Around the world, forests are generally being fragmented and as plant populations decline in both sizeand number of individuals, the genetic variation will also decrease whitch in the end leads to totalextinction of the plant. In this paper, I wanted to investigate what specific species of trees and shrubsyou usually find in the edge and core habitats in some of the forests in the Baltic Sea region. I alsowanted to identify the edge effects and their sources and finally compare the results between thedifferent regions.The data sources used are derived from the ongoining research project Landscape structures, patterns ofbiodiversity and conservation strategies in the Baltic Sea region by Kari Lehtilä, Patrik Dinnétz ochTiina Vinter who have made a record of all herbaceous plant species in four randomly chosen forestregions situated around the Baltic Sea: Estonia, Skåne, Södermanland and Germany. I made statisticalanalyses, using the computer program R, concerning the distribution of species in the edge habitats ofthe forests as well as in the core habitats. I performed generalized linear models and then variationanalyses with the factors light and biomass in order to investigate wether edge effects might appear dueto these factors. I also used the ecological characteristics – Ellenberg indicators – light, soil pH andnitrogen performing linear regression models. I then compared the results – within the regions but alsobetween them.As the results showed great variancy both within the regions and between them no general explanationto the edge effects could be affirmed. The Ellenberg analyses showed no difference between the species,i. e. the ecological characteristics could not explain why some species were associated to edge habitatsand some were not. All four regions had in common that the greatest biodiversity were to be found inthe edge habitats, which is characteristical for a habitat in an early successional state. Due to the thefeatures of the forests, the specific species that received the label ”edge species” or ”core species” werenot always mutual in all regions. For example Quercus robur turned out to be a typical forest species inGermany while in Estonia it was strongly associated to edge habitats and in this investigation one mightdiscuss later states of successions in Germany rather than stronger edge effects in Estonia.

El paisaje, concebido como una unidad espacial y temporalmente pluriescalar caracterizada por unos patrones de distribución - una estructura-, unas funciones y una red de flujos de materia, energía e información (Forman y Godron, 1986), constituye un modelo apropiado para estudiar el territorio (Marull, 2002). En la presente investigación se hace un análisis de los cambios ocurridos en la estructura del mosaico paisajístico de la comarca de l´Alt Empordà entre 1957 y 2001, para ellos se divide la comarca en unidades paisajísticas basadas en criterios fisiográficos determinados a escala 1:25000. El análisis de la estructura paisajística de las diferentes unidades paisajísticas se ha realizado a través de indicadores de composición y de estructura según clases paisajísticas (cubiertas o usos del suelo), mediante el cálculo y análisis de indicadores de estructura desarrollados por la ecología del paisaje, los cuales, han permitido caracterizar y analizar las transformaciones en el tamaño, la forma y el arreglo espacial de los parches tipo que configuran el mosaico paisajístico. Para el proceso de cálculo y análisis espacial se han empleado los sistemas de información geográfica (SIGs), el programa Patch Analyst 1.2. La información cartográfica se elaboró a partir de ortofotomapas digitales y fotos aéreas generados por el ICC, así como de fuentes secundarias.Además, el trabajo incluye una aplicación teórico-metodológica a la identificación de redes ecológicas a través del uso de indicadores, así como el uso de inventarios fitosociológicos en la evaluación de hábitats borde. / Landscape is conceptualized as a pluriscalar spatial and temporal unit, characterized by distribution patterns -structure- function and a net of flows of matter, energy and information giving territorial dynamics (Forman y Godron 1986), which permits us study territories from a ecosystem approach (Marull, 2002).This research is concern with the changes in the landscape structure of the comarca Alt Empordà between 1957 and 2001. In order to conduct the analysis, the territory was divided into landscape units based on physiographic criteria using a map scale of 1: 25 000. The structure of each landscape unit was then calculated and analysed based on cover and landuse classes (patches) using fractal indicators such as type of patch, size, form and spatial distribution. The analysis was conducted by using aereal photographs developped by the Instituto Cartográfico de Cataluña, geographic information systems and the sofware Patch Analysist 2.1.In addition, this reaserch includes a landscape ecologypcal approach identifying econets throw the use of different structure indicators. Forthemore, it incorporates an analysis of edge habitats based on phytosociologic information.