Del Rosario Cosme, Steven N.

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    Population structure and distribution of a new population of the endagered Aristida portoricensis (Poaceae) in Mayagüez, Puerto Rico
    (2021-07) Del Rosario Cosme, Steven N.; Puente Rolón, Alberto R.; College of Arts and Sciences - Sciences; Van Ee, Benjamin; Monsegur Rivera, Omar A.; Department of Biology; Zapata Medina, Rocío
    The genus "Aristida" (Poaceae) is a varied and well-distributed group of grass within the subfamily Aristidoideae. In Puerto Rico, we count with an endemic species, "Aristida portoricensis", commonly known as "Pelos del Diabo". This species is restricted to southwest Puerto Rico, where it is considered rare, and was listed as an endangered species in 1990. In 1994, the US Fish and Wildlife Service developed a recovery plan, but many agreements have not been met yet. The objectives of this study were to learn better about the spatial distribution, demography, phenology, and the species’ response to competition on a recently discovered population in Mayagüez municipality. Spatial images from the years 1930, 1977, and 2010 were analyzed, comparing the open area of the study sites between these dates. Despite the reduction seen in the open area, no significant difference was found between the different dates. For demography, the tufts were classified by categories (youngsters, young adults, adults, old adults). For the studied populations, all had the same demographic distribution, where the population was mainly composed of small tufts (classified as young adults). The spatial distribution was also the same in the four populations, where they presented an aggregated distribution. For phenology, the individuals were marked for monitoring different phenophases (shoots, young spikelets, flower, ripe spikelets, and empty glumes) for a whole year, with a monthly visit. Two groups were taken within the population of Pura Brisas, which were classified as affected by the endophyte mature stromata (EMS) of "Balansia aristidae" and those not affected with EMS. Phenophases were compared with the rainfall showing a correlation between the number of the shoot and the rainfall. However, the stromata’s damage to the studied populations does not represent an imminent threat to the species.