7 resultados para Mediterranean climate
em Repositório Científico da Universidade de Évora - Portugal
Resumo:
tWater use control methods and water resources planning are of high priority. In irrigated agriculture, theright way to save water is to increase water use efficiency through better management. The present workvalidates procedures and methodologies using remote sensing to determine the water availability in thesoil at each moment, giving the opportunity for the application of the water depth strictly necessaryto optimise crop growth (optimum irrigation timing and irrigation amount). The analysis is applied tothe Irrigation District of Divor, Évora, using 7 experimental plots, which are areas irrigated by centre-pivot systems, cultivated to maize. Data were determined from images of the cultivated surface obtainedby satellite and integrated with atmosphere and crop parameters to calculate biophysical indicatorsand indices of water stress in the vegetation—Normalized Difference Vegetation Index (NDVI), Kc, andKcb. Therefore, evapotranspiration (ETc) was estimated and used to calculate crop water requirement,together with the opportunity and the amount of irrigation water to allocate. Although remote sensingdata available from satellite imagery presented some practical constraints, the study could contribute tothe validation of a new methodology that can be used for irrigation management of a large irrigated area,easier and at lower costs than the traditional FAO recommended crop coefficients method. The remotesensing based methodology can also contribute to significant saves of irrigation water.
Resumo:
O presente estudo teve como objetivo a caracterização de variações anátomo-fisiológicas que decorrem do processo de aclimatação sazonal em bovinos leiteiros com alto (Altas) e baixo (Baixas) potencial leiteiro, com vista a selecionar animais que conciliem bons desempenhos produtivos e índices de adaptabilidade que possibilitem a mudança de homeostase face às condições climáticas presentes no clima mediterrânico. O estudo foi realizado numa herdade comercial, situada no Alentejo, utilizando 13 vacas multíparas (6 Baixas e 7 Altas), durante três períodos: P1 (animais aclimatados ao verão; presença de stresse térmico); P2 (animais aclimatados ao verão; termoneutralidade); P3 (animais aclimatados ao inverno; termoneutralidade). Em stresse térmico (P1), verificaram-se maiores esforços termolíticos e maiores armazenamentos de calor no grupo das Altas. Observou-se também que a produção de leite das Altas foi afetada pelo stresse térmico, evidênciando uma redução 24-48h após os valores de temperatura retal mais elevados. Nesta situação, as Baixas apresentaram uma variação na produção oposta à das Altas. Em P1, os valores de proteína e de gordura no leite foram significativamente mais baixos que em P3, em ambos os grupos. A ureia no leite foi significativamente mais elevada nas Altas durante o P1, revelando potencial como biomarcador de stresse térmico. Do P1 para o P3 obser-vou-se uma redução gradual do hematócrito, da hemoglobina e da triiodotironina (T3). As Altas apresentaram uma maior redução de triiodotironina (T3) que as Baixas, como consequência de uma maior intensidade de aclimatação. Nos pelos não se registaram diferenças entre os períodos, o que contrasta com alguma bibliografia. Porém, a ausência da insolação direta poderá ter sido um fator determinante; ABSTRACT: The main objective of the present study was the characterization of anatomical and physiological variations that occur in the seasonal acclimatization process of dairy cows with high (Altas) and low (Baixas) milk yield potential. In this way it should be possible to do a selection of animals with good productive traits and also with adaptability indexes that allow a change in homeostasis to cope with the climatic conditions of the mediterranean climate. Meteorological, clinical, productive, physiological and anatomical data were collected. The study was conducted in an Alentejo's dairy farm, using 13 multiparous cows (6 with low milk yield and 7 with high milk yield), during three periods: P1 (animals acclimated to summer, in heat stress); P2 (animals acclimated to summer, thermoneutrality); P3 (animals acclimated to winter; thermoneutrality). In thermal stress (P1), the high milk yield group (Altas) shown greater thermolytic efforts and also higher heat storage. The milk yield in this group was also affected by heat stress, showing a decrease in production when the rectal temperature increased, with a delay of 24-42 hours. In this situation the Baixas group showed an opposite milk production variation. In P1, the protein and fat milk content was lower than in P3, in both groups. Milk urea levels were significantly higher during P1 in the Altas group, revealing potential as an heat stress biomarker. Hematocrit, hemoglobin and triiodothyronine (T3) values gradualy decreased from P1 to P3. T3 values were lower in Altas than in Baixas group, as a consequence of a more intense acclimatization. The hair analysis didn’t show the standard seasonal acclimatization process, indicating the absence of direct solar radiation as a determinant factor.
Resumo:
Since the middle age wildflower meadows are used to bring the flowers from the natural and rural areas into urban landscapes. Wildflowers meadows can improve the quality of Green Infrastructures as they increase biodiversity. However, after a few centuries of given flowers a principal part, lawns started to be used in every kind of places leading to a green obsession. Nowadays, urban lawns are cover more than 70% of urban green spaces all over the world. Frequently design options aren’t environmental or economical friendly, and lawns are this example. Lawns are green deserts with low biodiversity, and unsustainable. Wildflower meadows are an alternative to lawns, more sustainable, less resources consumer and much more biodiverse. In the regions with a Mediterranean climate water is a limit factor, especial in summer.
Resumo:
Modifications in vegetation cover can have an impact on the climate through changes in biogeochemical and biogeophysical processes. In this paper, the tree canopy cover percentage of a savannah-like ecosystem (montado/dehesa) was estimated at Landsat pixel level for 2011, and the role of different canopy cover percentages on land surface albedo (LSA) and land surface temperature (LST) were analysed. A modelling procedure using a SGB machine-learning algorithm and Landsat 5-TM spectral bands and derived vegetation indices as explanatory variables, showed that the estimation of montado canopy cover was obtained with good agreement (R2 = 78.4%). Overall, montado canopy cover estimations showed that low canopy cover class (MT_1) is the most representative with 50.63% of total montado area. MODIS LSA and LST products were used to investigate the magnitude of differences in mean annual LSA and LST values between contrasting montado canopy cover percentages. As a result, it was found a significant statistical relationship between montado canopy cover percentage and mean annual surface albedo (R2 = 0.866, p < 0.001) and surface temperature (R2 = 0.942, p < 0.001). The comparisons between the four contrasting montado canopy cover classes showed marked differences in LSA (χ2 = 192.17, df = 3, p < 0.001) and LST (χ2 = 318.18, df = 3, p < 0.001). The highest montado canopy cover percentage (MT_4) generally had lower albedo than lowest canopy cover class, presenting a difference of −11.2% in mean annual albedo values. It was also showed that MT_4 and MT_3 are the cooler canopy cover classes, and MT_2 and MT_1 the warmer, where MT_1 class had a difference of 3.42 °C compared with MT_4 class. Overall, this research highlighted the role that potential changes in montado canopy cover may play in local land surface albedo and temperature variations, as an increase in these two biogeophysical parameters may potentially bring about, in the long term, local/regional climatic changes moving towards greater aridity.
Resumo:
This essay addresses the application of indigenous plants in Landscape Architecture projects, based on studies carried out in the field of phytosociology and sinphytosociology. Through this knowledge, it is possible to increase and improve the use of indigenous plants in Projects, aiming at the preservation of biodiversity. Thus, to better understand the western Mediterranean territory, we present a brief biophysical characterization, in which we point out the main factors which contribute to the ground coverage’s distribution in the landscape, namely, concerning climate (oceanity, ombroclimate and thermoclimate) and substrate (geology and lithology). In view of the high level of uniqueness of the identified conditions, a synthesis of the potential main existing climatophilous woods is carried out, regarding sinphytosocialogical class/order, furthermore, pointing out, the main serial stages, their vegetation bioindicators and the ecological peculiarities of each stage (regressive or progressive). Therefore, based on the study area, we point out the vegetation bioindicator’s value as a work tool during analysis, thus allowing us to understand the existing edaphoclimatic conditions, as well as to elaborate a quick diagnosis of each potential climatophilous vegetation series. Moreover, based on the main stages of substitution, it is also possible to identify the presence of endemic plants, or under protection status, and finally, the conservation state of the study area. Further ahead, in project proposal phase, based on information gathered previously, we point out the possibility of elaborating a list of plants correctly adapted to the existing mesologicall conditions. Thus, within each serial stage, the necessary ecological conditions for a correct adaption of the vegetation material are referred, therefore, avoiding possible limiting factors to their development, such as precipitation, soil erosion, light availability, salinity, among many others. Lastly, some considerations are made about the main ideas that should be remembered throughout this essay, namely, regarding the importance of the use of sinphytosociology’s knowledge as an analysis tool, as well as of high interest for the elaboration of proposals which aim at the floristic heritage’s conservation and the landscape’s scenic quality. Ce travail traite de l`application de plantes autochtones dans des projets d`Architecture Paysagiste ayant pour base des études réalisées dans le cadre de la phytosociologie et Symphytosociologie. À travers ces connaissances, il est possible d`incrémenter et améliorer l`utilisation de plantes autochtones dans les Projets basés sur la conservation de la biodiversité. Ainsi, afin de mieux comprendre le territorie de la méditérrannée occidentale, on présente une brève caractérisation biophysique, dans laquelle nous soulignons les principaux facteurs qui contribuent à la répartition de la végétation dans le paysage, notamment au niveau climatique (l`océanité, ombrothermique et thermoclimatique) et du substrat (géologie et lithologie). Face aux conditions, identifiées ci-dessus, élévées en originalité, il est utile d`élaborer une synthèse des principaux bois potentiels climatophiles existants au niveau de la classe/ordre symphitosociologique, en soulignant également les principales étapes de série, leurs bioindicateurs végétaux et aux particularités écologiques de chaque étape (régressive ou progressive). Ainsi, sur la base de l`interprétation de la zone d`étude, le bioindicateur végétal se distingue comme un outil de travail durant l`analyse, permettant de cette façon comprendre les conditions édapho-climatiques existantes, ainsi comme élaborer un rapide diagnostic de chaque série de végétation potentielle climatophile. En outre, sur la base des principales étapes de remplacement, il est également possible d`identifier la présence de plantes endémiques, ou avec un statut de protection et enfin l`état de conservation de la zone d`étude. Déjà au stade de proposition du projet, basée sur l`information recueillie précédemment, il y a la possibilité d`établir une liste de plantes bien adaptées aux conditions mésologiques. Ainsi, dans chaque étape de série, les conditions écologiques nécessaires à une bonne adaptation de la matière végétale sont référées, évitant ainsi des facteurs limitant à son développement, tels que les précipitations, l`érosion des soís, disponibilité de la lumière, de la salinité, parmi beaucoup d`autres. Et enfin, quelques considérations se tissent sur les principales idées à retenir tout au long du travail, notamment l`importance d`utiliser la connaissance de la symphytosociologie comme un outil d`analyse d`un grand intérêt pour la développement de propositions pour la conservation du patrimoine floristique et la qualité pittoresque du paysage.
Resumo:
The effects of climate change can result in dramatic consequences in specific ecosystems such as montados that are seriously threatened by the absence of cork and holm oak (Quercus suber and Q. rotundifolia) natural regeneration. Shrubs of the genus Cistus, which are among the most important elements of encroached montados, seem to promote soil rehabilitation and enhance oak regeneration (Simões et al. 2009). In this context, we compared the life strategies and evaluated the potential ability of Cistus species to adapt to the increasing drought expected for the Mediterranean region, and thus their role on the sustainability of cork oak montados.
Resumo:
Non-perennial rivers and streams (NPRS) cover >50% of the global river network. They are particularly predominant in Mediterranean Europe as a result of dry climate conditions, climate change and land use development. Historically, both scientists and policy makers underestimated the importance of NRPS for nature and humans alike, mainly because they have been considered as systems of low ecological and economic value. During the past decades, diminishing water resources have increased the spatial and temporal extent of artificial NPRS as well as their exposure to multiple stressors, which threatening their ecological integrity, biodiversity and ecosystem services. In this paper, we provide a comprehensive overview of the structural and functional characteristics of NPRS in the European Mediterranean, and discuss gaps and problems in their management, concerning their typology, ecological assessment, legislative and policy protection, and incorporation in River Basin Management Plans. Because NPRS comprise highly unstable ecosystems, with strong and often unpredictable temporal and spatial variability - at least as far as it is possible to assess - we outline the future research needs required to better understand, manage and conserve them as highly valuable and sensitive ecosystems. Efficient collaborative activities among multidisciplinary research groups aiming to create innovative knowledge, water managers and policy makers are urgently needed in order to establish an appropriate methodological and legislative background. The incorporation of NPRS in EU-Med River Basin Management Plans in combination with the application of ecological flows is a first step towards enhancing NPRS management and conservation in order to effectively safeguard these highly valuable albeit threatened ecosystems