Orazio Rossi

Statistical detection of multiscale landscape patterns

Detection of discontinuities in landscape patterns is a crucial problem both in ecology and in environmental sciences since they may indicate substantial scale changes in generating and maintaining processes of landscape patches. This paper presents a statistical procedure for detecting distinct scales of pattern for irregular patch mosaics using fractal analysis. The method suggested is based on a piecewise regression model given by fitting different regression lines to different ranges of patches ordered according to patch size (area). Proper shift-points, where discontinuities occur, are then identified by means of an iterative procedure. Further statistical tests are applied in order to verify the statistical significance of the best models selected. Compared to the method proposed by Krummel et al. (1987), the procedure described here is not influenced by subjective choices of initial parameters. The procedure was applied to landscape pattern analysis of irregular patch mosaics (CORINE biotopes) of a watershed within the Map of the Italian Nature Project. Results for three different CORINE patch types are herein presented revealing different scaling properties with special pattern organizations linked to ecological traits of vegetation communities and human disturbance.

Understanding the role of chronic environmental disturbance in the context of island biogeographic theory

Island biogeographic theory offers a powerful conceptual framework for understanding and managing insular diversity. The human impact on insular environments is constantly growing, especially because of tourism. We performed a simulation study aimed at improving the understanding of the role of disturbance in islands. We also built an individual-oriented computer model of an archipelago subjected to chronic disturbance of varying degree. Results are discussed in the light of island biogeographic theory. Relevant results show the importance of autoecological characteristics of the species considered, regarding the attainment of equilibrium and the species-area relationship in both disturbed and undisturbed cases. The possibility of bias in the predictions of the equilibrium model is pointed out. Fundamental criticisms concerning the ecological relevance of the equilibrium theory are discussed.

Bird claws and bird of prey talons: Where is the difference?

The questions asked were (1) whether claws and toes of birds of prey are actually different from those of other perching birds, and, if so, (2) what parameter can describe such a difference. The structure of toes and claws of the first and third toe was then evaluated in three groups of birds: Falconiformes, Strigiformes and non‐raptorial species. One adult male per species was considered, and, among non‐raptorial birds, only species belonging to typically or partially perching families. Only one specimen per species was chosen, from museum skin bird collections. All species examined occur in the western Palearctic, according to Cramp & Simmons (1977–1994). Discriminant Function Analysis showed clear separation of the groups. In particular, the first canonical function segregated Falconiformes from Strigiformes, whereas the second separated Strigiformes from non‐raptorials. However, Falconiformes and non‐raptorials partially overlapped and were not separated. The characteristics segregating Falconiformes from Strigiformes mainly concerned claw curvature, claw length in relation to toe length, and the last phalanx shape, thin or rounded. Characters contributing to segregate Strigiformes from non‐raptorials were claw curvature in relation to their radius and the shape, thin or rounded, of both claws and last phalanxes. Results indicate that Strigiformes toes and claws only superficially resemble those of Falconiformes and the shape of claws and toes of Falconiformes are much more similar to those of non‐raptorial species than they are to those of Strigiformes.

Stability of natural communities: Loop analysis and computer simulation approach

Abstract The stability analysis of a natural community gives rise to conceptual and methodological problems for the ecologist. It is indeed often difficult to state or recognize when a community is stable, i.e. when it is able to return to a steady state after a displacement from equilibrium due to environmental disturbances. The evaluation of stability, based on the computation of the eigenvalues obtained from the interaction coefficients matrix, requires that one quantifies ecological processes like predation, competition etc., and these phenomena are by no means easily measured in field experiments. This study combines loop analysis and computer simulation to calculate the conditions of stability for a series of simple models of hypothetical or real communities. The simulation generates all the possible combinations of values for the coefficients related to the various models, and the stable configurations, evaluated with the loop analysis, are defined as a percentage over the total amount of cases. The results highlight in quantitative form the stabilizing role of terminal predators and the potentially destabilizing effect of competitive interactions.

Demographic factors and land-use planning in the small islands of Southern Europe

Since the end of the 1970s, the southern European countries have shown an exceptional reduction in fertility rate. From the highest levels among the developed nations, these countries dropped beneath the substitution rate level: in Greece there is an average of about 1.5 children per woman, and Italy (starting three to four years ago), with 1.3 children per woman, is now the country with the lowest fecundity rate in the world. Land-use planning in southern European small islands therefore requires substantial revision. In the areas where western civilization began, which are highly populated and have a long history, cultural and ethnic aspects of tradition are fundamental to environmental management and to the defense of historical heritage. They also place a strong value on sustaining tourism, the most relevant economic activity, that allows them to survive and maintain a high welfare level. For some decades they have had populations with a marked presence of young people and high emigration rates, but now they are fast becoming dominated by the elderly and must prepare for a period of fast reduction in youth of the workforce, while the peripheral areas of Asia and Africa are entering a sudden demographic growth phase.The demographic structure has also been deeply altered both by previous migrations and by random variations, as usually happens in all small communities. Social services for younger and older people have had to be adapted rapidly, reorganizing high-school management, hospital and health-care structures, in-house assistance, and so on. There is a need to rethink the job market and favor the immigration of highly specialized workers, which is a necessity for technical evolution. Sustainable development is constrained nowadays not only by the scarcity of natural resources, but also by the quality and quantity of human resources. Proper policies for population and land-use planning are highly correlated factors; they have to be considered with respect of these new, rapid demographic changes.

Ecological Risk Assessment Through Landscape Science Approaches

Risk assessment of landscape biological integrity, associated with ecotypes or ecotype mosaics, is addressed by simple multi-scale conceptual models incorporating metrics related to current human disturbance, based on native species most threatened with extinction and reduction. We aim at identifying gaps in the Italian existing reserve network to establish new reserves and protected areas to get a more representative network of regional biological diversity, based on (1) their “natural values”, and (2) “fragility”. Distribution maps of habitat sensitivity and fragility give policy makers and land managers information on impacts their land-use decisions will have on existing risks to biological integrity. Such approaches have application in Central Asian ecological evaluation and environmental decision-making.

The aeolian project: a MAB‐UNESCO investigation to promote sustainable tourism in the mediterranean area

The Aeolian archipelago is undergoing social and economical changes that threaten its natural and cultural patrimony, which is also the essence of a tourist appeal, as an image of uncontaminated sites, where natures ancestral phenomena and seasonal rhythms are experienced. Salina island may serve as a prototype for exploring the possibility of implementing conservation strategies compatible with human needs, landscape preservation and sustainable economic development. By means of the CORINE methodology, “ecological sensitivity” (from a functional viewpoint) and “ecological vulnerability” (either physical or ecological) maps have been drawn to objectively quantify the environmental risk. Some final remarks are devoted to clarify the concepts of “environmental perception” and “citizens’ consent”.

Socio‐environmental enquiry in the salina island (Aeolian Archipelago, Italy)

Modern integrated techniques of environmental analysis are helpful to address a specific process of social‐economic growth: to favour a better quality of life, to sustain the reached standards for future generations, etc. In all this, provided that the “development process” will respect the local people and their right expectations, choices and decisions have to be made together with the inhabitants. Projects of the Aeolian future become reality if, and only if, understood and accepted by those who live and work in the archipelago. In such a context, the set‐up of a multi‐specific opinion poll becomes an indispensable instrument for testing any programme of development before to have it operating. For each of the proposed aspects, 130 sample interviewed people, stratified for activity, sex, and municipality of origin, have been invited to freely express qualitative answers (unknown, minimal, perceptible, consistent, relevant, essential, fundamental) to 30 questions regarding the state of environment, soci...

Some problems related to an environmental factual database: the case Aeolian project

Factual databanks can make an important contribution to environmental management. They help considerably with the difficult processes of integrating the various scientific languages used, and also with the development of valid methods for interdisciplinary research. In the planning the Aeolian project (a multidisciplinary study of an Archipelago north of Sicily), it was considered useful to include a group of workers on methodology and computer science. The hope is that they will help to facilitate the exchange of data and thus contribute to a better understanding of the various phenomena occurring on the islands. This paper discusses the conceptual working aspects of environmental information, together with those characteristics that render it suitable for inclusion in a modern computer‐based system.