A quantitative study of modern pollen–vegetation relationships in southern Brazil's Araucaria forest

Cárdenas, Macarena L.; Wilson, Oliver J.; Schorn, Lauri Amândio; Mayle, Francis E.; Iriarte, José

doi:10.1016/j.revpalbo.2019.03.003

Cited by 8 publications

(10 citation statements)

References 101 publications

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“…During the penultimate glacial, cooler temperatures in Colônia (on average 4 °C lower than during the last glacial) favoured the presence of permanent cool mixed evergreen forest with conifers Araucaria and Podocarpus associated with strong southern circulation towards the tropics. This has been assumed since recent estimates based on modern pollen climate calibration in the Atlantic forest domain showed that the continuous strong northward shifts of southern air masses were linked to expansion of the cool mixed forest 27,34,41 . In addition, a contrasting land-sea anomalies gradient (−7.4 ± 1.2) could explain a reduced SASM intensity to the study site, due to the effect of cooler land temperatures compared to the SST during that period ( Fig.…”

Section: Discussion Palaeoclimate and Vegetation Responses To Glacialmentioning

confidence: 99%

“…The first phase of biomass burning (71 to 50 ka) suggests that fires were caused by a change in seasonality with an increase in precipitation during austral winter and a decrease during the austral summer. Additionally, the presence of a cool mixed evergreen forest in the region with Araucaria and Podocarpus 34,41,46 points to the influence of southern air masses in southeastern Brazil. The strengthening of the SASM and high summer precipitation during a high precession www.nature.com/scientificreports www.nature.com/scientificreports/ phase 9 between 50 and 40 ka reduced biomass burning and increased the mixed evergreen forest cover (Fig.…”

Section: Discussion Palaeoclimate and Vegetation Responses To Glacialmentioning

confidence: 99%

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Shut down of the South American summer monsoon during the penultimate glacial

Rodríguez‐Zorro

Ledru

Bard

et al. 2020

Sci Rep

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We analysed changes in mean annual air temperature (MAAt), vegetation and biomass burning on a long and continuous lake-peat sediment record from the colônia basin, southeastern Brazil, examining the responses of a wet tropical rainforest over the last 180 ka. Stronger southern atmospheric circulation up to the latitude of colônia was found for the penultimate glacial with lower temperatures than during the last glacial, while strengthening of the South American summer monsoon (SASM) circulation started during the last interglacial and progressively enhanced a longer wet summer season from 95 ka until the present. Past MAAT variations and fire history were possibly modulated by eccentricity, although with signatures which differ in average and in amplitude between the last 180 ka. Vegetation responses were driven by the interplay between the SASM and southern circulation linked to Antarctic ice volume, inferred by the presence of a cool mixed evergreen forest from 180 to 45 ka progressively replaced by a rainforest. We report cooler temperatures during the marine isotope stage 3 (MIS 3: 57-29 ka) than during the Last Glacial Maximum (LGM: 23-19 ka). Our findings show that tropical forest dynamics display different patterns than mid-latitude during the last 180 ka.

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Section: Discussion Palaeoclimate and Vegetation Responses To Glacialmentioning

confidence: 99%

Section: Discussion Palaeoclimate and Vegetation Responses To Glacialmentioning

confidence: 99%

Shut down of the South American summer monsoon during the penultimate glacial

Rodríguez‐Zorro

Ledru

Bard

et al. 2020

Sci Rep

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“…The different R-values for the forest group between Vila Velha and Aparados da Serra are likely due to differences in forest composition, with higher abundances of pollen from Myrtaceae, Ilex and Myrsine in Aparados da Serra in the pollen samples. Cárdenas et al (2019) indeed estimate higher R-values for several tree taxa, including Clethra, Myrsine and Podocarpus, compared to A. angustifolia. Also, taxa including the Myrtaceae family, identified as low pollen producers, revealed high R-values in other studies (Gosling et al 2009;Cárdenas et al 2019).…”

Section: Representation Of Pollen Taxa and Pollen Productivitymentioning

confidence: 66%

“…The above mentioned weak local pollen signal of Poaceae and A. angustifolia has been observed in other studies from southern Brazil. For instance, a pollen vegetation comparison in the Araucaria-grassland mosaic in Santa Catarina State (Cárdenas et al 2019) While grasses are the most abundant taxon in open vegetation types of South America and make up nearly onethird of the plant cover in the two study areas, they also act as high pollen producers, being the most abundant pollen type in the air. This high regional deposition of Poaceae pollen results in the pollen type also being abundant in surface samples from woodland patches with low grass cover.…”

Section: Representation Of Openness In the Pollen Spectra From The Araucaria Forest-grassland Mosaicmentioning

confidence: 99%

“…Montade et al (2016) published averaged pollen vegetation ratios for three isolated mountains in Ceará, north-eastern Brazil, based on a collection of surface soil samples and botanical surveys. Analysing the pollen composition of moss cushions collected in a private forest reserve compared to vegetation survey and long-term monitoring data, Cárdenas et al (2019) provide ratios of average pollen versus vegetation proportions. Overall, quantitative pollen vegetation studies are indeed rare and have so far not developed beyond the R-value approach.…”

Section: Introductionmentioning

confidence: 99%

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Towards quantifying changes in forest cover in the Araucaria forest-grassland mosaic in southern Brazil

Bermúdez

Theuerkauf

Giesecke

2021

Veget Hist Archaeobot

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Quantitative estimates of past vegetation cover are needed both regionally so human-landscape interactions can be better understood, and globally to evaluate the effects of changing vegetation cover on the climate system. Models reducing the bias in the pollen representation of vegetation cover have been developed in the temperate regions of the northern hemisphere, while experience applying them in other parts of the world is limited. The Araucaria forest-grassland mosaic of southern Brazil is an area where open and forested plant communities exist naturally and have changed their cover over time due to changing climate and human activities. Therefore, this area is of particular interest for such studies. Modern pollen and vegetation comparisons were carried out in two protected areas: Vila Velha State Park in Paraná state and Aparados da Serra National Park in Rio Grande do Sul. Vegetation mapping and analysis focused on Araucaria angustifolia as the characteristic tree of this vegetation type. In the Araucaria forest-grassland mosaic open vegetation and woodland change at a scale of hundreds of metres. These changes are difficult to capture based on pollen proportions in surface samples. While the abundance of Poaceae pollen is not a good indicator of locally open conditions, several pollen taxa can be used as indicators of the local vegetation cover. Pollen vegetation ratios (R-values) compare well between the two study regions, indicating that pollen production of individual species within the large plant families of Poaceae and Asteraceae are similar within the overall region. Araucaria angustifolia pollen is underrepresented with regards to its vegetation cover, while Poaceae are among the highest pollen producers in the region. Diverse woodland species other than A. angustifolia were grouped as one forest taxon and as the species composition of woodlands differed between the two study areas, so did the estimated pollen productivity of this group. It would be rewarding in future investigations to estimate pollen productivity for groups of trees with the same pollen dispersal syndrome. The application of pollen dispersal models designed for closed canopy in the protected areas was challenging. Further model development is required to deal with pollen released at different levels in semi-open vegetation types.

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