Geographical distribution and habitat characterization of Poa schizantha (Poaceae), a narrow endemic of the coastal sand dunes of southern Pampas, Argentina

CELSI C, Y GIUSSANI L. M

BOTANICAL JOURNAL OF THE LINNEAN SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2020 vol. 192 p. 296 - 313

0024-4074

Poa schizantha is a dioecious psammophilous grass endemic to Atlantic coastal dunes in Argentina, South America. We quantified the distribution area of this rare endemic species and characterized its habitat in the southern Pampas region. Convex hull and α-hull methods were employed to estimate and map the overall species geographic range. Ecological characterization was based on location, environmental variables, floristic composition and vegetation covera total of 117 quadrats was sampled during spring season. The convex hull (7553 ha) was split ?after excluding discontinuities? into two polygons: Area 1 (968 ha; novel area for the species) and Area 2 (449 ha) separated by 36 km, indicating two geographically distinct population groups. Within active coastal dune fields, Poa schizantha occurs mainly on interdune slacks, associated with herbaceous, short, grassland-type vegetation and moist sandy soils with low vegetation cover, which suggest high habitat specificity. Based on TWINSPAN classification and ordination analysis, Poa schizantha is related to two main vegetation groups with 100% constancy and ca. 30% Relative Importance: subgroups E (dominated by pioneer dune species) and F (associated with hygrophilous and ubiquitous species). Considering the Extent of Occurrence restricted to less than 100 km2, and the severely fragmented habitat condition, we propose the species categorization as Critically Endangered, following IUCN criteria. Actions aimed towards the survival of this species must prioritize population monitoring and dune-habitat conservation.