For long, farmers and agronomists have known that their fields do not produce the same in all areas. However, the factors affecting yield do not always behave in the same way from year to year. As such, this dissertation will try to identify and understand the main factors driving within-field variability in an irrigated maize to answer the following questions: 1) Can topography explain the spatial variability of yield in irrigated maize? 2) When does the variability within-field appear in the growing season? To answer these questions, we used data from a farm located in Azinhaga, Portugal, near the Tagus River, where the fields are very flat, and most soils are fluvisoils. Contrary to what is written in the literature, in this work there was no robust evidence supporting that the distribution of water with-in field caused variability in production. These results are explained by the fact that the soils of the farm under study are fertile, well-drained, and the irrigation management is done efficiently, and small retention basins are dug between the rows, avoiding surface runoff. The effect of topography on yield variation was higher when the elevation increased, leading to the conclusion that in other locations, where the field is steeper, the distribution of water in the field is an essential factor in explaining with-in field variability. This study also concluded that there is great variability in the field right after the emergence, but that it quickly disappears, not affecting yield. On the other hand, most of the variability that affects yield arises between the v6 stage and tasseling. After this moment, there is some variability, but it no longer affects the final yield. This variability is to some extent linked to the distribution of water in the field

The INSHORE system (INtegrated System for High Operational REsolution in shore monitoring) is a land-base survey system designed and developed for the specific task of monitoring the evolution in time of sandy shores. This system was developed with two main objectives: (1) to produce highly accurate 3D coordinates of surface points (in the order of 0.02 to 0.03 m); and (2) to be extremely efficient in surveying a beach stretch of several kilometres. Previous tests have demonstrated that INSHORE systems fulfil such objectives. Now, the usefulness of the INSHORE system as a survey tool for the production of Digital Elevation Models (DEMs) of sandy shores is demonstrated. For this purpose, the comparison of DEMs obtained with the INSHORE system and with other relevant survey techniques is presented. This comparison focuses on the final DEM accuracy and also on the survey efficiency and its impact on the costs associated with regular monitoring programmes. The field survey method of the INSHORE system, based on profile networks, has a productivity of about 30 to 40 ha/h, depending on the beach surface characteristics. The final DEM precision, after interpolation of the global positioning system profile network, is approximately 0.08 to 0.12 m (RMS), depending on the profile network's density. Thus, this is a useful method for 3D representation of sandy shore surfaces and can permit, after interpolation, reliable calculations of volume and other physical parameters.

Previous earthquake provided evidence of significant effects of topographic irregularities on seismic site response. It is remarkable that the importance of topographical effects, moreover, has been discussed by a series of analytical and numerical studies. But, very few studies have focused on the effect of topography amplification on the seismic vulnerability of building adjacent to slope. In this study Fragility curves were extended for three steel moment resistant frame (SMRF) adjacent to slope, based on “match up damage index to damage thresholds” method in HAZUS. Modeling of the soil was implemented using a finite-element method in a form of two-dimensional in ABAQUS software. Six models of combination of soil- structure and topography are considered. Likewise, three types of buildings with steel moment frames at different distances from the crest of the slope are considered. The results indicate that considered slope lead to 0 to 35% increase in the damage probability in the SMRF buildings.

Forests in drylands are crucial to maintaining important ecosystem services. However, dryland forests are being degraded by multiple pressures, mainly climate change and land-use intensification, leading to an increase in tree mortality and decreasing natural regeneration. Therefore, is critical to understand the underlying environmental factors that are limiting tree cover and distribution in dryland forests. The aim of this thesis was to unravel the contribution of local-scale factors, mainly microclimatic conditions, to explain forest performance in different stages of tree development: productivity, mortality and natural regeneration in oak woodlands of Mediterranean drylands. Particularly, we aimed to i) compare the relative importance of local-scale factors with broad-scale factors in explaining tree productivity, ii) identify what are the most important local-scale factors explaining tree productivity, mortality and regeneration, and iii) understand how microclimate can influence tree productivity, mortality and regeneration. For that, we used broad- (>500 m) and local-scale (<500 m) factors as main predictors of tree productivity, mortality and natural regeneration with high spatial resolution. Our approach used geographic information, remote sensing, multivariate statistics, and field data. This thesis showed that: i) local-scale factors and their interaction with broad-scale factors explained more tree productivity variance than broad-scale factors alone, ii) the most important local-scale factors that limited tree productivity were related to microclimatic conditions, particularly water availability in the soil and Potential Solar Radiation, iii) tree mortality increases in areas where water availability in the soil derived from topographic indices was lower or when groundwater was more distant from the tree roots, iv) very dry microclimatic conditions are the main limiting factor for tree natural regeneration in the long term (more than 60 years), particularly in the tree establishment phase. These results highlight the importance of including variables with a high spatial resolution to model and map the potential of tree productivity, mortality and regeneration over space and time. Modelling dryland forests' response using local-scale factors improves the precision of reforestation and restoration plans, increasing management efficiency and the long-term sustainability of these forests.

The use of GPS tracking technologies has revolutionized the study of animal movement providing unprecedentedly detailed information. The characterization of GPS accuracy and precision under different conditions is essential to correctly identify the spatial and temporal resolution at which studies can be conducted. Here, we examined the influence of fix acquisition interval and device deployment on the performance of a new GPS/GSM solar powered device. Horizontal and vertical accuracy and precision of locations were obtained under different GPS fix acquisition intervals (1min, 20 min and 60 min) in a stationary test. The test devices were deployed on pre-fledgling white storks (Ciconia ciconia) and we quantified accuracy and precision after deployment while controlling for bias caused by variation in habitat, topography, and animal movement. We also assessed the performance of GPSError, a metric provided by the device, at identifying inaccurate locations (> 10 m). Average horizontal accuracy varied between 3.4 to 6.5 m, and vertical accuracy varied between 4.9 to 9.7 m, in high (1 min) and low frequency (60 min) GPS fix intervals. These values were similar after the deployment on white storks. Over 84% of GPS horizontal positions and 71% of vertical positions had less than 10m error in accuracy. Removing 3% of data with highest GPS-Error eliminated over 99% of inaccurate positions in high GPS frequency intervals, but this metric was not effective in the low frequency intervals. We confirmed the suitability of these devices for studies requiring horizontal and vertical accuracies of 5-10m. For higher accuracy data, intensive GPS fix intervals should be used, but this requires more sophisticated battery management, or larger batteries and devices

Fire provides a fundamental ecological function to many ecosystems. Nevertheless, in the past decades, the occurrence of very large, severe fires, has called for attention from managers, scientists and society in general. Understanding fire drivers constitutes an important step to identify regions of higher risk, establish priorities for protection, and manage the landscape to increase its fire resilience. The main goal of the present work is to explore relationships between fire, vegetation, topography and meteorology at landscape scale. It applies principal component analysis and circular statistics to determine the existence of spatial patterns in fire perimeter orientation, in two mediterranean climate regions, relying on a 31-year fire atlas for Portugal and 100-year fire atlas for California. Additionally it applies quantile regression to evaluate the relationship between fire size and fire selectivity towards different land cover types, in Portugal. The results presented here reinforce the importance of meteorological conditions as the primary driver of fire spread, at landscape scale and in the regions considered.

Polymers have gained a remarkable place in the biomedical fi eld as materials for the fabrication of various devices and for tissue engineering applications. The initial acceptance or rejection of an implantable device is dictated by the crosstalk of the material surface with the bioentities present in the physiological environment. Advances in microfabrication and nanotechnology offer new tools to investigate the complex signaling cascade induced by the components of the extracellular matrix and consequently allow cellular responses to be tailored through the mimicking of some elements of the signaling paths. Patterning methods and selective chemical modifi cation schemes at different length scales can provide biocompatible surfaces that control cellular interactions on the micrometer and sub-micrometer scales on which cells are organized. In this review, the potential of chemically and topographically structured micro- and nanopolymer surfaces are discussed in hopes of a better understanding of cell–biomaterial interactions, including the recent use of biomimetic approaches or stimuli-responsive macromolecules. Additionally, the focus will be on how the knowledge obtained using these surfaces can be incorporated to design biocompatible materials for various biomedical applications, such as tissue engineering, implants, cell-based biosensors, diagnostic systems, and basic cell biology. The review focusses on the research carried out during the last decade.

Titulo em espanhol e portugues: La tierra en America Tropical; A terra na America Tropical v.1. A guide to climate, landscapes and soils for agronomists in Amazonia, the Andean piedmont, Central Brazil and Orinoco; v.2. pt. 1 Legend to the land systems map; pt.2. Individual zones of the land systems map; v.3. Computer summary and soil profile descriptions of the land systems.

ABSTRACT The sloth is known for its slow movements and arboreal habits. Most parts of its anatomy need yet to be unveiled, in order to understand the peculiarities that justify its behavior. In this sense, an investigation of the external characteristics of the heart of the three-toed sloth, Bradypus variegatus, was carried out to indicate the shape, the faces, the dimensions, the topography, and the coating of this organ. For this purpose, fifteen corpses destined for dissection and four healthy specimens were used to carry out thorax digital x-ray. Based on the obtained results, it was noticed that the heart of the species in question presents conical shape, situated obliquely in the mediastinum, is displaced to the left and has latero-lateral slight flattening. Among the animals, discrepancies were found in the organ skeletopy, which presents the tapered apex and the base, in which the large vessels can be observed, whose arrangements also proved to be variables. The heart presents faces (right and left), margins (cranial and caudal) and is surrounded by the pericardium, which gives off two ligaments, sternopericardial and phrenico pericardial. Its size is proportional to the age and length of the individual, with measurements, in general, slightly larger in males.

In the Atlantic Montane Rain Forest of South-eastern Brazil, a study was carried out to describe and evaluate canopy gap colonization. Gap composition by herb species was assessed through their soil coverage and woody species by measuring and identifying all individuals taller than one meter. Gap structure (gap size, number and diameter of treefalls), topographic position and surrounding vegetation were also measured. Two genera of Marantaceae were markedly frequent and abundant inside gaps. The more abundant and frequent woody species were shade tolerant. Species-rich families found inside gaps did not differ from the forest as a whole. Results revealed that direct and indirect influences of topography were important to determine gap composition of woody species. Evidently gap colonization had a considerable influence of topography and pre-established individuals besides variables of gap structure.