Changing environmental conditions substantially affect genetic variation and its dynamics in forest ecosystems and various systems of plantations. In response to these challenges, the present book focuses on the response to stress in terms of case studies which address physiological and genetic characters as well as various metric traits. Furthermore a choice of studies is presented which refers to diversity and geographic variation of various species and site conditions, respectively. In addition, genetic resources are characterised and a variety of studies is compiled which address reproduction and migration as well as management aspects. Finally, a set of studies is presented which focus on forest tree breeding with respect to uncertain climatic futures.