Amazon Forests Green-Up During 2005 Drought

Saleska, S. R.; Didan, Kamel; Huete, Alfredo; Rocha, Humberto Ribeiro da

doi:10.1126/science.1146663

Cited by 533 publications

(526 citation statements)

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“…However, the magnitude and location of the sink of CO2 show large uncertainties [5,6], which lead to continuous researches focusing on monitoring vegetation activity change in the middle and high latitudes of the Northern Hemisphere. There are many investigations about the interannual variation in vegetation activity over the middle and high latitudes of the Northern Hemisphere based on the satellite-derived long-term records of Normalized Difference Vegetation Index (NDVI) data sets [7][8][9][10][11]. The vegetation activity in the northern middle and high latitudes demonstrated a consistent increasing trend according to the studies with the Global Inventory Monitoring and Modeling Studies (GIMMS) group produced NDVI data sets during 1981-1991 [12] and 1981-1999 [7].…”

Section: Introductionmentioning

confidence: 99%

A Comparative Analysis between GIMSS NDVIg and NDVI3g for Monitoring Vegetation Activity Change in the Northern Hemisphere during 1982–2008

et al. 2013

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Abstract:The long-term Normalized Difference Vegetation Index (NDVI) time-series data set generated from the Advanced Very High Resolution Radiometers (AVHRR) has been widely used to monitor vegetation activity change. The third version of NDVI (NDVI3g) produced by the Global Inventory Modeling and Mapping Studies (GIMMS) group was released recently. The comparisons between the new and old versions should be conducted for linking existing studies with future applications of NDVI3g in monitoring vegetation activity change. Based on simple and piecewise linear regression methods, this study made a comparative analysis between NDVIg and NDVI3g for monitoring vegetation activity change and its responses to climate change in the middle and high latitudes of the Northern Hemisphere during 1982-2008. Our results indicated that there were large differences between NDVIg and NDVI3g in the spatial patterns for both the overall changing trends and the timing of Turning Points (TP) in NDVI time series, which spread over almost the entire study region. The average NDVI trend from NDVI3g was almost twice as great as that from NDVIg and the detected average timing of TP from NDVI3g was about one year later. Although the general spatial patterns were consistent between two data sets for detecting the responses of growing-season NDVI to temperature and precipitation changes, there were large differences in the response magnitude, with a OPEN ACCESSRemote Sens. 2013, 5 4032 higher response magnitude to temperature in NDVI3g and an opposite response to precipitation change for the two data sets. These results demonstrated that the NDVIg data set may underestimate the vegetation activity change trend and its response to climate change in the middle and high latitudes of the Northern Hemisphere during the past three decades.

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Section: Introductionmentioning

confidence: 99%

A Comparative Analysis between GIMSS NDVIg and NDVI3g for Monitoring Vegetation Activity Change in the Northern Hemisphere during 1982–2008

et al. 2013

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“…Data from conventional optical sensors suggested inconclusive results. One study showed the greening of the forest (increase in vegetation index) due to higher active radiation (less clouds) during the early stages of drought [14], while others proposed either browning of the forest from water stress [15], or greening in later stages of drought from opening of the canopy from potential tree mortality [16]. Satellite optical observations over tropical forests are impacted by clouds and atmospheric aerosol, causing noise in surface reflectance data [15].…”

Section: Introductionmentioning

confidence: 99%

Response of African humid tropical forests to recent rainfall anomalies

Asefi-Najafabady

Saatchi

2013

Phil. Trans. R. Soc. B

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During the last decade, strong negative rainfall anomalies resulting from increased sea surface temperature in the tropical Atlantic have caused extensive droughts in rainforests of western Amazonia, exerting persistent effects on the forest canopy. In contrast, there have been no significant impacts on rainforests of West and Central Africa during the same period, despite large-scale droughts and rainfall anomalies during the same period. Using a combination of rainfall observations from meteorological stations from the Climate Research Unit (CRU; 1950–2009) and satellite observations of the Tropical Rainfall Measuring Mission (TRMM; 1998–2010), we show that West and Central Africa experienced strong negative water deficit (WD) anomalies over the last decade, particularly in 2005, 2006 and 2007. These anomalies were a continuation of an increasing drying trend in the region that started in the 1970s. We monitored the response of forests to extreme rainfall anomalies of the past decade by analysing the microwave scatterometer data from QuickSCAT (1999–2009) sensitive to variations in canopy water content and structure. Unlike in Amazonia, we found no significant impacts of extreme WD events on forests of Central Africa, suggesting potential adaptability of these forests to short-term severe droughts. Only forests near the savanna boundary in West Africa and in fragmented landscapes of the northern Congo Basin responded to extreme droughts with widespread canopy disturbance that lasted only during the period of WD. Time-series analyses of CRU and TRMM data show most regions in Central and West Africa experience seasonal or decadal extreme WDs (less than −600 mm). We hypothesize that the long-term historical extreme WDs with gradual drying trends in the 1970s have increased the adaptability of humid tropical forests in Africa to droughts.

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“…Although severe soil moisture depletion during prolonged drought may lead to stomatal closure and a decline in leaf area (Nepstad et al, 1994), there is still controversy on whether draught-induced water deficit limits tree growth in the Central Amazon. During the 2005 drought, for example, Saleska et al (2007) reported an enhanced vegetation index of the forest based on moderate resolution imaging spectroradiometer (MODIS) satellite data. This is contrary to what should be expected, as changes in precipitation can alter growth rates (Lewis et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Leaf traits and gas exchange in saplings of native tree species in the Central Amazon

Mendes¹,

Marenco²

2010

Sci. agric. (Piracicaba, Braz.)

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Global climate models predict changes on the length of the dry season in the Amazon which may affect tree physiology. The aims of this work were to determine the effect of the rainfall regime and fraction of sky visible (FSV) at the forest understory on leaf traits and gas exchange of ten rainforest tree species in the Central Amazon, Brazil. We also examined the relationship between specific leaf area (SLA), leaf thickness (LT), and leaf nitrogen content on photosynthetic parameters.

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Amazon Forests Green-Up During 2005 Drought

Cited by 533 publications

References 5 publications

A Comparative Analysis between GIMSS NDVIg and NDVI3g for Monitoring Vegetation Activity Change in the Northern Hemisphere during 1982–2008

A Comparative Analysis between GIMSS NDVIg and NDVI3g for Monitoring Vegetation Activity Change in the Northern Hemisphere during 1982–2008

Response of African humid tropical forests to recent rainfall anomalies

Leaf traits and gas exchange in saplings of native tree species in the Central Amazon

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