Ecology, biogeography, and distribution of the rare species Iris brandzae in Romania

Iris brandzae is a threatened plant species, distributed in Romania's North-East and South-East regions. The present study aims to examine the environmental conditions and update the species distribution in Romania. For environmental conditions, information about climatic, topographic, and soil chemical factors were collected and analyzed. For the biogeographic analysis, studies from the literature were consulted, and to update the species distribution, the populations mentioned in the literature were verified. Iris brandzae was recorded in 21 locations in Botoșani, Buzău, Iași and Vaslui counties, of which ten populations were recorded for the first time. The current trend of the area that the population occupies is stable (59%), while 41% of the population is decreasing. The conservation status of these populations, along with changes in their habitat distribution, is assessed as unfavourable-inadequate. The number of individuals per 100 m² in the studied habitats varied from 5 to 25. The species grows on slightly acidic to neutral soils with moderate phosphorus and high potassium concentrations. The elevations were moderate, from 47 to 294 m a.s.l. on gentle and moderate slopes with northern, eastern aspects and frequently in communities with Festuca valesiaca . Moreover, I. brandzae has the most significant ecological adaptability in the southern aspects. The main threat is overgrazing. From a phytocoenological perspective, I. brandzae occurs in the more mixed landscape, found only in the nemoral forest-steppe region west and northwest of the Black Sea. In this context, these populations must be monitored over the long term to understand population dynamics. It is also necessary to carry out public awareness campaigns regarding the importance of the species, the expansion and designation of protected areas, and grassland management.