Search results for " VEGETATION"
showing 10 items of 435 documents
Vegetation dynamics from NDVI time series analysis using the wavelet transform
2009
A multi-resolution analysis (MRA) based on the wavelet transform (WT) has been implemented to study NDVI time series. These series, which are non-stationary and present short-term, seasonal and long-term variations, can be decomposed using this MRA as a sum of series associated with different temporal scales. The main focus of the paper is to check the potential of this MRA to capture and describe both intra- and inter-annual changes in the data, i.e., to discuss the ability of the proposed procedure to monitor vegetation dynamics at regional scale. Our approach concentrates on what wavelet analysis can tell us about a NDVI time series. On the one hand, the intra-annual series, linked to th…
The decline of the cork oak growing in Sicily is accompanied by the loss of the functions proper to agroforestry systems
2021
The cork oak is one of the most important tree species in the Mediterranean basin, where it covers more than 2 million hectares. Among evergreen oaks, Quercus suber stands out for the variety of cultural systems in which it has been successfully employed, including typical agroforestry systems. Accordingly, a wide range of ecosystem services may be associated to cork oak, including the preservation of biodiversity, carbon sequestration and forage production. In the Mediterranean, the cork oak represents a key species for many natural and seminatural landscapes and habitats, as well as playing a prominent role for the economic and social development of local communities. However, there is in…
First insights into weed communities of rice agrocoenoses in southern Thailand
2015
The study presents the results of geobotanical investigations conducted in rice fields in southern Thailand in 2013. It is focussed on the classification of plant communities poorly investigated from a geobotanical standpoint. Altogether 125 phytosociological relevés were collected, using the Braun-Blanquet method. We noted more than 100 species in the vegetation plots, including many rare ones. We classified the vegetation into seven communities, including six associations. Five associations are proposed as new: Nymphaeetum nouchali, Fimbristylido miliaceae-Sphenocleetum zeylanicae, Ischaemo rugosi-Cyperetum pulcherrimi, Pentapeto phoeniceae-Aeschynomenetum indicae and Marsileetum minutae.…
How Universal Is the Relationship between Remotely Sensed Vegetation Indices and Crop Leaf Area Index? A Global Assessment
2016
This study aims to assess the relationship between Leaf Area Index (LAI) and remotely sensed Vegetation Indices (VIs) for major crops, based on a globally explicit dataset of in situ LAI measurements over a significant set of locations. We used a total of 1394 LAI measurements from 29 sites spanning 4 continents and covering 15 crop types with corresponding Landsat satellite images. Best-fit functions for the LAI-VI relationships were generated and assessed in terms of crop type, vegetation index, level of radiometric/atmospheric processing, method of LAI measurement, as well as the time difference between LAI measurements and satellite overpass. These global LAI-VI relationships were evalu…
Exploring the validity of the long term data record V4 database for land surface monitoring
2015
The last (and final) version of the Long Term Data Record (LTDR) — Version 4 — has been released recently by NASA. This database includes daily information for all AVHRR (Advanced Very High Resolution Radiometer) channels, as well as ancillary data, since July 1981 up to present. This database is the longest available record of remotely sensed data useful for land surface monitoring, since it allows the estimation of vegetation indices at daily resolution, as well as the daily estimation of land surface temperature (LST). Here, we analyze the fitness of this database for land surface monitoring. To that end, we first estimated NDVI (Normalized Difference Vegetation Index), LST, as well as e…
The ‘recent’ forests of Mount Venda (Padua, Italy): when historical cartography and archaeobotany tell quite a different story
2018
Forests, like agricultural systems and housing, are an integral part of the human landscapes. They evolve over time, not only in response to environmental factors (e.g. climate change) but also in response to developments in human society. This work on the analysis of forest dynamics in Euganean hills is the result of research carried out as part of the research programmes THISTLE (MSCA Fellowship, grant agreement: 656397) and MEMOLA (EU FP7 Project , grant agreement: 613265). The work is focused on two mountains in particular: Monte Venda and Monte della Madonna. The archaeobotanical investigations reveal the presence of ancient forests (since the 14th century) in these areas , although th…
Archaeogenetics and Landscape Dynamics in Sicily during the Holocene: A Review
2021
The Mediterranean islands and their population history are of considerable importance to the interpretation of the population history of Europe as a whole. In this context, Sicily, because of its geographic position, represents a bridge between Africa, the Near East, and Europe that led to the stratification of settlements and admixture events. The genetic analysis of extant and ancient human samples has tried to reconstruct the population dynamics associated with the cultural and demographic changes that took place during the prehistory and history of Sicily. In turn, genetic, demographic and cultural changes need to be understood in the context of the environmental changes that took place…
1200 years of decadal-scale variability of Mediterranean vegetation and climate at Pantelleria Island, Italy.
2013
A new sedimentary sequence from Lago di Venere on Pantelleria Island, located in the Strait of Sicily between Tunisia and Sicily was recovered. The lake is located in the coastal infra-Mediterranean vegetation belt at 2 m a.s.l. Pollen, charcoal and sedimentological analyses are used to explore linkages among vegetation, fire and climate at a decadal scale over the past 1200 years. A dry period from ad 800 to 1000 that corresponds to the 'Medieval Warm Period' (WMP) is inferred from sedimentological analysis. The high content of carbonate recorded in this period suggests a dry phase, when the ratio of evaporation/precipitation was high. During this period the island was dominated by thermop…
The effects of vegetation on indoor thermal comfort: the application of a multi-scale simulation methodology on a residential neighborhood renovation…
2017
Abstract Despite the acknowledged positive effects of vegetation at urban, neighborhood and building scales, there are still only limited comprehensive design tools for multi-scale evaluation of the microclimate and thermal benefits of plants and building-integrated vegetation (BIV) systems. The paper describes a case study in the city of Palermo (Italy) that applied simulation methodology to quantitatively assess the microclimate effects of different neighborhood and building retrofit scenarios where vegetation plays a main role. The simulation workflow moves from a micro-urban to a building scale assessment by linking the ENVI-met software to the building energy simulation program EnergyP…
Feasibility of hyperspectral vegetation indices for the detection of chlorophyll concentration in three high Arctic plants: Salix polaris, Bistorta v…
2018
Remote sensing, which is based on a reflected electromagnetic spectrum, offers a wide range of research methods. It allows for the identification of plant properties, e.g., chlorophyll, but a registered signal not only comes from green parts but also from dry shoots, soil, and other objects located next to the plants. It is, thus, important to identify the most applicable remote-acquired indices for chlorophyll detection in polar regions, which play a primary role in global monitoring systems but consist of areas with high and low accessibility. This study focuses on an analysis of in situ-acquired hyperspectral properties, which was verified by simultaneously measuring the chlorophyll conc…