Search results for "PHENOLOGY"
showing 10 items of 146 documents
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 …
Diversity and Phenology of the Braconid Community (Hymenoptera: Braconidae) in the Mediterranean Protected Landscape of Sierra Calderona (Spain)
2014
The diversity of the Braconidae subfamilies (Hymenoptera) in the protected landscape of the Natural Park of Sierra Calderona (Eastern Spain) is analysed. Samplings have been carried out along 2010 in three different habitats: almond crop, Oak forest (Quercus suber L.) and Pine forest (Pinus halepensis Miller). In total, 2166 braconid specimens, belonging to 23 subfamilies, have been captured. Alpha, beta and gamma diversities are analysed. As a result, almond crop habitat is proven to show the greatest diversity. The structure of the community and the phenology in each habitat are also analysed.
Global land surface phenology trends from GIMMS database
2009
A double logistic function has been used to describe global inventory mapping and monitoring studies (GIMMS) normalized difference vegetation index (NDVI) yearly evolution for the 1981 to 2003 period, in order to estimate land surface phenology parameter. A principal component analysis on the resulting time series indicates that the first components explain 36, 53 and 37% of the variance for the start, end and length of growing season, respectively, and shows generally good spatial homogeneity. Mann-Kendall trend tests have been carried out, and trends were estimated by linear regression. Maps of these trends show a global advance in spring dates of 0.38 days per year, a global delay in aut…
PHENOLOGICAL AND MORPHOLOGICAL STUDIES OF PISTACIA TEREBINTHUS L. GENOTYPES NATIVE OF BULGARIA WITH DIFFERENT ASSET OF TREE SEXUALITY
2009
The genus Pistacia is a dioecious species staminate and pistillate inflorescences born on different trees and are wind pollinated. In pistachio orchards, female and male flowering periods are often not synchronized. In fact, male trees spread their pollen before the flowers of female trees become receptive. Pollination is commonly devoted to spontaneous males of P. terebinthus. In this research authors refer to the results obtained observing the phenology of the blooming period of monoicous genotypes of P. terebinthus discovered in the Rhodope Mountains (Bulgaria). In some selected trees phenological stages have been observed in situ. The blooming date is influenced by local environmental c…
A new species of Ferula (Apiaceae) from Malta
2018
Ferula melitensis, a new species from the Malta Archipelago, is described and illustrated. It belongs to the taxonomic group of F. communis, showing close relationships mainly with F. tunetana, F. arrigonii, F. communis s.str. and F. glauca, from which it differs in several features regarding the stem, leaves (mainly for shape and size of terminal segments), flowers and mericarps; other significant differences regard the ecology and phenology. The investigations, carried out on living plants, herbarium material and literature data, regard the morphological analysis of vegetative and reproductive structures, the anatomy of terminal leaf segments and mericarps, as well as the shape and size o…
Phenology of Migratory Bat Activity Across the Baltic Sea and the South-Eastern North Sea
2014
We compiled the available information on the occurrence and timing of migratory bat activity across the Baltic Sea and south-eastern North Sea coasts and islands, based on ultrasonic monitoring projects at 19 localities in 2007–2009. The data refer to three species; Nathusius' pipistrelle Pipistrellus nathusii, soprano pipistrelle P. pygmaeus and common noctule Nyctalus noctula. Pipistrellus nathusii occurred at all sites (north to 61°N in Finland), while the other species were scarcer, particularly at the northernmost sites. The status of the recorded individuals is unknown. However, the activity most likely was of migrating individuals or individuals on migration stopover, because very fe…
ANNUAL ACTIVITY CYCLE OF THE JAVELIN SAND BOA ERYX JACULUS (LINNAEUS, 1758) IN SICILY
2022
The Javelin sand Boa Eryx jaculus is a snake little known from an eco-ethological point of view. Here, some aspects of its phenology are described for the first time. 229 observations were collected in Sicily, with the aim of describing the annual activity of this population. The activity of adult males and juveniles presents a similar trend, with a sharp peak between May and July. Juveniles sharply declined in the following months. Adult females have three peaks of activity of similar amplitude. The activity cycle of the Javelin sand Boa could be modulated by some aspects of his trophic behaviour. In fact, juveniles and adult males prefer prey types highly available only during their maxim…
Late frost damage risk for viticulture under future climate conditions: a case study for the Luxembourgish winegrowing region
2013
Background and Aims Late frosts are a significant risk to grape production in frost-prone viticultural regions. Increasing air temperature because of climate change is likely to advance grape budburst and last frost events in spring. So far, it is unclear whether one trend will be more pronounced than the other, and hence, whether the risk of late frost damage will increase or decrease. The aim of this work was to investigate the future frost risk in the Luxembourgish winegrowing region by assessing the effect of simulated future climate conditions on the timing of budburst and last frost date. Methods and Results Late frost risk was assessed by combining: (i) a phenological model for budbu…
NDVI seasonal amplitude and its variability
2008
NDVI (Normalized Difference Vegetation Index) is a remotely sensed index of vegetation greenness. Its yearly cycle gives information on vegetation type or health, and monitoring its temporal evolut...
Preliminary study on the biology, natural enemies and chemical control of the invasive Macrohomotoma gladiata (Kuwayama) on urban Ficus microcarpa L.…
2015
[EN] The phenology and natural enemies of Macrohomotoma gladiata (Kuwayama) (Hemiptera. Homotomidae) on Ficus microcarpa L. in Valencia (Spain) were studied in 2013. During the study, all immature instars of the pest were found on infested shoots indicating overlapping generations. However, two consistent increases in the proportion of the first two nymphal instars were detected in early March and June, possibly suggesting the beginning of spring and summer generations. Eggs of Macrohomotoma gladiata were usually found below the stipules of new healthy shoots, arranged in groups of 15-30 units. First two nymphal instars usually preferred the innermost part of the shoot, whereas the older de…