Search results for "Annual plants"
showing 4 items of 4 documents
Floristic, phenological and chorological differences in the annual vegetation of Sardinia.
2007
The therophytic flora of Sardinia has been split into four main groups, basing on the ecologic requirements of species. The following groups have been recognized: flora of dry entisoils, flora of periodically swampy or submerged entisoils, flora of coastal sites, flora of fields, road edges and human settlements. Either, most frequent or exclusive species were ascribed to each group. A species was considered “exclusive” when its relative frequency outside a given group was estimated ≤10%. Differences have been highlighted within the groups, dealing with chorology, growth form, flowering time, colour of flowers, pollination and seed dispersal strategies.
Using coupled hidden markov chains to estimate colonization and seed bank survival in a metapopulation of annual plants
2022
The study of ecological systems is often impeded by components that escape perfect observation, such as the trajectories of moving animals or the status of plant seed banks. These hidden components can be efficiently handled with statistical modeling by using hidden variables, which are often called latent variables.Notably, the hidden variables framework enables us to model an underlying interaction structure between variables (including random effects in regression models) and perform data clustering, which are useful tools in the analysis of ecological data.This book provides an introduction to hidden variables in ecology, through recent works on statistical modeling as well as on estima…
Contribution to the knowledge of the therophytic flora of Sardinia
2003
The abundance of therophytes, largely contributes to the naturalistic value of Sardinia. Moreover, most of the annual species belonging to the Sardinian flora have an historical and cultural value, as they followed the men in his migrations and still reflect the different ways of traditional land exploitation characterising the island. As a matter of fact, the development of human technology increased number and frequency of the annual plants of Sardinia. Nowadays, annuals occur in several habitats of the island, where they play a primary ecological role, both as biomass producers and protecting the soil from rill erosion during the rainy season, at least where the environmental factors do …
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…