Life history strategies of perennial grassland plants : bet hedging in time and metapopulation viability in fragmented landscapes Landscape fragmentation intensification of land use and climate change are going to strongly impact future plant populations. Currently plant ecologists are unable to assess the interactions between changes in landscape structure local disturbance regime and plant traits. Thus new models and conceptual frameworks are needed to predict the viability of plant populations in fragmented landscapes based on plant traits landscape properties and the environmental stochasticity of local habitats. Methodologically this thesis is based on non spatial and spatially explicit matrix population models. Non spatial matrix models assume homogeneity in space spatially explicit models describe different subpopulations inhabiting patches of variable habitat quality and the exchange of individuals in space i.e. seed dispersal. In the first chapter I used non spatial matrix models to find optimal life history strategies for grassland plants inhabiting stochastic environments differing in predictability and harshness. ...