Pollen traps B11 - June-October 2018

Study area: B11 plots - EFForTS-CRC990 project Period: June - October 2018 Method in the field: To collect pollen/spore rain, Behling pollen traps (Jantz et al. 2013) were installed from June until October 2018. Each trap consists of a plastic tube which is placed about 30 cm above the ground and is hold by a fixing pole. The tube is filled with 5 ml liquid glycerol, synthetic cotton and on the top it is covered by a mosquito net to reduce disturbance from animals or litter and prevent the cotton from being removed. In tropical regions heavy rainfalls occur, thus it is necessary to prevent the pollen from pouring out of the pollen trap. In the Behling trap glycerol is used, which has a higher density compared to water. Consequently the incoming rainfall can flow out of the trap without taking the pollen, which is trapped in the synthetic cotton and in the glycerol (Jantz et al. 2013). The Behling traps were modified in order to mimic the surrounding environment and maximize recovery. In total 168 pollen traps were installed in the plots (3x plot). Of the total 56 plots, the pollen traps were not recovered in 3 plots (P28, P34, P47). Method in the laboratory: One pollen trap from each 53 plot was processed and analyzed. Firstly, each pollen trap was washed with distilled water through a 2 mm mesh sieve to remove large size materials. Afterwards, the pollen traps were sieved through a 150 µm mesh sieve to exclude medium size materials from the samples. Two Lycopodium tablets were added as markers to each sample to estimate palynomorph concentrations (Stockmarr 1971) and the Erdtman acetolysis (Bush et al. 2001) was applied, to remove cellulose material. Residues were mounted in glycerol jelly for pollen visualization, identification, and counting. Microscopy analysis: Pollen and spore analyses were carried out using light microscopy. All identified pollen and spore types were photographed using a Leica photomicroscope with a 400× magnification. For each trap, a total sum of at least 100 pollen grains were counted. Pollen and spore grains can rarely be identified to species level and the level of taxonomic identification varies for different groups of plants. As a consequence, a reduction to the family level has been proposed for studies involving analysis of palynological diversity in the tropics (Jantz et al. 2014).