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4 resultados encontrados para: AUTOR: Malhi, Yadvinder Singh
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Resumen en: Inglés |
Resumen en inglés

We combined two existing datasets of vegetation aboveground biomass (AGB) (Proceedings of the National Academy of Sciences of the United States of America, 108, 2011, 9899; Nature Climate Change, 2, 2012, 182) into a pan-tropical AGB map at 1- km resolution using an independent reference dataset of field observations and locally calibrated high-resolution biomass maps, harmonized and upscaled to 14 477 1-km AGB estimates. Our data fusion approach uses bias removal and weighted linear averaging that incorporates and spatializes the biomass patterns indicated by the reference data. The method was applied independently in areas (strata) with homogeneous error patterns of the input (Saatchi and Baccini) maps, which were estimated from the reference data and additional covariates. Based on the fused map, we estimated AGB stock for the tropics (23.4 N–23.4 S) of 375 Pg dry mass, 9–18% lower than the Saatchi and Baccini estimates. The fused map also showed differing spatial patterns of AGB over large areas, with higher AGB density in the dense forest areas in the Congo basin, Eastern Amazon and South-East Asia, and lower values in Central America and in most dry vegetation areas of Africa than either of the input maps. The validation exercise, based on 2118 estimates from the reference dataset not used in the fusion process, showed that the fused map had a RMSE 15–21% lower than that of the input maps and, most importantly, nearly unbiased estimates (mean bias 5 Mg dry mass ha 1 vs. 21 and 28 Mg ha 1 for the input maps). The fusion method can be applied at any scale including the policy-relevant national level, where it can provide improved biomass estimates by integrating existing regional biomass maps as input maps and additional, country-specific reference datasets.


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Resumen en: Inglés |
Resumen en inglés

We summarise the contemporary carbon budget of South America and relate it to its dominant controls: population and economic growth, changes in land use practices and a changing atmospheric environment and climate. Component flux estimate methods we consider sufficiently reliable for this purpose encompass fossil fuel emission inventories, biometric analysis of old-growth rainforests, estimation of carbon release associated with deforestation based on remote sensing and inventories, and agricultural export data. Alternative methods for the estimation of the continental-scale net land to atmosphere CO2 flux, such as atmospheric transport inverse modelling and terrestrial biosphere model predictions, are, we find, hampered by the data paucity, and improved parameterisation and validation exercises are required before reliable estimates can be obtained. From our analysis of available data, we suggest that South America was a net source to the atmosphere during the 1980s (~ 0.3–0.4 Pg C a−1) and close to neutral (~ 0.1 Pg C a−1) in the 1990s. During the latter period, carbon uptake in old-growth forests nearly compensated for the carbon release associated with fossil fuel burning and deforestation.

Annual mean precipitation over tropical South America as inferred from Amazon River discharge shows a long-term upward trend. Although, over the last decade dry seasons have tended to be drier, with the years 2005 and 2010 in particular experiencing strong droughts. On the other hand, precipitation during the wet seasons also shows an increasing trend. Air temperatures have also increased slightly. Also with increases in atmospheric CO2 concentrations, it is currently unclear what effect these climate changes are having on the forest carbon balance of the region. Current indications are that the forests of the Amazon Basin have acted as a substantial long-term carbon sink, but with the most recent measurements suggesting that this sink may be weakening. Economic development of the tropical regions of the continent is advancing steadily, with exports of agricultural products being an important driver and witnessing a strong upturn over the last decade.


3.
Artículo
*En hemeroteca, SIBE-San Cristóbal
Changes in growth of tropical forests: evaluating potential biases
Phillips, Oliver L. ; Malhi, Yadvinder Singh (coaut.) (1968-) ; Vinceti, Barbara (coaut.) ; Baker, T. (coaut.) ; Lewis, Simon L. (coaut.) ;
Contenido en: Ecological Applications. A Publication of the Ecological Society of America Vol. 12, no. 2 (April 2002), p. 576-587 ISSN: 1051-0761
Bibliotecas: San Cristóbal
Cerrar
SIBE San Cristóbal
B10160 (Disponible)
Disponibles para prestamo: 1
Nota: En hemeroteca, SIBE-San Cristóbal
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4.
Artículo
*En hemeroteca, SIBE-San Cristóbal, SIBE-Tapachula
Changes in the carbon balance of tropical forests: evidence from long-term plots
Phillips, Oliver L. ; Malhi, Yadvinder Singh (coaut.) (1968-) ; Higuchi, Niro (coaut.) ; Laurence, William F. (coaut.) ; Núñez, Percy V. (coaut.) ;
Contenido en: Science V. 282, no. 5388 (16 october 1998), p. 439-446 ISSN: 0036-8075
Bibliotecas: San Cristóbal , Tapachula
Cerrar
SIBE San Cristóbal
28622-10 (Disponible)
Disponibles para prestamo: 1
Cerrar
SIBE Tapachula
28622-20 (Disponible)
Disponibles para prestamo: 1
Nota: En hemeroteca, SIBE-San Cristóbal, SIBE-Tapachula