Floristic Diversity and Distribution Patterns Along an Elevational Gradient in the Northern Part of the Ardabil Province Rangelands, Iran

Variations in Plant Richness, Biogeographical Composition, and Life Forms along an Elevational Gradient in a Mediterranean Mountain

“…The prevalence of hemicryptophytes and chamaephytes in our study system follows our predictions, and it is consistent with their dominant role commonly observed in high mountain ecosystems [6,33,38,40,42,77,107]. In general, it has been observed that the proportion of hemicryptophytes increases with elevation [33,36,40,41,108] in response to increasing precipitation and decreasing temperature [40,108], with this life form being the most dominant at high elevations [109,110].…”

“…The small number of therophytes recorded in our study system can be therefore explained by the mountainous character of the study area (as expected), and is in line with the small number of annual species typically recorded at high elevations, where they usually represent less than 2% of the total alpine flora [6,41]. Therophytes tend to prevail in disturbed habitats [40,103,104], increasing their proportion in heavily grazed areas [42,105]. Thus, the scarcity of therophytes in our samples is also consistent with the low incidence of anthropogenic pressures in the study area.…”

“…The position of buds close to soil surface may offer the hemicryptophytes some protection from the harsh climatic conditions of higher elevations [78], especially during winter when the perennial structures are protected by the snow. Low disturbance conditions at higher elevations may favor the hemicryptophytes [42], which are less tolerant of grazing than species with subterranean over-wintering buds [111,112].…”

“…(3) Regarding the life forms, we predicted that, because of the mountainous character of the study area, the therophytes, which are a predominant group in low Mediterranean areas with thermo-xeric climatic conditions [6,20,40,41], will be the less represented group. By contrast, we predicted a dominance of hemicryptophytes and chamaephytes, which are the most represented life forms in high mountain ecosystems [6,33,38,40,42,77]. In accordance with their ability to cope with cold climate due to their buds near the soil surface [78], we predicted an increase in the proportion of hemicryptophytes with elevation.…”

“…Since species responses to environmental factors are mediated by their traits and are reflected by their distribution, vegetation studies frequently take advantage by classifying species into life forms [23][24][25][26][27] and biogeographical categories [28][29][30][31][32]. Surprisingly enough, however, only a few studies have investigated variations in plant biogeographical [18,33] and life form (e.g., [18,20,[33][34][35][36][37][38][39][40][41][42]) composition along elevational gradients.…”