Short Communication Conservation status of the narrow endemic gypsophile Ononis tridentata subsp. crassifolia in southern Spain: effects of habitat disturbance M IGUEL B ALLESTEROS ,A NA F ORONDA ,E VA M ARÍA C AÑADAS ,J ULIO P EÑAS and J UAN L ORITE Abstract Ononis tridentata L. subsp. crassifolia (Leguminosae) is a narrow endemic plant restricted to gypsum outcrops in south-east Spain. Its habitat and populations are currently threatened by anthropogenic disturbance. Because of the paucity of information concerning its distribution, abundance and response to disturbance, we assessed its status and evaluated the impacts of quarrying, ploughing, grazing and afforestation. Distribution and population size were estimated by field surveys, censuses and mapping. We measured cover, plant volume, fruit and seed production, seed predation and seedling recruitment to asses any effects of disturbance. The species’ area of occupancy is 1.6 km 2 and its extent of occurrence 337 km 2 , in 29 habitat patches and 16 populations between 705 and 1,125 m altitude, and its population size was estimated to be 531,605. Quarrying, ploughing, overgrazing and afforestation negatively affected the species, in this order. We recommend this subspecies be categorized as Vulnerable on the IUCN Red List. A species recovery plan is required, and the ecological restoration of altered areas would mitigate negative effects on the species and improve the overall conservation of gypsum habitats. Keywords Conservation status, grazing, gypsophile, gyp- sum quarrying, habitat disturbance, narrow endemic, Ononis tridentata, ploughing This paper contains supplementary material that can be found online at http://journals.cambridge.org G ypsum outcrops harbour rare and endemic flora restricted to this substrate (Mota et al., 2004, 2011), which is often negatively affected by human disturbances, especially quarrying (Mota et al., 2003, 2004). Ononis tridentata subsp. crassifolia (Dufour ex Boiss.) Nyman (Leguminosae) is a rare subspecies with a narrow distri- bution restricted to gypsum outcrops in south-east Spain (centre-west Granada province), where its habitat quality is declining because of anthropogenic disturbance (Ballesteros et al., 2011). The Ononis tridentata complex is endemic to gypsum outcrops in Spain and Morocco (Supplementary Fig. S1). Other than taxonomic studies (Devesa & López, 1997) there is little information on the biology, distribution and conservation status of O. tridentata subsp. crassifolia. It is categorized on the Red List of the vascular flora of Andalusia as Data Deficient (Cabezudo et al., 2005). Assessment of the conservation status of Data Deficient species is vital, as it can reveal the existence of threats (e.g. Good et al., 2006). Following a preliminary assessment as Near Threatened (Ballesteros et al., 2011), the aims of this study were to (1) assess thoroughly the subspecies’ conservation status, (2) quantify the impact of human disturbance, and (3) recommend conservation measures. The distribution of O. tridentata subsp. crassifolia was first determined using biodiversity databases, including the Global Biodiversity Information Facility (GBIF, 2008) and Anthos (Castroviejo et al., 2008), herbarium records (GDA and GDAC), and available literature (Devesa & López, 1997; Marchal et al., 2008). Neighbouring areas potentially suitable for the subspecies were identified based on the ecology of known populations and aerial photo- graphs. Field surveys were conducted during 2008–2011. Presence records were mapped, using Quantum GIS v. 1.7 (Quantum GIS Development Team, 2011), to establish the subspecies’ known extent of occurrence (EOO) and area of occupancy (AOO; IUCN, 2001). We estimated population size by counting all reproductive individuals in a total of 142 linear transects of 25 × 2 m(50 m 2 ) throughout the subspecies’ known range, and extrapolating mean density to AOO. All the information available was then used to assess the status of O. tridentata subsp. crassifolia using the IUCN criteria (2001, 2011). The impact of habitat disturbance was determined using qualitative data (IUCN/SSC, 2001), available literature (Cabezudo et al., 2005; Escudero, 2009), information on land use (REDIAM, 2008) and earlier observations (Ballesteros et al., 2011). Areas with four types of disturbance M. BALLESTEROS, (Corresponding author), A. FORONDA, E.M. CAÑADAS, J. PEÑAS and J. LORITE Departamento de Botánica, Facultad de Ciencias, Universidad de Granada, E-18071, Granada, Spain. E-mail miguelballesterosjimenez@gmail. com Received 14 May 2012. Revision requested 10 October 2012. Accepted 16 November 2012. © 2013 Fauna & Flora International, Oryx, 47(2), 199–202 doi:10.1017/S0030605312001688