Notes on the Ecology of central Transylvanian sunny slopes
by S. S.Badarau and St. Dezsi
Here I want to present for you a very interesting situation concerning the spatial situation of Stipa species in Transylvania. Here they appear in belts on steep sunny slopes. At the basal part of them, which is less steep, there are mesoxerophyle grasslands dominated by Festuca rupicola and Carex humilis. When the grade is over 20 degr in the middle part of the slope, these species are replaced by Stipa dominated xerophyle grasslands. Stipa lessingiana is more xerophytic than S. pulcherrima; the former is the dominating species on the southern flanks of the slopes while St. pulcherrima dominates the south western or south eastern ones.
On the upper part of the slope there is a shrubby belt with Amygdalus nana and at the top a ultraxerophyle one with Agropyron pectiniforme (in eastern Europe / Western Asia this species occurs in half deserts over vast areas). On the plateaus above these slopes there are large surfaces with Stipa stenophylla (mesoxerophyle species).
The show offered by these slopes with steppe like vegetation is a magic one, the different vegetation belts catching one's eye at different times. In April the belt with Amygdalus nana (=Prunus tenella) is bursting into deep pink. In late May and early June the belt with feathergrasses, Stipa lessingiana (S) / St. pulcherrima (SW, SE) becomes silvery. In late June the silver moves on to the plateaus where the mesoxerophyle feathergrass Stipa stenophylla is flowering. During this time the grasses with Festuca rupicola at the basal part of the slopes are deep green and the ones with Agropyron pectiniforme are bluish.