In situ or ex situ seed conservation: which is the more effective way to maintain seed longevity of an endangered cactus? JOANA PAULA BISPO NASCIMENTO* and MARCOS VINICIUS MEIADO† *Postgraduate Program in Ecology and Conservation, Campus Prof. José Aloísio de Campos, Federal University of Sergipe, Av. Marechal Rondon, s/n, Jardim Rosa Elze, São Cristóvão, 49100-000; and †Department of Bioscience, Campus Prof. Alberto Carvalho, Federal University of Sergipe, Av. Vereador Olímpio Grande, s/n, Centro, 49500-000, Itabaiana, Sergipe, Brazil Abstract With restricted populations and a small number of individuals, Discocactus bahiensis Britton & Rose (Cactaceae) is an endangered species in Brazil and its capacity for the formation of seed banks in the soil and the maintenance of seed viability remains unknown. Thus, the aim of the present study was to determine the most efficient way to maintain viability during storage of seeds of D. bahiensis. Seeds were stored in paper bags and either kept in a cold chamber (7  2  C) in the dark (ex situ conservation) or buried in the soil to a depth of 5 cm in an area of natural occurrence of the species (in situ conservation). Germinability of the seed banks was evaluated monthly for 20 months. During the first 10 months of storage, germinability of the seeds conserved in situ and ex situ was similar to that of recently collected seeds. After this period, a 70% reduction in germinability was found for the seeds maintained in situ and there was nearly complete loss of viability after 12 months of storage in the field (germinabil- ity < 10% in the last 8 months of the experiment), indicating the ability to form persist- ent soil seed banks. In contrast, the seeds stored in the cold chamber maintained greater than 70% germinability throughout the entire analysis period, demonstrating that ex situ conservation is the most efficient way to maintain the viability of the seeds of this endangered species. Keywords: Cactaceae, Discocactus bahiensis, seed germination, soil seed bank, storage. Received 8 December 2014; revision received 7 March 2015; accepted 28 February 2016 Introduction As ecosystems face climate change, strong anthropogenic pressures, genetic erosion and loss of diversity, the con- servation of genetic resources should be seen as a world- wide priority and a very important future research issue (Draper et al. 2004). The conservation of both plant and animal organisms is traditionally grouped into two cate- gories, namely in situ and ex situ conservation, in which the conservation of populations, species and/or germ- plasms occurs, respectively, within or outside its site of origin (Draper et al. 2004). There are different ways to preserve all or part of a vegetal organism, such as in vivo conservation, in vitro conservation, cryopreservation and seed banks (Assis et al. 2011). The presence of viable seed banks in the soil (in situ) is one of the main indicators of the potential for regenera- tion of an ecosystem. Species that form seed banks in the soil exhibit different longevity periods and germination behaviors. Simpson et al. (1989) classified seed banks as either transient (germination within 1 year after disper- sal) or persistent (viability for more than 1 year). The for- mation of seed banks is an important reproductive strategy for plants, especially those that undergo long periods of severe climate conditions, such as in semi-arid ecosystems, which can be unfavorable to seedling devel- opment and survival (Moles et al. 2003). However, the physiological ecology of seeds of native species under natural conditions is under-investigated and it is Correspondence: Marcos V. Meiado Email: meiado@ufs.br. © 2016 The Society for the Study of Species Biology Plant Species Biology (2016) doi: 10.1111/1442-1984.12131