Emilio Díaz-Varela

Spatiotemporal analysis of vehicle collisions involving wild boar and roe deer in NW Spain

Ungulate-vehicle collisions pose a serious traffic safety hazard in the North of Spain. The understanding of underlying temporal and spatial structure of these non-random events is imperative to develop appropriate mitigation measures. This study analyses the temporal, spatial and spatiotemporal patterns of car crashes involving wild boar and roe deer in the province of Lugo (NW Spain) in the period 2006-2010 using geographic information systems (GIS) and spatial statistics. The temporal analysis--conducted at three scales: daily, weekly and seasonal--revealed that accidents are related to specific animals life cycles and to interactions with human activities. The localization of collision points with GIS discovered the sections of the autonomic road network where accidents with the two studied species concentrate. Besides, the spatial arrangement of significant hotspots was mapped through kernel density estimation over two time scales (daily and seasonal), distinguishing among 41 sets, sequentially arranged to facilitate clustering comparison and determination of spatiotemporal risky areas. This work is of valuable help for road managers to design the appropriate mitigation measures that will improve traffic safety and animal welfare.

Landscape metrics for characterization of forest landscapes in a sustainable management framework: Potential application and prevention of misuse

Abstract• The use of landscape indices in the analysis of forest landscapes offers great potential for integration of spatial pattern information in management processes, but requires understanding of the limitations and correct interpretation of results. In this sense, awareness of scale effects on landscape indices is essential, especially when the data available is restricted to low-resolution maps.• In this study, developed within the framework of the FORSEE project, the objective was to define accurately the potential usefulness of applying landscape indices to low-resolution maps commonly used in forestry studies. Landscape indices were applied to two maps differing in spatial resolution, and subsets were defined for three spatial extensions. Correlation analysis and comparison of the results were carried out to enable identification of the most suitable indices for use with low resolution data.• The analysis enabled identification of the least scale-dependent indices, which are thus more useful for extrapolating results from low-resolution data. In general terms, diversity and edge indices provided the best results.• We conclude that some (but not all) of the landscape indices can be used to analyse low-resolution maps with acceptable results. Additional advice is made to prevent misuse of the application of landscape indices.Résumé• L’utilisation d’indices de paysage dans l’analyse des paysages forestiers offre un grand potentiel pour l’intégration d’informations de modèles spatiaux dans les processus de gestion, mais exige la compréhension des limitations et une interprétation correcte de résultats. Dans ce sens, la conscience des effets d’échelle sur les indices de paysage est essentielle, particulièrement quand les données disponibles sont limitées aux cartes de basse résolution.• Dans cette étude, développée dans le cadre du projet FORSEE, l’objectif était de définir précisément l’utilité potentielle d’application des indices de paysage aux cartes de basse résolution, généralement utilisées dans les études de sylviculture. Les indices de paysage ont été appliqués à deux cartes différant par la résolution spatiale et les sous-ensembles ont été définis pour trois extensions spatiales. Une analyse de corrélation et la comparaison des résultats ont été effectuées pour permettre l’identification des indices les plus appropriés pour une utilisation avec des données de basse résolution.• L’analyse a permis l’identification des indices les moins dépendants de l’échelle, qui sont ainsi plus utiles pour extrapoler les résultats de données de basse résolution. En termes généraux, la diversité et des indices de bord ont fourni les meilleurs résultats.• Nous concluons que certains (mais pas tous) indices de paysage peuvent être utilisés pour analyser les cartes de basse résolution avec des résultats acceptables. Un conseil supplémentaire est fait pour prévenir une mauvaise utilisation des indices de paysage.

Multiscale delineation of landscape planning units based on spatial variation of land-use patterns in Galicia, NW Spain

The success of landscape planning and environmental management strategies depends largely on the congruence between the operational scales of landscapes and the spatial scope of the planning instruments. In order to achieve good results, landscape planning units should be designed to fit the structural and functional characteristics of the landscape. This paper describes a simple, straightforward methodology for the delineation of landscape units based on the differentiation among areas according to the trend in heterogeneity of their spatial structure. A moving-window analysis was performed with varying window sizes. This analysis enabled modeling of the spatial response of heterogeneity to multiple scales and detection of two different domains of scale. The information obtained was used to delineate a multiscale structure for landscape units. A subsequent study of the composition and configuration of landscape structure in these units verified that they all have distinct characteristics and therefore different planning needs. The areas thus differentiated can be considered as targets of specific and differentiated planning strategies, and can be seen as a preliminary zonation in which the relevant planning methodologies can be developed according to each case.

Relating growth and nutrition to site factors in young chestnut plantations established on agricultural and forest land in northern Spain

The growth and nutritional status of 97 hybrid chestnut plantations on former agricultural land and forest land were studied in relation to site conditions (climatic variables and soil properties). A single family of curves was obtained for classifying the early height growth of hybrid and sweet chestnut. Soil limitations and nutrient deficiencies were evident in the former forest land, whereas the agricultural soils were found to be generally suitable for growing chestnut. The stands with highest growth rates were characterized by high foliar concentrations of K, P and Ca. Successful growth of the plantations was always related to high summer precipitation, low elevation and absence of long periods of risk of frost. The results confirm the adaptability of chestnut to most sites where it has been planted for timber production.

Use of ecosystem information derived from forest thematic maps for spatial analysis of ecosystem services in northwestern Spain

A clear link between ecosystem services (ES) and human well-being has been established in the recent decades. Thus, forests are recognised as extremely important ecosystems in relation to their capacity to provide goods and services to society. Nevertheless, this capacity greatly depends on the type of forest and on the management applied. Some types of data often used for this type of analysis, such as land use/land cover maps produced for general purposes, are not always appropriate for representing forest ecosystems and the services they offer. In this study, we used a forest map (Spanish National Forest Map: scale 1:25,000) and information describing composition and structure to assess six services closely associated with forest ecosystems in a forest-dominated zone of northwestern Spain on a regional scale. The following ES were considered: provision of food (basically fruits), provision of materials (timber and pulp), provision of biomass for energy (firewood), climate regulation (carbon storage by above-ground biomass), erosion regulation (protection against erosion), and cultural (recreational use and nature tourism). By combining information about tree species and cover with forest harvest data and other statistics, we established representative spatial models for the six ES representing different categories of the potential supply of each one. The six models were analysed by different methods (Spearman’s correlation, Moran’s I and Getis-Ord Gi*), enabling detection of hotspots and coldspots and the characteristic spatial scales for ES supply. The combined use of highly detailed map data, nonspatial databases and spatial analysis yielded accurate ES supply assessment.

A methodology for the analysis of the relationships between farms and their physical environment

Agricultural activity involves direct interaction with the physical environment factors in the environmental context in which the activity is developed. Galicia, northwest Spain, is an environmentally heterogeneous region that encompasses territorial spaces with different levels of suitability for each agricultural activity. In barely 30 years, the production systems of the region have evolved from self-sufficiency to commercial production; however, the requirements of production for each differ greatly. During such a transformation, many farms have disappeared while other farms have conformed to the requirements of the current production systems without changing location. Decision-making in rural planning requires knowing the spatial distribution of farms, the evolution of farm distribution and the relationship between the spatial location of farms (associated with some specific environmental characteristics) and the production systems used. The current paper describes a methodology for analysing the spatial distribution of farms and for determining the relationships between the spatial location of farms and the values of the physical environment factors that are characteristic of each spatial location. The methodology has been developed by using Agricultural Census data and is exemplified through the analysis of two crops (wheat and potato) and one farming activity (dairy farming). Results show the location of farms and the production systems used, and reveal different degrees of fit to the physical environment factors considered.

The spatial level of analysis affects the patterns of forest ecosystem services supply and their relationships

The implementation of the Ecosystem Services (ES) framework (including supply and demand) should be based on accurate spatial assessments to make it useful for land planning or environmental management. Despite the inherent dependence of ES assessments on the spatial resolution at which they are conducted, the studies analyzing these effects on ES supply and their relationships are still scarce. To study the influence of the spatial level of analysis on ES patterns and on the relationships among different ES, we selected seven indicators representing ES supply and three variables that describe forest cover and biodiversity for Catalonia (NE Iberian Peninsula). These indicators were estimated at three different scales: local, municipality and county. Our results showed differences in the ES patterns among the levels of analysis. The higher levels (municipality/county) removed part of the local heterogeneity of the patterns observed at the local scale, particularly for ES indicators characterized by a finely grained, scattered distribution. The relationships between ES indicators were generally similar at the three levels. However, some negative relationships (potential trade-offs) that were detected at the local level changed to positive (and significant) relationships at municipality and county. Spatial autocorrelation showed similarities between patterns at local and municipality levels, but differences with county level. We conclude that the use of high-resolution spatial data is preferable whenever available, in particular when identifying hotspots or trade-offs/synergies is of primary interest. When the main objective is describing broad patterns of ES, intermediate levels (e.g., municipality) are also adequate, as they conserve many of the properties of assessments conducted at finer scales, allowing the integration of data sources and, usually, being more directly relevant for policy-making. In conclusion, our results warn against the uncritical use of coarse (aggregated) spatial ES data and indicators in strategies for land use planning and forest conservation.

Preservation of spatial information in rasterization processes: a practical approach using real categorical data and landscape metrics.

Rasterization (i.e., vector-to-raster conversion) is a common process in geographic information systems. As it implies redistribution of map information, it is important to know how much data are lost when a particular resolution is chosen, in order to use data successfully. This study explores the potential of landscape metrics to reflect sensitivity to rasterization processes. A vectorial land use map was rasterized to an array of cell sizes. Deviation from original data was estimated, and landscape metrics were calculated for each land cover class. Results allowed grouping of classes—with respect to how information was preserved—depending on their landscape characteristics.