Basin-wide variation in tree hydraulic safety margins predicts the carbon balance of Amazon forests

Tropical forests face increasing climate risk1,2, yet our ability to predict their response to climate change is limited by poor understanding of their resistance to water stress. Although xylem embolism resistance thresholds (for example, [Formula: see text]50) and hydraulic safety margins (for example, HSM50) are important predictors of drought-induced mortality risk3-5, little is known about how these vary across Earth's largest tropical forest. Here, we present a pan-Amazon, fully standardized hydraulic traits dataset and use it to assess regional variation in drought sensitivity and hydraulic trait ability to predict species distributions and long-term forest biomass accumulation. Parameters [Formula: see text]50 and HSM50 vary markedly across the Amazon and are related to average long-term rainfall characteristics. Both [Formula: see text]50 and HSM50 influence the biogeographical distribution of Amazon tree species. However, HSM50 was the only significant predictor of observed decadal-scale changes in forest biomass. Old-growth forests with wide HSM50 are gaining more biomass than are low HSM50 forests. We propose that this may be associated with a growth-mortality trade-off whereby trees in forests consisting of fast-growing species take greater hydraulic risks and face greater mortality risk. Moreover, in regions of more pronounced climatic change, we find evidence that forests are losing biomass, suggesting that species in these regions may be operating beyond their hydraulic limits. Continued climate change is likely to further reduce HSM50 in the Amazon6,7, with strong implications for the Amazon carbon sink.

Publishing in English is associated with an increase of the impact factor of Brazilian biodiversity journals

English is the lingua franca for scientific communication, but some journals, especially in developing countries, still publish non-English studies. A shift towards publishing in English may promote internationalization and more visibility of scientific journals. Here we compared quality indexes between Brazilian journals that have always published in English and journals that have published in languages other than English. We also investigated whether a temporal shift towards publishing in English led to elevated quality measures. Our analyses covered 16 Brazilian biodiversity journals and accounted for 12640 papers published since 2007. The mean impact factor was on average 55% higher in journals that have published consistently in English, compared to the so-called multilanguage journals. The proportion of publications in English increased to nearly three times the original value in multilanguage journals between 2007 and 2016, and the impact factor tripled during this period. At the same time, the Qualis-Capes classifications (B1-B2-B3) tended to fall. Publishing in English can be a first step to increased visibility, and this is particularly important for biodiversity journals, since Brazilian ecosystems are considered of interest to the international scientific community and nature conservation.