This paper presents a microeconomic model of residential location that explores the emergence of a mixed belt where residents and farmers coexist beyond a city. The model is based on integrating ...urban economics with cellular automata in order to simulate equilibrium patterns in 2D and through time. Households commute to a CBD and enjoy neighbourhood externalities that are a function of both local residential density and farmland, or open space. They bid on the competitive land market and locate so as to maximize utility. Incremental population growth changes the neighbourhood and leads to rent adaptations. With appropriate parameter values a mixed belt may emerge between the urban and agricultural specialized areas. Settlements within this mixed area are more or less clustered or scattered depending on preferences and neighbourhood size.
We present a study on the impact of soil and climatic variability on the yield of winter wheat in the Hérault-Libron-Orb Valley in southern France. The study was based on the use of a crop simulation ...model (Euro-ACCESS), run at 63 individual sites throughout the study area, for the current climate (1976 to 1984) and for potential future changes in temperature and precipitation (2047 to 2054). Three climate scenarios were selected to represent low, mid and high changes, although significant winter wheat yield decreases were only observed for the climate scenario with the largest change. In general, the influence of climate change on yields was small (less than 0.1 t ha–¹ over the whole simulation period), but strong inter-annual variation was found, which is typical of the Mediterranean climate. Soil variability within the study region was the most important source of spatial variability for the simulated yields, and the soil available water capacity was identified as a good indicator of yield change for large climatic change. Soil variability was important in this study because of the small size of the study region and because of the strong influence of water limitation on crop growth in Mediterranean areas. Statistical relationships were established between crop yields, yield changes and the soil available water capacity. These relationships were used to extrapolate the crop simulation results from individual sites to the whole region using data from soil maps at a scale of 1:250 000. This modelling exercise demonstrated the importance of explicit consideration of soil as well as climatic variability in crop-climate impact studies.
In this paper we present a method to analyse data from observed population statistics in order to create a stylised location typology based on household profiles (microgeographic level). The ...household profiles are used to inform the development of rules for an agent-based model of residential population mobility. The method is demonstrated with the 2001 Population Census data for East Anglia, UK. Household profiles are derived from a principal components analysis to reduce dimensionality in the census data combined with a cluster analysis to aggregate the observations. We test whether a range of household archetypes that link specific locations to specific profiles can be identified simultaneously at both mesogeographic and macrogeographic levels. Results reaffirm conventional archetypes: single people concentrate in city centres, families mainly locate in the suburbs and periurban areas, and retirees are more prevalent in the suburbs and close to the coast. Surprisingly, however, there is a clear distinction between locations with cohabiting couples (located at the fringe of the periurban areas) and locations with married couples (located in the countryside). The observed spatial distributions reveal different location choices between different household profiles. Identification of these household profiles supports the development of residential mobility models that may be used to explore regional and local planning issues with respect to future population projections and environmental change.
There is increasing evidence that areas with high concentrations of species tend to have high concentrations of human activities. Would this tendency be altered with projected environmental changes? ...We investigate this possibility using the most extensive available dataset on species distributions in Europe, providing data for 3143 species. Observed land uses were utilised to generate three indicators of anthropogenic ‘pressure’ for 1971–2000: urbanisation, cropland and grassland use intensities. Storylines describing alternative development pathways were used to create four land-use scenarios for 2021–2050. Exposure of biodiversity to human activities was measured as changes in the degree of pressure recorded in hypothetical reserve networks selected to maximize the representation of plant, breeding bird, mammal, amphibian, and reptile species. In all socio-economic scenarios there was a tendency for increasing urbanisation and decreasing cropland intensities within selected conservation areas. Pressures arising from increasing grassland use were variable across scenarios and taxa. Our results challenge the idea that a single development strategy might provide reduced impacts in all regions and taxonomic groups. We show that impacts are likely to be complex and that tradeoffs might exist among development strategies. Nevertheless, results are contingent on the data, scale, and type of analyses conducted and further research is required to assess the impacts of alternative human-development scenarios.
A simple global food system model JIANG, Li; CUI, Xuefeng; XU, Xia ...
Agricultural economics (Praha),
01/2014, Letnik:
60, Številka:
4
Journal Article
Recenzirano
Odprti dostop
In this study, we develop a simple dimension model to construct the food system in response to the population growth, the land use change and various socio-economic developments. The model simulates ...the consumption and production of agricultural goods in the individual countries, and maintains the global balance of food through the international trade flows between countries. Although there are some biases in the model results at the country levels, we suggest that such a simple model is feasible for simulating the global food supply system and assessing the uncertainties coming from various environmental and socio-economic factors.
The effects of climate change on crop suitability in England and Wales were estimatedby systematically adjusting agroclimatic data inputs to a land evaluation model. Mean temperature risesof 1 and ...2°C increased drought risk and reduced the length of time whe soil was at field capacity over-winter by raising potential evapotranspiration. In eastern England, this change had a detrimental effect on the potential for cultivating winter wheat because of drought stress. In northern and western England and Wales, drier conditions promoted greater opportunities for soil tillage, especially when temperature rises wereassociated with decreased precipitation. The effect of increased temperature was offset by increased precipitation. The magnitude of the drought stress and length of field capacity periods are similar to current mean conditions when a + 1 °C temperature change is coupled with a 10% increase in precipitation. This demonstrates that winter wheat suitability in England and Wales is affected more by changes in precipitation than by changes in temperature. The local limitations of soils and relief notwithstanding, it appears that the northern and western areas of England and Wales are most likely to gain from a warmer, drier climate.
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