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CD-04 Abstract

Measuring the effects of logging on the CO2 and energy exchange of a primary forest in Tapajos National Forest

Michael L. Goulden — University of California Irvine (US-PI)
Humberto Rocha — USP (Universidade de Sao Paulo) (SA-PI)

Objectives





We propose to directly measure the effects of selective logging on the exchanges of CO2

and energy by a primary forest in the Tapajos National Forest (TNF), Pará using

continuous, long-term eddy covariance. We will make these measurements, beginning one year

before harvest and continuing for five years pending renewal, above a 2 by 5 km commercial

cut that has been scheduled for 1999 by the International Tropical Timber Organization

(ITTO) and the Brazilian Institute for the Environment and Renewable Resources (IBAMA)

with the US Forest Service (USFS) as a technical partner.






We will use the measurements from the year before the cut to determine whether the

undisturbed forest was losing or gaining carbon, and also whether the site was comparable

to a nearby undisturbed control. We will use the measurements from the four years

following the cut to determine how much carbon was lost, and when and if the forest

resumed carbon accumulation. We will complement the eddy flux measurements with continuous

observations of above- and below-canopy microclimate, soil respiration using automated

chambers and individual-tree gas exchange using sap-flow sensors; intermittent

measurements of stem respiration using portable chambers and wood increment using

dendrometers; and a survey of logging damage, to understand how and why forest

photosynthesis and respiration change during logging and recovery.







Table 1: Proposed Measurements































































































































































Sensor

Location(s)

Sonic anemometer; Probably Solent Research HS

(horizontally symmetrical head)
~65 m *
Eddy flux CO2-H2O; LI-6262 on

tower
~65 m *
Profile CO2- H2O; LI-6262 ~8 at .5,1,2,4,10,20,40,65 m *
Wind speed and direction; Cup anemometer and vane ~65 m *
Air temperature; Aspirated and shielded

thermocouples
Same as CO2 profile &
Rainfall; Tipping bucket Clearing or tower&
Net radiation; REBS Q*7 ~65 m *
PPFD; Licor LI-190SB ~65 m *&
Solar radiation; Epply thermopile pyranometer ~65 m*
Soil and biomass temperature 5 soil profiles at 5, 10, 20, 50, 100 cm plus stem

and slash #$
Forest floor PPFD; GaAsP photodiodes 5 clusters of 10 sensors #$
Soil heat flux; REBS HFT3 10 cm depth, 10 plates total #$
Soil water; TDR, either multiplexed or stand-alone

probes
5 depths through top meter of soil, 10 profiles #$
Throughfall 2 gutters attached to tipping buckets #$
Continuous soil respiration 15 chambers $
Respiration survey; LI-6200 Stem, soil and slash
Dendrometers 100 Trees $
Sap flow; Granier type 30 Trees $




* Actual height(s) to be determined later.


# 40% of these instruments will placed at the start of study, and the remaining 60%

placed after the cut adjacent to the automated chambers, including 20% in mechanically

compacted regions and 20% in uncompacted regions (Tab. 1).


& A backup set of weather sensors will be recorded independently to ensure a

continuous record.


$ In undisturbed forest, gaps and gap edges.

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