Effect of bracken vegetation and litter on seedling recruitment of Clusia species in Bolivia

We studied the effect of vegetation and litter removal of bracken (Pteridium arachnoideum) on seedling recruitment, survival and growth of three shade-tolerant Clusia species. We carried out field experiments in the tropical montane forest of Bolivia at eight sites between 1900 and 2500 m of elevation, separated by at least 1 km from each other. At each site, we installed a 240 m-long transect perpendicular to the forest edge, where we selected three distances, one in the forest interior (at 160 m from the forest edge), one in the degraded habitat close to the forest edge (at 5 m) and one in the degraded habitat far from the forest edge (at 80 m), each distance constituted one block. Each block comprised two 1x2 m plots. In one plot we cut the vegetation taller than 0.5 m prior and three months after sowing (VN), while the other plot was not manipulated (VY). Each plot was divided in eight subplots (50 x 50 cm each). In four subplots, we removed the litter (LN), while the other four subplots were not manipulated (LY). We selected three Clusia species that naturally grow in the area (C. lechleri, C. sphaerocarpa and C. trochiformis). We sowed twenty seeds of each Clusia species in one subplot with and one subplot without litter by spreading seeds across the subplot. One subplot of each litter treatment was left as a control. In total our experiment was set out at 8 sites x 3 habitat types x 2 vegetation treatments x 2 litter treatments x 3 species x 20 seeds, comprising 5760 sown seeds. We recorded seedling recruitment three months and one year after sowing. We labelled each recruited seedling with a plastic tag and recorded the height of each seedling.