Rapid loss of biomass and viability of air-exposed food reserve tubers from a dynamic wetland system in Mozambique

Climate change is already affecting East Africa. This includes the Banhine area, the driest region in Mozambique, but with a steadily increasing population. In favourable times people live from subsistence farming, which depends on rainfall. However, during prolonged dry periods when crops fail they depend on wild plant reserves such as Bolboschoenus glaucus tubers. Larger areas of surface-exposed tubers of this key plant species have been found in the Banhine area, probably dug up by burrowing animals. With the intention of imitating increasingly long periods of drought, we investigated the consequences when B. glaucus tubers are moved upwards from the substrate in an empirical greenhouse experiment. We observed that once brought up from the soil substrate, these storage organs rapidly lose mass and do not retain their vitality even for half a year. Our findings imply that these tubers are best kept in situ. The lack of resistance of these edible plants to disturbances in dry climate conditions can have serious consequences for emergency food supply of local populations and animals. Therefore, follow-up studies are warranted and awareness should be raised.