Seed desiccation-tolerance is a common feature of threatened taxa in metalliferous tropical grasslands from southeastern DR Congo

In Katanga (southeastern Democratic Republic of Congo), the flora of copper and cobalt deposits is highly threatened by mining. Until mining activity ceases and restoration can take place, seed banking is one of the strategies to be considered for the conservation of these metallophytes of which 32 are strict endemics. In the tropics, however, many species have recalcitrant (desiccation-sensitive) seeds, making them unsuitable for longterm conservation. This study aimed at characterising the seed storage behaviour of 14 taxa of concern from metalliferous tropical grasslands in order to determine their storability in ex situ seed banks. Germination tests of 38 populations from 9 different sites were undertaken on fresh seeds and after 6, 12, 24 and 96 months in drycold conditions. The vast majority (93 %) of the sampled species exhibited high seed viability (> 75 %). For each taxon studied, there was no significant decline in seed viability during storage. In general, seeds germinated faster after 8 years of storage. This study provides evidence that seed desiccation-tolerance is common among the metallicolous species of Katanga. This highlights their ability to be stored under dry-cold conditions, which opens the way for ex situ conservation programs in seed banks.