Analyzing the commercial activities of a street network by ranking their nodes: a case study in Murcia, Spain

Urban researchers and planners are often interested in understanding how economic activities are distributed in urban regions, what forces influence their special pattern and how urban structure and functions are mutually dependent. In this paper, we want to show how an algorithm for ranking the nodes in a network can be used to understand and visualize certain commercial activities of a city. The first part of the method consists of collecting real information about different types of commercial activities at each location in the urban network of the city of Murcia, Spain. Four clearly differentiated commercial activities are studied, such as restaurants and bars, shops, banks and supermarkets or department stores, but obviously we can study other. The information collected is then quantified by means of a data matrix, which is used as the basis for the implementation of a PageRank algorithm which produces a ranking of all the nodes in the network, according to their significance within it. Finally, we visualize the resulting classification using a colour scale that helps us to represent the business network.

Community attributes determine facilitation potential in a semi-arid steppe

Studies on positive plant–plant relations have traditionally focused on pair-wise interactions. Conversely, the interaction with other co-occurring species has scarcely been addressed, despite the fact that the entire community may affect plant performance. We used woody vegetation patches as models to evaluate community facilitation in semi-arid steppes. We characterized biotic and physical attributes of 53 woody patches (patch size, litter accumulation, canopy density, vegetation cover, species number and identity, and phylogenetic distance), and soil fertility (organic C and total N), and evaluated their relative importance for the performance of seedlings of Pistacia lentiscus, a keystone woody species in western Mediterranean steppes. Seedlings were planted underneath the patches, and on their northern and southern edges. Woody patches positively affected seedling survival but not seedling growth. Soil fertility was higher underneath the patches than elsewhere. Physical and biotic attributes of woody patches affected seedling survival, but these effects depended on microsite conditions. The composition of the community of small shrubs and perennial grasses growing underneath the patches controlled seedling performance. An increase in Stipa tenacissima and a decrease in Brachypodium retusum increased the probability of survival. The cover of these species and other small shrubs, litter depth and community phylogenetic distance, were also related to seedling survival. Seedlings planted on the northern edge of the patches were mostly affected by attributes of the biotic community. These traits were of lesser importance in seedlings planted underneath and in the southern edge of patches, suggesting that constraints to seedling establishment differed within the patches. Our study highlights the importance of taking into consideration community attributes over pair-wise interactions when evaluating the outcome of ecological interactions in multi-specific communities, as they have profound implications in the composition, function and management of semi-arid steppes.

Playas y paseos marítimos. El nuevo paisaje urbano de Benidorm (1956-1986)

Esta comunicación recorre la evolución del paisaje urbano de Benidorm, como ciudad vertical (acotado entre dos fechas clave: 1956 y 1986), con la aprobación de su PGOU, inspirado en un urbanismo funcionalista (CIAM), enfocado a un turismo de masas en aumento año tras año. Acontecimientos, turismo y planeamiento justificaban las diferentes ampliaciones urbanas de Benidorm, sometidas a constantes modificaciones y que se reflejaba en una libertad a través del análisis y relación entre el nuevo skyline vertical (de bloques y rascacielos de uso privado) y el tándem paseo marítimo-playa (de espacios urbanos de uso público). Para este seguimiento se hace necesario conocer cómo se construye la propia ciudad y, en particular, sus nuevos frentes marítimos que constituyen la postal más importante de cualquier ciudad turística litoral –su imagen–, la que se publicita como reclamo: la fachada que se extiende tras sus playas y cuyo éxito depende de la capacidad de articulación los espacios públicos que entrelazan la trama urbana con su frontera marítima.

The genus Callistethus (Coleoptera: Scarabaeidae: Rutelinae) in the Neotropics: new data and new species from Costa Rica

The species Callistethus carbo sp.n., C. flavodorsalis sp.n., C. fuscorubens sp.n., C. lativittis sp.n., C. levigatus sp.n., C. macroxantholeus sp.n., C. microxantholeus sp.n., C. multiplicatus sp.n., C. parapulcher sp.n., C. pseudocollaris sp.n. and C. stannibractea sp.n. from Costa Rica are described. Synonymy of Callistethus kolbei (Ohaus, 1897) with Callistethus specularis (Bates, 1888) is proposed. A phylogenetic analysis based on the genes 16S, COI and 28S is carried out for Costa Rican species and diagnostic morphological features for the genus are tested on it for phylogenetic signal. An identification key for Callistethus species of Costa Rica is provided. The distribution patterns of Callistethus species in Costa Rica are discussed.