Sap flow rates of Minquartia guianensis in central Amazonia during the prolonged dry season of 2015–2016

Principal component regression analysis demonstrates the collinearity-free effect of sub estimated climatic variables on tree growth in the central Amazon

“…Beside the effect of temperature on photosynthesis, a raise in temperature has also an effect on transpiration via the effect of temperature on water viscosity (Darcy´s Law). In fact, in this experimental site, EVT can increase in the dry season when temperatures are higher (Antezana-Vera & Marenco, 2020).…”

“…Yang et al (2018) observed a decrease in solar-induced fluorescence during the drought of 2015-2016 in the Amazon region. Likewise, in a study carried out at the same experimental site, Antezana-Vera and Marenco (2020) found that transpiration significantly increased with an increase in PAR and VPD. An increase in transpiration rates does not mean an increase in g s and photosynthesis.…”

“…Some studies that aim to assess the effect of rainfall seasonality on tree growth in the Amazon have led to different results. Dias and Marenco (2016) and Silva et al, (2003) found no increase in tree growth during the wet season, whereas Wagner et al (2014), Méndez (2018), and Antezana-Vera and Marenco (2020) reported that tree growth increased with an increase in rainfall intensity. Likewise, Lee et al (2013) and Yang et al (2018) reported a decline in photosynthesis-related activity during the dry season.…”

“…Rainfall and SWC seem to be the major factors that affect tree growth in the Amazon region, but there is still under debate whether Amazonian trees grow faster in the wet season than in the dry season. Although in most studies tree growth or ecosystem photosynthesis seems to decrease in the dry season (Méndez, 2018;Wagner et al, 2014;Yang et al, 2018;Antezana-Vera & Marenco, 2020), the opposite effect has also been reported (Laurance et al, 2009;Green, et al, 2020). Whereas Laurance et al (2009) reported that tree growth was fastest during the dry period and positively correlated with maximum temperatures (T max ), Wagner et al (2014) found no significant effect of T max on tree growth.…”

“…The Amazon rainforest has a significant impact on both water and carbon cycles, due to its enormous extension (~ 5.1 × 10 6 km 2 ) and the high amount of carbon stored in its vegetation, about 86 Pg (Saatchi, Houghton, Alvalá, Soares, & Yu, 2007). Tree growth can be defined as the increase of biomass through time and it is often estimated by measuring the increment of stem diameter over time -a proxy of biomass gains at the ecosystem level (Wagner, Rossi, Stahl, Bonal, & Herault, 2012;Wagner et al, 2014;Dias & Marenco, 2016;Antezana-Vera & Marenco, 2020). As tree growth is greatly affected by factors that affect photosynthesis, sun-induced fluorescence -a proxy of ecosystem photosynthesis has been used to estimate the effect of environmental factors on total carbon gain of the ecosystem (Lee et al, 2013;Yang et al, 2018;Green et al, 2020).…”