The response of an Eastern Amazonian rain forest to drought stress: results and modelling analyses from a throughfall exclusion experiment

Fisher, Rosie A.; Williams, Mathew; Costa, Antonio Lola da; Malhi, Yadvinder; Costa, Rafael; Almeida, Samuel; Meir, Patrick

doi:10.1111/j.1365-2486.2007.01417.x

Cited by 277 publications

(374 citation statements)

References 74 publications

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“…Two recent manipulation experiments have attempted to address these questions by excluding a fraction of the incoming throughfall of precipitation to the soil in 1-ha rainforest plots in E. Amazonia (24)(25)(26). Both experiments shifted a rainfall regime typical of evergreen forest into one near to or within the savanna bioclimatic zone (Fig.…”

Section: Vegetation Response To a Drying Amazonmentioning

confidence: 99%

Exploring the likelihood and mechanism of a climate-change-induced dieback of the Amazon rainforest

Malhi

Aragão

Galbraith

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

790

780

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We examine the evidence for the possibility that 21st-century climate change may cause a large-scale ''dieback'' or degradation of Amazonian rainforest. We employ a new framework for evaluating the rainfall regime of tropical forests and from this deduce precipitation-based boundaries for current forest viability. We then examine climate simulations by 19 global climate models (GCMs) in this context and find that most tend to underestimate current rainfall. GCMs also vary greatly in their projections of future climate change in Amazonia. We attempt to take into account the differences between GCM-simulated and observed rainfall regimes in the 20th century. Our analysis suggests that dry-season water stress is likely to increase in E. Amazonia over the 21st century, but the region tends toward a climate more appropriate to seasonal forest than to savanna. These seasonal forests may be resilient to seasonal drought but are likely to face intensified water stress caused by higher temperatures and to be vulnerable to fires, which are at present naturally rare in much of Amazonia. The spread of fire ignition associated with advancing deforestation, logging, and fragmentation may act as nucleation points that trigger the transition of these seasonal forests into fire-dominated, low biomass forests. Conversely, deliberate limitation of deforestation and fire may be an effective intervention to maintain Amazonian forest resilience in the face of imposed 21st-century climate change. Such intervention may be enough to navigate E. Amazonia away from a possible ''tipping point,'' beyond which extensive rainforest would become unsustainable.carbon dioxide ͉ drought ͉ fire ͉ tropical forests ͉ adaptation

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Section: Vegetation Response To a Drying Amazonmentioning

confidence: 99%

Exploring the likelihood and mechanism of a climate-change-induced dieback of the Amazon rainforest

Malhi

Aragão

Galbraith

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

790

780

View full text Add to dashboard Cite

show abstract

“…In fact, the ability of some areas of the Amazon rainforest to maintain high ET rates and, eventually, keep growing or begin leaf flushing (108) during the dry season does not guarantee that humid forest could be resilient to extreme and prolonged droughts. In situ observations of the impact of "natural" extreme droughts (109) and artificially induced droughts for several years (110)(111)(112) showed that forest responds with interruption of growth and mortality of some species during a prolonged drought period. The results of artificially induced and natural droughts have shown that the larger trees [diameter at breast height (dbh) > 30 cm], together with lianas, are the most vulnerable ones (112).…”

Section: Impacts Of Anthropogenic Drivers Of Change In the Amazonmentioning

confidence: 99%

Land-use and climate change risks in the Amazon and the need of a novel sustainable development paradigm

Nobre

Sampaio

Borma

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

602

432

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For half a century, the process of economic integration of the Amazon has been based on intensive use of renewable and nonrenewable natural resources, which has brought significant basin-wide environmental alterations. The rural development in the Amazonia pushed the agricultural frontier swiftly, resulting in widespread land-cover change, but agriculture in the Amazon has been of low productivity and unsustainable. The loss of biodiversity and continued deforestation will lead to high risks of irreversible change of its tropical forests. It has been established by modeling studies that the Amazon may have two "tipping points," namely, temperature increase of 4°C or deforestation exceeding 40% of the forest area. If transgressed, large-scale "savannization" of mostly southern and eastern Amazon may take place. The region has warmed about 1°C over the last 60 y, and total deforestation is reaching 20% of the forested area. The recent significant reductions in deforestation-80% reduction in the Brazilian Amazon in the last decade-opens up opportunities for a novel sustainable development paradigm for the future of the Amazon. We argue for a new development paradigm-away from only attempting to reconcile maximizing conservation versus intensification of traditional agriculture and expansion of hydropower capacity-in which we research, develop, and scale a high-tech innovation approach that sees the Amazon as a global public good of biological assets that can enable the creation of innovative high-value products, services, and platforms through combining advanced digital, biological, and material technologies of the Fourth Industrial Revolution in progress.Amazon tropical forests | Amazon sustainability | Amazon land use | Amazon savannization | climate change impacts

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“…Flexas and Medrano, 2002;Bréda et al, 2006). Structural changes reducing photosynthesis include reductions in leaf area and specific leaf area or changes in leaf geometry or orientation (Bréda et al, 2006;Fisher et al, 2007). Via increased tree mortality, droughts can also severely impact ecosystem level photosynthesis 30 long after the drought event itself (e.g.…”

mentioning

confidence: 99%

Impacts of droughts and extreme temperature events on gross primary production and ecosystem respiration: a systematic assessment across ecosystems and climate zones

Buttlar¹,

Zscheischler²,

Rammig³

et al. 2017

Preprint

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Abstract.Extreme climatic events, such as droughts and heat stress induce anomalies in ecosystem-atmosphere CO 2 fluxes, such as gross primary production (GPP) and ecosystem respiration (R eco ), and, hence, can change the net ecosystem carbon balance.However, despite our increasing understanding of the underlying mechanisms, the magnitudes of the impacts of different types of extremes on GPP and R eco within and between ecosystems remain poorly predicted. Here we aim to identify the major 5 factors controlling the amplitude of extreme event impacts on GPP, R eco , and the resulting net ecosystem production (NEP).We focus on the impacts of heat and drought and their combination. We identified hydrometeorological extreme events in consistently downscaled water availability and temperature measurements over a 30 year time period. We then used FLUXNET eddy-covariance flux measurements to estimate the CO 2 flux anomalies during these extreme events across dominant vegetation types and climate zones. Overall, our results indicate that short-term heat extremes increased respiration more strongly than 10 they down-regulated GPP, resulting in a moderate reduction of the ecosystem's carbon sink potential. In the absence of heat stress, droughts tended to have smaller and similarly dampening effects on both GPP and R eco , and, hence, often resulted in neutral NEP responses. The combination of drought and heat typically led to a strong decrease in GPP, whereas heat and drought impacts on respiration partially offset each other. Taken together, compound heat and drought events led to the strongest C sink reduction compared to any single-factor extreme. A key insight of this paper, however, is that duration matters most: 15 for heat stress during droughts, the magnitude of impacts systematically increased with duration, whereas under heat stress without drought, the response of R eco over time turned from an initial increase to a down-regulation after about two weeks.This confirms earlier theories that not only the magnitude but also the duration of an extreme event determines its impact. Our study corroborates the results of several local site-level case studies, but as a novelty generalizes these findings at the global scale. Specifically, we find that the different response functions of the two antipodal land-atmosphere fluxes GPP and R eco can 20 also result in increasing NEP during certain extreme conditions. Apparently counterintuitive findings of this kind bear great potential for scrutinizing the mechanisms implemented in state-of-the-art terrestrial biosphere models and provide a benchmark for future model development and testing.

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The response of an Eastern Amazonian rain forest to drought stress: results and modelling analyses from a throughfall exclusion experiment

Cited by 277 publications

References 74 publications

Exploring the likelihood and mechanism of a climate-change-induced dieback of the Amazon rainforest

Exploring the likelihood and mechanism of a climate-change-induced dieback of the Amazon rainforest

Land-use and climate change risks in the Amazon and the need of a novel sustainable development paradigm

Impacts of droughts and extreme temperature events on gross primary production and ecosystem respiration: a systematic assessment across ecosystems and climate zones

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