María F. Schmitz

Shrub encroachment in Argentinean savannas

Abstract In the Wet Chaco region of Argentina, increasing shrub encroachment in savannas over the last few decades has led to important changes in the structure and functioning of the landscape. Some sectors of this territory are characterized by the appearance of circular clusters of woody patches, dispersed throughout the grassland matrix. The increasing size of these patches leads to a gradual change from grassland to dense shrubland. We studied these circular woody patches in the eastern region of the Argentine province of Formosa and characterized the variation in terms of floristic composition, diversity and predominant seed dispersal mode in different size patches. We observed an increase in species richness, diversity and compositional heterogeneity among patches with increasing patch size. Seed dispersal by animals, especially birds, is an important factor in the expansion of these woody vegetation patches within the grassland matrix. Nomenclature: Zuloaga et al. (1994, 1996a, b). Some native names were included using quotation marks.

Relationship between landscape typology and socioeconomic structure. Scenarios of change in Spanish cultural landscapes

Abstract We formalized the canonical correspondence between the socioeconomic structure and the cultural landscape in a large county in the NE of Spain. The reference units consisted of a set of municipalities, at which scale the socioeconomic information is registered. We described the landscape using multivariate ordination analyses of data characterizing the physiognomy of the municipalities. We interpreted the dispersion of these municipalities on the plane obtained with the main ordination axes. The relationship between ‘landscape typology’ and ‘socioeconomic structure’ was expressed by multiple stepwise regression, where the independent variables were socioeconomic descriptors of the municipalities, and the dependent variable the coordinates of these on the ordination axes. We obtained a regression equation for each axis. Each of these allowed us to establish the optimum number of socioeconomic variables, and the importance and sign of these, in order to characterize the landscape variability. The relationship encountered is presented on maps as trend surface analysis, showing ‘classes’ or discrete types of landscape. We considered hypotheses of change in the main socioeconomic indicators and, using the trend surfaces as a base, we calculated the resulting changes in the landscape typology (the municipalities change position on the trend surfaces maps). We also tested, among others, scenarios based on the development of activities linked to the abandonment of agricultural activities. The procedure experimented shows a more or less high and significant dependence among different variation tendencies of the landscape in the county studied and its socioeconomic structure. Formalizing this dependence involves 12 variables of the set of descriptors used in the socioeconomic characterization of the county. The models experimented enable us to convey this relationship to simulated scenarios and to evaluate the implications of certain socioeconomic policies for landscape typology.

Influence of landscape complexity and land management on woody plant diversity in northern Spain

Abstract. Changes in land use, particularly the type of forest management, and their spatial pattern, especially woody plant diversity, were related to each other in an area in the Basque region (Spain). The number and diversity of boundaries between landscape patches is related to the development of the spatial complexity of the landscape, C(s), measured in bits and defined as: C(s) = H(b) H(l), where H(b) is the boundary diversity H(1) the spatial heterogeneity generated by these boundaries. As to the vegetation types, changes in land use over the last 50 yr have resulted in a less diversified and more fragmented landscape, especially on a small scale. Forest plantation has become the predominant land use. The frequency of land use changes is studied regarding its influence on the present levels of woody plant diversity.

A fragmented landscape in northern Spain analyzed at different spatial scales: Implications for management

Changes in landscape pattern are analyzed through sampling plots of different size taken along a time series of aerial photographs at three scales of observation. The results indicate that variation in the landscape pattern shows a less pronounced change at the local scale than at larger scales and that appreciation of the structure of this landscape and descrip- tion of its temporal variation are scale-dependent. Analysis of the spatial complexity on different scales, measured by the C(s) index (Rescia et al. 1994), shows that the number of types of boundary between patches is the most important landscape component on all scales. Spatial com- plexity and the number of boundary types are related to woody plant diversity at a local scale. In the studied landscape, human activities on a local scale strongly influence the spatial configuration on a regional scale. This concerns territorial planning, the main problem of which is not found in selecting a correct observation scale, but in recognizing that the change under study occurs at various scales at the same time. This underlines the importance of analysing the landscape pattern at different scales with the design of plans and conservation programs in mind.

Ascribing plant diversity values to historical changes in landscape: a methodological approach

Abstract This paper analyses the way in which the present levels of plant diversity in different patches of an area are affected by changes to landscape heterogeneity. The change to heterogeneity is analysed through the variations in the number and nature of boundaries between the patches, native leafy forests and pine plantations, and the other patches adjacent to them between 1946 and 1990. The changes are due to the replacement of traditional farming methods by more modern, intensive uses. The result has been a growing predominance of pine trees in the landscape, the shrinking size of patches, and increased fragmentation and boundaries between a given patch and different uses. Three histories of change in the type of boundaries between land uses can be recognised: (i) the persistence of contacts between traditional uses; (ii) contacts between traditional uses and new pine plantations; (iii) contacts between pine plantations since 1946. All three are related significantly to the current values of plant diversity, measured by the Shannon-Wiener index. These values decline as the antiquity of contact with the pines increases. The patches that have preserved contacts with traditional uses thus have a greater plant diversity than those which have had many contacts with pine plantations since the 1940s.

Integrating Landscape Analysis and Planning: A Multi-Scale Approach for Oriented Management of Tourist Recreation

Tourism and landscape are interdependent concepts. Nature- and culture-based tourism are now quite well developed activities and can constitute an excellent way of exploiting the natural resources of certain areas, and should therefore be considered as key objectives in landscape planning and management in a growing number of countries. All of this calls for careful evaluation of the effects of tourism on the territory. This article focuses on an integrated spatial method for landscape analysis aimed at quantifying the relationship between preferences of visitors and landscape features. The spatial expression of the model relating types of leisure and recreational preferences to the potential capacity of the landscape to meet them involves a set of maps showing degrees of potential visitor satisfaction. The method constitutes a useful tool for the design of tourism planning and management strategies, with landscape conservation as a reference.

Changes in land use in Northern Spain : Effects of forestry management on soil conservation

Abstract The substitution of agricultural land uses and native forests in the North of Spain by Pinus radiata plantations was studied. The variability of a set of soil samples taken in these plantations, and other types of land uses, was analyzed. The sites studied have had characteristic changes in land use, being submitted to different degrees of exploitation and types of management practices. Clear-cutting and planting techniques, along with the selective logging from the main mass of trees and the clear felling of the understorey, cause an alteration of the edaphic system which is seen in its lesser ability to mobilize necromass, recycle nutrients and increase the carbon/nitrogen ratio. Old pine plantations, forests of Fagus sylvatica and Quercus spp. and pastures also show a noteworthy variability in their edaphic characteristics depending on the type of management. Forests with very similar appearance may have soils with very different necromass recycling capabilities. The same occurs with pine plantations. The usual procedure involved in land planning, characterizing the degree of nature conservation by means of identification of large units of vegetation or farmland uses is highlighted. In territories with intense human management, as here considered, this degree can best be assessed through the study of the soil characteristics.

Selection of ecological indicators for the conservation, management and monitoring of Mediterranean coastal salinas

Salinas systems are artificial wetlands which are interesting from the viewpoint of nature conservation. They play an important role both as habitats for migratory waterbird species and as nodes of biotic connectivity networks. In the Mediterranean basin, where the coastal salinas are highly significant as alternative and complementary habitats for waterbirds, a process of abandonment occurs, and many seminatural systems of this kind are disappearing. This abandonment is having serious consequences for migratory bird populations and for the ecological role these play. In the present paper, this group of waterbird species has been used to evaluate these wetlands for conservation purposes. We have developed a methodological approach for the selection of ecological indicators for the conservation and management of these Mediterranean habitats and waterbird assemblages, the main consumers therein. The stepwise procedure developed constitutes a practical tool for this task. Application thereof enabled us to differentiate the habitats available for the waterbirds and to identify the biotic and abiotic indicators for the maintenance and management of the salina ecosystems. These variables can then be incorporated into monitoring programs.

Identifying socio-ecological networks in rural-urban gradients: Diagnosis of a changing cultural landscape

Socio-ecological systems maintain reciprocal interactions between biophysical and socioeconomic structures. As a result of these interactions key essential services for society emerge. Urban expansion is a direct driver of land change and cause serious shifts in socio-ecological relationships and the associated lifestyles. The framework of rural-urban gradients has proved to be a powerful tool for ecological research about urban influences on ecosystems and on sociological issues related to social welfare. However, to date there has not been an attempt to achieve a classification of municipalities in rural-urban gradients based on socio-ecological interactions. In this paper, we developed a methodological approach that allows identifying and classifying a set of socio-ecological network configurations in the Region of Madrid, a highly dynamic cultural landscape considered one of the European hotspots in urban development. According to their socio-ecological links, the integrated model detects four groups of municipalities, ordered along a rural-urban gradient, characterized by their degree of biophysical and socioeconomic coupling and different indicators of landscape structure and social welfare. We propose the developed model as a useful tool to improve environmental management schemes and land planning from a socio-ecological perspective, especially in territories subject to intense urban transformations and loss of rurality.

Summer rainfall variability in European Mediterranean mountains from the sixteenth to the twentieth century reconstructed from tree rings

Since the end of the last glacial period, European Mediterranean mountains have provided shelter for numerous species of Eurosiberian and Boreal origin. Many of these species, surviving at the southern limit of their range in Europe and surrounded by Mediterranean ones, are relatively intolerant to summer drought and are in grave danger of loss, as a result of increasingly long and frequent droughts in this region. This is the case of the Scots pine (Pinus sylvestris) and the Austrian pine (Pinus nigra ssp. salzmannii) which are found on Central Iberian Peninsula at the edge of their natural range. We used a tree ring network of these two species to reconstruct past variations in summer rainfall. The reconstruction, based upon a tree ring composite chronology of the species, dates back to 1570 (adjusted R2 = 0.49, P < 0.000001) and captures interannual to decadal scale variability in summer precipitation. We studied the spatial representativeness of the rainfall patterns and described the occurrence rate of extremes of this precipitation. To identify associations between macroclimatic factors and tree radial growth, we employed a principal component analysis to calculate the resultant of the relationship between the growth data of both species, using this resultant as a dependent variable of a multiple regression whose independent variables are monthly mean temperature and precipitation from the average records. Spatial correlation patterns between instrumental precipitation datasets for southern Europe and reconstructed values for the 1950–1992 period indicate that the reconstruction captures the regional signal of drought variability in the study region (the origin of this precipitation is convective: thermal low pressure zones induced in the inland northeastern areas of the Iberian Peninsula). There is a clear increase in the recurrence of extreme dry events as from the beginning of twentieth century and an abrupt change to drier conditions. There appears to be a tendency toward recurrent exceptionally dry summers, which could involve a significant change for the Eurosiberian refugee species.