Comparison of the mass and energy exchange of a pasture and a mature transitional tropical forest of the southern Amazon Basin during a seasonal transition

This research utilized tower-based eddy covariance to quantify the trends in net ecosystem mass (CO2 and H2O vapor) and energy exchange of important land-cover types of NW Mato Grosso during the March-December 2002 seasonal transition. Measurements were made in a mature transitional (ecotonal) tropical forest near Sinop, Mato Grosso, and a cattle pasture near Cotriguacu ´ , Mato Grosso, located 500 km WNW of Sinop. Pasture net ecosystem CO2 exchange (NEE) was considerably more variable than the forest NEE over the seasonal transition, and the pasture had significantly higher rates of maximum gross primary production in every season except the dry-wet season transition (September-October). The pasture also had significantly higher rates of whole-ecosystem dark respiration than the forest during the wetter times of the year. Average ( � 95% CI) rates of total daily NEE during the March-December 2002 measurement period were 26 � 15 mmol m � 2 day � 1 for the forest (positive values indicate net CO2 loss by the ecosystem) and � 38 � 26 mmol m � 2 day � 1 for the pasture. While both ecosystems partitioned more net radiation (Rn) into latent heat flux (Le), the forest had significantly higher rates of Le and lower rates of sensible heat flux (H) than the pasture; a trend that became more extreme during the onset of the dry season. Large differences in pasture and forest mass and energy exchange occurred even though seasonal variations in micrometeorology (air temperature, humidity, and radiation) were relatively similar for both ecosystems. While the short measurement period and lack of spatial replication limit the ability to generalize these results to pasture and forest regions of the Amazon Basin, these results suggest important differences in the magnitude and seasonal variation of NEE and energy partitioning for pasture and transitional tropical forest.

[1]  E. Davidson,et al.  The role of deep roots in the hydrological and carbon cycles of Amazonian forests and pastures , 1994, Nature.

[2]  P. E. Rijtema.  Soil moisture forecasting , 1969 .

[3]  William James Shuttleworth,et al.  Dry Season Micrometeorology of Central Amazonian Ranchland , 1992 .

[4]  George L. Vourlitis,et al.  Seasonal variations in the evapotranspiration of a transitional tropical forest of Mato Grosso, Brazil , 2002 .

[5]  Tilden P. Meyers,et al.  A comparison of summertime water and CO2 fluxes over rangeland for well watered and drought conditions , 2001 .

[6]  W. Laurance,et al.  A crisis in the making: responses of Amazonian forests to land use and climate change. , 1998, Trends in ecology & evolution.

[7]  John Moncrieff,et al.  The propagation of errors in long‐term measurements of land‐atmosphere fluxes of carbon and water , 1996 .

[8]  T. Meyers,et al.  Measuring Biosphere‐Atmosphere Exchanges of Biologically Related Gases with Micrometeorological Methods , 1988 .

[9]  M. Hodnett,et al.  Seasonal soil water storage changes beneath central Amazonian rainforest and pasture , 1995 .

[10]  Eduardo S. Brondizio,et al.  INTEGRATING AMAZONIAN VEGETATION, LAND-USE, AND SATELLITE DATA , 1994 .

[11]  C. Tucker,et al.  Tropical Deforestation and Habitat Fragmentation in the Amazon: Satellite Data from 1978 to 1988 , 1993, Science.

[12]  J. Kauffman,et al.  Deforestation, Fire Susceptibility, and Potential Tree Responses to Fire in the Eastern Amazon , 1990 .

[13]  W. A. Dugas,et al.  Carbon dioxide fluxes over bermudagrass, native prairie, and sorghum , 1999 .

[14]  S. Wright,et al.  Tropical forest litter dynamics and dry season irrigation on Barro Colorado Island, Panama , 1995 .

[15]  Philip M. Fearnside,et al.  Global Warming and Tropical Land-Use Change: Greenhouse Gas Emissions from Biomass Burning, Decomposition and Soils in Forest Conversion, Shifting Cultivation and Secondary Vegetation , 2000 .

[16]  William F. Laurance,et al.  Biomass Collapse in Amazonian Forest Fragments , 1997 .

[17]  Ü. Rannik,et al.  Gap filling strategies for defensible annual sums of net ecosystem exchange , 2001 .

[18]  Andrew E. Suyker,et al.  Gap filling strategies for long term energy flux data sets , 2001 .

[19]  Yadvinder Malhi,et al.  Carbon dioxide transfer over a Central Amazonian rain forest , 1998 .

[20]  D. Baldocchi,et al.  Energy and CO(2) flux densities above and below a temperate broad-leaved forest and a boreal pine forest. , 1996, Tree physiology.

[21]  J. William Munger,et al.  Measurements of carbon sequestration by long‐term eddy covariance: methods and a critical evaluation of accuracy , 1996 .

[22]  R. Tibshirani,et al.  An introduction to the bootstrap , 1993 .

[23]  P. Régnier,et al.  Simulation of mesoscale circulations in a deforested area of rondonia in the dry season , 1996 .

[24]  Yadvinder Malhi,et al.  The use of eddy covariance to infer the net carbon dioxide uptake of Brazilian rain forest , 1996 .

[25]  Dennis D. Baldocchi,et al.  Seasonal and interannual variability of energy fluxes over a broadleaved temperate deciduous forest in North America , 2000 .

[26]  R. K. Dixon,et al.  Carbon Pools and Flux of Global Forest Ecosystems , 1994, Science.

[27]  George L. Vourlitis,et al.  EFFECTS OF METEOROLOGICAL VARIATIONS ON THE CO2 EXCHANGE OF A BRAZILIAN TRANSITIONAL TROPICAL FOREST , 2004 .

[28]  C. Potter,et al.  Large-scale impoverishment of Amazonian forests by logging and fire , 1999, Nature.

[29]  C. J. Moore,et al.  Transpiration from an Amazonian rainforest calculated from stomatal conductance measurements , 1993 .

[30]  Carlos A. Nobre,et al.  OBSERVATIONS OF CLIMATE, ALBEDO, AND SURFACE RADIATION OVER CLEARED AND UNDISTURBED AMAZONIAN FOREST , 1993 .

[31]  G. Vourlitis,et al.  Seasonal variations in the net ecosystem CO2 exchange of a mature Amazonian transitional tropical forest (cerradão) , 2001 .

[32]  R. McMillen,et al.  An eddy correlation technique with extended applicability to non-simple terrain , 1988 .

[33]  D. Baldocchi,et al.  CO2 fluxes over plant canopies and solar radiation: a review , 1995 .

[34]  Robert Clement,et al.  Momentum, water vapor, and carbon dioxide exchange at a centrally located prairie site during FIFE , 1992 .

[35]  John Moncrieff,et al.  Eddy-covariance CO2 flux measurements using open- and closed-path CO2 analysers: Corrections for analyser water vapour sensitivity and damping of fluctuations in air sampling tubes , 1990 .

[36]  G. Topp,et al.  THE MEASUREMENT OF SOIL WATER CONTENT USING A PORTABLE TDR HAND PROBE , 1984 .

[37]  Dennis D. Baldocchi,et al.  Seasonal variations of CO2 and water vapour exchange rates over a temperate deciduous forest , 1996 .

[38]  George M. Woodwell,et al.  Missing sinks, feedbacks, and understanding the role of terrestrial ecosystems in the global carbon balance , 1998 .

[39]  R. Buschbacher,et al.  A disturbing synergism between cattle ranch burning practices and selective tree harvesting in the eastern Amazon. , 1985 .

[40]  Üllar Rannik,et al.  Autoregressive filtering versus linear detrending in estimation of fluxes by the eddy covariance method , 1999 .

[41]  E. K. Webb,et al.  Correction of flux measurements for density effects due to heat and water vapour transfer , 1980 .

[42]  J. Goudriaan,et al.  The bare bones of leaf-angle distribution in radiation models for canopy photosynthesis and energy exchange , 1988 .

[43]  W. James Shuttleworth,et al.  Eddy correlation measurements of energy partition for Amazonian forest , 1984 .

[44]  W. J. Shuttleworth,et al.  Evaporation from Amazonian rainforest , 1988, Proceedings of the Royal Society of London. Series B. Biological Sciences.

[45]  David Y. Hollinger,et al.  Carbon dioxide exchange between an undisturbed old-growth temperate forest and the atmosphere , 1994 .