Transpiration and canopy conductance of secondary vegetation in the eastern Amazon

Sommer, Rolf; Sá, T. D. de A.; Vielhauer, K.; Araújo, Alessandro; Fölster, H.; Vlek, Paul L. G.

doi:10.1016/s0168-1923(02)00044-8

Cited by 99 publications

(55 citation statements)

References 31 publications

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“…Measurements taken over a 2.5-year-old secondary forest in the eastern part of the basin showed intermediate values of evaporation compared to typical estimates for pastures and primary forests (Hölscher et al, 1997). More recently, it has been observed that a nearby site with slightly more mature vegetation (3.5 years old) may be able to release evapotranspiration rates similar to those of forests (Sommer et al, 2002). Furthermore, measures of the saturated hydraulic conductivity under different land-surface areas -forest, secondary forest and pasture -showed that the hydraulic properties of the corresponding soil profiles are similar below all three sites -at least, between 20 and 50 cm depths (Godsey and Elsenbeer, 2002).…”

Section: Catchment and Point Observationsmentioning

confidence: 83%

The effects of deforestation on the hydrological cycle in Amazonia: a review on scale and resolution

D’Almeida

Vörösmarty

Hurtt

et al. 2007

Intl Journal of Climatology

233

137

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Abstract:This paper reviews the effects of deforestation on the hydrological cycle in Amazonia according to recent modeling and observational studies performed within different spatial scales and resolutions. The predictions that follow from future scenarios of a complete deforestation in the region point to a restrained water cycle, while the simulated effects of small, disturbed areas show a contrasting tendency. Differences between coarsely spatially averaged observations and finely sampled data sets have also been encountered. These contrasts are only partially explained by the different spatial resolutions among models and observations, since they seem to be further associated with the weakening of precipitation recycling under scenarios of extensive deforestation and with the potential intensification of convection over areas of land-surface heterogeneity. Therefore, intrinsic and interrelated scale and heterogeneity dependencies on the impact of deforestation in Amazonia on the hydrological cycle are revealed and the acknowledgement of the relevance of these dependencies sets a few challenges for the future.

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Section: Catchment and Point Observationsmentioning

confidence: 83%

The effects of deforestation on the hydrological cycle in Amazonia: a review on scale and resolution

D’Almeida

Vörösmarty

Hurtt

et al. 2007

Intl Journal of Climatology

233

137

View full text Add to dashboard Cite

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“…Results from the Anglo-Brazilian Amazonian Climate Observation Study (ABRACOS; Gash et al 1996) and the more recent Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) (LBA 1996, Avissar et al 2002, Keller et al 2004 have provided a better understanding of the controls of forest E T at seasonal and interannual time scales. These studies have shown not only a higher E T in the dry season than in the wet season but also a higher E T over areas with less rainfall during the dry season in eastern and central Amazonia (Shuttleworth 1988, Nepstad et al 1994, Malhi et al 2002, Sommer et al 2002 well under heavy aerosol and biomass burning conditions, which are frequent in the region (Miura et al 1998). The aim of this work was to develop an empirical approach for the estimation of E T based on the vegetation condition inferred from the EVI and surface net radiation from the International Satellite Cloud Climatology Project (ISCCP; Zhang et al 1995Zhang et al , 2004).…”

Section: Introductionmentioning

confidence: 94%

An empirical approach to retrieving monthly evapotranspiration over Amazonia

Juarez

Goulden

Myneni

et al. 2008

International Journal of Remote Sensing

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The extent of evapotranspiration (E T ) over the Brazilian Amazon rainforest remains uncertain because in situ measurement sites do not cover the entire domain, and the fetch of these sites is only of the order of 10 3 m. In this investigation we developed an empirical method to estimate E T over the Brazilian Legal Amazon (BLA). The work was based on an improved physical understanding of what controls E T over the Amazonia rainforest resulting from analyses of recent in situ observations. Satellite data used in this study include the Enhanced Vegetation Index (EVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the surface radiation budget from the International Satellite Cloud Climatology Project (ISCCP). The empirical model was validated by measurements performed at four upland forest sites. The observed values and the calculated modelled values at these sites had the same mean and variance. On a seasonal scale, regional modelled E T peaks during the austral spring (September to November), as reported in the literature. In addition, the empirical model allows us to estimate the regional seasonal and interannual distributions of E T /precipitation rates.

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“…Lond. B (2004) rainfall to the atmosphere (Sommer et al 2002). Owing to the significant increase in the partitioning of incoming radiation into sensible versus latent heat production under future climate scenarios, surface temperatures soar, reaching, on average, 38°C (table 1).…”

Section: (B) Climate Scenarios and Simulationsmentioning

confidence: 99%

Contrasting simulated past and future responses of the Amazonian forest to atmospheric change

Cowling

Betts

Cox

et al. 2004

Phil. Trans. R. Soc. Lond. B

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Modelling simulations of palaeoclimate and past vegetation form and function can contribute to global change research by constraining predictions of potential earth system responses to future warming, and by providing useful insights into the ecophysiological tolerances and threshold responses of plants to varying degrees of atmospheric change. We contrasted HadCM3LC simulations of Amazonian forest at the last glacial maximum (LGM; 21 kyr ago) and a Younger Dryas-like period (13-12 kyr ago) with predicted responses of future warming to provide estimates of the climatic limits under which the Amazon forest remains relatively stable. Our simulations indicate that despite lower atmospheric CO 2 concentrations and increased aridity during the LGM, Amazonia remains mostly forested, and that the cooling climate of the Younger Dryas-like period in fact causes a trend toward increased above-ground carbon balance relative to today. The vegetation feedbacks responsible for maintaining forest integrity in past climates (i.e. decreased evapotranspiration and reduced plant respiration) cannot be maintained into the future. Although elevated atmospheric CO 2 contributes to a positive enhancement of plant carbon and water balance, decreased stomatal conductance and increased plant and soil respiration cause a positive feedback that amplifies localized drying and climate warming. We speculate that the Amazonian forest is currently near its critical resiliency threshold, and that even minor climate warming may be sufficient to promote deleterious feedbacks on forest integrity.

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Transpiration and canopy conductance of secondary vegetation in the eastern Amazon

Cited by 99 publications

References 31 publications

The effects of deforestation on the hydrological cycle in Amazonia: a review on scale and resolution

The effects of deforestation on the hydrological cycle in Amazonia: a review on scale and resolution

An empirical approach to retrieving monthly evapotranspiration over Amazonia

Contrasting simulated past and future responses of the Amazonian forest to atmospheric change

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