Quantitative pollen-vegetation modeling of Patagonian high Andean steppe and tree-line communities.

G. D. SOTTILE; BUNTING, M.J; TONELLO, M.S.; MANCINI, M. V.; MARCOS, M.A; PALACIOS, P

Dublin

Congreso; INQUA Congress; 2019

INQUA

Quantitative pollen-vegetation modeling of Patagonian high Andean steppe and tree-line communities.INQUA Congress 2019: Dublin, from 25 Jul 2019 - 31 Jul 2019.Sottile, G.D.; Bunting, M.J.; Tonello, M.S.; Mancini, M.V.; Marcos, M.A; Palacios, P. Understanding long-term dynamics of high Andean steppe and upper tree-line communities from Patagonia is a key note step to design conservation and management strategies for these ecosystems under the current climate change scenario. Vegetation landcover reconstruction of the last 1200 years based on pollen records would bring up light about a range of communities changes under different climatic scenarios. However, applying vegetation landcover methods in Patagonia is still a challenge because of the unknown pollen productivity estimates (PPEs) of the main Patagonian vegetation taxa and relevant source area of pollen (RSAP) of peat and lake basins. The contribution of Burry et al (2001) and Sottile et al. (2016) following Davis? R-value model (1963), has shown a basic approach on understanding shrubs, herbs and trees of Patagonian pollen-vegetation cover relationship. Regarding Patagonia Andean communities Sottile et al. (2016) studied Nothofagus pollen-vegetation cover relationship at different concentric radius/radio (250-2000 m) at 45 sites (moss polster) from 1000 m2 open areas and vegetation cover measured from satellite images following the main wind direction. The authors found the best pollen-vegetation cover fit at 1500 m radius. During this study we aim to model pollen-vegetation relationship following ERV (Extended R- Value)models based on 20 sites between 46.9°S and 49.4°S and compare these new outcomes with previously published results. Detailed vegetation surveys within 5, 15, 30, 50 m radius around each sampling point were carried out following the main wind blow direction. Beyond 50 m up to 2000 m, vegetation data was recovered from digitized maps. The multivariate analysis of the pollen content of the moss polster samples showed that Nothofagus, Poaceae, Asteraceaesubf. Asteroideae, Empetrum, Gaultheria, Apiaceae, Azorella, Mulinum and Nassauvia were the most important variables separating forest versus non forest communities. Estimates of pollen fall speeds for the nine taxa were estimates by measuring diameters of 30 grains of each taxa. Pollen productivity estimates were calculated using the ERV model as well as the RSAP. The calculation of the RSAP based on a group of taxa including entomophilous and anemophilous grains shows considerable minor RSAP than the 1500 m radius reported by Sottile et al. (2016).These results help to understand the scale of paleoecological inferences and set bases for future quantitative vegetation reconstruction based fossil pollen samples. ReferencesBurry, L.S., Trivi de Mandri, M.E., Palacio P.I., Lombardo, M.C. 2001. Relaciones polen-vegetación de algunos taxa de la estepa patagónica (Argentina). Revista Chilena de Historia Natural 74: 419?427.Davis, M.B. 1963. On the theory of pollen analysis. American Journal of Sciences, 261, 897-912.Sottile, G.D., Tonello, M.S., Mancini, M.V. 2016. Potentiality of past vegetation land cover reconstruction in forest-high Andean steppe ecotone of Southern Patagonia, Argentina. First results.XIV IPC, X IOPC, Salvador, Brazil.