Under lång tid har mayafolkets landskap, av arkeologer, ansetts vara homogent. Detta har bidragit till tolkningen att det förhållande som mayabefolkningen hade till sin urbana levnadsmiljö respektive omgivande topografi, likväl som förhållande till det kulturella livet har sett likadant ut oberoende av region. I realiteten är det naturliga landskapet i Mesoamerika heterogent, vilket då även resulterar i urbana och kulturella skillnader mellan regionerna. I denna uppsats kommer undersökas och diskuteras de skillnader som finns mellan de olika mayakulturerna och hur detta kan ha påverkat jordbruket inom regionerna. Dessutom kommer regionerna jämföras med avseende på potentiella skillnader i kultur likväl som rumsliga skillnader i topografi och det urbana landskapet. Den klassiska tidsepoken (250-950 e.Kr.) kommer vara i fokus, men som referenspunkter och med grund i att olika städer uppstod vid olika epoker kommer även andra tidsperioder att behandlas i uppsatsen. Denna uppsats är baserad på litteratur studier och är en kvalitativ undersökning.

In this work we studing a generalized predator-prey system in a spatial domain, in terms of formation. We show parameter, regions where transcritical, Hopf and Turing bifurcations appear are presented, and also some spatial patterns that arise for specific parameters in the Turing region are also shown. / Neste trabalho estudamos um sistema presa-predador generalizado, num domínio espacial, sob o aspecto de formação de bifurcações. Regiões de parâmetros onde bifurcações transcrítica, de Hopf e de Turing aparecem são apresentadas, assim como alguns padrões espaciais que surgem para parâmetros específicos na região de Turing também são mostrados.

In high-motorisation, car-dependent countries, transport affordability is intimately linked to the price of oil derived motor fuels, which may become increasingly volatile in the future due to global oil price movements and environmental taxation. The negative impacts of fuel price spikes in terms of increased household expenditure and economic stress are unevenly spatially and socially distributed. Previous research has found that vulnerability to fuel price increases is higher in peripheral, peri-urban and rural areas, and that low income tends to be co-located with high car dependence and low vehicle fuel efficiency, with a compounding effect on vulnerability. The goal of this article is to test these hypotheses for England, providing new evidence on spatial patterns of vulnerability to fuel price increases at the small-area level. We propose a composite vulnerability indicator combining data on income, accessibility, vehicle inspection and vehicle registration for 2011. Within English city-regions, we find little evidence of the socially regressive patterns previously identified in the literature. This is explained by the persistent concentration of poverty in urban cores, as well as by the poor fuel economy of the vehicle fleet in wealthier areas, due to the prevalence of powerful vehicles there. On the other hand, our analysis suggests that the impacts of fuel price increases would be very unequal between city-regions, as the least sensitive metropolitan area (Greater London) is also characterised by high levels of adaptive capacity. We conclude by setting out an agenda for future research on spatial vulnerability to fuel price increases.

Elucidating the ecological determinants of community structure and how they vary spatially has a long history in ecology, but there still is no consensus on the mechanisms behind diversity patterns. The primary objective of this dissertation was to focus on spider assemblages to investigate how the fine-scale habitat associations of organisms may drive their community composition at larger scales. Research was conducted in the Bear River Mountains, Utah, in an attempt to elucidate the potential role of species-microhabitat associations in driving three well-known patterns of community composition that have typically been investigated at broad scales: 1) elevation gradients of species diversity, 2) the response of species assemblages to neighboring habitat structure and 3) community composition at the edges of habitat patches. Slope aspect was a significant predictor of spider density and species richness when communities were compared at the same elevation, suggesting that fine-scale topographic variables may play an important role in shaping elevational patterns of species composition. Cursorial spider composition was strongly linked to site temperature only, whereas differences across web spider assemblages significantly increased with dissimilarities in woody plant cover and temperature. The study on the effects of neighboring habitat structure revealed markedly reduced cursorial spider densities in shrubs without surrounding structure, and more cursorial species in control shrubs, whereas web spiders lacked any significant response to treatments. These contrasting responses indicate that data should be collected at larger spatial extents for mobile species, and that mobility may mediate the outcome of surrounding habitat modifications on the local composition of communities. In the last study, I focused on communities in which the edge-dwelling spiders Theridion and Dictyna strongly differed in terms of concealment and substrate generalization and found that microhabitat choice may affect the sensitivity of species to habitat geometry, a characteristic associated with habitat fragmentation. This work suggests that a better understanding of the links between the biological traits of species and their fine-scale environmental requirements may help uncover the mechanisms behind spatial patterns of community composition at larger scales.

The Unified Neutral Theory of Biodiversity has been advanced as a universal theory for species coexistence in forests worldwide, but few studies have examined its relevance to high-elevation, stressful environments. I established the Utah Forest Dynamics Plot (UFDP) in a heterogeneous subalpine forest at 3,091 m elevation on the Colorado Plateau to examine three underlying assumptions of neutral theory (functional equivalence, ecological equivalence, and habitat generality) and one prediction (the species abundance distribution). The UFDP comprises 27,845 stems ≥1 cm diameter at breast height of 17 species, 10 genera, and 6 families over 13.6 ha. The neutral model was a poor fit to the observed species abundance distribution, but I did not find the alternative lognormal model to provide a better fit. Using spatial pattern analyses of tree data, topography, and soil type, I found some limited support for the neutral theory assumptions of functional and ecological equivalency, with notable exceptions. Populus tremuloides, Pinus flexilis, and Pinus longaeva were characterized by non-neutral recruitment processes, and Abies bifolia and Populus tremuloides exhibited asymmetric competitive and facilitative interactions. The assumption of habitat generality was strongly contradicted, with all ten abundant species in the UFDP having habitat preference. In this subalpine temperate forest, species diversity and community structure are influenced more by habitat heterogeneity, species differences, and niche selection, with neutral processes playing a lesser role.

Discovered in 2000, the Gray Fossil Site provides a snapshot of the flora and fauna that lived during late Miocene to early Pliocene time in eastern Tennessee. These fossils occur in sediments consisting of fine-grained clays and sands of lacustrine origin, which were deposited after multiple sinkholes formed in the underlying Knox Group basement carbonates. Three-dimensional nearest neighbor analysis has been applied to fossils of Tapirus polkensis, characterizing the spatial patterns exhibited. These analyses determined the importance of taphonomic and depositional processes that occurred during the sites formation. Six characteristics were analyzed, four at the bone level including carnivore utilization, weathering, abrasion, and arthritis, and two at the specimen level, articulation and age class. Weathering, arthritis, and articulation, show clustered patterns indicating that the site had active predators, it consisted of many microenvironments, and deposition occurred in a passive setting. Although the current state of excavation makes any spatial analyses and taphonomic interpretations difficult, spatial analysis in both dimensions can be accomplished.

Modern forestry research and management emphasize infusing management practices with an understanding of natural disturbance regimes -- often called ecological forestry. Forestry practices emulating aspects of natural disturbance regimes are considered an effective tool to balance silvicultural and ecological objectives. Size, shape, and spatial distribution of canopy gaps formed by Hurricane Michael were studied across multiple site factors in a longleaf pine (Pinus palustris Mill.) woodland in southwest Georgia. No significant differences were observed in gap size or shape among landscape factors, but spatial distribution of gaps differed among landscape factors. The results observed highlight the ecological importance of the event and provide some insight into interactions at the landscape level. The implementation of a large, rapid, single disturbance event as a model for ecological silviculture may be more practically applied than disturbances such as lightning or insects which occur over longer timeframes.

No description available.

Scholars have frequently considered the analysis of sustainable design and performance of the built fabric over the past two decades with regard to diversity, density and accessibility. They fall short of developing a holistic, systematic and objective assessment system for the analysis of the sustainable urban form. Subsequently, there is still a noticeable gap regarding the relationship between these dimensions and the patterns and the layout of built environments in the Middle East in general and in Iraq in particular. Intense and rapid economic development and urbanisation in Northern Iraq has resulted in expansive urban of built environments to accommodate the ever increasing urban population and level of activity in the city of Erbil. Architectural, planning and urban design trends at the intra-urban and neighbourhood levels indicate a state of disharmony and random physical forms that lack frameworks for understanding sustainable urban form in relation to urban patterns and layout. In this context, Accessibility, Connectivity, Compatibility, Diversity, Nodality, Density, Urban Identity, and Adaptability have been considered as analysis criteria to evaluate the sustainability of spatial patterns of urban form. The thesis aims to explore and examine the relationship between urban patterns and sustainable urban form in Erbil city in the context of sustainability through developing a customised but context-based framework for sustainable urban fabric indicators. To accomplish this, five case studies of residential projects with variable states of occupancy, completion, and social profiling have been chosen to investigate the practice of the sustainable urban form indicators. The research adopted a mixed-methodological approach, which combines quantitative and qualitative surveys of users, planners, and decision makers to enhance an understanding of the local perception of urban sustainability. A random sampling process is applied for the quantitative survey when distributing the questionnaires. The successful sample size, which was analysed, was 252 respondents. Using comparative analysis of sustainable urban form indicators in the recent local residential projects, quantitative findings have noticeably indicated significant variation in the effectiveness of indicators' performance, and consequently support the research assumption with statistical evidence that urban patterns have a significant impact on achieving sustainable urban forms in developing countries. The study concludes that the urban pattern indicator framework offers an efficient and rigorous approach that enables a credible assessment of the design strategies and planning decision-making in residential developments to achieve sustainable urban forms. These findings have evident implications for urban planners and policy makers during the design stage. The study has proposed practical planning and design guidelines which aim to enhance the local built environment.

Os reservatórios urbanos estão suscetíveis a uma variedade de interferências antropogênicas que acarretam grande variabilidade espacial e temporal. Contudo, possuem uma dinâmica própria na qual o hidroclima e micro e macro-eventos meteorológicos atuam sobre os processos físicos, químicos e biológicos resultando em respostas particulares de cada corpo de água. No presente estudo a existência de padrões espaciais e temporais na formação de florescimentos de algas, cianobactérias e macrófitas no reservatório Guarapiranga, São Paulo, SP, foi avaliada por meio de experimento de curta escala de tempo durante o evento da entrada de uma frente fria. Foram amostrados 64 pontos em todo o reservatório, e o estudo intensivo de florescimento algal e de cianobactérias em dois ciclos nictemerais, em um ponto selecionado no reservatório. Um modelo tridimensional de hidrodinâmica foi aplicado ao estudo compartimentalizado dos tempos de residência e imagens de satélite foram analisadas para determinação de padrões temporais e espaciais durante períodos de tempo mais amplos. Os resultados revelaram que os períodos mais favoráveis ao surgimento de florescimentos de cianobactérias são geralmente os meses mais quentes, de dezembro e janeiro, ou aqueles em que ocorrem estratificações mais fortes como no fim do inverno, em julho, e após as primeiras chuvas nos meses de setembro e outubro. Existem padrões espaciais recorrentes na formação dos florescimentos, controlados em grande parte pela ação do vento, que no reservatório Guarapiranga é predominantemente nas direções leste e sudeste empurrando os florescimentos na direção da foz dos tributários Embu Mirim e Embu Guaçu e ocasionalmente na direção da foz do rio Parelheiros. As simulações hidrodinâmicas evidenciam as forçantes que determinam os padrões observados e reforçam a importância de se discretizarem os tempos de residência de diferentes compartimentos do reservatório. As séries temporais amplas permitiram a determinação da qualidade da água em cada região e fornecem subsídios para o futuro manejo do reservatório. Como esse comportamento não se restringe ao reservatório Guarapiranga, o tipo de modelagem aqui utilizada pode ser útil para obter informações importantes no processo de planejamento e seleção de medidas para o gerenciamento de reservatórios urbanos tropicais polimíticos, em geral. / Urban reservoirs are susceptible to a variety of anthropogenic interferences, that leads to large spatial and temporal variability, however they have themselves a proper dynamics in which the hydroclimate and micro and macro meteorological events act upon physical, chemical and biological processes, resulting in a singular signature for each water body. In the present study the existence of spatial and temporal patterns for the formation of algal, cyanobacterial and macrophyte blooms in Guarapiranga Reservoir, São Paulo, SP, was evaluated by means of a short-time scale experiment during the event of a cold front passage. Sampling was carried out in 64 points in the whole reservoir and the intensive study of an algal and cyanobacterial during two nictemeral cycles, at a selected point in the reservoir. A tri-dimensional hydrodynamics model was applied to the study of discrete residence time of the main reservoir tributaries. Satellite images and long term data sets were analyzed aiming to determine spatial and temporal patterns at long time scale. The results obtained have shown that the most favorable periods for algal and cyanobacterial blooms are usually the hottest months, December and January, or those with stronger thermal stratification at the end of the winter in July and after the first rains in September and October months. There are recurrent spatial patterns in the formation of blooms, largely controlled by wind action, that in Guarapiranga Reservoir are predominantly from East and Southeast directions frequently pushing the blooms towards Embu Mirim and Embu Guaçu tributaries and occasionally towards Parelheiros River mouth. Hydrodynamic simulations evidenced the forcing functions that control the observed patterns and reinforced the importance of residence time discretization according to each main reservoir compartment. The temporal data series allowed to assess each compartment water quality and provided information for future reservoir management. Considering that the patterns found are not restricted to Guarapiranga Reservoir, the type of model here used could be useful to get relevant information to be used in the planning or selection of management actions for tropical polymictic urban reservoirs in general.