgard S. Tribuzy, Liliane M. Teixeira, Ligia C. Toledo, Roseana da Silva, Joaquim dos Santos, Niro Higuchi, and Susan E. Trumbore

2. The Central Amazon Manaus Work carried out on reserves managed by
Nossos trabalhos estao feitos em reservas perto de cidade Manaus que voce pode ver nesse imagem satelite. Este Rio aqui e o Rio Negro, e este e o Solimoes. Este fragmento de floresta e Reserva Ducke, com comprimento de 10 por 10 kilometros.
Work carried out on reserves managed by
Instituto Nacional de Pesquisas da Amazônia (INPA)

3. Seasonal Changes: Tree Growth
Each tree with dendrometer
— trees of various sizes
— monthly growth w/ calipers
— precipitation variables
Este projeto foi liderado por Rose da Silva, que ja terminou o mestrado dela no INPA.

4. Seasonal Changes: Tree Growth
What drives variability?
— Precipitation (30 day sum)
— Dry days (distribution of precip.)
— Month – why important?
— evolutionary constraints important
Dark green data, light green empirical model. Top figure only precipitation variables, bottom figure with precipitation and “month” as variables. Probably demonstrates importance of phenology; what is expected instead of what happens.

5. Ecosystem Respiration Components

6. Partitioning of Ecosystem Respiration Components
Reco= 7.8 Ra
5.6 mmol m-2 s-1 Rh
2.2 mmol m-2 s-1
Units = mmol m-2 s-1
Tulane University:

7. Moisture Control Over Fine Surface Litter Respiration
Respiratory flux from surface litter sensitive to moisture stress
Respiration can be modeled as function of precipitation history

8. Ecosystem Fine Surface Litter Respiratory Flux
1997 El Niño 2200 mm
1999 La Niña 3200 mm
Difference between wet and dry year ~0.4 Mg C ha-1 yr-1

9. Estimating Ecosystem Carbon Use EfficiencyRa Pg Pn
CUE = Pn/(Ra + Pn)
CUE = 30%
Only about 30% of carbon assimilated in photosynthesis was used to construct new tissues, the remainder being respired back to the atmosphere as autotrophic respiration.
Temperate Forest and Suggested Global Constant:
CUE = 50%
Chambers, J. Q., E. S. Tribuzy, L. C. Toledo, B.O. Crispim, N. Higuchi, J. d. Santos, A. C. Araújo, B. Kruijt, A. D. Nobre, and S. E. Trumbore. In press. Respiration from a Tropical Forest Ecosystem: Partitioning of Sources and Low Carbon Use Efficiency. Ecological Applications.

10. Potential Explanations for Low CUE
Higher respiratory costs in tropical forests
CUE increases with mean annual temperature
Not carbon limited: many trees are assimilating more carbon than needed for construction and maintenance respiration
CH2- + O2
cytochrome
alternate
CO2 + H2O + ATP
CO2 + H2O + heat
oxidase
Does the alternate oxidase control an overflow pathway?

11. carbon allocated to woody tissue
Carbon Overflow Hypothesis
carbon allocated to woody tissue
respiration
growth
maint.
waste
1 m
growth
Carbon Partitioning in Woody Tissues: Resources Limited

12. carbon allocated to woody tissue
Carbon Overflow Hypothesis
carbon allocated to woody tissue
respiration
growth
maint.
waste
1 m
growth
Carbon Partitioning in Woody Tissues: Resources Increased

13. Overview of the BIONTE Logging Experiment
Km-22
Km-23
Vicinal ZF-2
Bloco 4
Bloco 2
Bloco 1 A
Acampamento
Estrada de escoamento da madeira
Escala 1:
P1, P2, ... : PICADA
SP1, SP2, ... : SUB-PARCELA
BLOCO
600 m
400 m
200 m
SP1
SP3
SP2
SP5
SP4
SP6
SP7
SP8
SUB-BLOCO P1 P2 P3 P4 P5 P6 P7 P8
Treatments: % of commercial species basal area removed:
T0: Control (3 ha)
T1: 32% (3 ha)
T2: 42% (3 ha)
T3: 69% (3 ha)
How does growth and woody tissue respiration of surviving tree respond to this disturbance?

14. Comparative Woody Tissue Respiration and Growth:
Jacaranda/BIONTE
Methods:
Closed dynamic chambers
50 trees from Jacaranda plots
continuous forest
five growth classes
80 trees from BIONTE plots
control plots
three logging treatments
Growth rate from dendrometer bands, corrected for density and carbon content.

15. Some Factors Accounting for Variability in Respiratory Flux
Multiple regression and ANOVA
Growth rate, tree size and treatment together explained about 50% of the variability in woody tissue respiration rates. The strongest treatment effect was between the BIONTE control plots and the undisturbed forest site.
Analyses based on average rates over a number of months

16. Average Respiratory Flux for Statistically Equivalent
Tree Size and Growth Rate
Why was woody tissue respiration in the BIONTE control plots 50% less than the continuous forest site?

17. Changing Dynamics of Tropical Forests
Forest turnover (recruitment + mortality) doubled from
Phillips, O. L., and A. H. Gentry Increasing turnover through time in tropical forests. Science 263:
Phillips, O. L., Y. Malhi, N. Higuchi, W. F. Laurance, P. V. Núñez, R. M. Vásquez, S. G. Laurance, L. V. Ferreira, M. Stern, S. Brown, and J. Grace Changes in the carbon balance of tropical forests: evidence from long-term plots. Science 282:
Phillips, O. L., R. V. Martinez, L. Arroyo, T. R. Baker, T. Killeen, S. L. Lewis, Y. Malhi, A. M. Mendoza, D. Neill, P. N. Vargas, M. Alexiades, C. Ceron, A. Di Fiore, T. Erwin, A. Jardim, W. Palacios, M. Saldias, and B. Vinceti Increasing dominance of large lianas in Amazonian forests. Nature 418:
Tree biomass has increased in Neotropics since 1980 at about Mg C ha-1 yr-1
Relative dominance of lianas/trees has doubled over the past 20 years
What is causing this non-equilibrium behavior?

18. Catastrophic and Background Mortality
Permanent plot data provide information on background mortality
What is the effect of catastrophic mortality on forest carbon balance?
Little information on frequency and extent
200 m
Severe downburst winds associated with late dry season storms

19. Summary
Various transient ecological processes can account for year-to-year variations in carbon exchange with the atmosphere, but not represent a directional change in ecosystem carbon balance.
Trees surviving elevated mortality responded to increase in resources with faster growth rates, a decrease in woody tissue respiratory flux, and an increase in carbon use efficiency.
Hypothesis: many Central Amazon trees exist in a state of elevated carbon supply, and are poised to quickly respond when additional resources become available.
Relatively small elevated mortality events lead to changes in forest carbon metabolism that may appear as biomass accumulation, but better characterized as a recovery phase.
What portion of time are undisturbed tropical forests in biomass recovery phase as opposed to biomass loss phase?

20. Acknowledgments Instituto Nacional de Pesquisas da Amazônia (INPA)
NASA LBA-ECO
Projeto Piculus (PPG7)
Japanese International Cooperation Agency (JICA)
Tulane University