Prunetum tenellae Soó 1951 Vincetosum herbaceae Pînzaru subass. nova (Prunion fruticosae R. Tx. 1952) in the cliff vegetation of the Republic of Moldova

This article presents the characterization of the phytocoenoses dominated by Amygdalus nana that occur in the cliff area of the Dniester river basin, Republic of Moldova, which have been grouped in a new sub-association – vincetosum hederaceae Pînzaru subass. nova, in the association Prunetum tenellae Soó 1951. This sub-association includes xerophilous, thermophilic, western-Pontic phytocoenoses, occurring on sandy clays or on rendzina soils, on the limestone hills of the Dniester river basin, at altitudes of 60-150 m. The fl oristic composition of these phytocoenoses is dominated by the Eurasian elements (50%), followed by the European (10%), the Pontic-Mediterranean (9,6%) and the Central European elements (5,2%). The subassociation Prunetum tenellae Soó 1951 vincetosum herbaceae Pînzaru is of high value in terms of biodiversity conservation and deserves to be included in the List of Protected Plant Associations of the Republic of Moldova

A review of plant diversity, vegetation, and phytogeography of the Khorassan-Kopet Dagh floristic province in the Irano-Turanian region (northeastern Iran–southern Turkmenistan)

The Khorassan-Kopet Dagh (KK) floristic province is located in the northeastern parts of Iran and partly in southern Turkmenistan. The area is a transition zone and a corridor connecting different provinces of the Irano-Turanian region and also Hyrcanian montane forests of the Euro-Siberian region. The unique combination of Irano-Turanian species and also presence of a local center of endemism are evidence of a separate biogeographic entity. The complicated topography, high habitat heterogeneity and vegetation history are reasons for the development of diverse vegetation types. In order to achieve up-to-date information on the plant diversity and distribution patterns, a database was prepared using all floristic records from the area defined as KK. A total of 2576 species/infraspecific taxa belonging to 702 genera and 112 families of vascular plants have been reported from the area, 2498 of which occur within Iran. Altogether, 28 different distribution patterns are recognized among five major phytogeographical groups, including widespread, tri-regional, bi-regional, Euro-Siberian and Irano-Turanian patterns. Irano-Turanian elements, which make up the core flora of KK, are subdivided further into 14 distribution patterns. A significant number of species, i.e. 356 species (13.8%), are endemic to the area. The flora of KK is highly influenced by central Irano-Turanian elements. The main vegetation types of the area include Juniperus woodlands, Pistacia vera woodlands, some isolated enclaves of Hyrcanian forests and scrub, cliff vegetation, mountain steppe communities, semi-desert steppes, loess and marl vegetation, halophytic vegetation, aquatic and hygrophilous communities, and ruderal/invasive plant communities. There are several major threats to the ecosystems and biodiversity of the area. The areas presently protected do not cover all of the vegetation types, and therefore many threatened species are not safe.

Effects of natural habitat fragmentation on the species richness, diversity, and composition of cliff vegetation

Plant species richness, diversity, and some aspects of species composition were measured on natural limestone cliff fragments of varying size within the Niagara Escarpment Biosphere Reserve, Canada. This information was collected because knowledge about how different components of community structure change in response to natural fragmentation may permit the prediction of the effects of future anthropogenic fragmentation. The number and relative abundance of vascular plant, bryophyte, and lichen species were determined on cliff fragments that varied in area from 185 to 126 000 m2. Latitude, aspect, percent available photosynthetically active radiation on the cliff face, distance from the nearest neighbouring cliff, and length of the nearest neighbouring cliff were also measured. Regression analysis was used to test for a significant relationship between fragment area and diversity of vascular plants, bryophytes, and lichens both separately and combined. Multiple regression with all subsets selection was used to find the best predictors of species richness from among all variables measured for the 21 cliff fragments. Multivariate analyses were used to study the effect of fragmentation on the structure of the vegetation as a whole. The results showed no significant relationship between cliff fragment area and richness or diversity for vascular plants and bryophytes, and only a marginally significant increase in richness with area for lichens. The multivariate analyses also showed that only one community type exists, and that its structure mainly varies as a function of latitude. These results indicate that very small fragments of cliff face can support a similar plant biodiversity as do large continuous portions of the Niagara Escarpment.Key words: habitat fragmentation, plant species richness, lichens, bryophytes, cliff vegetation.