Abstract (eng)
Iran is a mountainous country where rather small patches of alpine habitats are scattered across large mountain areas. The diverse flora and vegetation of these habitats have been poorly investigated so far, despite the high rate of narrowly distributed plant species which are expectedly very vulnerable to climate change impacts.
The aim of this thesis is to study the flora and vegetation of the high alpine to subnival-nival elevation belts of Iran with emphasis on N- (Alborz) and NW-Iran (Sahand and Sabalan), its biodiversity in relation to elevation and its vegetation patterns in comparison with neighboring mountain systems, as well as its potential threats through climate warming.
The thesis is divided into two related research foci, the first on high-altitude species, the second on their vegetation patterns.
The first study deals with assessing the plant diversity and phytogeography of vascular plants occurring in the uppermost elevation belts of Iran, and attempts to give a first estimate on the risk of biodiversity losses through effects of climate change. This work was based on an extensive literature research and on additional field observations. All vascular plant species living in the subnival–nival zone of Iranian mountains (151 species) and those restricted to this zone (51) were identified. The elevational and geographical distribution patterns of these species were analyzed and the current distribution patterns are discussed with respect to potential warming-induced species losses. The rate of endemics (endemic to Iran, in most cases however far more restricted distributions) increases sharply with increasing elevation.
The narrow distribution of most of Iran’s cold-adapted mountain flora and the low potential of alternative cold habitats render it highly vulnerable to climate change.
Furthermore, Iran’s high mountains may host a number of still unknown species, as this study revealed two subnival-nival vascular plant species new to science: Senecio subnivalis (on Hezar Mts in south Iran) and Nepeta sahandica, (on Sahand, NW Iran), and a highly disjunct occurrence of Gagea alexii. The original descriptions of these discoverings and of these species’ vegetation ecology are arranged in a separate chapter.
The second main research focus of the thesis was on the vegetation of the alpine and subnival-nival zones of N and NW Iran. In total, about 700 vegetation relevés have been collected from different habitats of the study area during the MSc and PhD theses. This thesis mainly deals with high-elevation scree vegetation, using 141 relevés for analysis and phytosociological classification. A synoptic table of the most important alliances of scree vegetation in the European Alps, the Balkan Peninsula, the Caucasus, Anatolia, as well as the alliances described in the present paper was prepared to show the floristic and syntaxonomic relationship of these regions. All high-alpine and subnival scree communities of the study area were arranged in one class, two orders, and three alliances which are new for the science. This was the first formal syntaxonomic classification of the high mountain scree vegetation of Iran.