Search results for " dry grasslands"

Origin and evolution of the Mediterranean dry grasslands.

2007

In the Mediterranean region, three main structural types of dry grasslands can be recognized: those dominated by perennial caespitose grasses (wintergreen perennial dry grasslands, Lygeo-Stipetea), those dominated by thermoxerophilous therophytes (ephemeral dry grasslands, Tuberarietea guttatae), those dominated by chamaephytes, thistles and relatively small hemicryptophytes (summergreen perennial dry grasslands, Festuco-Brometea). All three kinds are commonly represented all over the Mediterranean territories, especially in the dry most areas. Relevant physiognomic, adaptive and floristic differences are featuring the three mentioned typologies. Lygeo-Stipetea and Festuco-Brometea may grad…

The Lygeo-Stipetea class in Sicily

2009

On the origin and evolution of the Mediterranean dry grasslands.

2006

A synthesis on the functional types of Mediterranean dry grasslands is outlined. Three different types are outlined: wintergreen perennial dry grasslands, wintergreen ephemeral dry grasslands, summergreen perennial dry grasslands. The first type is the most primitive, including several relict species, often characterized by very disjoint, sometimes anfi-saharian distribution ranges. The second type is resulting from an evolutionary trend towards short-lived life strategy, triggered by climatic and topographic perturbations that affected the Mediterranean region in the Plio- and Pleistocene. The third type, only marginally occurring in the Mediterranean region, is deriving from Holarctic and…

An “Uncertainty Principle” for the Mediterranean annual dry grasslands

2009

Preliminary results of diachronic researches on the spatial arrangement and species richness in Mediterranean annual dry grasslands (Tuberarietea guttatae) demonstrated that the patchiness resulted minimized and the temporal stability maximized at elevations offering the best compromise between the summer drought stress and the winter cold stress. Moreover, the temporal stability of the Mediterranean annul dry grasslands could not necessarily be related with their demographic inertia, meaning that the turnover and rearrangement of species within the community do not necessarily implicate significant changes in the average species composition over time. On the other hand, the survival chance…

Effects of temperatures on the spatial arrangement in Mediterranean annual dry grasslands

2009

Some preliminary results of diachronic researches on the spatial arrangement and species richness in Mediterranean annual dry grasslands belonging to the class Tuberarietea guttatae are presented. Our results are based on 12 permanent plots, set in three places at different heights in Southern and Central Sardinia. Sites were chosen to have annual species richness and plant density not significantly different. The relationship between patchiness and temporal stability was investigated at the scale of the square plots. We used the mean abundance divided by the SD in abundance (S = xm/r), as the measure of temporal stability of populations (Tilman 1999) and the Shannon-Wiener index to evaluat…

The Lygeo-Stipetea class in Sicily

2010

Basing on literature data and unpublished relevés from Sicily, a survey of the syntaxa belonging to the class Lygeo-Stipetea Rivas-Martínez 1978 is presented. This perennial vegetation is characterized by the dominance of big caespitose hemicryptophytes, and it is widely distributed in Sicily from the sea level up to 1500 m a.s.l. The class is represented in Sicily by two orders, floristically and ecologically well differentiated: Lygeo-Stipetalia, including the sole alliance Moricandio-Lygeion exclusively of clayey substrates, and Hyparrhenietalia hirtae, including five alliances (Hyparrhenion hirtae, Avenulo cincinnatae-Ampelodesmion mauritanici, Thero-Brachypodion ramosi, B…