Are There Resource Allocation Constraints to Floral Production in the Endangered Barbarea vulgaris subsp. lepuznica (Southern Carpathians, Romania)?

Given the endangered status and very limited distribution of Barbarea vulgaris R.Br. subsp. lepuznica (Nyár.) Soó in stressful, high-elevation habitats, where these plants must prioritise the resource acquisition and vegetative growth to sustain their survival and persistence, we aimed to reveal possible abiotic/biotic-driven constraints in biomass allocation for flower production. Three functional traits, i.e., the tallest shoot height, leaf mass area (LMA) and number of inflorescences (racemes), were measured in thirty plants in each of the three studied populations differing in altitude and sheep grazing intensity (P1—1700 m, grazed; P2—1900 m, ungrazed; P3—2100 m, ungrazed). The LMA and dominant shoot height were significantly higher and, respectively, lower in P3 compared with P1. Although the mean number of racemes in P1 was lower than in P2 and P3, the differences were not statistically significant. The tallest shoot height, followed by the LMA, displayed the highest contribution to differentiating the three populations. The raceme count decreased significantly with increasing height of the dominant shoot in P1 and P2, and also with increasing LMA in P3. The observed constraint in raceme production within all populations is very likely one facet of the trade-off between reproductive and vegetative allocation under harsh edapho-climatic conditions. The studied plants have adopted a conservative-tolerant strategy to cope with the abiotic stress at higher elevations, but an acquisitive-tolerant strategy in face of grazing. The subspecies lepuznica seems to be in a favourable conservation status, but a close monitoring in grazed areas is recommended.