Uma comparação entre diferentes estimativas da condutância superficial numa floresta primária na Amazônia Central

Dallarosa, R.; Clarke, Robin T.

doi:10.1590/1809-43922000302303

Cited by 3 publications

(2 citation statements)

References 10 publications

(13 reference statements)

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“…Daily cycles representing averaged days of incident (Si), net (Rn), reflected (So) and longwave net radiation (Ln), are presented in Figures 7b (dry season) and 7c (wet season). There appears to be a tight correspondence between Rn and Si, similar to reports by Malhi et al [2002] and Dallarosa and Clarke [2000].…”

Section: Resultssupporting

confidence: 86%

Comparative measurements of carbon dioxide fluxes from two nearby towers in a central Amazonian rainforest: The Manaus LBA site

et al. 2002

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[1] Forests around Manaus have staged the oldest and the longest forest-atmosphere CO 2 exchange studies made anywhere in the Amazon. Since July 1999 the exchange of CO 2 , water, and energy, as well as weather variables, have been measured almost continuously over two forests, 11 km apart, in the Cuieiras reserve near Manaus, Brazil. This paper presents the sites and climatology of the region based upon the new data sets. The landscape consists of plateaus dissected by often waterlogged valleys, and the two sites differ in terms of the relative areas of those two landscape components represented in the tower footprints. The radiation and wind climate was similar to both towers. Generally, both the long-wave and short-wave radiation input was less in the wet than in the dry season. The energy balance closure was imperfect (on average 80%) in both towers, with little variation in energy partitioning between the wet and dry seasons; likely a result of anomalously high rainfall in the 1999 dry season. Fluxes of CO 2 also showed little seasonal variation except for a slightly shorter daytime uptake duration and somewhat lower respiratory fluxes in the dry season. The net effect is one of lower daily net ecosystem exchange (NEE) in the dry season. The tower, which has less waterlogged valley areas in its footprint, measured a higher overall CO 2 uptake rate. We found that on first sight, NEE is underestimated during calm nights, as was observed in many other tower sites before. However, a closer inspection of the diurnal variation of CO 2 storage fluxes and NEE suggests that at least part of the nighttime deficits is recovered from either lateral influx of CO 2 from valleys or outgassing of soil storage. Therefore there is a high uncertainty in the magnitude of nocturnal NEE, and consequently preliminary estimates of annual carbon uptake reflecting this range from 1 to 8 T ha À1 y À1 , with an even higher upper range for the less waterlogged area. The high uptake rates are clearly unsustainable and call for further investigations into the integral carbon balance of Amazon landscapes.

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Section: Resultssupporting

confidence: 86%

Comparative measurements of carbon dioxide fluxes from two nearby towers in a central Amazonian rainforest: The Manaus LBA site

et al. 2002

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“…The first period (1973)(1974)(1975)(1976)(1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984) was selected as the baseline period because approximately 95% of the IRB remained covered by forest. In fact, the aridity and evaporative indexes in the period fit well with the Zhang curve for forested areas (L. Zhang et al, 2001), and the average AET calculated by water balance was 1,465 mm/year, which is very similar to that of previous studies in Amazon forests (Jipp et al, 1998;Leopoldo et al, 1995;Dallarosa & Clarke, 2000), although higher than 1,310 mm/year obtained by Shuttleworth (1988) via micrometeorological methods for 2 years in a Amazon region with higher precipitation.…”

Section: Limitations Of the Methods Used To Separate Human-and Climatsupporting

confidence: 86%

Opposite Effects of Climate and Land Use Changes on the Annual Water Balance in the Amazon Arc of Deforestation

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Souza-Filho

et al. 2019

Water Resources Research

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The hydrological effects of forest cover loss are difficult to discern in the case of large‐scale basins with gradual changes and difficult to isolate when climate variability is also present. In the present study, we evaluated the effects of climate variability and human activity on the annual streamflow in a basin in the Amazon arc of deforestation. We statistically analyzed the components of the annual water balance and monthly streamflow and used the currently used Tomer‐Schilling, elasticity, and decomposition of Budyko‐type curve methods to separate climate‐induced changes and anthropogenic effects. Annual series of the monthly maximum and minimum streamflow, total streamflow, and total reference evapotranspiration presented statistically significant increasing trends. No significant trend was observed for precipitation. The greatest change in the average annual runoff coefficient was observed between the first (1973–1984) and second (1985–1994) analyzed periods. Even with the continuous reduction in the forested area, the third (1994–2004) and fourth analyzed periods (2003–2016) showed only relatively small changes, most likely due to the intensity of slash‐and‐burn activities and vegetation regrowth. The methods showed that deforestation was the primary cause of the streamflow changes, but with different intensities, and a small recuperation was observed in the last analyzed period. On average, the annual water yield would increase between 26% and 58% after the first time interval without the opposite effect of climate variability, which must be considered in basin management. Future research should focus on analyzing the water storage and the dependence of the precipitation‐runoff relationship from the climate.

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The role of protected and deforested areas in the hydrological processes of Itacaiúnas River Basin, eastern Amazonia

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Cavalcante

Sahoo

et al. 2019

Journal of Environmental Management

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Uma comparação entre diferentes estimativas da condutância superficial numa floresta primária na Amazônia Central

Cited by 3 publications

References 10 publications

Comparative measurements of carbon dioxide fluxes from two nearby towers in a central Amazonian rainforest: The Manaus LBA site

Comparative measurements of carbon dioxide fluxes from two nearby towers in a central Amazonian rainforest: The Manaus LBA site

Opposite Effects of Climate and Land Use Changes on the Annual Water Balance in the Amazon Arc of Deforestation

The role of protected and deforested areas in the hydrological processes of Itacaiúnas River Basin, eastern Amazonia

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