Search results for " VEGETATION"

One Chara does not make Charetea in the Mediterranean aquatic vegetation

2019

The results of preliminary phytosociological investigations on freshwater communities of Sicily biotopes with a significant presence of Characeae are presented. In spite of the relatively frequent occurrence of Characeae, a typical Charetea intermediae vegetation is rather rare in the investigated biotopes. Indeed, the Characeae are mainly part of communities attributable to the classes Potamogetonetea, Phragmito-Magnocaricetea, Juncetea maritimi and Isoeto-Nanojuncetea. Some ecological and functional implications are discussed, along with some consequences on conservation measures and policies, caused by the lack of knowledge on the Characeae of Sicily.

The impact of Pinus halepensis mill. afforestation on mediterranean spontaneous vegetation: do soil treatment and canopy cover matter?

2012

We investigated central Mediterranean Pinus halepensis plantations under semi-arid climate in order to evaluate the combined effect of soil treatment and afforestation practices on spontaneous plant species composition, richness and evenness, and on the trend and speed of vegetation dynamics. Phytosociological releves of three different plot typologies, i.e. (1) soil-treatment and plantation, (2) only soil-treatment, (3) no soil-treatment and no plantation, were compared by (a) multivariate analysis and (b) with reference to species richness and evenness. Moreover, in order to compare vegetation dynamics within the plantations with those ones ongoing in semi-natural garrigue communities, we…

Tertiary relict laurophyll vegetation in the Madonie mountains (Sicily)

2014

Laurel woodlands in the Madonie mountains (Sicily) are characterized by the presence of Laurus nobilis, Rhamnus lojaconoi and Vitis vinifera subsp. sylvestris. The results of a phytosociological study are presented, and a new endemic association, Rhamno lojaconoi–Lauretum nobilis, is described. Present Mediterranean laurel communities are the result of an adaptive response by Tertiary laurel forest to the peculiar microclimatic conditions that characterize the refugia where they persist. These refugia have been recently considered as a priority habitat under the Directive 92/43/EEC, and their plant communities are very vulnerable. Protection measures of the studied laurel populations are ne…

Fire danger estimation from MODIS Enhanced Vegetation Index data: application to Galicia region (north-west Spain)

2011

Galicia, in north-west Spain, is a region especially affected by devastating forest fires. The development of a fire danger prediction model adapted to this particular region is required. In this paper, we focus on changes in the condition of vegetation as an indicator of fire danger. The potential of the Enhanced Vegetation Index (EVI) together with period-of-year to monitor vegetation changes in Galicia is shown. The Moderate Resolution Imaging Spectroradiometer (MODIS), onboard the Terra satellite, was chosen for this study. A 6-year dataset of EVI images, from the product MOD13Q1 (16-day composites), together with fire data in a 10 × 10-km grid basis, were used. Logistic regression was…

Monitoring water stress in Mediterranean semi-natural vegetation with satellite and meteorological data

2014

In arid and semi-arid environments, the characterization of the inter-annual variations of the light use efficiency ε due to water stress still relies mostly on meteorological data. Thus the GPP estimation based on procedures exclusively driven by remote sensing data has not found yet a widespread use. In this work, the potential to characterize the water stress in semi-natural vegetation of three spectral indices (NDWI, SIWSI and NDI7) – from MODIS broad spectral bands – has been analyzed in comparison to a meteorological factor (Cws). The study comprises 70 sites (belonging to 7 different ecosystems) uniformly distributed over Tuscany, and three eddy covariance tower sites. An operational…

Mapping sub-pixel burnt percentage using AVHRR data. Application to the Alcalaten area in Spain

2010

The purpose of this work is to estimate at sub-pixel scale the percentage of burnt land using the Advanced Very High Resolution Radiometer AVHRR through a simple approach. This methodology is based on multi-temporal spectral mixture analysis MSMA, which uses a normalized difference vegetation index NDVI and a land-surface temperature LST image as input bands. The area of study is located in the Alcalaten region in Castellon Spain, a typical semi-arid Mediterranean region. The results have shown an extension of approximately 55 km2 affected by fire, which is only 5% lower than the statistic reports provided by the Environmental Ministry of Spain. Finally, we include a map of the area showing…

Characterization of the interannual and intraseasonal variability of West African vegetation between 1982 and 2002 by means of NOAA AVHRR NDVI data

2007

AbstractThe interannual and intraseasonal variability of West African vegetation over the period 1982–2002 is studied using the normalized difference vegetation index (NDVI) from the Advanced Very High Resolution Radiometer (AVHRR).The novel independent component analysis (ICA) technique is applied to extract the main modes of the interannual variability of the vegetation, among which two modes are worth describing. The first component (IC1) describes NDVI variability over the Sahel from August to October. A strong photosynthetic activity over the Sahel is related to above-normal convection and rainfall within the intertropical convergence zone (ITCZ) in summertime and is partly associated …

Long-Term Hydrological Regime Monitoring of a Mediterranean Agro-Ecological Wetland Using Landsat Imagery: Correlation with the Water Renewal Rate of…

2021

The Natural Park of Albufera (Valencia, Spain) is one of the Spanish Mediterranean wetlands where rice is cultivated intensively. The hydrology of the Albufera Lake, located in the center, combines natural contributions with complex human management. The aim of our study was to develop a new methodology to accurately detect the volume of flood water in complex natural environments which experience significant seasonal changes due to climate and agriculture. The study included 132 Landsat images, covering a 15-year period. The algorithm was adjusted using the NDWI index and simultaneous measurements of water levels in the rice fields. The NDVI index was applied to monitor the cultivated area…

New insight on Mediterranean and sub-Mediterranean syntaxa included in the Vegetation Prodrome of Italy

2015

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…