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

Abstract

Despite the increasing interest in elevational patterns in biodiversity, few studies have investigated variations in life forms and biogeographical composition, especially in the Mediterranean biome. We investigated elevational patterns in species richness, biogeographical composition (chorotypes) and life forms (Raunkiaer classification) along an elevational gradient in a Mediterranean mountain (Central Italy). We found a general hump-shaped pattern of species richness, which can be explained by harsher conditions at the lowest and highest elevations. This pattern is distinctly related to prevalence at mid elevations of species with European and Euro-Asiatic distribution, which are favored by a temperate climate. Phanerophytes and geophytes (which are mainly associated with woods) were concentrated at mid elevations where woodlands prevail. Hemicryptophytes increased with elevation, consistently with their ability to cope with high altitude climatic conditions. Mediterranean species declined with elevation because they are negatively affected by decreasing temperatures. Chamaephytes showed a U-shaped pattern, suggesting they are able to cope with arid and cold conditions at the extremes of the gradient. Endemics increased with elevation because of their association with mountainous areas as key places for endemism evolution. These results illustrate how elevational patterns in species richness, biogeographical composition and life forms are interrelated and demonstrate reciprocal insights for understanding current vegetation settings.

Italian Vascular Flora: New Findings, Updates and Exploration of Floristic Similarities between Regions

“…Factors directly related to elevation (e.g., temperature, rainfall, light intensity, nitrogen availability) are indicated as the main factors that regulate the distribution and number of taxa [189,190]. Despite most of the studies on species richness variation along elevational gradients found either a monotonic decline with increasing elevation or a hump-shaped pattern with a mid-elevational peak [191][192][193], the presence of high mountains favors the processes of plant speciation. Indeed, in recent years, many species were discovered or described for mountain areas also in Italy [194][195][196].…”

Niche Variation in Endemic Lilium pomponium on a Wide Altitudinal Gradient in the Maritime Alps

“…Ecological gradients in relation to altitude have long been a dominant theme in plant ecology. As a result, we now benefit from a wealth of studies detailing patterns in the proportion of endemic species and species diversity [ 1 , 2 , 3 , 4 ], associations among species [ 5 ], pollination strategies [ 6 , 7 , 8 ], reproductive traits [ 9 , 10 , 11 ], and potential variation in functional traits [ 12 , 13 , 14 ] along altitudinal gradients. In more recent years, the observation of changes in species distribution and their colonisation of higher latitudes and altitudes in relation to warming climates [ 15 , 16 , 17 ], have renewed interest in the understanding of the ecological interactions that govern distribution patterns in mountain plants.…”

Ecology and Evolution of Plants in the Mediterranean Basin: Perspectives and Challenges

“…At the local scale, vascular plant species richness and assemblages' diversity are influenced by meso-climate features of the different territories and their geomorphology; in particular elevation gradients and mountain distribution have a crucial role. However, there are not many papers dealing with the effects of elevation gradients on vascular plant diversity; Di Biase et al [7] sheds light on this intriguing aspect of Mediterranean plant diversity, whose importance was already underlined by Thompson [4]. Di Biase et al [7] describe the variation of the ecological (life-forms) and the geographical (chorologic types) contingents of the Mt.…”

“…However, there are not many papers dealing with the effects of elevation gradients on vascular plant diversity; Di Biase et al [7] sheds light on this intriguing aspect of Mediterranean plant diversity, whose importance was already underlined by Thompson [4]. Di Biase et al [7] describe the variation of the ecological (life-forms) and the geographical (chorologic types) contingents of the Mt. Genzana (central Apennines, Italy) flora, showing the increase of the endemic component with the increase of the elevation.…”

“…Overall, our Special Issue opens a window not only on the state-of-the-art of scientific research on plant diversity in the Mediterranean, but also on crucial and promising future developments. There is increasing evidence that biological diversity is not a static concept but needs to be continuously monitored at multiple spatial scales, from regional [6], to local [7], to detailed niche adaptation [10]. If we go further to the very detailed, even organisms, such as plants and animals, can be considered at spatial scale as we are aware that they (we) are true ecosystems [15].…”