Flowering sex ratios and spatial distribution of dioecious trees in a South-East Asian seasonal tropical forest

Few studies have investigated multiple dioecious species at the community level. We, therefore, documented flowering sex ratios and analysed the relative spatial distributions of males and females in a diverse suite of tree species in a little-studied tropical forest in Xishuangbanna, south-western China. Male-biased sex ratios were common. Population-level male-biased sex ratios were found in four of the eight species studied and female-biased sex ratios in one. Significant malebiased sex ratios were found in at least one size class in all eight species. Male bias was caused by the onset of flowering at smaller sizes in males than females in four species. Male and female individuals had random to aggregated spatial distributions relative to each other. We concluded that similar selection pressures drove the evolution and ecology of dioecious species in many forest ecosystems