14 results on '"Calvão, Teresa"'
Search Results
2. The biogeographic and floristic importance of Djebel Antar (Western Saharan Atlas) for regional biodiversity protection.
- Author
-
Djelid, Selma Amina, Calvão, Teresa, Ballouche, Aziz, Megharbi, Ahmed, and Abdoun, Fatiha
- Subjects
PLANT diversity ,VEGETATION dynamics ,BOUNDARY disputes ,ENDANGERED species ,WILDLIFE conservation - Abstract
The north western Atlas Mountains (Béchar region) act as refugia for relict populations of many species which highlights their interest as priority areas for conservation. Further work since the beginning of the last century has been difficult because of restricted access in a military area with long-standing border conflicts. This paper aims to analyse the temporal dynamics of the vegetation communities, to assess the floristic diversity of one of those isolated djebels, Djebel Antar, and to contribute to the knowledge of the conservation status of the species found. Surveys from 1925,1951 (published data) and 2017 (fieldwork) were interpreted and investigations were carried out on honey harvesting, production, and marketing in the Benzireg area to better understand and contribute to the development of beekeeping. A high proportion of endemic and very rare species was found. A tendency towards the homogenisation of the flora was detected with a decrease in plant diversity. Beekeeping is being tested as a means of enhancing biodiversity and contributing to the fight against vegetation degradation by reducing pastoral pressure. Djebel Antar retains its function as a refuge for biodiversity and may play an important role in conservation measures. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
3. The paradigm of high concentration of metals of natural or anthropogenic origin in soils – The case of Neves-Corvo mine area (Southern Portugal)
- Author
-
Pelica, João, Barbosa, Sofia, Reboredo, Fernando, Lidon, Fernando, Pessoa, Fernanda, and Calvão, Teresa
- Published
- 2018
- Full Text
- View/download PDF
4. Coexistence of insect species in a phloem feeding guild: Deterministic and stochastic processes.
- Author
-
Pimentel, Carla S., Firmino, Paulo N., Almeida, Raquel P., Lombardero, Maria J., Ayres, Matthew P., and Calvão, Teresa
- Subjects
COEXISTENCE of species ,STOCHASTIC processes ,WOOD borers ,DETERMINISTIC processes ,PHLOEM ,DEAD trees ,PINE - Abstract
1. Niche theory, neutral theory, and more recently the unifying theory of biodiversity offer alternative views of the structure (or not) of ecological communities. The relative importance of these theories has not been so thoroughly used to explain community assembly processes in phytophagous insects. 2. We studied the mechanisms of community assembly in pine trees phloem feeders, exploring the relative contributions of deterministic and stochastic processes. 3. Temporal and spatial partitioning of wood borers and bark beetles belonging to the pine phloem feeding gild, was assessed through flight traps and pine bolts extracted from felled live Pinus pinaster trees presenting evidence of decline/wilting. 4. We found that deterministic factors explained most cases of coexistence between species, with partitioning in space and time reducing asymmetric competition for resources and intraguild predation, mediated by differences in size. However, in the case of very closely related species with minimum differences in size—in this case three species of Arhopalus—they occupied the same niche in space and time, suggesting that stochastic processes are more likely to maintain co‐occurrence. 5. The present work indicates that both niche and stochastic processes contribute to the assembly of the phloem feeding community. This could be one more example of accordance with the unifying theory of biodiversity. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
5. What happens to species at the rear‐edge of their distribution in arid regions? The case of Juniperus thurifera L. in the Aurès Mountains (Algeria).
- Author
-
Kafi, Imen, Calvão, Teresa, and Yahi, Nassima
- Subjects
SPECIES distribution ,ARID regions ,JUNIPERS ,NATURE conservation ,DROUGHTS ,CURRENT distribution ,DROUGHT tolerance ,SPATIAL resolution - Abstract
Algerian populations of Juniperus thurifera are the most restricted in terms of distribution and the least studied among all populations of the entire range of the species in the western Mediterranean region. Although this species is regarded as being of least concern according to the International Union for Conservation of Nature (IUCN), many studies have pointed to the need for its conservation, especially in North Africa, where populations are fragmented and the potential for regeneration is reduced. Understanding the current range of distribution of J. thurifera in Algeria and the environmental factors responsible for this is of key importance for the protection and restoration of these populations. In the present study, a maximum entropy approach (MaxEnt) was used to model the distribution of J. thurifera. Thirty occurrence records were analyzed in combination with climatic, topographic, and anthropogenic predictors at two different spatial resolutions (900 m and 30 m). The best‐performing model included climatic, topographic, and anthropogenic predictors, suggesting that the distribution of the species is influenced by a combination of factors, while the performance of climatic and topographic models was similar. The most important predictors of the occurrence of Algerian J. thurifera are water‐related factors. However, when considering only topographic variables, altitude has a huge impact. Finally, using improved resolution for modeling distribution enhanced the prediction capability of the model (AUC = 0.942). The findings of the present study confirmed the resilience of J. thurifera, and highlighted the tolerance to drought of Algerian populations. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
6. Sublethal infection of different pine species by the pinewood nematode.
- Author
-
Pimentel, Carla S., McKenney, Jessica, Firmino, Paulo N., Calvão, Teresa, and Ayres, Mathew P.
- Subjects
PINEWOOD nematode ,CONIFER wilt ,PINE ,CNIDARIA ,HIGH temperatures ,PINACEAE ,NEMATODES - Abstract
Bursaphelenchus xylophilus, the pinewood nematode and causal agent of pine wilt disease (PWD), is a globally destructive pine pest. PWD is favoured by high temperatures and drought, but B. xylophilus can also persist in symptomless hosts in areas not prone to PWD. We compared seedlings of different Pinus species that were inoculated with B. xylophilus when well‐watered and under moderate temperatures, conditions that favour sublethal infections. We compared isolates of B. xylophilus in south‐west Europe (Portugal) and south‐east USA (Louisiana). P. pinea, P. pinaster, and P. radiata were challenged in both areas with inoculations of local B. xylophilus. P. sylvestris in Portugal and P. palustris in Louisiana were also tested. Seedling mortality was low, as expected, but nematode establishment was common. There were higher nematode densities and more damage in seedlings of P. sylvestris and P. radiata, followed by P. pinaster, with P. pinea and P. palustris proving to be more tolerant. Life history of hosts was a better predictor of resistance to B. xylophilus than geographical origin, even under sublethal conditions. Fast‐growing species (P. radiata and P. pinaster) appeared most likely to be symptomless carriers in areas not prone to the development of PWD. Cold‐adapted species (P. sylvestris) may still be suitable hosts for the pathogen, even at the sublethal conditions of their distribution areas. There were more nematodes per gram of host using nematode isolates from Portugal. Nonetheless, our results opposed the hypothesis that North American pinewood nematodes have such low virulence that they are obligatorily saprophytic. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
7. Climate and landscape patterns of pine forest decline after invasion by the pinewood nematode.
- Author
-
Calvão, Teresa, Duarte, Cláudio M., and Pimentel, Carla S.
- Subjects
FOREST declines ,PINEWOOD nematode ,AUTOCORRELATION (Statistics) ,CLIMATE change ,FOREST density - Abstract
Highlights • We investigated if there is a spatial structure of pine forest decline in Portugal. • Pine forest decline was spatially aggregated, presenting spatial autocorrelation. • Forest decline patterns could not be dissociated from climate effects. • Landscape diversity and forest density also seem to have an impact on pine decline. Abstract Context The pinewood nematode, Bursaphelenchus xylophilus , has been identified as being responsible for the decline of pine forests in Portugal, since its detection in the territory about 20 years ago. Forest decline due to disease and/or pests is a complex phenomenon, and a knowledge of the spatial patterns of tree mortality is important for providing an understanding of forest susceptibility and pest dynamics. Objectives The aim of the present study was to investigate the relationship between the spatial structure of pine mortality and that of different climatic, edaphic and landscape variables in an area of Portugal where B. xylophilus is known to have spread during the last decade. Methods Pine mortality was assessed in the field, in a large, complex area of Central-North Portugal. An ArcGis database with a range of environmental variables was created for the study area. Spatial autocorrelation of the different variables was investigated by means of Moran's I and Mantel r analysis. The relationship between pine decline and the different variables was analyzed using bivariate Moran's I. Results Environmental descriptors exhibit a clear spatial pattern, influenced by an undulating landscape. Pine mortality is spatially aggregated; warm, dry locations with higher evapotranspiration present high values, and in areas of extensive pine occupancy in a diverse landscape mortality decreases. Conclusions Forest mortality attributed to infestation by a non-native forest pathogen cannot be dissociated from the effects of climate and landscape diversity associated with pine forests. The analysis of landscape patterns appears to be crucial for gaining an understanding of forest pathology and decline. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
8. Spatial patterns at host and forest stand scale and population regulation of the pine processionary moth Thaumetopoea pityocampa.
- Author
-
Pimentel, Carla S., Ferreira, Claudia, Santos, Marcia, and Calvão, Teresa
- Subjects
THAUMETOPOEA ,POPULATION dynamics ,LARVAL ecology ,PLANT-pathogen relationships ,FORESTS & forestry - Abstract
Different spatial processes are likely to generate variability at different scales. Thus, the explanation of patterns may be facilitated by knowledge about the spatial scales where variation in patterns occurs. In the present study, the link between spatial patterns of the pine processionary moth Thaumetopoea pityocampa Den. & Schiff. (Lepidoptera, Notodontidae) at two different scales, as well as its population dynamics, was assessed., First, the spatial patterns of T. pityocampa population were assessed at the forest stand scale by surveying the distribution of larval colonies within the pine forest, indicative of adult dispersion. Second, egg-laying patterns across individual host-plants, indicative of female oviposition choices, were assessed, as well as their impact on the survival of immature stages., It was found that T. pityocampa presents a gregarious distribution in homogeneous pine forests, over distances of a few dozen metres. At the pine tree scale, females tend to aggregate their egg batches, whereas aggregation increases with population density. Natural enemies such as parasitoids do not appear to play an important role in regulating the population dynamics of the species. At the same time, aggregation in individual hosts leads to increased mortality in the period from hatching to the third instar, which is notable at high population densities., A patchy distribution in the landscape over short distances has a potentially positive effect on population dynamics of the species, avoiding the Allee effect, and allowing for a rapid increase in population, even where initial numbers are low, leading to localized outbreaks. At the same time, increased mortality as a result of egg-batch clumping at high population densities is a potential density-dependent mechanism of population regulation. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
9. Monochamus galloprovincialis and Bursaphelenchus xylophilus life history in an area severely affected by pine wilt disease: Implications for forest management.
- Author
-
Firmino, Paulo N., Calvão, Teresa, Pimentel, Carla S., and Ayres, Matthew P.
- Subjects
FOREST ecology ,FOREST management ,MONOCHAMUS ,BURSAPHELENCHUS ,PATHOGENIC microorganisms - Abstract
Bursaphelenchus xylophilus is an insect-vectored pathogen and the causal agent of the pine wilt disease (PWD). In Portugal, where B. xylophilus is a recent invasive pest, the native pine sawyer beetle, Monochamus galloprovincialis, is its only vector. Epidemics of PWD emerge from three-way interactions among B. xylophilus , M. galloprovincialis , and host pine trees. However, the basic ecology of these interactions is poorly known. We studied M. galloprovincialis with respect to its life history, host selection, and phoresy by B. xylophilus in an area severely affected by PWD in Portugal. We assessed: (1) seasonal patterns of phoresy related to the flight phenology of the vector; and (2) distribution of M. galloprovincialis within and among host pine trees. Monochamus galloprovincialis in Portugal flies from May through October, and is probably bivoltine, but phoresy by B. xylophilus only occurs within a short period in early summer, when infection of new pine hosts most likely occurs. Peaks of M. galloprovincialis emergence and B. xylophilus phoresy immediately precede onset of the Mediterranean dry season, favoring PWD because B. xylophilus succeeds best on trees suffering from severe water deficits. The abundance of phoretic nematodes was more evident when their vectors were trapped as free flying adults rather than emerging from dying trees. Bursaphelenchus xylophilus were highly aggregated on a subset of M. galloprovincialis , which were aggregated in a subset of dying trees. However none of the host parameters related to size and bark thickness, could explain host selection. Despite its importance for PWD, M. galloprovincialis is a minor component of the bark and wood-boring insects of pine trees in Portugal. Interactions within this community are likely important to the epidemiology of PWD. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
10. Remote sensing in food production - a review.
- Author
-
Calvão, Teresa and Pessoa, Maria Fernanda
- Subjects
- *
REMOTE sensing , *FOOD production , *FOOD security , *VEGETATION monitoring , *CROPS , *MANAGEMENT - Abstract
FAO's most recent assessments indicate that, globally, in 2011-13, about one in eight people in the world are likely to have suffered from chronic hunger, not having adequate food supplies for an active and healthy life. Food security crises are now caused, almost exclusively, by problems in access to food, not absolute food availability, but, monitoring agricultural production remains fundamental. Traditional ground-based systems of production estimation have many limitations which have restricted their use. However, remotely sensed satellite data offer timely, objective, economical, and synoptic information for crop monitoring. The objective of this paper is to review the contribution of remote sensing techniques in the classification, monitoring of crop phenology and condition and estimation of production. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
11. Impact of climatic variation on populations of pine processionary moth Thaumetopoea pityocampa in a core area of its distribution.
- Author
-
Pimentel, Carla, Calvão, Teresa, and Ayres, Matthew P.
- Subjects
- *
CLUSTER pine , *INSECT populations , *CLIMATE change , *THAUMETOPOEA , *LEPIDOPTERA , *PHYSIOLOGICAL effects of solar radiation , *INSECT larvae , *INSECT eggs - Published
- 2011
- Full Text
- View/download PDF
12. Arthropod diversity sheltered in Thaumetopoea pityocampa (Lepidoptera: Notodontidae) larval nests.
- Author
-
BRANCO, MANUELA, SANTOS, MÁRCIA, CALVÃO, TERESA, TELFER, GILLIAN, and PAIVA, MARIA-ROSA
- Subjects
ARTHROPODA ,ANIMALS ,ARTHROPOD surveys ,THAUMETOPOEA ,NOTODONTIDAE ,PLANTS ,PLANT diversity - Abstract
1. In pine ecosystems, the role of the larval nests of the Mediterranean defoliator Thaumetopoea pityocampa as shelter of other arthropods, was studied for the first time. In Portugal, Pinus stands which differed in understorey plant diversity and level of attack by T. pityocampa were compared. 2. The arthropod fauna found sheltering inside the nests consisted of 60 species, representing 12 foraging types. Both arthropod richness and abundance were positively correlated with nest size, expressed as larval biomass. Arthropod richness was further positively correlated with understorey plant diversity, while no correlation was detected between arthropod richness and nest density. 3. Spiders accounted for up to 50% of the species richness, while 80% of the individuals collected were either juveniles, or females with brood, implying that T. pityocampa nests are used for overwintering and brood care. Seventy-six per cent of the Araneae were nocturnal ground foragers and specialised cryptic hunters, demonstrating the occurrence of indirect interactions among species belonging to different communities, namely ground vegetation layers and forest pine coppice. 4. It was concluded that, in Mediterranean pine ecosystems, T. pityocampa nests (i) create habitat diversification and contribute to improve overwintering survival of a wide range of arthropod species; (ii) play a functional role in the food web of pine ecosystems, by promoting indirectly mediated interactions among species from different communities; and (iii) do not contribute to create habitat for symtopic phytophagous arthropods, since contrary to literature references for different types of shelters, 98% of the associated species belonged to foraging types other than T. pityocampa. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
13. Disentangling the effects of climate and defoliation on forest growth: The case of an outbreak of a Thaumetopoea pityocampa population with a shifted phenology in a Pinus pinaster monoculture.
- Author
-
Campôa, João, Calvão, Teresa, Firmino, Paulo N., and Pimentel, Carla S.
- Subjects
CLUSTER pine ,FOREST microclimatology ,TREE growth ,PHENOLOGY ,FOREST management ,MEDITERRANEAN climate ,DROUGHTS ,PLANT phenology - Abstract
• It was evaluated the effect of defoliation and climate on pine trees growth. • Precipitation and temperature have a positive effect on tree growth. • Defoliation and droughts decrease growth but do not act synergistically. • Defoliated trees are less affected by droughts than non-defoliated trees. • Defoliated trees are not able to take advantage of favourable climate. Forests are widely affected by disturbances, both abiotic, climate related, and biotic, like insect outbreaks. However, the impact of the interaction of these disturbances on tree growth is still not well understood. On the present work the impact of climatic and long-term defoliation by Thaumetopoea pityocampa (Dennis and Schiff.) during summer on Pinus pinaster growth was evaluated. At the National Pine Forest of Leiria, in Portugal, we sampled defoliated and non-defoliated forest plots covered by monocultures of young P. pinaster trees. Growth was assessed using dendrochronological techniques, and its relationship with climatic variability, including severe droughts, and defoliation, was analysed using hierarchical partitioning models. Results suggest that long term defoliation result in trees not being able to take advantage of favourable climatic conditions, leading to a reduced radial and height growth. Droughts were the major climatic disturbance, causing growth reduction as well, although the impacts of both disturbances did not act synergistically. Additionally, models showed that previous year climatic conditions have a significant effect on annual growth, namely, previous year annual precipitation and temperature. Yet, the best model obtained include a positive effect of the previous year annual precipitation and a negative effect of the interaction between this climatic parameter and defoliation. This work illustrates the potential of defoliation and climate to reduce forest productivity and the importance of water availability for tree development in Mediterranean climates. In addition, our results also emphasise the need to simultaneously evaluate the effects of different disturbances, particularly in a time of global change when an increase in forests disturbances is expected. This approach will certainly contribute to a more informed management of production forests. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
14. Heavy metal content of edible plants collected close to an area of intense mining activity (southern Portugal).
- Author
-
Reboredo, Fernando H., Pelica, João, Lidon, Fernando C., Ramalho, José C., Pessoa, Maria F., Calvão, Teresa, Simões, Manuela, and Guerra, Mauro
- Subjects
EDIBLE plants ,PHYSIOLOGICAL effects of heavy metals ,COPPER mining ,AGRICULTURAL productivity ,MINES & mineral resources ,BIOACCUMULATION - Abstract
The Neves-Corvo mining complex (MC) situated in southern Portugal exploits one of the most world’s important copper deposits. Agricultural soils surrounding the MC, used by the inhabitants for crop production, contain excessive amounts of As, Cu, Pb, and Zn. Thus, a potential risk to human consumption exists if edible plants grow on these substrata. Arsenic and Pb were not detected in edible samples collected near the MC and 5 km away, but in the leaves—structural or adsorbed onto the surface. In general, Zn was the most mobile element in both contaminated and reference areas as seen by the bioaccumulation factors (BAF). The tolerable upper intake (TUI) values for Cu are a reason of concern, since in 57.1% of the cases, the TUI values are above the recommended upper limit of 5 mg/day, in the case of Ficus carica, Cucurbita pepo, and Phaseolus vulgaris, whereas in 28.6% of the cases, the TUI values are near this limit (C. pepo and Citrus x sinensis). The consumption of such vegetables from these areas must be banned or strongly reduced, since long-term accumulation of Cu can cause a chronic toxicity in humans. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.