The enigma of the Amazonian carbon balance

Dolman, A. J.; Janßen, Thomas

doi:10.1088/1748-9326/aac78e

Cited by 6 publications

(5 citation statements)

References 12 publications

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“…This limitation can reduce the strength of the terrestrial carbon sink and, in some cases, even lead to temporary carbon sources in terrestrial ecosystems (Jung et al, 2017;Phillips et al, 2009). This temporary reversion from carbon sink into a source has been reported in Amazon forest during 2005 and 2010 (Chai et al, 2021;Dolman & Janssen, 2018), as well as in Europe during 2003 (Ciais et al, 2005), due to droughts events. Another possible driving factor is nutrient limitations, specifically nitrogen and phosphorus supplies, which may restrict CO 2 -induced biomass enhancement and related carbon sequestration (Oren et al, 2001;Reich et al, 2006, Reich & Hobbie, 2013.…”

supporting

confidence: 57%

Characteristics and drivers of vegetation productivity sensitivity to increasing CO₂ at Northern Middle and High Latitudes

Chai,

2024

Ecology and Evolution

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Understanding and accurately predicting how the sensitivity of terrestrial vegetation productivity to rising atmospheric CO2 concentration (β) is crucial for assessing carbon sink dynamics. However, the temporal characteristics and driving mechanisms of β remain uncertain. Here, observational and CMIP6 modeling evidence suggest a decreasing trend in β at the Northern Middle and High Latitudes during the historical period of 1982–2015 (−0.082 ± 0.005% 100 ppm−1 year−1). This decreasing trend is projected to persist until the end of the 21st century (−0.082 ± 0.005% 100 ppm−1 year−1 under SSP370 and −0.166 ± 0.006% 100 ppm−1 year−1 under SSP585). The declining β indicates a weakening capacity of vegetation to mitigate warming climates, posing challenges for achieving the temperature goals of the Paris Agreement. The rise in vapor pressure deficit (VPD), that triggers stomata closure and weakens photosynthesis, is considered as the dominated factor contributing to the historical and future decline in β, accounting for 62.3%–75.2% of the effect. Nutrient availability and water availability contribute 15.7%–21.4% and 8.5%–16.3%, respectively. These findings underscore the significant role of VPD in shaping terrestrial carbon sink dynamics, an aspect that is currently insufficiently considered in many climate and ecological models.

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confidence: 57%

Characteristics and drivers of vegetation productivity sensitivity to increasing CO₂ at Northern Middle and High Latitudes

Chai,

2024

Ecology and Evolution

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“…Increasing the amount of PFTs by adding undergrowth shade-tolerant species could affect the derived uncertainty of AGB, GPP, and AWP, but at the same time this complexity relies on additional uncertain tree allometries of those tree species. A further simplification of our approach is that it does not consider the influence of nutrients on forest growth 48 .…”

Section: Discussionmentioning

confidence: 99%

From small-scale forest structure to Amazon-wide carbon estimates

et al. 2019

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Tropical forests play an important role in the global carbon cycle. High-resolution remote sensing techniques, e.g., spaceborne lidar, can measure complex tropical forest structures, but it remains a challenge how to interpret such information for the assessment of forest biomass and productivity. Here, we develop an approach to estimate basal area, aboveground biomass and productivity within Amazonia by matching 770,000 GLAS lidar (ICESat) profiles with forest simulations considering spatial heterogeneous environmental and ecological conditions. This allows for deriving frequency distributions of key forest attributes for the entire Amazon. This detailed interpretation of remote sensing data improves estimates of forest attributes by 20–43% as compared to (conventional) estimates using mean canopy height. The inclusion of forest modeling has a high potential to close a missing link between remote sensing measurements and the 3D structure of forests, and may thereby improve continent-wide estimates of biomass and productivity.

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“…Amazonia hosts the largest rainforest in the world: it holds 10-15% of global land biodiversity 1,2 and generates 17-20% of global runoff to the oceans 3,4 . Future changes in Amazonia's temperature and precipitation will play a key role in the global carbon, energy and water cycles 5 .…”

Section: Introductionmentioning

confidence: 99%

Constraining Amazonian land surface temperature sensitivity to precipitation and the probability of forest dieback

et al. 2021

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The complete or partial collapse of the forests of Amazonia is consistently named as one of the top ten possible tipping points of Planet Earth in a changing climate. However, apart from a few observational studies that showed increased mortality after the severe droughts of 2005 and 2010, the evidence for such collapse depends primarily on modelling. Such studies are notoriously deficient at predicting the rainfall in the Amazon basin and how the vegetation interacts with the rainfall is poorly represented. Here, we use long-term surface-based observations of the air temperature and rainfall in Amazonia to provide a constraint on the modelled sensitivity of temperature to changes in precipitation. This emergent constraint also allows us to significantly constrain the likelihood of a forest collapse or dieback. We conclude that Amazon dieback under IPCC scenario RCP8.5 (crossing the tipping point) is not likely to occur in the twenty-first century.

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The enigma of the Amazonian carbon balance

Cited by 6 publications

References 12 publications

Characteristics and drivers of vegetation productivity sensitivity to increasing CO₂ at Northern Middle and High Latitudes

Characteristics and drivers of vegetation productivity sensitivity to increasing CO₂ at Northern Middle and High Latitudes

From small-scale forest structure to Amazon-wide carbon estimates

Constraining Amazonian land surface temperature sensitivity to precipitation and the probability of forest dieback

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The enigma of the Amazonian carbon balance

Cited by 6 publications

References 12 publications

Characteristics and drivers of vegetation productivity sensitivity to increasing CO2 at Northern Middle and High Latitudes

Characteristics and drivers of vegetation productivity sensitivity to increasing CO2 at Northern Middle and High Latitudes

From small-scale forest structure to Amazon-wide carbon estimates

Constraining Amazonian land surface temperature sensitivity to precipitation and the probability of forest dieback

Contact Info

Product

Resources

About

Characteristics and drivers of vegetation productivity sensitivity to increasing CO₂ at Northern Middle and High Latitudes

Characteristics and drivers of vegetation productivity sensitivity to increasing CO₂ at Northern Middle and High Latitudes