HABITAT INFLUENCES

Author: GARCÍA RODRÍGUEZ EZEQUIEL.
Year: 2004.
University: POLITÉCNICA DE MADRID [www.upm.es].
Place of defense: E.T.S. INGENIEROS DE MONTES.
Place of preparation: E.T.S. INGENIEROS DE MONTES.

Summary: In predicting the height of the free surface of the water and the distribution of velocities, in general terms, accuracy was better in the one-dimensional modeling, while the distribution of velocities for the flow prediction was almost equally accurate both models. In areas with cross-flow velocity distribution was predicted more accurately by using two-dimensional modernization, as the model used in the simulation dimensional simply "not entirely" directly that there is this kind of flow. The main problem of modernization in the estimation of two-dimensional velocities was relatively high speeds off some discrepancy from the shores of the channel, with regard to the speeds measures, which led to an increase in overall speeds discrepancy regarding the simulated measures. As for the Habitat Potentially Usable (HPU) calculated for the growth stages of the four target species, it is concluded that as the flow increases and the stadium in life is younger, live with the model estimated IB tends to be less than the estimated model 2D, Barbus bocagei, Salmo trutta and Chondrostoma polylepsi. In the case of Squalius pyrenaicus observed the same behavior as the flow rate increases. Finally, based on the simulation results habitat is recommended to be careful when selecting the approach used in the modernization of the hydrodynamics river, especially when the objective of the project is relevant to studies of younger fish species, and that difference was found d enasta the 36% between Habitat Potentially estimated usable for these life stages, the simulation based on the habitat of the two-dimensional hydrodynamic modeling woe based on the one-dimensional. These differences are attributed mainly to the way they allocate values between cross sections of habitat, and that while the one-dimensional modeling extrapolating the rejected along the channel considering the stretch of river divided into cells uniforms defined on the basis the horizontal actions, in the two-dimensional modeling simulation hábital is considering the stretch of the river formed by a series of cells that are defined on the basis of benchmarking distributed throughout the length and breadth of course, achieving a more realistic representation . In addition, the simulation using habitat of the one-dimensional hydrodynamic model, the height of the free surface water is assumed horizontal cross sections, and can lead errors sub-representación of shallow, suitable for the development of stadiums life younger, in curves and islands where the difference of height of water in the ends of the sections can be significant (ice., on the order of tens of centimeters).

Author: CALVO IGLESIAS MARÍA SILVIA.
Year: 2004.
University: SANTIAGO DE COMPOSTELA [www.usc.es].
Place of defense: Escola Politécnica Superior de Lugo.
Place of preparation: de Compostela.

Summary: In this research have developed several methods for the characterization and study of the dynamics of cultural landscapes in Galicia, with GIS and remote sensing for planning and management. The study area covers six municipalities in the north of Galicia (Spain NO) in 1956/57 and 2000. The main sources were used to map agricultural landscapes of Galicia produced by Bouhier (1979), a set of aerial photographs of 1956/57 and 2000, parcelarios cadastre in digital format and statistical information on farming and population. Tests were conducted on the basis of information from 82 sampling points selected through a stratified random sampling of 10% of the settler population in the study area based on the type of landscape. Around each sampling point were charted a plot of 500 meter radius so that the total area sampled was 10% of the study area. Semi-structured interviews were conducted in randomly selected farmers in each plot sampling in order to obtain information on the traditional and current farming system, the toponymy of the plots labradío, cultural heritage and perception on changes in the landscape. In order to identify structural elements of the complex agricultural landscapes Added information from interviews with the results of photo interpretation and microtoponimia of parcelarios cadastral. The soil cover in 1957 and 2000 was identified and scanned from aerial photographs, which allowed the subsequent calculation of the dominant classes of coverage, the parent contingency and indices partners, as well as indices of landscape pattern in each one of the sampling plots. The characterization led to the identification of the main types of landscape in each plot sampling from its structural features, analysis of their differences respects to environmental parameters, socio-economic (ie soil cover system and uses) and the characteristics of the pattern landscaping. Assuming the existence of changes as an inherent characteristic of the landscape, the study of dynamics involved examining the directions of change in the soil cover, and changes in the landscape pattern through multivariate analysis, as well as developments in the agricultural landscapes and their relationship with social changes and socio-economic. Traditional knowledge has proved a key source of information in the inventory of the items of cultural landscape, identifying further changes in the landscape at the local level, which is very important in the development of indicators of landscape on cultural values and the state of conservation of cultural landscapes. It is also an essential source of information for managing the landscape at the local level, which allows the identification of cultural practices that contribute to the maintenance of the landscape and its biodiversity. This investigation showed concordance between descriptions Bouhier (1979) on the system uses a regional scale with those provided by local communities in the 8 area be7 study. In general, the agreement was observed between the agricultural landscapes identified in the study area, as identified by Bouhier, although differences were observed with respect to its range and limits. The aerial photography at a scale of detail is an essential source of information for the identification and mapping of the landscape and its structural elements. It facilitates the identification of individual structural elements of the landscapes and terraces bocage, however has not shown a satisfactory effectiveness in identifying the agras, it required the use of additional sources. The microtoponimia contained in parcelarios cadastral contributed to the identification of the structures of landscapes agras in aerial photographs. As for the characteristics of the main agricultural landscapes, it was observed as landscapes agras and bocage showed statistically significant differences in altitude, earrings and variable pattern landscape, as well as its system of exploitation. The study of the dynamics of landscape led to the identification of changes in land cover associated with the reorientation of farming, in some cases, and the marginalization of agriculture in other cases. Changes in the landscape pattern were increasing fragmentation due to increased infrastructure and increasing heterogeneity in the soil cover by the introduction of forest uses to cropland. Regarding the soil cover, the landscape has been changed from a clear dominance of the growing areas, the dominance of grasslands, and stocking in some cases. Contrary to what happened to the soil cover, the structural elements are the landscapes that offer greater resistance to change, except for areas where actions have made reparcelling. The observed changes in the landscape, moderate and in some cases dramatic elsewhere, the apparent existence of an evolution itself uncontrollably, which brings uncertainty about the future of the agricultural landscapes, necessitating the implementation of policy planning for conservation and management.

Author: VALLE PÉREZ CARLOS.
Year: 2004.
University: ALICANTE [www.ua.es].
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: This paper aims to evaluate the effect of four types of impacts caused by man on the population of fish in the coastal province of Alicante gracious. These four impacts are: i) of trawling on the prairie of Posidonia oceanica: ii) the regeneration of a beach on the population of fish and the economic impact on the artisanal fleet; iii) a isntalación of aquaculture on the open sea and its effect on the population naturally and iv) the immersion, using, in all cases, analysis multiescalares in order to identify different sources of variation below the hypothesis originally proposed. The results showed that the structural complexity and the availability of microhábitas are one of the most important aspects to increase the wealth of fish and therefore habitat conservation must be taken into account in managing the coast. The impacts caused studied: a habitat alteration or destruction of Posidonia oceanica (MPAs). The causes that led to the general distribution of species observed were: the selection of habitat, predation or food, shelter and recruitment.

Author: GANZEDO LÓPEZ UNAI.
Year: 2004.
University: LAS PALMAS DE GRAN CANARIA [www.ulpgc.es].
Place of defense: FACULTAD DE CIENCIAS DEL MAR.
Place of preparation: FACULTAD DE CIENCIAS DEL MAR.

Summary: We analyze the degree of complexity between two species of tuna (Thunnus thynnus and T.alalunga) and the changes in climate in the Atlantic. There is an environmental component that has a dramatic impact on the availability of the resource for the fishery (this climate variability explains 73.14% of oscillations recorded in the series of catches of bluefin tuna in the Atlantic almadrabas of southern Spain). In this regard, the cycles of solar activity (22 years, or double cilo solar, and 80 years or cycles Gleissberg) governing greater variations in abundance in the medium and long term. Here, for bluefin tuna (Thunnus thynnus) and albacore tuna (Thunnus alalunga), a negative index of the North Atlantic Oscillation (NAO) favors an increase in catches in the Eastern Central Atlantic, as it increases the temperature seawater, and more clearly in the area of the Canary Islands. Simultaneously, in the Western Atlantic (areas FAO 31 and 21) will have the opposite effect. Fluctuations in catches can be regarded as a good indicator of changes in abundance, so that the analysis of long series of data allows us to separate the effect attributable to the fishery caused by climate change on the abundance and size of latitudinal and transoceanic journeys of these fish.

Author: SANZ RONDA FRANCISCO JAVIER.
Year: 2005.
University: VALLADOLID [www.uva.es].
Place of defense: E.T.S. DE INGENIERÍAS AGRARIAS.
Place of preparation: E.T.S. DE INGENIERÍAS AGRARIAS DE PALENCIA.

Summary: Quantification of river habitat is the most important part of the studies of environmental flows that are based on models of the physical habitat. This is done by dividing the study area into segments (stretches of river with a flow regime and some geomorphologic features homogeneous), which are analyzed using two basic strategies: the stretch representative and the election of mesohábitats. Within each there are various options to select sampling sites, their length and how to extrapolate the amount of habitat. Depending on the procedure used and the intensity of sampling, model habitat provides different results, which may lead to the choice of alternatives for managing the flow erroneous. This thesis assesses different sampling techniques, in both methods (tranches representative and mesohabitats) comparing the total actual habitat in a river segment of 810 m in length and 10 m in width bankfull, habitat getting in each type of sampling. The habitat has been quantified using physical variables (number of Froude, ratio of the speed and depth and substrate of the bed) and biological (potential volume useful, net inflow of energy and indices of uniformity and diversity de Shannon-Wiener). KEYWORDS: method stretch representative method of mesohábitats sizes sampling, sampling strategies, environmental flows, habitat models, PHABSIM