Periodic Reporting for period 1 - PalmHydraulics (Palm hydraulics linking biodiversity and functioning of tropical forests under climate change)
Reporting period: 2016-08-01 to 2018-07-31
To document the global patterns of palm abundance variation, we strength our collaboration with researchers from University of Aarhus Ecoinformatics and Biodiversity group (palm ecology and distribution experts) and University of Leeds Ecology and Global Change group (host of the largest tropical forest plot inventory repository). From the data collected by over a hundred field ecologists and botanists, we were able to assemble the most comprehensive (2,544 plots, 661,194 individual palms) dataset of arborescent palm abundance variation at the global scale. The second important result from PalmHydraulics project (Muscarella & Emilio et al. in preparation) was to show that palms are not abundant elsewhere as they are in the Neotropics. At least not large arborescent palms. Small understorey and climbing palms are largely unsampled in forests inventories and expect to increase the contribution of palms to biomass in over of 80% of the locations outside of the Neotropics. We also found that although it is not unexpected that estimates of aboveground biomass are more affected in locations were palm abundance is higher, the direction and strength of this effect are unpredictable, varying from +5% to -16%.
To gain a more mechanistic view on palm functioning we started a collaboration with a world-leading research group on plant hydraulics from INRA/University of Bordeaux (France). Together we performed in vivo visualization of embolism formation in palms for the first time. The main experiments we conducted at Soleil Synchrotron in the Spring of 2017, followed by additional experiments at BIOGECO in 2017 and 2018. The third important result (Emilio et al., under review) was to show that palms are not as vulnerable to drought-induced embolism (the main cause of plant mortality under drought) as we previously thought from their hydraulic structure. For the first time, we discover that palms show the entire range of embolism resistance of angiosperms in general. Besides that, we demonstrate with high-resolution micro-CT images that hydraulic functioning of palm leaves is supported by a large amount of water stored in their parenchyma.