Genetic diversity and species diversity are both crucial for ecosystem stability. Analysis of plant diversity aims to understand the organisation and the variability of biological populations within ecosystems. This book provides a review on chemotaxonomical criteria helping to understand complex structures of plant diversity. It focuses particularly on the chemotaxonomic usefulness of phenolic compounds in analysis of chemical polymorphisms at different taxonomic levels. The relationship between grazing pressure and grassland vegetation is also examined, using drastically improved information technology such as remote sensing, Geographic Information System (GIS) and Ground Positioning Systems (GPS). Furthermore, an overview of the unique ecosystem of the South Brazilian Campos grasslands are given. The role of disturbance in maintaining Campos biodiversity and dynamics, and the importance of its conservation, is looked at as well. Other chapters in this book discuss the relationship between management and vegetation, and also suggest ways to conserve the species diversity of both plants and butterflies in semi-natural grassland.