Diachronic Mapping Research Articles

In-between sprawl and fires: long-term forest expansion and settlement dynamics at the wildland–urban interface in Rome, Italy

Understanding the intimate dynamics of urban–wildland interfaces in Mediterranean landscapes is particularly challenging because of multiple biophysical factors (dry or arid climate, low-quality soils, poor vegetation cover) determining an increased environmental sensitivity to human pressure. Although dense and compact cities were sprawling rapidly in the most recent decades, many suburban areas in southern Europe still preserve biodiversity-rich habitats, traditional crop mosaics and high-quality relict forest stands. Diachronic forest and settlement maps were analysed over two time intervals (1936–1974 and 1974–2006) representing different socio-economic contexts on a local scale with the aim to assess trends in forest land cover vis à vis urban growth in Rome, central Italy. Forests expanded into agricultural land during the whole time period following cropland abandonment and benefiting from a higher level of land protection from urbanisation, especially during the most recent decades. Although the broadleaved wood dominated the composition of forest fragments at the wildland–urban interface at both the beginning and the end of the study period, coniferous stands showed a slower decrease compared to other wood types, such as those dominated by chestnut or beech. The observed changes in forest composition are the result of a higher disturbance level, possibly triggered by the increase of fire frequency and severity, a higher fragmentation of natural land, intense soil sealing and a larger occurrence of invasive species. Forest diversity increased especially in areas with medium-density settlements, indicating a tendency towards more heterogeneous forest structures at the urban–wildland interface compared to natural landscapes. A long-term monitoring of settlement dynamics and woodland expansion is required to inform a sustainable management of Mediterranean suburban forests.

Analysing Space-Time Accessibility Towards the Implementation of the Light Rail System: The Case Study of Brescia

This paper proposes a methodology for investigation of the space–time relations of accessibility to public services and collective mobility. The paper assesses the space–time efficiency of local public transport facilities and makes an accessibility analysis as a baseline for evaluating future changes. It explains the potential for improvement and the effects on planning paradigms. Public transport accessibility greatly changes during day and night time so they should be assessed through multi-scaled and diachronic maps as a contribution to the timetable plan and overall planning strategies. The case study of Brescia, Italy is used to test the methodology. The new light rail system of Brescia entered into operation in 2013 and could change the entire form of urban mobility.

Forest transition and urban growth: exploring latent dynamics (1936–2006) in Rome, Italy, using a geographically weighted regression and implications for coastal forest conservation

Peri-urban Mediterranean landscapes preserve high-quality environments with biodiversity strictly dependent on relict forests and mixed agroforest systems. The assessment of long-term land-use changes at the urban-wildland interface is particularly interesting for policies coping with natural land conservation and man- agement. The dynamics of Mediterranean fringe forests were rather mixed over the last century alternating decline due to deforestation and clear-cutting up to World War II and a recovery afterwards. Forest transition theory (FTT) has been used to describe a turnaround in land-use trends for a given territory from a period of net forest area loss to a period of net forest area gain. The present paper analyses forest expansion in Rome's province in the light of the FTT using diachronic maps, which cover two time intervals (1936-1974 and 1974-2006) corresponding to distinct socioeconomic contexts at the local scale. Our results indicate a slight increase in forest areas along the whole study period owing to natural reforestation following the abandonment of agricultural land and the higher level of forest protection. Geographically weighted regression indicates the growing importance of the urban gradient in forest dynamics. This may reflect settlement dispersion and higher disturbance to forests due to soil sealing, wildland fires, habitat fragmentation, cropland abandonment, and invasive species increase. The tendency towards a more mixed and heterogeneous woodland structure at the urban- wildland interface, especially in coastal areas, should be contrasted through sustainable land management practices integrating urban planning and environmental policies into a unique strategy for the protection of relict agroforest systems.

Topographic and road control of mega-gullies in Kinshasa (DR Congo)

Diachronic mapping (1957, 1967, 2007 and 2010) shows an exponentially growing mega-gully network since roads were constructed through in the forests and plantations which occupied the sandy soils of the high town of Kinshasa. We found that the spatial occurrence of the mega-gullies (width≥5m) in this newly urbanized environment is controlled by two factors. First, there is a topographic control, given by the relation S=0.00008A−1.459, with S being the slope gradient (mm−1) of the soil surface at the gully head and A the drainage area (ha) above the head. There is also a ‘road’ control, expressed by S=22.991Lc−1.999, with Lc being the cumulated length of roads in the basin above the gully head. The co-existence of both controls reflects the fact that the local sands are highly permeable and hence roads are more important generators of continuous runoff. The S–A relation noted above should not be applied outside the town where the road network is less dense. In contrast, the S–Lc relation may be used in both the town and rural areas underlain by porous soils where roads are the only generators of continuous runoff. We further conclude that the high town of Kinshasa is one of the most vulnerable places for gullying, and gullying can potentially transform the town into a badland. ‘Artisanal’ gully treatment is more successful than generally believed and the S–Lc relation can be a tool for mega-gully prevention.

Inside and outside the city: an outline of the geography of visual artists in Brussels (19th‑21st centuries)

Based on detailed diachronic mapping, this article analyses artists’ areas of residence in Brussels from 1830 until today. Powerful spatial logic has taken shape over time, marking the appearance, decline and permanence of poles with a concentration of artists, which must be understood in the context of urban dynamics which have shaped the urban fabric. Three periods may be identified, corresponding to the development (or redevelopment) of specific areas in the city: the second half of the 19th century, associated with the urbanisation of artists’ suburbs in the northeast; the interwar period, characterised by concentrations on the outskirts; and the end of the 20th century, when the former southeast pole became popular once again, at the same time that new concentrations appeared in connection with the renovation of central areas. The mapping work and the results obtained provide an original view of the structuring of the artistic world in Brussels, while revealing the importance of a historical approach in the analysis of contemporary urban dynamics with artists in the spotlight.

Chronologies of a (sub)urbanized territory: Reimagining (sub)urbanization processes in southwest Flanders, Belgium

Chronologies of a (Sub)urbanized Territory explores how the depth and scope of an atlas can be increased through a careful engineering of the interplay between its constituent maps. This research aims to develop a structure for an atlas that can include the plural and often very diverse historical processes affecting the territory without jeopardizing the coherence of the atlas as a whole. Chronologies of a (Sub)urbanized Territory explores the perpetual reproduction of the heavily (sub)urbanized territory in southwest Flanders. The atlas is comprised of three diachronic map series: Frames, A Classic Chronology and Interrelations. Each series pictures the passage of time in a specific way and therefore offers a distinct ‘take' on the history of the region. Perpendicular to these three diachronic map series, synchronic readings of the territory can be composed: the variation between the three series in terms of scale, and in the categories that are displayed, enable the reader to gain a multi-angled perspective on specific spatial phenomena at delimited periods of time. The different components of the atlas, and how they interrelate, are clarified by a metamap. The metamap is not merely a top-down organizational tool, but is intended to form the basis from which the reader can start to construct his or her own interpretations of the territory. ‘Phenomena intersect, to see but one is to see nothing.’ Victor Hugo (as cited in Jarvis 1997 )

Diachronic Mapping of LUCC in the Northwest of China over the last half Century: Conversion of CORONA Panchromatic reflectance into LANDSAT NDVI Imagery

It is only by using the first collection of intelligence satellite imagery acquired by CORONA, that time seriesof NDVI imagery can go back for a time period of nearly 50 years,basedon diachronic mapping . This is an exceptionally long time period if not the longest, for which remote sensing imagery is available to estimate land use change for specificregions on the globe. The P.R. ofChina and the formerUSSR can be documented to nearly 50 years back in time, using CORONA satellite imagery. Typically-for many regions of the globeisthat a 50 year time span represents the principal time period in which many anthropogenicland usechanges have taken place. In thispaper,an account is given of the land use change which took place over the last 44 years in the

Comparison of methods for LUCC monitoring over 50 years from aerial photographs and satellite images in a Sahelian catchment

Land use/cover change (LUCC) is a major indicator of the impact of climate change and human activity, particularly in the Sahel, where the land cover has changed greatly over the past 50 years. Aerial and satellite sensors have been taking images of the Earth's surface for several decades. These data have been widely used to monitor LUCC, but many questions remain concerning what type of pre-processing should be carried out on image resolutions and which methods are most appropriate for successfully mapping patterns and dynamics in both croplands and natural vegetation. This study considers these methodological questions. It uses multi-source imagery from 1952 to 2003 (aerial photographs, Corona, Landsat Multispectral Scanner (MSS), Landsat Thematic Mapper (TM) and Satellite Pour l'Observation de la Terre (SPOT) 5 images) and pursues two objectives: (i) to implement and compare a number of processing chains on the basis of multi-sensor data, in order (ii) to accurately track and quantify LUCC in a 100 km2 Sahelian catchment over 50 years. The heterogeneity of the spatial and spectral resolution of the images led us to compare post-classification methods aimed at producing coherent diachronic maps based on a common land-cover nomenclature. Three main approaches were tested: pixel-based classification, vector grid-based on-screen interpretation and object-oriented classification. Within the automated approaches, we also examined the influence of spectral synthesis and spatial homogenization of the data through the use of composite bands (principal component analysis (PCA) and indices) and by resampling images at a common resolution. Classification accuracy was estimated by computing confusion matrices, by analysing overall change in the relative areas of land use/cover types and by studying the geographical coherence of the changes. These analyses indicate that on-screen interpretation is the most suitable approach for providing coherent, valid results from the multi-source images available over the study period. However, satisfactory classifications are obtained with the pixel-based and object-oriented approaches. The results also show significant sensitivity, depending on the method considered, to the combinations of bands used and to resampling. Lastly, the 50-year trends in LUCC point out a large increase in croplands and erosional surfaces with sparse vegetation and a drastic reduction in woody covers.

Late Pleistocene colonization of North America from Northeast Asia: New insights from large-scale paleogeographic reconstructions

Advances in large-scale paleogeographic reconstruction define physical and environmental constraints relevant to understanding the timing and character of the first colonization of the Americas during the Late Pleistocene. Diachronic mapping shows continental glaciers coalesced in central Canada during the Last Glacial Maximum (LGM) 20,000–14,000 years ago while unglaciated refugia existed along the Northwest Coast. The Bering Land Bridge connected Asia and North America until about 10,000 years ago when the two continents were separated by rising sea level. This visual analysis from large-scale synthesis of recent geological and environmental research establishes timelines for biotically viable colonization corridors connecting eastern Beringia to southern North America and provides insights into probable Paleoindian origins and subsistence strategies.

Space–time distribution of ancient and active alluvial karst subsidence: examples from the central Ebro Basin, Spain

Space and time variations of alluvial karst subsidence in the central Ebro Basin are analysed in trenches (paleodolines), aerial photographs (historical dolines) and field surveys (present-day active dolines). The measured subsidence rates, as well as a comparison between densities of paleodolines computed in randomly selected scan-lines and density of active dolines computed in maps, suggest that present-day subsidence in favourable areas is more intense than that of Pleistocene times. According to diachronic maps drawn from (a) different aerial photographs taken after 1946 and (b) field surveys on deformations in urbanized areas, subsidence behaved as a nearly steady process while the whole area was used for agriculture. In contrast, rapid changes (through periods of several tens of years) have occurred in urbanized areas, in which dolines expand their boundaries through small marginal collapses, shifting sharply their sinking centres to neighbouring sites. These rapid changes do not have an equivalent in observed paleodolines.

First occurrence of the house mouse (Mus musculus domesticus Schwarz & Schwarz, 1943) in the Western Mediterranean: a zooarchaeological revision of subfossil occurrences

This paper provides a critical analysis of archaeological small mammal collections in the Mediterranean area, from the Late Glacial to the first centuries AD, to validate the presence/absence of the house mouse through zooarchaeological criteria. The results have been synthesized through a diachronic map, whose chronological phases are related to socio-economic and cultural human evolution. The house mouse (Mus musculus domesticus) progression in the Mediterranean begins with a quick but limited diffusion in the Eastern Mediterranean Basin achieved around the 8th millennium BC. Until the 1st millennium BC, the invasive process seems to have stopped or drastically slowed, despite the increasing opportunities of passive transport during the Bronze Age. During the 1st millennium BC, there was mass colonization by the house mouse of the entire Western Mediterranean Basin and Northern Europe. We propose to explain this chronological gap in the colonization of the Eastern and Western Mediterranean using source-sink theory considering that the western environments acted like sinks until the first millennium BC. At that time the Western Mediterranean was fully opened to Eastern influences and migrations, and the human pressures on the environment drastically increased. This may have favoured definitively the adaptation of the house mouse to the Western commensal niches.

Un engraissement côtier résultant de l’érosion des bassins-versants cultivés : exemple de la baie du Galion à la Martinique

Coastal accretion as a result of erosion of farmed watersheds: example of the Galion Bay. The progradation of the shores of the Galion Bay (Martinique) has been measured based on diachronic mapping analysis. The sedimentary volume which accumulates along the coast and in the bay (under the water surface) is unknown. Erodibility has been surveyed on a square meter scale and extrapolated to the watersheds. The results show that most sediments originate from the farmed surfaces, they are then entrained by the runoff and the Galion river and deposited along the coast, where the bathymetry and currentology of the bay facilitate sediment retention. The harmful effects of anthropogenic influence in the area are discussed. © 2000 Ifremer / CNRS / IRD / Éditions scientifiques et médicales Elsevier SAS Martinique / soil erodibility / accretion of the coastline / coast / environment

Érosion des bassins-versants et engraissement côtier : le cas de la baie du Galion (Martinique)

Abstract Measurement of the progradation of the shores of the Galion Bay (Martinique) was based on diachronic mapping analysis. Erodibility was surveyed on a square metre scale and extrapolated to the watersheds. The sedimentary volume, which accumulates along the coast and in the bay (under the water surface), is unknown. The results show that most sediments are released by the farmed surfaces, then drained by the runoff and the Galion river, and deposited along the coast, where the bathymetry and currentology of the bay facilitate retention of the sediment. The harmful effects of anthropogenic influence in the area are discussed.